# Patent

## Title
Fused ring dicationic anti-protozoan agents and their prodrugs

## Abstract

Novel fused ring dicationic anti-protozoan compounds. Representative protozoan species include but are not limited to Trypanosoma brucei rhodesiense (T.b.r.) and Plasmodium falciparum. Prodrugs of these compounds can be used as an oral treatment for malaria and human African trypanosomiasis.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 60/525,018, filed Nov. 24, 2003, the disclosure of which is incorporated herein by reference in its entirety.


TECHNICAL FIELD
The presently disclosed subject matter relates to methods of combating microbial infections with dicationic compounds. More particularly, the presently disclosed subject matter relates to methods of combating microbial infections with fused ring dicationic compounds, and to the novel compounds themselves.
ABBREVIATIONS


    
    
        δ=chemical shift
        Ac=acetyl
        AcO=acetoxyl
        AcOH=acetic acid
        Ac2O=acetic anhydride
        Am=amidine
        AmOH=amidoxime
        BOC=t-butoxycarbonyl
        Bu=butyl
        °C.=degrees Celsius
        calcd=calculated
        cm=centimeters
        dec=decomposition point
        DIBAL=diisobutylaluminium hydride
        DMF=dimethylformamide
        DMSO=dimethylsulfoxide
        D2O=deuterium oxide
        EtOAc=ethyl acetate
        EtOH=ethanol
        FAB=fast atom bombardment
        g=grams
        h=hours
        HCl=hydrogen chloride
        HPLC=high-pressure liquid chromatography
        Hz=hertz
        kg=kilograms
        KO-t-Bu=potassium tert-butoxide
        L. d.=Leishmania donovani 
        M=molar
        Me=methyl
        MeO=methoxyl
        MHz=megahertz
        mL=milliliters
        mm=millimeters
        mM=millimolar
        m.p.=melting point
        MS=mass spectroscopy
        Na2CO3=sodium carbonate
        Na2SO4=sodium sulfate
        NBS=N-bromosuccinimide
        NH2OH.HCl=hydroxylamine hydrochloride
        NMR=nuclear magnetic resonance
        p=para
        Pd—C=10% palladium on carbon
        P. f.=Plasmodium falciparum 
        psi=pounds per square inch
        spp.=species
        T. br.=Trypanosoma brucei rhodesiense 
        THF=tetrahydrofuran
        TLC=thin-layer chromatography
        TMS=trimethylsilyl
        UV=ultraviolet
    
    


BACKGROUND
The incidence of microbial infections (e.g., mycobacterial, fungal, and protozoal infections) in the immunocompromised population has significantly increased over the past several years. In particular, Candida species, especially Candida albicans, are often significant pathogens in patients infected with human immunodeficiency virus (HIV). Another pathogen, Pneumocystis carinii, causes a form of pneumonia (PCP) that is believed to be one of the leading causes of death in patients suffering from AIDS. Further, Human African trypanosomiasis (HAT) has reemerged as a threat to over 60 million people. Current estimates are that between 350,000 and 450,000 people are infected. Other severe and life-threatening microbial infections are caused by Mycobacterium tuberculosis, Aspergillus spp., Cryptosporidium parvum, Giardia lamblia, Plasmodium spp., Toxoplasma gondii, Fusarium solani, and Cryptococcus neoformans. 
The antimicrobial properties of dicationic molecules have been studied since the 1930's. Compounds of this type have typically utilized amidine groups as the cationic moieties, and their activities against a number of pathogens including Cryptosporidium parvum, Giardia lamblia, Leishmania spp., Plasmodium spp., Pneumocystis carinii, Toxoplasma gondii, Trypanosoma spp., Candida albicans, Aspergillus spp. and Cryptococcus neoformans have been reported. See, e.g., King, H. et al., Ann. Trop. Med. Parasitol. 1938, 32, 177-192; Blaqburn, B. L. et al., Antimicrob. Agents Chemother. 1991, 35, 1520-1523; Bell, C. A. et al., Antimicrob. Agents Chemother. 1991, 35, 1099-1107; Bell, C. A. et al., Antimicrob. Agents Chemother. 1990, 34, 1381-1386; Kirk, R. et al., Ann. Trop. Med. Parastiol. 1940, 34,181-197; Fulton, J. D. Ann. Trop. Med. Parasitol. 1940, 34, 53-66; Ivady, V. G. et al., Monatschr. Kinderheilkd. 1958, 106, 10-14; Bovkin, D. W. et al., J. Med. Chem. 1995, 38, 912-916; Boykin, D. W. et al., J. Med. Chem. 1998, 41, 124-129; Francesconi, I. et al., J. Med. Chem. 1999, 42, 2260-2265; Lindsay, D. S. et al., Antimicrob. Agents Chemother. 1991, 35, 1914-1916; Lourie, E. M. et al., Ann. Trop. Med. Parasitol. 1939, 33, 289-304; Lourie, E. M. et al., Ann. Trop. Med. Parasitol. 1939, 33, 305-312; Das, B. P. et al., J. Med. Chem. 1976, 20, 531-536; Del Poeta, M. et al., J. Antimicrob. Chemother. 1999, 44, 223-228; Del Poeta, M. et al., Antimicrob. Agents Chemother. 1998, 42, 2495-2502; Del Poeta, M. et al., Antimicrob. Agents Chemother. 1998, 42, 2503-2510.
Despite the broad range of activity exhibited by diamidines, only one compound of this chemical type, pentamidine, has seen significant clinical use. Pentamidine has been used clinically against African trypanosomiasis, antimony-resistant leishmaniasis, and P. carinii pneumonia. See, e.g., Apted, F.I.C., Pharmacol. Ther. 1980, 11, 391-413; Bryceson, A. D. M. et al., Trans. Roy. Soc. Trop. Med. Hyg. 1985, 79, 705-714; Hughes, W. T. et al., Antimicrob. Agents Chemother. 1974, 5, 289-293.
Thus, there is a need for compounds having antimicrobial activity, whether against the representative pathogens referenced above or against other pathogens. More particularly, there is a need for a compound having activity in the treatment of human African trypanosomiasis, an infectious disease for which oral treatment in its second stage is not currently available.
SUMMARY
The presently disclosed subject matter describes a compound of Formula I:




wherein:

    
    
        X and Y are each independently selected from the group consisting of CH, CH2, N, C═O, O, S, and NR3,
        
            wherein R3 is selected from the group consisting of H, alkyl, aryl, alkoxyl, and aryloxyl, and
            Y can be present or absent;
        
        
        R1 and R2 are each independently selected from the group consisting of H, alkyl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;
        m and n are integers from 0 to 3, provided that when m is zero, R1 is an implied hydrogen, and when n is zero, R2 is an implied hydrogen;
        p and q are integers from 0 to 1;
        A and A′ are each independently selected from one of:
    
    






    
    
        wherein:
        
            R4, R5, R6, R7, and R5 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, am inoa lkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or
            R5 and R6 together represent a C2 to C10 alkyl, hydroxyalkyl, or alkylene; or
            R8 is
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.
                
                
            
            
        
        
    
    


In some embodiments, the presently disclosed subject matter relates to a pharmaceutical formulation comprising a compound of Formula I in a pharmaceutically acceptable carrier.
In some embodiments, the presently disclosed subject matter relates to a method of treating a microbial infection, comprising administering an effective amount of a compound of Formula I to a subject in need thereof.
In some embodiments, the presently disclosed subject matter relates to the use of an active compound as described hereinabove (i.e., a compound of Formula I) for the preparation of a medicament for treating a microbial infection.
Accordingly, in some embodiments, the presently disclosed subject matter provides compounds that are useful in the treatment of microbial infections. In some embodiments, the presently disclosed subject matter provides pharmaceutical formulations for use in the treatment of microbial infections. In some embodiments, the presently disclosed subject matter provides methods for treating microbial infections.
Certain embodiments of the presently disclosed subject matter having been stated hereinabove, which are addressed in whole or in part by the presently disclosed subject matter, other embodiments will become evident as the description proceeds when taken in connection with the accompanying Examples as best described herein below.


