Patent Publication Number: US-2007105937-A1

Title: Indole-3-propionamide and derivatives thereof

Description:
This application claims priority to U.S. Provisional Application No. 60/532,108, filed on Dec. 22, 2003.  
      Throughout this application, various publications are referenced, many in parenthesis. Full citations for these publications are provided at the end of each part of the application. The disclosures of these publications in their entireties are hereby incorporated by reference in this application.  
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
      The subject matter of this application was made with support from the United States Government, National Institutes of Health Grant No. AG16783. The government may have certain rights in this application. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to the synthesis of indole-3-propionamide (IPAM) and related compounds, including, but not limited to, pharmaceutical or nutritional compositions thereof, and methods of using the compounds and compositions for the following:  
      1) Preventative and therapeutic indications, including, but not limited to, inflammatory, degenerative, genetic, free-radical mediated, neoplastic (malignant or pre-malignant), age-related or age-associated, traumatic or infectious diseases affecting an organ or system or the whole organism, human or animal including, but not limited to: systemic illnesses including central nervous system disorders (e.g., atherosclerosis, degenerative joint disease, Alzheimer&#39;s disease, Parkinson&#39;s disease and other neurodegenerative conditions including, but not limited to, amyotrophic lateral sclerosis, Huntington&#39;s disease, Lewy body disease, epilepsy) and trauma to any bodily area including the head; promotion of neuronal or cellular regeneration in acute, subacute or chronic injuries or conditions afflicting humans or animals including, but not limited to, the nervous system; inflammatory and free-radical mediated disorders including, but not limited to, aging and age-associated conditions such as those mentioned above, and including other disorders such as atherosclerosis or osteoporosis; vascular or ischemic diseases of the nervous system that include, but are not limited to, stroke, vascular (ischemic) dementia and migraine; proliferative disorders and related conditions affecting humans or animals including cellular atypia, dysplasia, pre-malignant and malignant stages of acute, subacute or chronic conditions; and prevention of degeneration of nerve cells (neurodegeneration) in the acute, subacute or chronic phase of cerebral injuries including, but not limited to, trauma or acute, subacute or chronic disorders of the nervous system such as neurodegenerative or ischemic disorders and epilepsy. The method comprises administering an effective amount of IPAM or salts thereof as an active ingredient and may include an suitable carrier thereof to a human or animal subject in need thereof to prevent or treat the above mentioned disorders that specifically include, but are not limited to, the mentioned conditions. In all of the conditions described above free radicals are known to play a role at some point in the pathogenesis by either causing or amplifying damage to biomolecules.  
      2) A method for delaying, inhibiting or treating normal or pathological aging and age related conditions, in which it is known that free radicals are known to play a role at some point in the pathogenesis by either causing or amplifying damage to biomolecules, the method comprising administering an effective amount of IPAM to a live multi or unicellular organism including human, animal or plant.  
      3) A method comprising administering or adding an effective amount of IPAM or salts thereof as an active ingredient with or without a suitable carrier to nutritional products or derivatives of nutritional products for the prevention, inhibition or treatment of the disorders or injuries listed above afflicting unicellular or multicellular life or life-like form including, but not limited to, bacteria, fungi, or plants.  
      4) A method comprising administering or adding of an effective amount of IPAM or salts thereof as an active ingredient with or without a suitable carrier to nutritional products or derivatives of nutritional products, including but not limited to foodstuffs and nutritional supplements, or agricultural products for enhancing the health promoting properties of such products, for the preservation of the products themselves, or for the treatment or prevention of conditions or injuries affecting the products or the intended consumer of the products.  
     BACKGROUND OF THE INVENTION  
      Oxidative damage increases in aging and age related disorders and is widespread in many neurodegenerative conditions including Alzheimer&#39;s disease, Parkinson&#39;s disease and others. In some of these conditions, clinical and epidemiological evidence suggest that anti-oxidants such as vitamin E may lower the risk or delay clinical milestones. Previous studies conducted by Pappolla et al. and Poeggeler et al. (Pappolla et al. 1998; Poeggeler et al 2001) have shown that anti-oxidants like melatonin may be useful in Alzheimer&#39;s disease and in other conditions characterized by oxidative (free-radical) damage. Experiments in a transgenic mouse model of Alzheimer&#39;s amyloidosis showed that melatonin inhibited the expected time dependent elevation of Aβ amyloid, ameliorated memory deficits and decreased the mortality in transgenic mice (data presented in the World Alzheimer&#39;s congress, 2000, Matsubara,et al. 2003).  
      Melatonin is a hormone which is synthesized and secreted primarily by the pineal gland and it acts both as a neurotransmitter and neurohormone. The hormone has the following structure:  
                 
