TRIAMINO PLATINUM COMPLEXES AND A METHOD FOR THE SYNTHESIS THEREOF

Abstract: Compounds of general formula (I) [(am)2 Pt H2N-R Cl]<+> Cl<-> (HCl)n (H2O)m wherein: am is an amino monodentate ligand selected from the group consisting of NH3, straight or branched C1-C5 alkylamine, straight or branched C1-C3 dialkylamine, cyclopropylamine, cyclopentylamine, cyclohexylamine; or both am groups, taken together, from a bidentate amino ligand selected from the group consisting of a C2-C8 alkyl-1,2-diamine or a straight or cyclic C3-C8 alkyl-1,3-diamine; R is a group of formula p-NH2-C6H4-CO-X-(CH2)2-NRaRb where X is selected from the group consisting of O, NH and CH2, Ra and Rb, which are the same or different, are each a straight or branched C1-C4 alkyl and n and m, independently each other, are 0 or 1. Said complexes have antitumor activity.

Description: TRIAMINO PLATINUM COMPLEXES AND A METHOD FOR THE SYNTHESIS THEREOF The present invention relates to ionic cis-tria- mino platinum (II) complexes of general formula I [(a ) 2 Pt H 2 N-R Cl] + Cl " (HCl) n (H 2 0) m (I) wherein: a is an amino monodentate lig 3 and selected from the group consisting of NH straight or branched C,-C-. alkylamine, straight or branched C,-C 3 dialkylamine, cyclopropylamine, cyclopentylamine, cyclohexylamine ; or both a groups, taken together, from a bidentate amino ligand selected from the group consisting of a C.-C R alkyl-1, 2-diamine or a straight or cyclic C,-C ft alkyl- 1,3-diamine ; R is a group of formula p-NH.-CgH.-CO-X-(CH_ ) _-NRaRb where X is selected from the group consisting of O, NH and CH_, Ra and Rb, which are the same or different, are each a straight or branched C . -C . alkyl and n and m, independently each other, are 0 or 1. further objects of the present invention are a process for the preoaration of compounds of formula I and pharmaceutical compositions containing them. A straight or branched C--C-. alkylamine is prefe¬ rably propyla ine, isoDropylamine, n-pentylamine. A straight or branched C,-C, dialkylamine is pre¬ ferably diisopropylamine. A straight C.-CQ alkyl-1, 2-diamine is preferably 1, 2-ethylenediamine or 1, 2-butanediamine (1-, d- , dl- or eso) . A cycloaliphatic C,-C„ alkyl-1, 2-diamine is prefe- rably 1,2-cyclopentanediamine (1-, d-, dl- or meso 1,2-cyclohexanediamine (1-, d-, dl- or meso) or 1,2-c cloheptanediamine (I-, d-, dl- or meso). A straight C,-C 8 alkyl-1,3-diamine is preferab 1,3-propylenediamine. A cyclic C 3 -C 8 alkyl-1,3-diamine is preferab 1,1-bis-aminomethylcyclopentane or 1,1-bis-aminomethy cyclohexane. The most particularly preferred ligand a is t onodentate ligand NH-.; said amino monodentate ligan a are specifically cis-oriented with respect to the atom. Ra and Rb are preferably both ethyl. X is preferably 0. When n is the integer 1, the compounds of th invention are addition salts, when m is the integer 1 the compounds of the invention are solvates and contai a molecule of crystallization water. A particularly preferred compound of the inventio is cis-diamino-chloro-4-[diethylammoniumethoxycarbonyl phenyll mino-platinum (II) + bis-chloride monohydrate. The compounds of the invention of formula I ar obtained through a process consisting of the followin steps: a) reaction of a cis-dia ino dichloro platinum (II) complex of formula II (a m ) 2 Pt Cl 2 (II) wherein am is as above defined, with a molar excess of an amine or a salt thereof of formula III H 2 N-R (HCl) n (H 2 0) (III) wherein R, m and n are as above defined; b) purification and optional crystallization of a obtained compound of formula I. The reaction is preferably carried out by usi aqueous solutions or suspensions of the reactants, bu if desired, other solvents, such as C,-C, alcohols, d methylformamide and aqueous mixtures thereof, may used. Particularly preferred reaction conditions