DETAILED DESCRIPTION
The presently disclosed subject matter will now be described more fully hereinafter with reference to the accompanying Examples, in which representative embodiments are shown. The presently disclosed subject matter can, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this presently described subject matter belongs. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.
Throughout the specification and claims, a given chemical formula or name shall encompass all optical and stereoisomers, as well as racemic mixtures where such isomers and mixtures exist.
I. Definitions
As used herein the term “alkyl” refers to C1-20 inclusive, linear (i.e., “straight-chain”), branched, or cyclic, saturated or at least partially and in some cases fully unsaturated (i.e., alkenyl and alkynyl) hydrocarbon chains, including for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, ethenyl, propenyl, butenyl, pentenyl, hexenyl, octenyl, butadienyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, and allenyl groups. “Branched” refers to an alkyl group in which a lower alkyl group, such as methyl, ethyl or propyl, is attached to a linear alkyl chain. “Lower alkyl” refers to an alkyl group having 1 to about 8 carbon atoms (i.e., a C1-8 alkyl), i.e., 1, 2, 3, 4, 5, 6, 7, or 8 carbon atoms. “Higher alkyl” refers to an alkyl group having about 10 to about 20 carbon atoms, i.e., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms (i.e., a C10-20 alkyl). In certain embodiments, “alkyl” refers, in particular, to C1-8 straight-chain alkyls. In other embodiments, “alkyl” refers, in particular, to C1-8 branched-chain alkyls.
Alkyl groups can be optionally substituted with one or more alkyl group substituents, which can be the same or different. The term “alkyl group substituent” includes but is not limited to alkyl, halo, arylamino, acyl, hydroxyl, aryloxyl, alkoxyl, alkylthio, arylthio, aralkyloxyl, aralkylthio, carboxyl, alkoxycarbonyl, oxo, and cycloalkyl. There can be optionally inserted along the alkyl chain one or more oxygen, sulfur or substituted or unsubstituted nitrogen atoms, wherein the nitrogen substituent is hydrogen, lower alkyl (also referred to herein as “alkylaminoalkyl”), or aryl.
The term “aryl” is used herein to refer to an aromatic substituent that can be a single aromatic ring, or multiple aromatic rings that are fused together, linked covalently, or linked to a common group such as a methylene or ethylene moiety. The common linking group also can be a carbonyl as in benzophenone or oxygen as in diphenylether or nitrogen as in diphenylamine. The term “aryl” specifically encompasses heterocyclic aromatic compounds. The aromatic ring(s) can comprise phenyl, naphthyl, biphenyl, diphenylether, diphenylamine and benzophenone, among others. In some embodiments, the term “aryl” means a cyclic aromatic comprising from about 5 to about 10 carbon atoms, i.e., 5, 6, 7, 8, 9, or 10 carbon atoms, and including 5- and 6-membered hydrocarbon and heterocyclic aromatic rings.
The aryl group can be optionally substituted with one or more aryl group substituents which can be the same or different, wherein “aryl group substituent” includes alkyl, aryl, aralkyl, hydroxyl, alkoxyl, aryloxyl, aralkyloxyl, carboxyl, acyl, halo, nitro, alkoxycarbonyl, aryloxycarbonyl, aralkoxycarbonyl, acyloxyl, acylamino, aroylamino, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, arylthio, alkylthio, alkylene, and —NR′R′′, wherein R′ and R′′ can be each independently hydrogen, alkyl, aryl, and aralkyl.
Specific examples of aryl groups include but are not limited to cyclopentadienyl, phenyl, furan, thiophene, pyrrole, pyran, pyridine, imidazole, benzimidazole, isothiazole, isoxazole, pyrazole, pyrazine, triazine, pyrimidine, quinoline, isoquinoline, indole, carbazole, and the like.
A dashed line representing a bond in an aryl group indicates that the bond is either present or absent depending on the number of atoms comprising the aromatic ring and, in the case of a heterocyclic aromatic ring, the identity of the heteroatom.
When a named atom of an aromatic ring or a heterocyclic aromatic ring is defined as being “absent,” the named atom is replaced by a direct bond.
As used herein, the terms “substituted alkyl” and “substituted aryl” include alkyl and aryl groups, as defined herein, in which one or more atoms or functional groups of the aryl or alkyl group are replaced with another atom or functional group, including for example, halogen, aryl, alkyl, alkoxyl, hydroxyl, nitro, amino, alkylamino, dialkylamino, sulfate, and mercapto.
As used herein, the term “acyl” refers to an organic acid group wherein the —OH of the carboxyl group has been replaced with another substituent (i.e., as represented by RCO—, wherein R is an alkyl or an aryl group as defined herein). As such, the term “acyl” specifically includes arylacyl groups. Specific examples of acyl groups include acetyl and benzoyl.
“Cyclic” and “cycloalkyl” refer to a non-aromatic mono- or multi-cyclic ring system of about 3 to about 10 carbon atoms, i.e., 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms. The cycloalkyl group can be optionally partially unsaturated. The cycloalkyl group can be also optionally substituted with an alkyl group substituent as defined herein, oxo, and/or alkylene. There can be optionally inserted along the cyclic alkyl chain one or more oxygen, sulfur or substituted or unsubstituted nitrogen atoms, wherein the nitrogen substituent is hydrogen, lower alkyl, or aryl, thus providing a heterocyclic group. Representative monocyclic cycloalkyl rings include cyclopentyl, cyclohexyl, and cycloheptyl. Multicyclic cycloalkyl rings include adamantyl, octahydronaphthyl, decalin, camphor, camphane, and noradamantyl.
“Alkoxyl” or “alkoxyalkyl” refer to an alkyl-O— group wherein alkyl is as previously described. The term “alkoxyl” as used herein can refer to C1-20 inclusive, linear, branched, or cyclic, saturated or unsaturated oxo-hydrocarbon chains, including, for example, methoxyl, ethoxyl, propoxyl, isopropoxyl, butoxyl, t-butoxyl, and pentoxyl.
“Aryloxyl” refers to an aryl-O— group wherein the aryl group is as previously described. The term “aryloxyl” as used herein can refer to phenyloxyl or hexyloxyl, and alkyl, halo, or alkoxyl substituted phenyloxyl or hexyloxyl.
“Aralkyl” refers to an aryl-alkyl-group wherein aryl and alkyl are as previously described. Exemplary aralkyl groups include benzyl, phenylethyl, and naphthylmethyl.
“Aralkyloxyl” refers to an aralkyl-O— group wherein the aralkyl group is as previously described. An exemplary aralkyloxyl group is benzyloxyl.
“Dialkylamino” refers to an —NRR′ group wherein each of R and R′ is independently an alkyl group as previously described. Exemplary alkylamino groups include ethylmethylamino, dimethylamino, and diethylamino.
“Alkoxycarbonyl” refers to an alkyl-O—C(═O) group. Exemplary alkoxycarbonyl groups include methoxycarbonyl, ethoxycarbonyl, butyloxycarbonyl, and t-butyloxycarbonyl. An alkoxycarbonyl group can be further represented by the following structural formula:




wherein the “R” group represents an alkyl group as defined hereinabove. An alkoxycarbonyl group also can be referred to as an “alkyl ester” group. In some embodiments of the presently disclosed subject matter, R is an ethyl group and the alkoxycarbonyl group comprises the following formula:





“Aryloxycarbonyl” refers to an aryl-O—C(═O) group. Exemplary aryloxycarbonyl groups include phenoxy- and naphthoxy-carbonyl.
“Aralkoxycarbonyl” refers to an aralkyl-O—C(═O) group. An exemplary aralkoxycarbonyl group is benzyloxycarbonyl.
“Carbamoyl” refers to an H2N—C(═O) group.
“Alkylcarbamoyl” refers to a R′RN—C(═O) group wherein one of R and R′ is hydrogen and the other of R and R′ is alkyl as previously described.
“Dialkylcarbamoyl” refers to R′RN—C(═O) group wherein each of R and R′ is independently alkyl as previously described.
“Acyloxyl” refers to an acyl-O— group wherein acyl is as previously described.
“Acylamino” refers to an acyl-NH— group wherein acyl is as previously described.
“Aroylamino” refers to an aroyl-NH— group wherein aroyl is as previously described.
“Alkylene” refers to a straight or branched bivalent aliphatic hydrocarbon group having from 1 to about 20 carbon atoms, i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms. The alkylene group can be straight, branched or cyclic. The alkylene group can be also optionally unsaturated and/or substituted with one or more “alkyl group substituents.” There can be optionally inserted along the alkylene group one or more oxygen, sulfur or substituted or unsubstituted nitrogen atoms (also referred to herein as “alkylaminoalkyl”), wherein the nitrogen substituent is alkyl as previously described. Exemplary alkylene groups include methylene (—CH2—); ethylene (—CH2—CH2—); propylene (—(CH2)3—); cyclohexylene (—C6H10—); —CH═CH—CH═CH—; —CH═CH—CH2—; —(CH2)q—N(R)(CH2)r—, wherein each of q and r is independently an integer from 0 to about 20, i.e., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, and R is hydrogen or lower alkyl; methylenedioxyl (—O—CH2—O—); and ethylenedioxyl (—O—(CH2)2—O—). An alkylene group can have about 2 to about 3 carbon atoms and can further have 6-20 carbons.
The term “amino” refers to the —NH2 group.
The term “carbonyl” refers to the —(C═O)— group.
The term “carboxyl” refers to the —C(═O)OH group.
The terms “halo”, “halide”, or “halogen” as used herein refer to fluoro, chloro, bromo, and iodo groups.
The term “hydroxyl” refers to the —OH group.
The term “hydroxyalkyl” refers to an alkyl group substituted with an —OH group.
The term “mercapto” refers to the —SH group.
The term “oxo” refers to a compound described previously herein wherein a carbon atom is replaced by an oxygen atom.
The term “nitro” refers to the —NO2 group.
The term “thio” refers to a compound described previously herein wherein a carbon or oxygen atom is replaced by a sulfur atom.
The term “sulfate” refers to the —SO4 group.
When the term “independently selected” is used, the substituents being referred to (i.e., R groups, such as groups R1 and R2, or groups X and Y), can be identical or different. For example, both R1 and R2 can be substituted alkyls, or R1 can be hydrogen and R2 can be a substituted alkyl, and the like.
A named “R”, “R′,” “X,” “Y,” “Y′”, “A,” “A′”, “B,” “L,” or “Z” group generally will have the structure that is recognized in the art as corresponding to a group having that name, unless specified otherwise herein. For the purposes of illustration, certain representative “R,” “X,” “Y”, and “A” groups as set forth above are defined below. These definitions are intended to supplement and illustrate, not preclude, the definitions that would be apparent to one of ordinary skill in the art upon review of the present disclosure.
II. Novel Compounds
A. Compounds of Formula I
In some embodiments, the presently disclosed subject matter provides a compound of Formula I:




wherein:

    
    
        X and Y are each independently selected from the group consisting of CH, CH2, N, C═O, O, S, and NR3,
        
            wherein R3 is selected from the group consisting of H, alkyl, aryl, alkoxyl, and aryloxyl, and
            Y can be present or absent;
        
        
        R1 and R2 are each independently selected from the group consisting of H, alkyl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;
        m and n are integers from 0 to 3, provided that when m is zero, R1 is an implied hydrogen, and when n is zero, R2 is an implied hydrogen;
        p and q are integers from 0 to 1;
        A and A′ are each independently selected from one of:
    
    






    
    
        wherein:
        
            R4, R5, R6, R7, and R8 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or
            R5 and R6 together represent a C2 to C10 alkyl, hydroxyalkyl, or alkylene; or
            R8 is
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.
                
                
            
            
        
        
    
    


In some embodiments of the compound of Formula I, X is CH2 and Y is absent. In such embodiments, the fused-ring structure comprises 9H-fluorene. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 2- and 7-positions of the 9H-fluorene ring.

                
                
            
            
        
        
    
    


In some embodiments, m and n are both zero and R7 is H. In some embodiments, R4 is H and R8 is phenyl. In some embodiments, R4 is H and R8 is 2-pyridyl.
In some embodiments, R8 is




    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R4 and R9 are each H. In some embodiments, R4 is ethoxycarbonyl and R9 is H. In some embodiments, R10 is H. In some embodiments, R10 is methyl. In some embodiments, R10 is isopropyl. In some embodiments, R10 is methoxyl. In some embodiments, R10 is iso-butoxyl.

            
            
        
        
    
    


In some embodiments of the compound of Formula I, X is C═O and Y is absent. In such embodiments, the fused-ring structure comprises 9H-fluoren-9-one. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 2- and 7-positions of the 9H-fluoren-9-one ring. In some embodiments, m and n are both zero and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H. In some embodiments, R4 is ethoxycarbonyl.

            
            
        
        
    
    


In some embodiments of the compound of Formula I, X and Y are both C═O. In such embodiments, the fused-ring structure comprises 9,10-anthraquinone. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, m and n are both zero and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H.

            
            
        
        
    
    


In some embodiments of the compounds of Formula I, X is N and Y is CH. In such embodiments, the fused-ring structure comprises acridine. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 3- and 6-positions of the acridine ring. In some embodiments, m and n are both zero and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H.