 
 Being lipid soluble, melatonin rapidly crosses the blood brain barrier and other tissues. Once released from the pineal gland, which is highly vascularized, melatonin enters the general circulation and the cerebrospinal fluid (CSF). Melatonin acts on the central and peripheral nervous system as well as on peripheral endocrine target tissues and has been implicated in many human disorders. Some disorders are known to be linked to oxidative damage (free-radical damage) and others to chronobiologic abnormalities. 
 
      Interestingly, melatonin exhibits potent antioxidant and cellular protective (including neuroprotective) properties (Reiter, 1995), but, in contrast to conventional antioxidants, this hormone has a proposed physiologic role in the aging process (Pierpaoli, 1991; Pierpaoli et al., 1991) and decreased secretion of melatonin with aging is documented (Iguchi et al., 1982; Dori et al., 1994). In Alzheimer&#39;s disease, for example, there are reports of more profound reductions of melatonin secretion in populations with dementia than in non-demented controls (Souetre et al., 1989; Mishima et al., 1994). It has been suggested that altered secretion levels of the hormone may partially reflect the loss of daily variation in the concentration of melatonin in the pineals of elderly individuals and AD patients (Skene et al., 1990). Melatonin has also been shown to protect many cell types and tissues exposed to a large number of injuries including free-radical mediated, inflammation and others. Melatonin was shown to be effective in preventing death of cultured neuroblastoma cells as well as oxidative damage and intracellular Ca 2+  increases induced by a cytotoxic fragment of amyloid beta-protein (Pappolla et al., 1997). The use of melatonin for its cytoprotective effect in enhancing survivability of cells that have been subjected to the cytotoxic effects of amyloid beta protein (an abnormal neurotoxic substance that deposits in brains with Alzheimer&#39;s disease and also causes oxidative stress) as well as for treating patients afflicted with Alzheimer&#39;s Disease is disclosed in U.S. Pat. No. 5,958,964 (Pappolla) and U.S. Pat. No. 6,274,615 (Pappolla et al.).  
      In addition, it has been reported that melatonin has oncostatic properties in a variety of cancers, the most studied being melatonin&#39;s effects on estrogen receptor positive breast cancers (Blask et al 1986; Gonzalez et al. 1991; Lisoni et al. 1993; Shellard et al.1989; Philo et al. 1988; see U.S. Pat. No. 5,196,435 of Clemens et al. and U.S. Pat. No. 5,272,141 of Fraschini et al.).  
      Research into the structure of indoles by a number of laboratories suggests that the antioxidant and neuroprotective features of these substances might be preserved in a spectrum of many related compounds. Some of these are structurally related, but due to modifications in their chemical structure, they have preserved antioxidant and neuroprotective features with more therapeutically advantageous properties. An example of one such indole structure is indole-3-propionic acid (IPA), which has the following structure:  
                 