a those providing the use of aqueous solutions containi the hydrochlorides of the amines of formula III molar excess, which, with respect to cis-dichloro pl tinum (II) complex of formula II, can range from 1.5 5 molar equivalents. Particularly preferred mol excess ranges from 2.8 to 3.2 molar equivalents; be reaction conditions use at least three amine (or a sa thereof) molar equivalents per mole of dichlo platinum (II) comDlex of formula II. The reaction may be carried out both by mixing t aqueous solutions of the reactant and by adding dichloro platinum (II) complex of formula II to aqueous solution of an amine salt of formula III: t mixture is then kept under stirring for a time rangi from some hours to some days, at a temperature rangi from room temperature to the solvent reflux on Preferred reaction temperatures are those between and 80°C, for periods of time from 24 to 56 hours Particularly preferred reaction conditions are tho comprising a reaction temperature- of about 55°C and period of time of about 48 hours. The isolation and purification of the reacti products can be performed by column chromatography. example, the reaction mixture, after concentrating i to small volume, can directly be purified by means o preparative chromatography in a "low pressur preparative TC system", using water as the eluant at flow rate of 1.6 ml/ in. Such an operation is carried out on a chromato graphic device supplied by Pharmacia LKB and consistin of: one peristaltic pump Varioperpex II 2120, one column KX (72 x 1.6 cm), having Sephadex G10 as statio- nary phase, one UV-Vis detector Uvicord S 2138, opera¬ ting at / L 206 n (cell lenght = 5 cm, ABS range -. 1) , one potentiometric recorder LKB 2210 and one fraction collector LKB 2111 Multirac. The eluate is evaporated to dryness and, if desired, the solid residue is crystallized from an ap¬ propriate solvent. Preferred crystallization solvents are acetone, C,-C, alcohols, diethyl ether, methyl or ethyl formate or acetate, acetonitrile and mixtures thereof. Solvent elimination or concentration, if desired, is carried out by vacuum-evaporation or freeze-drying. The freeze-drying process is particularly preferred in the case of aqueous solutions. Cis-tria ino platinum (II) complexes of the inven- tion of formula I are highly soluble salts into aqueous solvents. The good to optimum water solubility of the "in toto" molecule is due to the platinum (II) complex part, which is Dresent as salt countercation. In the compounds of formula I of the invention, wherein n is the integer 1, the contemporaneous solvation of the trialkylammonium group brings a further contribution the solubility of the compounds into the aqueo solvents. The dichloro platinum (II) complexes of formula are well-known compounds, which are commercial available or easily prepared by means of well-kno methods . The amines (and the hydrochlorides thereof) formula III, wherein X is 0 or NH, are esters or amide of 4-aminobenzoic acid and are well-known for their us in therapy as local anaesthetics and antiarhytmi agents. On their turn, the compounds of formula III wherein X is CH_ , are Mannich bases of 4 aminoacetophenone, and also they are well-known or ca be prepared with well-known methods. The formation of a cis-triamino chloro platinu (II) ionic complex of formula I, after reacting a cis diamino platinum complex of formula II and an amine (o a salt thereof) of formula III, is rather unexpected when instead in the same experimental conditions, th alternative use of 4-aminobenzoic acid (or the carboxy late salts thereof) gives only cis-diamino platinu (II) complexes having classical structure (Italia Patent Application 91A002072, of 26.07.1991). As far as a wide literature describes the prepara tion of many cis-triamino-complexes (see references 13 16 in H. Steven