            
            
        
        
    
    


In some embodiments of the compound of Formula I, the compound is selected from the group consisting of: 2,7-bis-guanidino-9H-fluorene; 2,7-bis-guanidinofluoren-9-one; 2,7-bis-guanidinoanthraquinone; 3,6-bis-guanidinoacridine; 2,7-bis-(N′′-ethoxycarbonyl)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl)guanidinofluoren-9-one; 2,7-bis(N′′-ethoxycarbonyl-N′-methyl)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl-N′-isopropyl)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl-N′-methoxy)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl-N′-isobutoxy)guanidine-9H-fluorene; 2,7-bis(N′-methyl)guanidino-9H-fluorene; 2,7-bis(N′-iso-propyl)guanidino-9H-fluorene; 2,7-bis(N′-methoxy)guanidino-9H-fluorene; 2,7-bis(N′-isobutoxy)guanidine-9H-fluorene; 2,7-bis[(phenylimino)amino)]-9H-fluorene; and 2,7-bis[(2-pyridylimino)amino)-9H-fluorene.
In some embodiments, the compound of Formula I comprises a pharmaceutically acceptable salt. In some embodiments, the salt is a hydrochloride salt.
B. Prodrugs
In representative embodiments, compounds disclosed herein are prodrugs. A prodrug means a compound that, upon administration to a recipient, is capable of providing (directly or indirectly) a compound of this presently disclosed subject matter or an inhibitorily active metabolite or residue thereof. Prodrugs can increase the bioavailability of the compounds of the presently disclosed subject matter when such compounds are administered to a subject (e.g., by allowing an orally administered compound to be more readily absorbed into the blood) or can enhance delivery of the parent compound to a biological compartment (e.g., the brain or lymphatic system) relative to a metabolite species, for example. A number of the compounds (e.g., compounds 7a, 7b, 7c, 7d, 8c, and 10) discussed in Example 2 are prodrugs.
C. Pharmaceutically Acceptable Salts
Additionally, the active compounds of the presently disclosed subject matter can be administered as pharmaceutically acceptable salts. Such salts include the gluconate, lactate, acetate, tartarate, citrate, phosphate, borate, nitrate, sulfate, and hydrochloride salts. The salts of the compounds described herein can be prepared, in general, by reacting two equivalents of the base compound with the desired acid, in solution. After the reaction is complete, the salts are crystallized from solution by the addition of an appropriate amount of solvent in which the salt is insoluble. In some embodiments, the pharmaceutically acceptable salt is a hydrochloride salt.
III. Pharmaceutical Formulations
The compounds of Formula I, the pharmaceutically acceptable salts thereof, prodrugs corresponding to compounds of Formula I, and the pharmaceutically acceptable salts thereof, are all referred to herein as “active compounds.” Pharmaceutical formulations comprising the aforementioned active compounds also are provided herein. These pharmaceutical formulations comprise active compounds as described herein, in a pharmaceutically acceptable carrier. Pharmaceutical formulations can be prepared for oral, intravenous, or aerosol administration as described in greater detail herein below. Also, the presently disclosed subject matter provides such active compounds that have been lyophilized and that can be reconstituted to form pharmaceutically acceptable formulations for administration, as by intravenous or intramuscular injection.
The therapeutically effective dosage of any specific active compound, the use of which is in the scope of embodiments described herein, will vary somewhat from compound to compound, and patient to patient, and will depend upon the condition of the patient and the route of delivery. As a general proposition, a dosage from about 0.1 mg/kg to about 50 mg/kg will have therapeutic efficacy, with all weights being calculated based upon the weight of the active compound, including the cases where a salt is employed. Toxicity concerns at the higher level can restrict intravenous dosages to a lower level such as up to about 10 mg/kg, with all weights being calculated based upon the weight of the active base, including the cases where a salt is employed. A dosage from about 10 mg/kg to about 50 mg/kg can be employed for oral administration. Typically, a dosage from about 0.5 mg/kg to 5 mg/kg can be employed for intramuscular injection. In some embodiments, dosages range from between 1 μmol/kg to 50 μmol/kg of the compound for intravenous or oral administration. In some embodiments, dosages range from between 22 μmol/kg and 33 μmol/kg of the compound for intravenous or oral administration. The duration of the treatment typically is once per day for a period of two to three weeks or until the condition is essentially controlled. Lower doses given less frequently can be used prophylactically to prevent or reduce the incidence of recurrence of the infection.
In accordance with the presently disclosed methods, pharmaceutically active compounds as described herein can be administered orally as a solid or as a liquid, or can be administered intramuscularly or intravenously as a solution, suspension, or emulsion. Alternatively, the compounds or salts can be administered by inhalation, intravenously or intramuscularly as a liposomal suspension. When administered through inhalation the active compound or salt should be in the form of a plurality of solid particles or droplets having, in some embodiments, a particle size from about 0.5 microns to about 5 microns, and in some embodiments, a particle size from about 1 micron to about 2 microns.
Pharmaceutical formulations suitable for intravenous or intramuscular injection are further embodiments provided herein. The pharmaceutical formulations comprise a compound of Formula I described herein, a prodrug as described herein, or a pharmaceutically acceptable salt thereof, in any pharmaceutically acceptable carrier. If a solution is desired, water is the carrier of choice with respect to water-soluble compounds or salts. With respect to the water-soluble compounds or salts, an organic vehicle, such as glycerol, propylene glycol, polyethylene glycol, or mixtures thereof, can be suitable. In the latter instance, the organic vehicle can contain a substantial amount of water. The solution in either instance can then be sterilized in a suitable manner known to those in the art, and typically by filtration through a 0.22-micron filter. Subsequent to sterilization, the solution can be dispensed into appropriate receptacles, such as depyrogenated glass vials. Of course, the dispensing is preferably done by an aseptic method. Sterilized closures can then be placed on the vials and, if desired, the vial contents can be lyophilized.
In addition to compounds of Formula I or their salts or prodrugs, the pharmaceutical formulations can contain other additives, such as pH-adjusting additives. In particular, useful pH-adjusting agents include acids, such as hydrochloric acid, bases or buffers, such as sodium lactate, sodium acetate, sodium phosphate, sodium citrate, sodium borate, or sodium gluconate. Further, the formulations can contain anti-microbial preservatives. Useful anti-microbial preservatives include methylparaben, propylparaben, and benzyl alcohol. The anti-microbial preservative is typically employed when the formulation is placed in a vial designed for multi-dose use. The pharmaceutical formulations described herein can be lyophilized using techniques well known in the art.
In some embodiments of the subject matter described herein, there is provided an injectable, stable, sterile formulation comprising a compound of Formula I, or a salt thereof, in a unit dosage form in a sealed container. The compound or salt is provided in the form of a lyophilizate, which is capable of being reconstituted with a suitable pharmaceutically acceptable carrier to form a liquid formulation suitable for injection thereof into a subject. The unit dosage form typically comprises from about 10 mg to about 10 grams of the compound salt. When the compound or salt is substantially water-insoluble, a sufficient amount of emulsifying agent, which is physiologically acceptable, can be employed in sufficient quantity to emulsify the compound or salt in an aqueous carrier. One such useful emulsifying agent is phosphatidyl choline.
Other pharmaceutical formulations can be prepared from the water-insoluble compounds disclosed herein, or salts thereof, such as aqueous base emulsions. In such an instance, the formulation will contain a sufficient amount of pharmaceutically acceptable emulsifying agent to emulsify the desired amount of the compound or salt thereof. Particularly useful emulsifying agents include phosphatidyl cholines, and lecithin.
Additional embodiments provided herein include liposomal formulations of the active compounds disclosed herein. The technology for forming liposomal suspensions is well known in the art. When the compound is an aqueous-soluble salt, using conventional liposome technology, the same can be incorporated into lipid vesicles. In such an instance, due to the water solubility of the active compound, the active compound will be substantially entrained within the hydrophilic center or core of the liposomes. The lipid layer employed can be of any conventional composition and can either contain cholesterol or can be cholesterol-free. When the active compound of interest is water-insoluble, again employing conventional liposome formation technology, the salt can be substantially entrained within the hydrophobic lipid bilayer that forms the structure of the liposome. In either instance, the liposomes that are produced can be reduced in size, as through the use of standard sonication and homogenization techniques.
The liposomal formulations containing the active compounds disclosed herein can be lyophilized to produce a lyophilizate, which can be reconstituted with a pharmaceutically acceptable carrier, such as water, to regenerate a liposomal suspension.
Pharmaceutical formulations also are provided which are suitable for administration as an aerosol, by inhalation. These formulations comprise a solution or suspension of a desired compound described herein or a salt thereof, or a plurality of solid particles of the compound or salt. The desired formulation can be placed in a small chamber and nebulized. Nebulization can be accomplished by compressed air or by ultrasonic energy to form a plurality of liquid droplets or solid particles comprising the compounds or salts. In some embodiments, the liquid droplets or solid particles have a particle size in the range of about 0.5 microns to about 10 microns. In some embodiments, the liquid droplets or solid particles have a particle size in the range of about 0.5 to about 5 microns. The solid particles can be obtained by processing the solid compound or a salt thereof, in any appropriate manner known in the art, such as by micronization. In some embodiments, the size of the solid particles or droplets will be from about 1 micron to about 2 microns. In this respect, commercial nebulizers are available to achieve this purpose. The compounds can be administered via an aerosol suspension of respirable particles in a manner set forth in U.S. Pat. No. 5,628,984, the disclosure of which is incorporated herein by reference in its entirety.
When the pharmaceutical formulation suitable for administration as an aerosol is in the form of a liquid, the formulation will comprise a water-soluble active compound in a carrier that comprises water. A surfactant can be present, which lowers the surface tension of the formulation sufficiently to result in the formation of droplets within the desired size range when subjected to nebulization.
As indicated, both water-soluble and water-insoluble active compounds are provided by the presently disclosed subject matter. As used in the presently disclosed subject matter, the term “water-soluble” is meant to define any composition that is soluble in water in an amount of about 50 mg/mL, or greater. Also, as used in the presently disclosed subject matter, the term “water-insoluble” is meant to define any composition that has solubility in water of less than about 20 mg/mL. For certain applications, water-soluble compounds or salts can be desirable whereas for other applications water-insoluble compounds or salts likewise can be desirable.
Accordingly, in some embodiments, the presently disclosed subject matter provides a pharmaceutical formulation comprising:

    
    
        (a) a pharmaceutically acceptable carrier; and
        (b) a compound of Formula I:
    
    






wherein:

    
    
        X and Y are each independently selected from the group consisting of CH, CH2, N, C═O, O, S, and NR3,
        
            wherein R3 is selected from the group consisting of H, alkyl, aryl, alkoxyl, and aryloxyl, and
            Y can be present or absent;
        
        
        R1 and R2 are each independently selected from the group consisting of H, alkyl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;
        m and n are integers from 0 to 3, provided that when m is zero, R1 is an implied hydrogen, and when n is zero, R2 is an implied hydrogen;
        p and q are integers from 0 to 1;
        A and A′ are each independently selected from one of:
    
    






    
    
        wherein:
        
            R4, R5, R6, R7, and R8 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or
            R5 and R6 together represent a C2 to C10 alkyl, hydroxyalkyl, or alkylene; or
            R8 is
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl;

or a pharmaceutically acceptable salt thereof.

                
                
            
            
        
        
    
    


In some embodiments of the pharmaceutical formulation of a compound of Formula I, X is CH2 and Y is absent. In such embodiments, the fused-ring structure comprises 9H-fluorene. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 2- and 7-positions of the 9H-fluorene ring.

                
                
            
            
        
        
    
    


In some embodiments, m and n are both zero and R7 is H. In some embodiments, R4 is H and R8 is phenyl. In some embodiments, R4 is H and R8 is 2-pyridyl.
In some embodiments, R8 is




    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R4 and R9 are each H. In some embodiments, R4 is ethoxycarbonyl and R9 is H. In some embodiments, R10 is H. In some embodiments, R10 is methyl. In some embodiments, R10 is isopropyl. In some embodiments, R10 is methoxyl. In some embodiments, R10 is iso-butoxyl.