 
 IPA exhibited more powerful antioxidant properties than melatonin (about a 6 fold increase) but in contrast to most antioxidants (including melatonin), it did not form pro-oxidant intermediates (Chyan et al., 1999). Significantly, IPA also has a longer half-life than melatonin (4.5 hr versus 20 minutes). Despite the mentioned advantages, there remains the fact that IPA is not as lipophilic as melatonin and blood brain barrier penetration for IPA is rather poor (BBB penetration ratio melatonin: IPA=100:1), requiring large doses of the compound to attain the desired neuroprotective effects. The use of IPA to prevent cytotoxic effects of amyloid beta protein, to treat fibrillogenic diseases, to decrease oxidation in biological samples, and to treat diseases or other conditions where free radicals and/or oxidative stress play a role was disclosed in U.S. Pat. No. 6,395,768 (Pappolla et el.) and is hereby incorporated by reference. 
 
     SUMMARY OF THE INVENTION  
      In order to overcome the disadvantages of IPA, the inventors herein have discovered that IPAM, indole-3-propionamide (3-(3-indolyl)propionamide), its derivatives, analogs and related compounds have unique properties that are more effective for the disclosed uses than IPA and its derivatives. IPAM exhibits a three-dimensional structure of an amide resembling a “reversed melatonin” and integrates the best structural features of melatonin and IPA overcoming the main limitations of both drugs, i.e. poor BBB penetration and short half-live. The general structure of IPAM and its derivatives are represented by Formula III:  
                 
 
 wherein X and Y are either hydrogen or an alkyl, aryl or arylalkyl group; and R 1  through R 6  are either hydrogen, a halogen, or a hydroxy, alkoxy, alkyl, aryl, alkoxyalkyl, or alkyaryl group. 
 
      The general structure of IPAM related compounds are represented by Formula IV:  
                 
 
 wherein X and Y are either hydrogen or an alkyl, aryl or arylalkyl group; R 1  through R 6  are either hydrogen, a halogen, or a hydroxy, alkoxy, alkyl, aryl, alkoxyalkyl, or alkyaryl group; and R 7  is either an alkyl, aryl or arylalkyl group. 
 
      When the term “IPAM” is used herein it is understood that IPAM analogs and/or derivatives and related compounds, and pharmaceutically suitable salts thereof, are included by the term.  
      In contrast to indole-3-propionic acid which bears a polar carboxyl group which is ionized at physiological pH carrying a negative charge, IPAM and its related compounds are non polar with sufficient lipophilicity (and amphiphilicity) to penetrate the BBB. In contrast to melatonin, IPAM and its related compounds are “reversed amides” lacking the methoxy group as an aromatic substituent. Melatonin is quickly metabolized in the liver by hydroxylation in para position to its large side chain (extensive first pass effect with rapid clearence) and excreted as the glucuronide or sulfate conjugate of 6-hydroxy-melatonin. IPAM and its related compounds, however, have a long half-live and can accumulate in mammalian tissues with its high stability and bioavailability due to the amide structure as illustrated.  
      The inventors herein initially discovered IPAM in rodent bile and have also observed endogenous IPAM in the gastrointestinal tract, brain and cerebrospinal fluid of mice and rats. Most significantly is IPAM lipophilic characteristics that allow this newly identified molecule to penetrate through many cell membrane compartments. Although indole-3-propionamide was already known as a molecular structure related to melatonin (Suzen et al 2001) its properties as documented herein were not previously recognized.  
      In the experiments detailed below, IPAM exhibits powerful free-radical scavenging properties like melatonin, IPA and other indole compounds but with superior pharmacokinetic properties making the compounds useful in a number applications including, but not limited to, increasing life span of human, animals and uni-cellular or multi-cellular organisms, but particularly in higher vertebrates and humans, in which both, penetration through biologic barriers and half life (IPAM has a better half life profile than other thus far known indole related structures) are paramount for therapy efficacy. These properties would make the compound useful for prevention and treatment of a large number of conditions, for use in health promoting strategies, and as a preservative or additive agent for foodstuffs, nutritional supplements or agricultural products. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  presents the results of a Thioflavin T spectrofluorometric analysis illustrating the inhibition of Aβ aggregation. 
    