Hollis et al. , Journal of Medicina Chemistry, _32, 128, 1989), only recently and in thi reference, the preparation and pharmacological charac teristics of 34 triamino-platinum complexes of formul IV [Pt(NH 3 ) 2 (N-donor)Cl] + (IV) wherein the "donor" group represents groups having dif ferent electron donor strenghth, such as alkylamines, pyrimidines, purines and pyridines, in the form of ci and trans analogues, have been described. Although al these triamino platinum complexes resulted at th screening less potent and active than cis platinum, the best combination of antitumor activity and potency was found in the compounds of formula IV having pyridine, 4-bromopyridine and 4-methylpyridine as N-donors. It was also observed that, having the same substituents, the analogues containing a secondary or tertiary hete- rocyclic ligand resulted active, on the contrary the activity was lost in the tris-amino platinum (II) com- plexes wherein a primary amino group (such as 2-propy- lamine, octilamine and N_-l-methoxyisopropylamine) was the -donor group. Generally, the cis configuration of platinum (II) complex proved to be an indispensable feature for the activity, as much as the nature of the chelating amine (A ) 2 (compounds wherein (A )_ is 1,2- diaminoethane or DACH were found inactive). As far as known to date, the great part of the active cis-platinum analogues are neutral complexes capable of binding in bidentate way to their supposed biological target (DNA) . Only for a very limited number of ionic platinum complexes a in vivo antitumor activity has been described; the ionic complexes endowed with a certain in vivo antitumor activity are for the major part anionic complexes (see J.P. Marquet et al. , J. Natl. Cancer Inst. , 2' 899 ' 1983 and E - Berganetti et al. , Inorg. Chim. Acta, 93, 167, 1984). The few examples of cationic complexes containing thr amino groups as donors ((M.J. Cleare et al. , Bioinor Chem. , 2_, 187, 1973 and J.P. Marquet et al. , vi supra), described before in the above cited Hollis paper, were always and invariably found devoid activity in screening on S180a and L 1210. The compounds of the invention, and particular cis-diamino-chloro-4-[diethylammoniumethoxycarbonylphe nyl . amino-platinum (II) bis-chloride monohydrate (ci DPR) , resulted instead to be endowed with a significa cytotoxyc activity, at least comparable with the one cis-platinu (cis-DDP), when tested in_ vitro again P388 murine leukemic cells, K562 human erhytroleukem cells and Jurkat human cells. The compounds of the invention proved to be acti also against cis-platin (cis-DDP) resistant tum cells. Cis-platinum (cis-DDP) and cis-DPR cytotoxic acti vities have been evaluated on the sensible and cis platinum resistant L 1210 murine leukemia cell lines by using the 24 hours-thymidine uptake method, afte continuous exposition to the drugs. In this test, 1210/cis-DDP line proved to be about 11 times more re sistant than the parental L 1210 line towards cis-DD cytotoxic activity, while the above line showed a resi stance index towards cis-DPR of about 1.9. As to th cis-DDP and cis-DPR IC 5Q s on L 1210/cis-DDP cell line cis-DPR showed an activity about 10 times greater tha the cis-DDP one. Cis-DPR resulted about 1.6 times mor active than cis-DDP also on the parenteral L 1210 cel line. The results shown in Table 1 suggest that cis-DP is capable of overcoming cisplatinum resistance. TABLE 1 IC 50 (μM) cis-DDP cis-DPR L1210 0. 84±0.09 0. 51±0. 08 v L1210 /cis-DDP 9 . 60±2.80 0. 97±0. 17 C IR d 11.4 1. 