            
            
        
        
    
    


In some embodiments of the pharmaceutical formulation of a compound of Formula I, X is C═O and Y is absent. In such embodiments, the fused-ring structure comprises 9H-fluoren-9-one. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 2- and 7-positions of the 9H-fluoren-9-one ring. In some embodiments, m and n are both zero; and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H. In some embodiments, R4 is ethoxycarbonyl.

            
            
        
        
    
    


In some embodiments of the pharmaceutical formulation of a compound of Formula I, X and Y are both C═O. In such embodiments, the fused-ring structure comprises 9,10-anthraquinone. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, m and n are both zero and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H.

            
            
        
        
    
    


In some embodiments of the pharmaceutical formulation of a compound of Formula I, X is N and Y is CH. In such embodiments, the fused-ring structure comprises acridine. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 3- and 6-positions of the acridine ring. In some embodiments, m and n are both zero; and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H.

            
            
        
        
    
    


In some embodiments of the pharmaceutical formulation of a compound of Formula I, the compound is selected from the group consisting of: 2,7-bis-guanidino-9H-fluorene; 2,7-bis-guanidinofluoren-9-one; 2,7-bis-guanidinoanthraquinone; 3,6-bis-guanidinoacridine; 2,7-bis-(N′′-ethoxycarbonyl)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl)guanidinofluoren-9-one; 2,7-bis(N′′-ethoxycarbonyl-N′-methyl)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl-N′-isopropyl)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl-N′-methoxy)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl-N′-isobutoxy)guanidine-9H-fluorene; 2,7-bis(N′-methyl)guanidino-9H-fluorene; 2,7bis(N′-iso-propyl)guanidino-9H-fluorene; 2,7-bis(N′-methoxy)guanidino-9H-fluorene; 2,7-bis(N′-isobutoxy)guanidine-9H-fluorene; 2,7-bis[(phenylimino)amino)]-9H-fluorene; and 2,7-bis[(2-pyridylimino)amino)-9H-fluorene.
IV. Methods Of Treating Microbial Infections
Subjects with microbial infections can be treated by methods described herein. These infections can be caused by a variety of microbes, including fungi, algae, protozoa, bacteria, and viruses. Exemplary microbial infections that can be treated by the method of the presently disclosed subject matter include, but are not limited to, infections caused by Trypanosoma species (e.g., Trypanosoma brucei rhodesiense), Pneumocytsis carnii, Giardia lamblia, Cryptosporidium parvum, Cryptococcus neoformans, Candida albicans, Candida tropicalis, Salmonella typhimurium, Plasmodium falciparum, Leishmania donovani, and Leishmania mexicana amazonensis. The methods of the presently disclosed subject matter are useful for treating these conditions in that they inhibit the onset, growth, or spread of the condition, cause regression of the condition, cure the condition, or otherwise improve the general well-being of a subject afflicted with, or at risk of contracting the condition.
Methods of treating microbial infections comprise administering to a subject in need of treatment an active compound as described herein. These active compounds, as set forth above, include compounds of Formula I, their corresponding prodrugs, and pharmaceutically acceptable salts of the compounds and prodrugs.
With regard to the presently described method embodiments, compounds of Formula I are defined as having a structure as follows:




wherein:

    
    
        X and Y are each independently selected from the group consisting of CH, CH2, N, C═O, O, S and NR3,
        
            wherein R3 is selected from the group consisting of H, alkyl, aryl, alkoxyl, and aryloxyl, and
            Y can be present or absent;
        
        
        R1 and R2 are each independently selected from the group consisting of H, alkyl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;
        m and n are integers from 0 to 3, provided that when m is zero, R1 is an implied hydrogen, and when n is zero, R2 is an implied hydrogen;
        p and q are integers from 0 to 1;
        A and A′ are each independently selected from one of:
    
    






    
    
        wherein:
        
            R4, R5, R6, R7, and R8 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or
            R5 and R6 together represent a C2 to C10 alkyl, hydroxyalkyl, or alkylene; or
            R8 is
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl;

or a pharmaceutically acceptable salt thereof.

                
                
            
            
        
        
    
    


In some embodiments of the method of treating a microbial infection by administering to a subject in need of treatment thereof a compound of Formula I, X is CH2 and Y is absent. In such embodiments, the fused-ring structure comprises 9H-fluorene. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
                wherein:
                
                    R11, is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 2- and 7-positions of the 9H-fluorene ring.

                
                
            
            
        
        
    
    


In some embodiments, m and n are both zero and R7 is H. In some embodiments, R4 is H and R8 is phenyl. In some embodiments, R4 is H and R8 is 2-pyridyl.
In some embodiments, R8 is




    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R4 and R9 are each H. In some embodiments, R4 is ethoxycarbonyl and R9 is H. In some embodiments, R10 is H. In some embodiments, R10 is methyl. In some embodiments, R10 is isopropyl. In some embodiments, R10 is methoxyl. In some embodiments, R10 is iso-butoxyl.

            
            
        
        
    
    


In some embodiments of the method of treating a microbial infection by administering to a subject in need of treatment thereof a compound of Formula I, X is C═O and Y is absent. In such embodiments, the fused-ring structure comprises 9H-fluoren-9-one. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 2- and 7-positions of the 9H-fluoren-9-one ring. In some embodiments, m and n are both zero and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H. In some embodiments, R4 is ethoxycarbonyl.

            
            
        
        
    
    


In some embodiments of the method of treating a microbial infection by administering to a subject in need of treatment thereof a compound of Formula I, X and Y are both C═O. In such embodiments, the fused-ring structure comprises 9,10-anthraquinone. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, m and n are both zero and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H.

            
            
        
        
    
    


In some embodiments of the method of treating a microbial infection by administering to a subject in need of treatment thereof a compound of Formula I, X is N and Y is CH. In such embodiments, the fused-ring structure comprises acridine. In some embodiments, A and A′ are each independently




    
    
        wherein:
        
            p and q are each 1;
            R4 and R7 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; and
            R8 is selected from the group consisting of aryl and
        
        
    
    






    
    
        
        
            wherein:
            
                R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
                wherein:
                
                    R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, A and A′ are in the 3- and 6-positions of the acridine ring. In some embodiments, m and n are both zero and R7 is H. In some embodiments, R8 is

                
                
            
            
        
        
    
    






    
    
        wherein:
        
            R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
            wherein:
            
                R11 is selected from the group consisting of H, alkyl, and aryl.

In some embodiments, R9 and R10 are both H. In some embodiments, R4 is H.

            
            
        
        
    
    


In some embodiments of the method of treating a microbial infection by administering to a subject in need of treatment thereof a compound of Formula I, the method comprises a compound of Formula I selected from the group consisting of: 2,7-bis-guanidino-9H-fluorene; 2,7-bis-guanidinofluoren-9-one; 2,7-bis-guanidinoanthraquinone; 3,6-bis-guanidinoacridine; 2,7-bis-(N′′-ethoxycarbonyl)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl)guanidinofluoren-9-one; 2,7-bis(N′′-ethoxycarbonyl-N′-methyl)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl-N′-isopropyl)guanidino-9H-fluorene; 2,7-bis(N′-ethoxycarbonyl-N′-methoxy)guanidino-9H-fluorene; 2,7-bis(N′′-ethoxycarbonyl-N′-isobutoxy)guanidine-9H-fluorene; 2,7-bis(N′-methyl)guanidino-9H-fluorene; 2,7-bis(N′-iso-propyl)guanidino-9H-fluorene; 2,7-bis(N′-methoxy)guanidino-9H-fluorene; 2,7-bis(N′-isobutoxy)guanidine-9H-fluorene; 2,7-bis[(phenylimino)amino)]-9H-fluorene; and 2,7-bis[(2-pyridylimino)amino)-9H-fluorene.
In some embodiments, the compound of Formula I is administered in the form of a pharmaceutically acceptable salt. In some embodiments, the pharmaceutically acceptable salt is a hydrochloride salt.
In some embodiments, the microbial infection is selected from one of a Trypanosoma brucei rhodesiense infection and a Plasmodium falciparum infection.
The subject treated in the presently disclosed subject matter in its many embodiments is desirably a human subject, although it is to be understood the methods described herein are effective with respect to all vertebrate species, which are intended to be included in the term “subject”. The methods described herein are particularly useful in the treatment and/or prevention of infectious diseases in warm-blooded vertebrates. Thus, the methods can be used as treatment for mammals and birds.
More particularly, provided is the treatment of mammals such as humans, as well as those mammals of importance due to being endangered (such as Siberian tigers), of economical importance (animals raised on farms for consumption by humans) and/or social importance (animals kept as pets or in zoos) to humans, for instance, carnivores other than humans (such as cats and dogs), swine (pigs, hogs, and wild boars), ruminants (such as cattle, oxen, sheep, giraffes, deer, goats, bison, and camels), and horses. Also provided is the treatment of birds, including the treatment of those kinds of birds that are endangered, kept in zoos, as well as fowl, and more particularly domesticated fowl, i.e., poultry, such as turkeys, chickens, ducks, geese, guinea fowl, and the like, as they also are of economical importance to humans. Thus, embodiments of the methods described herein include the treatment of livestock, including, but not limited to, domesticated swine (pigs and hogs), ruminants, horses, poultry, and the like.
EXAMPLES
The following Examples have been included to illustrate modes of the presently disclosed subject matter. Certain aspects of the following Examples are described in terms of techniques and procedures found or contemplated to work well in the practice of the presently disclosed subject matter. In light of the present disclosure and the general level of skill in the art, those of skill can appreciate that the following Examples are intended to be exemplary only and that numerous changes, modifications, and alterations can be employed without departing from the scope of the presently disclosed subject matter.
Methods and Materials For Examples 1-4
Melting points were recorded using a Thomas-Hoover (Uni-Melt® (Thomas Scientific, Swedesboro, N.J., United States of America)) capillary melting point apparatus and are uncorrected. TLC analysis was carried out on silica gel 60 F254 precoated aluminum sheets and detected under UV light. 1H and 13C—NMR spectra were recorded employing a Varian GX400 or Varian Unity Plus 300 spectrometer (Varian, Inc., Palo Alto, Calif., United States of America), and chemical shifts (δ) are in ppm relative to TMS as internal standard. Mass spectra were recorded on a VG Analytical 70-SE spectrometer (VG Analytical, Ltd., Manchester, United Kingdom). Elemental analyses were obtained from Atlantic Microlab Inc. (Norcross, Ga., United States of America) and are within ±0.4 of the theoretical values. The compounds reported as salts frequently analyzed correctly for fractional moles by water and/or ethanol of solivation. In each case 1H-NMR showed the presence of the indicated solvent(s). All chemicals and solvents (including anhydrous solvents) were purchased from Aldrich Chemical Co. (Milwaukee, Wis., United States of America), Fisher Scientific (Fairlawn, N.J., United States of America) or Frontier Scientific (Logan, Utah, United States of America) and used as purchased. Acetonitrile (CaH2) and triethylamine (CaH2) were distilled from the indicated drying agent. Synthesis of the bis-aminofluorenone (3b) and bis-aminoanthraquinone (3c) was achieved as described in Scheme 1 according to the literature. S-(2-naphthylmethyl) thioacetimidate was prepared adopting the reported procedure.
Example 1