    
     PREFERRED EMBODIMENTS OF THE INVENTION  
      In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.  
      Dosage and Formulation  
      IPAM and its related compounds can be administered by any means that produces contact of the active agent with the agent&#39;s site of action. Sites of action include the body of a subject or animal, a cell or living organism. Sites of action may also include, but are not limited to, foodstuffs, nutritional supplements or agricultural products. For any application, IPAM and its related compounds can be prepared by any conventional means available for use either alone or in conjunction with other pharmaceuticals, vitamins or cytoprotective or bioprotective agents. It can be administered totally alone, but the preferred means of administration is in conjuntion with a pharmaceutical carrier selected on the basis of the chosen route of administration and standard pharmaceutical practice. The pharmaceutical compositions of the invention may be adapted for oral, parenteral, rectal, transdermal and nasal administration, and may be in unit dosage form, as well known to those skilled in the pharmaceutical art. The active ingredient for oral administration in solid dosage forms includes, for example, tablets, capsules or powders, or in liquid dosage forms, such as aqueous or oily suspensions, disperse powders or granules, emulsions, hard or soft capsules, or syrups or elixirs. Compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions may contain one or more agents selected from the group consisting of sweetening agents, flavoring agents, coloring agents, and preserving agents in order to provide a pharmaceutically elegant and palatable preparation. Tablets contain the active ingredient in admixture with non-toxic pharmaceutically acceptable excipients, which are suitable for manufacture of tablets, for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate, or sodium phosphate; granulating disintegrating agents, e.g., maize starch, or alginic acid; binding agents, such as starch, gelatin, or acacia; and lubricating agents, for example, magnesium stearate, stearic acids or talc. The tablets may be uncoated or they may be coated by known techniques to delay disintegration and adsorption in the gastrointestinal tract. Thereby a sustained action over a longer period can be provided.  
      Formulations for oral use can also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, e.g., calcium carbonate, calcium phosphate, or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with an oil medium, such as arachis oil, liquid paraffin or olive oil.  
      Aqueous suspensions contain the active compound in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients are suspending agents including but not limited to sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, sodium alginate, polyvinylpyrrolidone, gum tragacanth, and gum acadia; dispersing or wetting agents, such as a naturally-occurring phosphatide, e.g., lecithin, or condensation products of an alkylene oxide with fatty acids, for example of polyoxyethylene stearate, or a condensation products of ethylene oxide with long chain aliphatic alcohols, e.g., heptadecaethyleneoxycetanol, or condensation products of ethylene oxide with partial esters derived from fatty acids and a hexitol, e.g., polyoxyethylene sorbitol monooleate, or a condensation product of ethylene oxide with partial esters derived from fatty acids and hexitol anhydrides, e.g., polyoxyethylene sorbitan monooleate. The aqueous suspensions can also contain one or more preservatives, for example ethyl, n-propyl, or p-hydroxy benzoate, one or more coloring agents, one or more flavoring agents, and one or more sweetening agents, such as sucrose, saccharin, or sodium or calcium cyclamate.  
      Disperse powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, suspending agent and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified by those already mentioned above. Additional excipients, for example, sweetening, flavoring, and coloring agents, can also be present.  
      Syrups and elixirs can be formulated with sweetening agents, such as glycerol, sorbitol or sucrose. Such formulations may also contain a demulcent, a preservative and flavoring and coloring agents. The pharmaceutical compositions can be in the form of a sterile injectable preparation, for example, as a sterile injectable aqueous suspension. This suspension can be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents, which have been mentioned above. The sterile injectable preparation can also be a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent, for example, as a solution in 1,3-butane diol.  
      In general, a pharmacologically effective daily dose can be from about 0.01 mg to about 10 g per dose, bearing in mind, or course, that in selecting the appropriate dosage in any specific case, consideration must be given to the subject&#39;s weight, general health, metabolism, age and other factors which influence response to a drug.  