9 a Concentration producing 50% of inhibition b Mean ±SD c p<0,01 compared to cis-DDP Resistance index. On the other hand, and advantageously, the sam compounds resulted significantly less active on bloo peripheral mononuclear and non tumoral cells stimulate with phorbol acetate (cis-DPR: IC- Q =1.88 ± 0.34(SD) versus cis-DDP: IC 5Q =0.97 ± 0.14(SD), p<0.05). An in vivo compared antitumor activity assay i BDF1 mice, infected with P388 leukemic cells, showe the high activity of cis-DPR, at least comparable to the one obtained with the maximum tolerated dose of cis-DDP in terms of percent body weight variation (a 4.5% increase with cis-DPR versus a 10.6% decrease with cis-DDP) at the doses giving the highest increase in life span (ILS 75%, 21 and 8 mg/kg, respectively, after single administration). The compounds of the invention are further charac ¬ terized by their poor (almost absent) renal toxicity. For example, after acute intraperitoneal administration to female BDFl mice of equitoxic cis-DPR and cis-DD doses (corresponding to the LE- CQ of the two compounds which were evaluated in 39.3 mg/kg (cis-DPR) and i 16.5 mg/kg (cis-DDP) dissolved into 0.9% aqueous NaCl) no evaluable kidney damages resulted after treatmen with cis-DPR nor as plasma BUN increase, nor after exa mination of renal tubules. The damages are well eviden in the case of cis-DDP, where plasma BUN increas appears to be well related with the degenerative modi fications of the proximal tubules, which are completel absent in the case of the compounds of the invention. Accordingly, the compounds of formula I are parti cularly advantageous and useful for the treatment o platinum-sensitive tumors. The high solubility an stability in the common aqueous solvents make the in travenous administration easy, contrarily to the othe platinum (II) complexes, which are poorly hydrosoluble The low renal toxicity of the compounds of th invention lead to think that, during and after thei administration, the occurrence to the prolonged hydra tion regimen of the patient (in order to preven hypotetic damages towards the kidney) will be les frequent with evident benefit for the therapeuti regimen compliance. The effective dosage of the compounds of the in vention can be determined by an expert physician wit well-known and conventional methods. The correlatio between the doses used with animals of several specie 2 and sizes and the human ones (based on mg/m of bod surface) is described by Freirech, E.J., et al. , i Cancer Chemother. Rep., 50, N. 4, 219-244, 1966. However, doses usually from 1 to 1200 mg/kg of th complex will be administered with a variable posolog depending on several factors which are well known t the expert physician. The treatment regimen can appropriately be varie according to the kind of tumor to be treated and the patient's conditions. The compounds of the invention are preferably administered in the form of sterile aqueous solutions, Dreferably by intravenous or in- traartherial route, although other administration routes may be appropriate in particular cases. The pharmaceutical compositions useful for the pa- renteral administrations comprise sterile aqueous solu¬ tions or powders for the extemporary preparation of solutions, as well as oleous formulations for intramu¬ scular or i traperitoneal administration. Other useful pharmaceutical compositions can be syrups or similar liquid compositions, as well as solid compositions such as tablets, capsules or the like. The following example illustrates a typical prepa¬ ration of the compounds of the invention. EXAMPLE 30 g of cis-diamino dichloro platinum (II) were added to 30 ml of an aqueous solution of N-diethylammo- niumethyl o-aminobenzoate chloride (82 mg) in a 1:3 molar ratio. The mixture was kept under constant stir¬ ring for 48 hours at 55°C, then the mixture was concen¬ trated, under reduced pressure in an rotary evaporator, down to 2 ml. The residue was injected in a low pres- sure TC preparative system; the elution was carried out with water at a flow rate of 1.6 ml/ in. 3.2 ml fractions were collected, the fractions 24-36, conta