Preparation of Bis(N′,N′′-di-BOCguanidino) Derivatives (General Procedure) (Scheme 1)
2,7-Bis(N′,N′′-di-BOCguanidino)-9H-fluorene (4a). To a solution of 2,7-diamino fluorene (3a) (0.49 g, 2.5 mmol) in anhydrous DMF (15 mL) was added 1,3-bis(tert-butoxycarbonyl)-2-methylthiopseudourea (1.56 g, 5.3 mmol), triethylamine (3.23 g, 32 mmol) and finally mercury(II)chloride (1.57 g, 5.7 mmol). The suspension was kept stirring at room temperature for 24 h. The reaction, diluted with CH2Cl2 and Na2CO3 solution, was filtered through a pad of Celite. The organic layer was washed with water (3×) followed by brine and then dried over anhydrous Na2SO4. After evaporating the solvent to dryness the obtained residue was recrystallized from CH2Cl2/MeOH giving a light yellow solid (1.15 g, 68%), mp>340° C. 1H-NMR (CDCl3): δ 1.52,1.54 (2s, 36H), 3.91 (s, 2H), 7.47 (d, J=8.4 Hz, 2H), 7.64 (d, J=8.4 Hz, 2H), 7.90 (s, 2H), 10.43 (s, 2H), 11.68 (s, 2H). 13C-NMR (CDCl3): δ 163.6, 153.5, 153.3, 144.2, 138.0, 135.2, 120.9, 119.7, 118.9, 83.6, 79.6, 37.2, 28.1, 28.1. Anal. Calcd. for C35H48N6O8 (680.79): C % 61.75, H % 7.11, N % 12.34. Found: C % 61.50, H %7.11, N % 12.36.
2,7-Bis(N′,N′′-di-BOCguanidino)fluoren-9-one (4b). Orange solid (1.16 g, 65%), mp>340° C. 1H-NMR (CDCl3): δ 1.51,1.54 (2s, 36H), 7.42 (d, J=8.4 Hz), 7.77 (s, 2H), 7.82 (d, J=8.4 Hz, 2H), 10.46 (br s, 2H), 11.63 (br s, 2H). 13C-NMR (CDCl3): δ 192.7, 163.3, 153.4, 153.2, 140.3, 137.4, 135.1, 128.0, 120.5, 118.5, 84.0, 79.9, 28.1, 28.0. Anal. Calcd. for C35H46N6O9-0.5H2O (703.78): C % 59.73, H % 6.73, N % 11.94. Found: C % 59.69, H % 6.76, N % 12.13.
2,7-Bis(N′,N′′-di-BOCguanidino)anthraquinone (4c). Yellow solid (1.24 g, 82%), mp>340° C. 1H-NMR (CDCl3): δ 1.56 (s, 36H), 8.24 (s, 2H), 8.30 (d, J=8.7 Hz, 2H), 8.43 (d, J=8.7 Hz, 2H), 10.82 (br s, 2H), 11.62 (br s, 2H). 13C-NMR (CDCl3): δ 182.5, 181.2, 163.1, 153.2, 142.3, 134.4, 129.4, 128.9, 126.7, 119.0, 84.4, 80.3, 28.1, 28.0. Anal. Calcd. for C36H46N6O10-0.5CH2Cl2 (765.25): C % 57.28, H % 6.19. Found: C % 57.30, H % 6.09.
3,6-Bis(N′,N′′-di-BOCguanidino)acridine (4d). Canary yellow fluffy solid (0.88 g, 73%), mp>340° C. 1H-NMR (CDCl3): δ 1.53, 1.55 (2s, 36H), 7.78 (dd, J=2.1 Hz, J=9.0 Hz, 2H), 7.9 (d, J=9.0 Hz, 2H), 8.45 (d, J=2.1 Hz, 2H), 8.6 (s, 1H), 10.69 (s, 2H), 11.68 (s, 2H). Anal. Calcd. for C35H47N7O8-0.5H2O (702.79): C % 59.81, H % 6.88, N % 13.95. Found: C % 59.97, H % 6.88, N % 13.90.
Deprotection of N′,N′′-Di-BOCguanidines (General Procedure) (Scheme 1)
2,7-Bis-guanidino-9H-fluorene Dihydrochloride (5a). The N′,N′′-di-BOC-guanidine (4a) (0.25 g, 0.4 mmol) was dissolved in CH2Cl2 (10 mL), diluted with dry EtOH (15 mL) and the chilled solution was saturated with dry HCl. The reaction was then kept stirring at room temperature for 3 days (drying tube), when by the product started forming a precipitate over time. After evaporating the solvent to dryness, the residue was washed with ether multiple times and was dried under vacuum at 50-60° C. over night to give whitish yellow solid of the bis-guanidine dihydrochloride (0.13 g, quantitative), mp>340° C. 1H-NMR (DMSO-d6): δ 3.95 (s, 2H), 7.24 (d, J=8.4 Hz, 2H), 7.45 (s, 2H), 7.58 (br s, 8H), 7.95 (d, J=8.4 Hz, 2H), 10.23 (br s, 2H). 13C-NMR (DMSO-d6): δ 156.1, 156.1, 144.5, 138.6, 133.8, 123.3, 121.4, 120.9, 36.8. MS (EI): m/z 277 (M++1) (14), 252 (100). Anal. Calcd. for C15H16N6.2HCl-0.25C2H5OH (364.76): C % 51.04, H % 5.39, N % 23.04, Cl % 19.44. Found: C % 50.74, H % 5.26, N % 22.99, Cl % 19.87.
2,7-Bis-guanidinofluoren-9-one Dihydrochloride (5b). Green solid (0.26 g, 89%), mp>340° C. 1H-NMR (DMSO-d6): δ 7.45 (m, 4H), 7.68 (br s, 8H), 7.86 (d, J=8.4 Hz, 2H), 10.25 (br s, 2H). 13C-NMR (DMSO-d6): δ 191.58, 159.03, 140.88, 136.54, 134.62, 130.77, 122.36, 119.86. MS (EI): m/z 295(M++1) (23), 278 (100). Anal. Calcd. for C15H14N6O-2HCl-0.35H2O (373.53): C % 48.23, H % 4.51, N % 22.49, Cl % 18.95. Found: C % 48.51, H % 4.55, N % 22.13, Cl % 18.93.
2,7-Bis-guanidinoanthraquinone Dihydrochloride (5c). Orange red solid (0.22 g, 91%), mp>340° C. dec. 1H-NMR (DMSO-d6): δ 7.75 (d, J=8.4 Hz, 2H), 7.97 (s, 2H), 8.06 (br s, 8H), 8.24 (d, J=8.4 Hz, 2H), 10.87 (br s, 2H). 13C-NMR (DMSO-d6): δ 181.5, 180.4, 155.5, 142.0, 134.1, 129.2, 128.9, 127.6, 119.3. MS (EI): m/z 290 (M+) (3). Anal. Calcd. for C16H14N6O2-2HCl-1.66H2O (425.15): C % 45.20, H % 4.58, N % 19.77. Found: C % 45.24, H % 4.58, N % 19.47.
3,6-bis-guanidinoacridine Trihydrochloride (5d). Orange solid (0.33 g, 85%), mp>340° C. 1H-NMR (DMSO-d6): δ 7.75 (dd, J=8.4 Hz, 2H), 7.96 (d, J=2.1 Hz, 2H), 8.06 (br s, 8H), 8.23 (d, J=8.4 Hz, 2H), 10.83 (br s, 2H). 13C-NMR (DMSO-d6): δ 181.5, 180.4, 155.5, 142.0, 134.1, 129.2, 128.9, 127.6, 119.3. Anal. Calcd. for C15H15N7-3HCl-C2H5OH-0.33H2O (454.72): C % 44.90, H % 4.46, N % 21.56. Found: C % 45.08, H % 5.10, N % 21.48.
Example 2




Preparation of Carbamoyl Thiourea Derivatives (Scheme 2)
2,7-Bis(N′′-ethoxycarbonylthiourea)-9H-fluorene (6a). A solution of 2,7-diamino-9H-fluorene (3a) (1g, 5.1 mmol) in CH2Cl2 (10 mL), added to which ethyl isothiocyanatoformate (1.47 g, 11.2 mmol), was stirred at room temperature for 24 h. After flash chromatography, the reaction was diluted with hexane and the precipitate formed was collected and dried to yield the bis-carbamoylthiourea as a light brown solid (2.32 g, quantitative), mp>340° C. dec. 1H-NMR (DMSO-d6): δ 1.27 (t, J=6.9 Hz, 6H), 3.95 (s, 2H), 4.23 (q, J=6.9 Hz, 4H), 7.75 (d, J=8.4 Hz, 2H), 7.89 (m, 4H), 11.28 (s, 2H), 11.64 (s, 2H). 13C-NMR(DMSO-d6): δ 163.2, 158.9, 143.6, 137.9, 135.8, 123.1, 121.1, 119.8, 59.5, 36.4, 28.0, 14.5. MS (EI): m/z 459 (M++1, 18), 374.1 (8), 328 (100), 319 (8), 151 (12).
2,7-Bis(N′′-ethoxycarbonylthiourea)fluoren-9-one (6b). To a suspension of 2,7-diaminofluorenone (3b) (0.3g, 1.4 mmol) in toluene (10 mL), was added 0.41 g (3.1 mmol) ethyl isothiocyanatoformate. The reaction mixture was refluxed for 10 h. After cooling to room temperature, the reaction was diluted with hexane. The orange precipitate obtained was filtered off, washed with hexane and dried under vacuum (0.66 g, 98%), mp>340° C. dec. 1H-NMR (DMSO-d6): δ 1.26 (t, J=7.2 Hz, 6H), 4.22 (q, J=7.2 Hz, 4H), 7.69 (dd, J=1.8, 8.1 Hz, 2H), 7.80 (d, J=8.1 Hz, 2H), 7.97 (d, J=1.8 Hz, 2H), 11.39 (s, 2H), 11.60 (s, 2H).
Preparation of N-Substituted Carbamoyl Guanidines (General Procedure) (Scheme 2)
2,7-Bis(N′′-ethoxycarbonyl)guanidino-9H-fluorene (7a). A stirred solution of carbamoyl thiourea (6a) (0.58 g, 1.2 mmol), ammonia (0.5M solution in dioxane) (10 mL, 5.0 mmol), and diisopropylethylamine (0.98 g, 7.5 mmol) in anhydrous CH2Cl2 (10 mL) was cooled to 0° C. EDCI (0.96 g, 5.0 mmol) was added, and the solution was stirred at room temperature over night. The reaction mixture was washed with water (3×), followed by brine and dried over anhydrous Na2SO4. The residue remaining after removal of the solvent was crystallized from EtOH/water (0.45 g, 84%), mp>340° C. 1H-NMR (DMSO-d6): δ 1.16 (t, J=7.2 Hz, 6H), 3.87(s, 2H), 3.98 (q, J=7.2 Hz, 4H), 7.33 (d, J=8.4 Hz, 2H), 7.65 (s, 2H), 7.75 (d, J=8.4 Hz, 2H), 9.31 (br s, 2H). 13C-NMR (DMSO-d6): δ 163.1, 159.0, 143.4, 136.8, 136.3, 120.4, 119.3, 118.3, 59.4, 36.4, 14.4. Anal. Calcd. for C21H24N6O4-0.5C2H5OH (447.48): C % 59.04, H % 6.08, N % 18.78. Found: C % 58.96, H % 5.74, N % 18.88.
2,7-Bis(N′′-ethoxycarbonyl)guanidinofluoren-9-one (7b). Brick red solid (0.35 g, 75%), mp>340° C. 1H-NMR (DMSO-d6): δ 1.17 (t, J=7.0 Hz, 6H), 4.00 (q, J=7.0 Hz, 4H), 7.47 (dd, J=1.8, 8.1 Hz, 2H), 7.59 (d, J=8.1 Hz, 2H), 7.77 (d, J=1.8 Hz, 2H), 9.31 (br s, 2H). 13C-NMR (DMSO-d6): δ 192.9, 162.5, 158.6, 139.6, 138.3, 134.1, 126.4, 120.8, 116.6, 59.8, 14.5. Anal. Calcd. for C21H24N6O5-0.15CH2Cl2 (451.17): C % 56.54, H % 5.08, N % 18.47. Found: C % 56.30, H % 4.98, N % 18.62.
2,7-Bis(N′′-ethoxycarbonyl-N′-methyl)guanidino-9H-fluorene (7c). Adopting the same procedure followed for preparation of (7a), methylamine (2M solution in THF) was used for transformation of the thiourea compound into N-substituted guanidine. The reaction yielded an off-white solid (0.53 g, 93%), mp 157-8° C. 1H-NMR (DMSO-d6): δ 1.15 (t, J=7.2 Hz, 6H), 2.83 (s, 6H), 3.90 (s, 2H), 3.94 (q, J=7.2 Hz, 4H), 7.32 (d, J=8.4 Hz, 2H), 7.54 (s, 2H), 7.83 (d, J=8.4 Hz, 2H). 13C-NMR (DMSO-d6): δ 161.9, 157.9, 143.7, 137.6, 135.9, 123.1, 121.0, 119.9, 59.9, 36.4, 28.3, 14.5. MS (FAB, thioglycerol): m/z 453 (M++1, 100), 407 (39), 323 (15). Anal. Calcd. for C23H28N6O4—H2O (470.52): C % 58.71, H % 6.42, N % 17.86. Found: C % 58.81, H % 6.39, N % 17.71.
2,7-Bis(N′′-ethoxycarbonyl-N′-iso-propyl)guanidino-9H-fluorene (7d). Using iso-propylamine and carrying out the same synthetic steps used for (7a), a beige solid was obtained (0.39 g, 88%), mp 1424° C. 1H-NMR (DMSO-d6): δ 0.84 (t, J=7.2 Hz, 6H), 1.17 (m, 12H), 3.88 (s, 2H), 3.93 (q, J=7.2 Hz, 4H), 4.11 (m, 2H), 7.31 (d, J=8.4 Hz, 2H), 7.52 (s, 2H), 7.80 (d, J=8.4 Hz, 2H). 13C-NMR (DMSO-d6): δ 163.4, 157.3, 143.5, 137.3, 136.2, 122.9, 120.9, 119.7, 59.6, 42.3, 36.4, 22.5, 14.5. MS (ES): m/z 509 (M++1) (19), 255 (100). Anal. Calcd. for C27H36N6O4-0.25 C2H5OH (520.13): C % 63.50, H % 7.26, N % 16.15. Found: C % 63.20, H % 7.06, N % 16.35.
2,7-Bis(N′′-ethoxycarbonyl-N′-methoxy)guanidino-9H-fluorene (7e). Adopting the general procedure and using methylhydoxylamine, a tan white solid was obtained (0.55 g, 87%), mp 180-2° C. 1H-NMR (DMSO-d6): δ 1.20 (t, J=7.2 Hz, 6H), 3.68 (s, 6H), 3.76 (s, 2H), 4.10 (q, J=7.2 Hz, 4H), 6.99 (d, J=8.1 Hz, 2H), 7.16 (s, 2H), 7.35 (dd, J=1.8, 8.1 Hz, 2H), 8.35 (s, 2H), 8.70 (s, 2H).
2,7-Bis(N′′-ethoxycarbonyl-N′-isobutoxy)guanidino-9H-fluorene (7f). Following the general procedure, O-isobutylhydroxylamine was used to prepare the target compound, which was obtained as creamy white crystals (0.8 g, 93%), 122-5° C.; 1H-NMR (DMSO-d6) 60.88-0.99 (m, 30H), 1.21 (t, J=7.2 Hz, 6H), 1.92-2.02 (m, 4H), 3.65 (d, J=6.6 Hz, 8H), 3.74-3.78 (m, 4H), 3.85 (q, J=7.2 Hz, 4H), 4.11 (q, J=7.2 Hz, 4H), 7.00 (d, J=8.1 Hz, 2H), 7.17 (s, 2H), 7.35 (d, J=8.1 Hz, 2H), 7.55-7.62 (m, 6H), 8.19 (br s, 1H), 8.21 (br s, 1H), 8.67 (br s, 1H), 8.68 (br s, 1H), 9.01 (br s, 1H), 9.02 (br s, 1H), 9.10 (br s, 1H), 9.11 (br s, 1H); 13C-NMR (DMSO-d6) δ 154.0, 153.9, 153.3, 143.4, 143.3, 143.1, 142.9, 142.9, 142.3, 142.2, 138.8, 138.6, 137.9, 137.7, 135.8, 135.6, 134.4, 134.2, 119.7, 119.4, 199.1, 118.8, 117.7, 117.6, 116.6, 114.5,79.5, 79.3, 61.1, 60.4, 36.6, 36.5, 36.3, 27.3, 27.3, 19.3, 14.4; MS (ESI) m/z (rel. int.) 569 (M++1, 100). Anal. Calcd. for C29H40N6O6 (568.66): C % 61.25, H % 7.08. Found: C % 61.12, H % 7.29.
Preparation of N-Substituted Guanidines (General Procedure) (Scheme 2)
2,7-Bis(N′-methyl)guanidino-9H-fluorene (8a). The substituted guanidine (7c) (0.5 g, 1.1 mmol) was suspended in EtOH (5 mL). 1 N KOH (11 mL, 11 mmol) was then added and the reaction mixture was kept stirring over night maintaining the temperature at 55-60° C. The solvent was evaporated to dryness, the residue was washed multiple times with water and recrystallized from aqueous EtOH to give a light orange solid (0.24 g, 70%), mp 240-2° C. dec. 1H-NMR (DMSO-d6): δ 2.6 (s, 6H), 3.69 (s, 2H), 6.70 (d, J=2.7 Hz, 2H), 6.90 (s, 2H), 7.50 (d, J=2.7 Hz, 2H). For preparing the HCl salt, the free base was dissolved in dry EtOH (20 mL) and the solution was chilled in an ice-bath. After passing HCl gas for 10 min, the reaction was concentrated under reduced pressure and then diluted with ether. The precipitate formed was collected by filtration to give an orange solid (0.16 g, 65%), mp 276-8° C. 1H-NMR (DMSO-d6): δ 2.84 (s, 6H), 3.96 (s, 2H), 7.25 (d, J=8.4 Hz, 2H), 7.46 (s, 2H), 7.77 (br s, 2H), 7.89 (br s, 2H), 7.95 (d, J=8.4 Hz, 2H), 10.01 (br s, 2H). 13C-NMR (DMSO-d6): δ 155.6, 144.5, 138.5, 134.1, 123.5, 121.5, 120.9, 36.5, 28.3. MS (ES): m/z 309 (M++1) (100), 155 (9). Anal. Calcd. for C17H20N6.2HCl-0.25C2H5OH-0.75H2O (406.33): C % 51.73, H % 6.20, N % 20.68. Found: C % 51.77, H % 6.24, N % 20.48.
2,7-Bis(N-iso-propyl)guanidino-9H-fluorene (8b). Free base: Starting with 7d and following the general procedure, a salmon orange solid (0.17 g, 79%), mp 247-9° C. dec. 1H-NMR (DMSO-d6): δ 1.11 (d, J=5.4 Hz, 12H), 3.68 (s, 2H), 3.85 (m, 2H), 4.93 (br s, 4H), 5.38 (br s, 2H), 6.69 (d, J=8.1 Hz, 2H), 6.89 (s, 2H), 7.49 (d, J=8.1 Hz, 2H). Dihydrochloride salt: Shiny yellow crystals, mp 308-9° C. dec. 1H-NMR (DMSO-d6): δ 1.18 (d, J=6.3 Hz, 12H), 3.94 (m, 4H), 7.23 (d, J=8.4 Hz, 2H), 7.43 (s, 2H), 7.71 (br s, 4H), 7.93 (d, J=8.4 Hz, 2H), 8.06 (br s, 2H), 9.88 (br s, 2H). 13C-NMR (DMSO-d6): δ 153.9, 144.8, 138.8, 134.5, 123.6, 121.6, 121.0, 43.8, 22.2. Anal. Calcd. for C21H28N6-2HCl-1.5H2O (464.54): C % 54.31, H % 7.16, N % 18.09. Found: C % 54.51, H % 6.74, N % 17.79.
2,7-Bis(N′-methoxy)guanidino-9H-fluorene (8c). Free base: Using 7e as a starting material, a pink solid (0.17 g, 79%), mp 200-2° C. dec. 1H-NMR (DMSO-d6): δ 3.34 (br s, 4H), 3.74 (s, 2H), 5.29 (s, 6H), 7.20 (dd, J=1.8, 8.1 Hz, 2H), 7.50 (m, 4H), 7.75 (br s, 2H). 13C-NMR (DMSO-d6): δ 151.6, 143.0, 139.5, 133.6, 118.7, 116.1, 114.1, 60.5, 36.5. Dihydrochloride salt: Shiny tan white solid, mp 264-7° C. dec. 1H-NMR (DMSO-d6): δ 1.18 (d, J=6.3 Hz, 12H), 3.94 (m, 4H), 7.23 (d, J=8.4 Hz, 2H), 7.43 (s, 2H), 7.71 (br s, 4H), 7.93 (d, J=8.4 Hz, 2H), 8.06 (br s, 2H), 9.88 (br s, 2H). 13C-NMR (DMSO-d6): δ 153.9, 144.8, 138.8, 134.5, 123.6, 121.6, 121.0, 43.8, 22.2. Anal. Calcd. for C17H20N6O2.2HCl-0.6H2O (424.11): C % 48.14, H % 5.51, N % 19.80. Found: C % 48.35, H % 5.38, N % 19.41.
2,7-Bis(N′-isobutoxy)guanidino-9H-fluorene (8d). Free base: Starting with 7f and using the general procedure provided a brick red solid (0.16 g, 62%), mp 198-200° C.; 1H-NMR (DMSO-d6) δ 0.90 (d, J=6.9 Hz, 12H), 1.93-2.02 (m, 2H), 3.55 (d, J=6.9 Hz, 4H), 3.74 (s, 2H), 5.32 (br s, 4H), 7.21 (dd, J=8.4, 1.8 Hz, 2H), 7.49-7.52 (m, 4H), 7.82 (br s, 2H); 13C-NMR (DMSO-d6) δ 151.5, 143.1, 139.4, 133.8, 118.8, 116.3, 114.3, 79.1, 36.5, 27.3, 19.3; MS (ESI) m/z (rel. int.) 425 (M++1, 100), 245 (10), 156 (56); MS (ESI) m/z (rel. int.) 425 (M++1, 100), 254 (10), 156 (55). Hydrochloride salt: Pink solid, mp 251-2° C. (dec.); 1H-NMR (DMSO-d6) δ 0.91 (d, J=6.9 Hz, 12H), 1.97-2.06 (m, 2H), 3.65 (d, J=6.9 Hz, 4H), 3.95 (s, 2H), 7.28 (d, J=8.4 Hz, 2H), 7.48 (s, 2H), 7.96 (d, J=8.4 Hz, 2H), 8.16 (br s, 4H), 10.36 (br s, 2H), 11.65 (br s, 2H). Anal. Calcd. for C23H32N6O2.2HCl (496.21): C % 55.53, H % 6.88, N % 16.89. Found: C % 55.45, H % 6.87, N % 16.70.
Example 3