ning the complex, were gathered and evaporated dryness under reduced pressure in a warm bath (40°C The solid residue was dissolved in methanol (10 ml after diluting the solution with diethyl ether a cr stalline precipitate separated. The crystallization w almost complete in about 1 hour at room temperatur after filtration and washing of the solids with 1 methanol/diethyl ether, 25 mg of cis-diamino-chloro- [diethylammoniumethoxycarbonylphenyl]amino-platinum (II) + bis-chloride monohydrate (cis-DPR) were colle ted, which after recrystallization from the sa solvent showed .p. 173-176°C with decomposition. Elemental analysis C.-H^Cl.N.Pt.H 2 0 found %: 26,58; H 4,95; N 9,36; calc. %: C 26,43; H 4,95; 9,48. The following Table 2 shows the most significa U.V. , I.R. and HNMR spectroscopy absorptions. TABLE 2 UV, IR and 1 H-NMR data of cis-DPR —1 X max log £ , wn (cm " ) <$ ■ (ppm) (n ) 202 4.22 3470-3300 (m) (NH 2 ) 8.10 (d, J=8 Hz, 2 -CH=C-C0-) 244 4.13 3160-3080 (m) (NH-.) 7.45 (d, J=8 Hz, 2 -CH=C-NH 2 ) t 2710-2660 (m) (NH + ) 3.65 (m, -C0-0-CH,-,-CH 2 -) 1710 (s) (O=0) 3.35 (q, J=7.4 Hz, 2 CH-.-CH 2 -) 1610 ( ) (C=C) 1.35 (t, J=7.4 Hz, 2 CH..-CH 2 -) 600- 400 (w) (Pt=N) 330 (w) (Pt-Cl)

Claims: CLAIMS 1. Compounds of general formula I [(am) I, Pt H,N-R Cl] + Cl~ (HCl) n n (H, _L0) m m (I wherein: am is an amino monodentate ligand selected from t group consisting of NH_ , straight or branched C,- alkylamine, straight or branched c ι ~ c 3 dialkylamin cyclopropylamine, cyclopentylamine, cyclohexylamine; both a groups, taken together, from a bidentate amin ligand selected from the group consisting of a C-.-C alkyl-1,2-diamine or a straight or cyclic C--C 8 alkyl 1,3-diamine; R is a group of formula p-NH_-C 8 H.-CO-X-(CH_) 2 -NRaR where X is selected from the group consisting of 0, N and CH„, Ra and Rb, which are the same or different are each a straight or branched C.-C. alkyl and n an , independently each other, are 0 or 1. 2. Compounds according to claim 1, wherein a is monodentate amine ligand selected from the group consi sting of: NH-, Dropylamine, isopropylamine, n-pentyla mine, diisopropyla ine, cyclopropylamine, cyclopentyla mine and cyclohexylamine. 3. Compounds according - to claim 1, ' wherein both a together form a bidentate aminic ligand ( a ) _ selecte from the group con si st ing of 1 , 2-ethylenediamine , 1 , 2 butanediamine , 1 , 2-cyclopentanediamine , 1 , 2-cyclohexa nediamine , 1 , 2-cyc loheptanediamine , 1 , 3-propylenedia mine , 1 , 1-bis aminomethylcyclopentane , 1 , 1-bis amino methylcyc lohexane . 4 . Compounds according to claims 1-2 , wherein both a are NH,, cis-oriented with respect to Pt atom. 5. Compounds according to claims 1-4, wherein X is 0, Ra and Rb are both ethyl, m and n are the integer 1. 6. A compound according to claim 1, which is cis-dia- mino-chloro-4-[diethylammoniumethoxycarbonylphenyl]ami- no-platinum (II) + bis-chloride monohydrate. 7. A process for the preparation of the compounds of the claims 1-6, which comprises: a) reaction of a cis-diamino dichloro platinum (II) complex of formula II wherein am is as above defined, with a molar excess of an amine or a salt thereof of formula III H 2,N-R (HC1)n (H2,0)m (III) wherein R, m and n are as above defined; b) purification and optional crystallization of a so obtained compound of formula I. 8. Pharmaceutical compositions containing one or more compounds of the claims 1-6 as active ingredients. 9. The use of the compounds of the claims 1-6 as the¬ rapeutic agents. 10. The use of the compounds of the claims 1-6 for the manufacturing of - a medicament having antitumor activity.

Inventors: ESPOSITO MAURO, ESPOSITO, MAURO
Applicants: IST NAZ RIC SUL CANCRO, ISTITUTO NAZIONALE PER LA RICERCA SUL CANCRO
Application year: 1992
Main classification: C07F15
IPC codes: A61K31, C07F15