Preparation of Reversed Amidines (General Procedure) (Scheme 3)
2,7-Bis[(phenylimino)amino]-9H-fluorene (9a). A solution of 2,7-diamino-9H-fluorene (0.3 g, 1.5 mmol) in dry MeCN (10 mL) was diluted with dry EtOH (15 mL) and chilled in an ice-water bath. The solution was then treated with S-(2-naphthymethyl)-thiobenzimidate hydrobromide (1.13 g, 3.2 mmol). Free base: The reaction was kept stirring at room-temperature for 24 h after which the solvent was evaporated to dryness leaving behind an oily residue that was triturated with ether to give a solid of the hydrobromide salt. The solid was then dissolved in EtOH, basified with 1 N NaOH and the free base extracted with EtOAc. After drying over Na2SO4, the solvent was evaporated to dryness, giving an off white solid (0.45 g, 63%), mp 240-2° C. 1H-NMR (DMSO-d6): δ 3.83 (s, 2H), 6.31 (br s, 4H), 6.83 (m, 2H), 7.04 (s, 2H), 7.45 (d, J=7.2 Hz, 6H), 7.71 (d, J=8.1 Hz, 2H), 7.97 (d, J=7.8 Hz, 4H). 13C-NMR (DMSO-d6): δ 153.9, 148.4, 143.7, 135.9, 135.7, 129.9, 127.9, 126.9, 120.2, 119.6, 118.3, 36.4. Hydrochloride salt: An ice-bath cold solution of the free base in Dry EtOH was treated with HCl gas for 5-10 min, after which the solvent was concentrated to near dryness and the suspension was diluted with ether to furnish a yellow solid (0.28 g), mp 286-8° C. 1H-NMR (DMSO-d6): δ 4.05 (s, 2H), 7.53 (d, J=8.4 Hz, 2H), 7.68 (m, 4H), 7.79 (m, 4H), 7.96 (m, 2H), 8.16 (d, J=8.4 Hz, 2H), 9.16 (br s, 2H), 9.86 (br s, 2H), 11.67 (br s, 2H). 13C-NMR: δ 163.0, 144.9, 140.1, 133.7, 133,6, 128.9, 128.6, 124.4, 122.4, 121.5, 36.95. MS (EI): m/z 402 (M+, 100), 299 (38), 197 (9), 196 (60), 151 (7), 103 (32), 77 (10). Anal. Calcd. for C27H22N4.2HCl-0.25C2H5OH—H2O (504.94): C % 65.41, H % 5.49, N % 11.09, Cl % 14.04. Found: C % 65.76, H % 5.40, N % 10.87, Cl % 14.09.
2,7-Bis[(2-pyridylimino)amino]-9H-fluorene (9b). Free base: Shiny yellow crystals (0.70 g, 67%), mp 230-2° C. 1H-NMR (DMSO-d6): δ 4.74 (s, 2H), 6.56 (br s, 4H), 7.79 (d, J=8.4 Hz, 2H), 7.99 (s, 2H), 8.41 (t, J=7.8 Hz, 2H), 8.61 (d, J=8.4 Hz, 2H), 8.81 (t, J=7.8 Hz, 2H), 9.16 (d, J=7.8 Hz, 2H), 8.48 (d, J=7.8 Hz, 2H). Hydrochloride salt: Yellow solid (0.33 g), mp 3024° C. 1H-NMR (DMSO-d6): δ 4.08 (s, 2H), 7.53 (d, J=8.1 Hz, 2H), 7.74 (s, 2H), 7.85, (t, J=7.5 Hz, 2H), 8.16 (d, J=7.5 Hz, 2H), 8.21 (t, J=7.5 Hz, 2H), 8.58 (d, J=7.5 Hz, 2H), 8.89 (d, J=7.5 Hz, 2H), 9.39 (br s, 2H), 10.18 (br s, 2H). 13C-NMR (DMSO-d6): δ 159.6, 149.7, 144.0, 143.8, 140.4, 138.4, 133.5, 128.6, 124.9, 124.2, 122.9, 121.8. MS (EI): m/z 404 (M+, 100), 300 (28), 283 (6), 196 (33), 152 (9), 105 (28), 78(21). Anal. Calcd. for C25H20N6.3.5HCl-0.33C2H5OH—H2O (565.29): C % 54.52, H % 4.89, N % 14.87, Cl % 21.95. Found: C % 54.57, H % 4.74, N % 14.97, Cl % 21.87.
Preparation of Amidines (General Procedure)
The amidines are made by standard protocols starting with readily available dibromo analogs, which are converted into the corresponding bis-nitriles. The key intermediate bis-nitriles are converted into the amidines using the Pinner approach. For standard protocols for preparing amidines, see Das, B. P. et al., J. Med. Chem. 1977, 20, 531; Boykin. D. W. et al., J. Med. Chem. 1995, 38, 912; and Ismail, M. et al. J. Med. Chem., 2003, 46, 4761-4769, which references are incorporated herein by reference.
Example 4
Table 1 shows potent in vitro data for certain compounds of Formula I. Two compounds (8a and 5b) show IC-50 values versus Trypanosoma brucei rhodesiense (T.b.r.) at 13 nM or less. Two compounds (5a and 8a) show IC-50 values versus Plasmodium falciparum (p.f.) at 10 nM or less. Compounds 8a and 8b give 3/4 and 4/4 cures versus the virulent STIP90° strain of T.b.r. in a mouse model. Prodrugs of these compounds hold promise as an oral treatment of both malaria and human African trypanosomiasis.







TABLE 1







Anti-protozoan Data for Fused Ring Dicationic Compounds.








 











DNA

In vivo





















ΔTm
T.b.r.
P.f.

T.b.r.







poly
IC50
IC50
T.b.r.
survival


Compound
X
Y
R
R′
dA-dT
nM
NM
Cures
days



















5a
CH2
Nil
H
H
13.6
24
2.3
0/4
6


5b
C═O
Nil
H
H
6.1
7.3
268
2/4
50.75


5c
C═O
C═O
H
H
7.2
128
23.5
0/4
27


5d
N
CH
H
H
7.7
67
227
0/4
16.25


7a
CH2
Nil
H
CO2Et
0.3
1.4k
2.1k
0/4
18.75


7b
C═O
Nil
H
CO2Et
−0.3
1.2K
3.2K
0/4
6


7c
CH2
Nil
Me
CO2Et

2.9k
1.0k


7d
CH2
Nil
i-Pr
CO2Et
−0.5
2.5K
6.3K
0/4
17.75


8a
CH2
Nil
Me
H
10.1
13
10
3/4
52


8b
CH2
Nil
i-Pr
H
9.3
40.4
35.7
4/4
60


8c
CH2
Nil
OMe
H


8d
CH2
Nil
Oi-Bu
H


9a
CH2
Nil
a)
H
22
292
481
0/4
7


9b
CH2
Nil
b)
H
15.2
894
1.2k





nil = absent;


Me = methyl;


Et = ethyl;


i-Pr = isopropyl;


i-Bu = isobutyl;


OMe = methoxyl; and Oi-Bu = isobutoxyl;


a dashed line in the aromatic ring indicates that the bond is either present or absent.


a) = NHR replaced by phenyl;


b) = NHR replaced by 2-pyridyl.






It will be understood that various details of the presently disclosed subject matter can be changed without departing from the scope of the presently disclosed subject matter. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation.

## Claims

1. A compound of Formula I:




wherein:
X and Y are each independently selected from the group consisting of CH, CH2, N, C═O, S, and NR3,
wherein R3 is selected from the group consisting of H, alkyl, aryl, alkoxyl, and aryloxyl, and
Y can be present or absent, and when absent, is replaced by a direct bond;

R1 and R2 are each independently selected from the group consisting of H, alkyl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;
m and n are integers from 0 to 3, provided that when m is zero, R1 is an implied hydrogen, and when n is zero, R2 is an implied hydrogen;
p and q are each 1;
A and A′ are each




wherein:
R4, R7, and R8 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or
R8 is






wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

2. The compound of claim 1, wherein:
X is CH2; and
Y is absent.

3. The compound of claim 2, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

4. The compound of claim 3, wherein:
m and n are both zero; and
R7 is H.

5. The compound of claim 4, wherein:
R4 is H; and
R8 is phenyl.

6. The compound of claim 4, wherein:
R4 is H; and
R8 is 2-pyridyl.

7. The compound of claim 4, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

8. The compound of claim 7, wherein R4 and R9 are each H.

9. The compound of claim 8, wherein R10 is H.

10. The compound of claim 8, wherein R10 is methyl.

11. The compound of claim 8, wherein R10 is isopropyl.

12. The compound of claim 8, wherein R10 is methoxyl.

13. The compound of claim 8, wherein R10 is iso-butoxyl.

14. The compound of claim 7, wherein:
R4 is ethoxycarbonyl; and
R9 is H.

15. The compound of claim 14, wherein R10 is H.

16. The compound of claim 14, wherein R10 is methyl.

17. The compound of claim 14, wherein R10 is isopropyl.

18. The compound of claim 14, wherein R10 is methoxyl.

19. The compound of claim 14, wherein R10 is iso-butoxyl.

20. The compound of claim 1, wherein:
X is C═O; and
Y is absent.

21. The compound of claim 20, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

22. The compound of claim 21, wherein:
m and n are both zero; and
R7 is H.

23. The compound of claim 22, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

24. The compound of claim 23, wherein R9 and R10 are both H.

25. The compound of claim 24, wherein R4 is H.

26. The compound of claim 24, wherein R4 is ethoxycarbonyl.

27. The compound of claim 1 wherein:
X and Y are both C═O.

28. The compound of claim 27, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

29. The compound of claim 28, wherein:
m and n are both zero; and
R7 is H.

30. The compound of claim 29, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

31. The compound of claim 30, wherein R9 and R10 are both H.

32. The compound of claim 31, wherein R4 is H.

33. The compound of claim 1, wherein:
X is N; and
Y is CH.

34. The compound of claim 33, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

35. The compound of claim 34, wherein:
m and n are both zero; and
R7 is H.

36. The compound of claim 35, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

37. The compound of claim 36, wherein R9 and R10 are both H.

38. The compound of claim 37, wherein R4 is H.

39. The compound of claim 1, wherein the compound is selected from the group consisting of:
2,7-bis-guanidino-9H-fluorene;
2,7-bis-guanidinofluoren-9-one;
2,7-bis-guanidinoanthraquinone;
3,6-bis-guanidinoacridine;
2,7-bis-(N′′-ethoxycarbonyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl)guanidinofluoren-9-one;
2,7-bis(N′′-ethoxycarbonyl-N′-methyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-isopropyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-methoxy)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-isobutoxy)guanidine-9H-fluorene;
2,7-bis(N′-methyl)guanidino-9H-fluorene;
2,7-bis(N′-iso-propyl)guanidino-9H-fluorene;
2,7-bis(N′-methoxy)guanidino-9H-fluorene;
2,7-bis(N′-isobutoxy)guanidine-9H-fluorene;
2,7-bis[(phenylimino)amino)]-9H-fluorene; and
2,7-bis[(2-pyridylimino)amino)-9H-fluorene.

40. A pharmaceutically acceptable salt, wherein the pharmaceutically acceptable salt is the salt of a compound of Formula I:




wherein:
X and Y are each independently selected from the group consisting of CH, CH2. N, C═O, S, and NR3,
wherein R3 is selected from the group consisting of H, alkyl, aryl, alkoxyl, and aryloxyl, and
Y can be present or absent, and when absent, is replaced by a direct bond;

R1 and R2 are each independently selected from the group consisting of H, alkyl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;
m and n are integers from 0 to 3, provided that when m is zero, R1 is an implied hydrogen, and when n is zero, R2 is an implied hydrogen;
p and q are each 1;
A and A′ are each




wherein:
R4, R7, and R8 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or
R8 is






wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

41. The pharmaceutically acceptable salt of claim 40, wherein the salt is a hydrochloride salt.

42. A pharmaceutical formulation comprising:
(a) a pharmaceutically acceptable carrier; and
(b) a compound of Formula I:





wherein:
X and Y are each independently selected from the group consisting of CH, CH2, N, C═O, S, and NR3,
wherein R3 is selected from the group consisting of H, alkyl, aryl, alkoxyl, and aryloxyl, and
Y can be present or absent, and when absent, is replaced by a direct bond;

R1 and R2 are each independently selected from the group consisting of H, alkyl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;
m and n are integers from 0 to 3;
p and q are each 1;
A and A′ are each




wherein:
R4, R7, and R8 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or
R8 is






wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl;




or a pharmaceutically acceptable salt thereof.

43. The formulation of claim 42, wherein:
X is CH2; and
Y is absent.

44. The formulation of claim 43, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

45. The formulation of claim 44, wherein:
m and n are both zero; and
R7 is H.

46. The formulation of claim 45, wherein:
R4 is H; and
R8 is phenyl.

47. The formulation of claim 45, wherein:
R4 is H; and
R8 is 2-pyridyl.

48. The formulation of claim 45, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

49. The formulation of claim 48, wherein R4 and R9 are each H.

50. The formulation of claim 49, wherein R10 is H.

51. The formulation of claim 49, wherein R10 is methyl.

52. The formulation of claim 49, wherein R10 is isopropyl.

53. The formulation of claim 49, wherein R10 is methoxyl.

54. The formulation of claim 49, wherein R10 is iso-butoxyl.

55. The formulation of claim 48, wherein:
R4 is ethoxycarbonyl; and
R9 is H.

56. The formulation of claim 55, wherein R10 is H.

57. The formulation of claim 55, wherein R10 is methyl.

58. The formulation of claim 55, wherein R10 is isopropyl.

59. The formulation of claim 55, wherein R10 is methoxyl.

60. The formulation of claim 55, wherein R10 is iso-butoxyl.

61. The formulation of claim 42, wherein:
X is C═O; and
Y is absent.

62. The formulation of claim 61, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

63. The formulation of claim 62, wherein:
m and n are both zero; and
R7 is H.

64. The formulation of claim 63, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

65. The formulation of claim 64, wherein R9 and R10 are both H.

66. The formulation of claim 65, wherein R4 is H.

67. The formulation of claim 65, wherein R4 is ethoxycarbonyl.

68. The formulation of claim 42 wherein:
X and Y are both C═O.

69. The formulation of claim 68, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

70. The formulation of claim 69, wherein:
m and n are both zero; and
R7 is H.

71. The formulation of claim 70, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

72. The formulation of claim 71, wherein R9 and R10 are both H.

73. The formulation of claim 72, wherein R4 is H.

74. The formulation of claim 42, wherein:
X is N; and
Y is CH.

75. The formulation of claim 74, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

76. The formulation of claim 75, wherein:
m and n are both zero; and
R7 is H.

77. The formulation of claim 76, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

78. The formulation of claim 77, wherein R9 and R10 are both H.

79. The formulation of claim 78, wherein R4 is H.

80. The formulation of claim 42, wherein the compound is selected from the group consisting of:
2,7-bis-guanidino-9H-fluorene;
2,7-bis-guanidinofluoren-9-one;
2,7-bis-guanidinoanthraquinone;
3,6-bis-guanidinoacridine;
2,7-bis-(N′′-ethoxycarbonyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl)guanidinofluoren-9-one;
2,7-bis(N′′-ethoxycarbonyl-N′-methyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-isopropyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-methoxy)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-isobutoxy)guanidine-9H-fluorene;
2,7-bis(N′′-methyl)guanidino-9H-fluorene;
2,7-bis(N′-iso-propyl)guanidino-9H-fluorene;
2,7-bis(N′-methoxy)guanidino-9H-fluorene;
2,7-bis(N′-isobutoxy)guanidine-9H-fluorene;
2,7-bis[(phenylimino)amino)]-9H-fluorene; and
2,7-bis[(2-pyridylimino)amino)-9H-fluorene.

81. A method of treating microbial infection in a subject in need thereof, the method comprising administering to the subject an effective amount of a compound of Formula I:




wherein:
X and Y are each independently selected from the group consisting of CH, CH2, N, C═O, S, and NR3,
wherein R3 is selected from the group consisting of H, alkyl, aryl, alkoxyl, and aryloxyl, and
Y can be present or absent, and when absent, is replaced by a, direct bond;

R1 and R2 are each independently selected from the group consisting of H, alkyl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;
m and n are integers from 0 to 3;
p and q are each 1;
A and A′ are each




wherein:
R4, R7, and R8 are each independently selected from the group consisting of H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or
R8 is






wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl;




or a pharmaceutically acceptable salt thereof.

82. The method of claim 81, wherein:
X is CH2; and
Y is absent.

83. The method of claim 82, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

84. The method of claim 83, wherein:
m and n are both zero; and
R7 is H.

85. The method of claim 84, wherein:
R4 is H; and
R8 is phenyl.

86. The method of claim 84, wherein:
R4 is H; and
R8 is 2-pyridyl.

87. The method of claim 84, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

88. The method of claim 87, wherein R4 and R9 are each H.

89. The method of claim 88, wherein R10 is H.

90. The method of claim 88, wherein R10 is methyl.

91. The method of claim 88, wherein R10 is isopropyl.

92. The method of claim 88, wherein R10 is methoxyl.

93. The method of claim 88, wherein R10 is iso-butoxyl.

94. The method of claim 87, wherein:
R4 is ethoxycarbonyl; and
R9 is H.

95. The method of claim 94, wherein R10 is H.

96. The method of claim 94, wherein R10 is methyl.

97. The method of claim 94, wherein R10 is isopropyl.

98. The method of claim 94, wherein R10 is methoxyl.

99. The method of claim 94, wherein R10 is iso-butoxyl.

100. The method of claim 81, wherein:
X is C═O; and
Y is absent.

101. The method of claim 100, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

102. The method of claim 101, wherein:
m and n are both zero; and
R7 is H.

103. The method of claim 102, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

104. The method of claim 103, wherein R9 and R10 are both H.

105. The method of claim 104, wherein R4 is H.

106. The method of claim 104, wherein R4 is ethoxycarbonyl.

107. The method of claim 81 wherein:
X and Y are both C═O.

108. The method of claim 107, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11;
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

109. The method of claim 108, wherein:
m and n are both zero; and
R7 is H.

110. The method of claim 109, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11,
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

111. The method of claim 110, wherein R9 and R10 are both H.

112. The method of claim 111, wherein R4 is H.

113. The method of claim 81, wherein:
X is N; and
Y is CH.

114. The method of claim 113, wherein R8 is selected from the group consisting of aryl and



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

115. The method of claim 114, wherein:
m and n are both zero; and
R7 is H.

116. The method of claim 115, wherein R8 is



wherein:
R9 and R10 are each independently selected from the group consisting of H, alkyl, aryl, and —OR11; and
wherein:
R11 is selected from the group consisting of H, alkyl, and aryl.

117. The method of claim 116, wherein R9 and R10 are both H.

118. The method of claim 117, wherein R4 is H.

119. The method of claim 81, wherein the compound is selected from the group consisting of:
2,7-bis-guanidino-9H-fluorene;
2,7-bis-guanidinofluoren-9-one;
2,7-bis-guanidinoanthraquinone;
3,6-bis-guanidinoacridine;
2,7-bis-(N′′-ethoxycarbonyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl)guanidinofluoren-9-one;
2,7-bis(N′′-ethoxycarbonyl-N′-methyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-isopropyl)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-methoxy)guanidino-9H-fluorene;
2,7-bis(N′′-ethoxycarbonyl-N′-isobutoxy)guanidine-9H-fluorene;
2,7-bis(N′-methyl)guanidino-9H-fluorene;
2,7-bis(N′-iso-propyl)guanidino-9H-fluorene;
2,7-bis(N′-methoxy)guanidino-9H-fluorene;
2,7-bis(N′-isobutoxy)guanidine-9H-fluorene;
2,7-bis[(phenylimino)amino)]-9H-fluorene; and
2,7-bis[(2-pyridylimino)amino)-9H-fluorene.

120. The method of claim 81, wherein the compound of Formula I is administered in the form of a pharmaceutically acceptable salt.

121. The method of claim 120, wherein the pharmaceutically acceptable salt is a hydrochloride salt.

122. The method of claim 81, wherein the microbial infection is selected from one of a Trypanosoma brucei rhodesiense infection and a Plasmodium falciparum infection.