      The preferred embodiment of this invention is the provision of pharmaceutical compositions in dosage unit form, which comprise from about 0.5 mg to about 500 mg of a compound of the above formulae.  
      The optimization of prophylactic or therapeutic efficacy in administering IPAM or related compounds according to the method of the present invention, which optimization includes dosage, formulation for delivery (i.e., sustained release), administration schedule (i.e., intervals), can be determined by those of skill in the art with routine experimentation using conventional practices.  
      For non-in vivo administration (such as addition of IPAM or its related compounds as a food preservative), the optimization of the amount of the compound needed can be determined by those of skill in the art with routine experimentation using conventional practices.  
      It will also be appreciated that the actual preferred amount of IPAM or related compounds to be administered according to the present invention will vary according to the particular active forms of the compound (active forms include the use of IPAM structure as a pharmacophore, which is the active structure of the drug), the particular composition formulated, and the mode of administration. Many factors that may modify the action of IPAM or its related compounds can be taken into account by those skilled in the art e.g., body weight, sex, diet, time of excretion, condition of the subject, drug combinations, and reaction sensitivities and severities. Administration can be carried out continuously or periodically within the maximum tolerated dose. Optimal administration rates for a given set of conditions can be ascertained by those skilled in the art using conventional dosage administration tests.  
      Suitable routes of administration include systemic administration (because IPAM and its related compounds will cross the blood-brain barrier). Systemic administration includes parenteral and oral administration, for example, as discussed in further detail below.  
      The pharmaceutical compositions of the present invention also include compositions for delivery across cutaneous or mucosal epithelia including transdermal, intranasal, sublingual, buccal, and rectal administration. Such compositions may be part of a transdermal device, patch, topical formulation, gel, etc. with appropriate excipients. Thus, the compounds of the present invention can be compounded with a penetration-enhancing agent such as 1-n-dodecylazacyclopentan-2-one or the other penetration-enhancing agents disclosed in U.S. Pat. Nos. 3,991,203 and 4,122,170, which are hereby incorporated by reference in their entirety to describe penetration-enhancing agents which can be included in the transdermal or intranasal compositions of this invention.  
      The pharmaceutical compositions can be formulated so that for every 100 parts by weight of the composition there are present between 1 and 99 parts by weight of the active ingredient.  
      Having now generally described the invention, the same will be more readily understood through reference to the following examples, which is provided by way of illustration and is not intended to be limiting of the present invention.  
     SYNTHESIS OF 3-(3-INDOLYL)PROPIONAMIDE  
      IPAM and its related compounds can be prepared by methods generally known to those skilled in the art or by novel methods described herein. The method described below is only one of many available to those skilled in the art and is not exclusive of other methods to arrive to the compounds. One such method for preparation of the active ingredient of the novel pharmaceutical compounds of the present invention will be illustrated by the following non-limitative specific examples:  
      A mixture of 30 g of indole-3-propionic acid and 10 ml of methanesulfonic acid in 200 ml of ethanol was stirred for 24 hours, poured into water, and extracted with ethylacetate. The ethylacetate solution was washed with NaHCO 3  solution and water and dried over magnesium sulfate. A solution of 800 mg of the crude product (indole-3-propionic acid ethyl ester) and 2 ml of hydrazine in 20 ml of ethanol was refluxed for 18 hours, and extracted with ethylacetate. The organic phase was washed with brine, dried over magnesium sulfate, and evaporated at reduced pressure to give with 93% yield the intermediate propanoic acid hydrazide as a solid. This material and 0.3 g of Raney nickel catalyst (W-4) in 25 ml of ethanol were refluxed for 2.5 hours. The solution was decanted and evaporated at reduced pressure and the residue chromatographed on silicia gel, eluting with ethylacetate, to give with 96% yield indole-3-propionamide.  
      Pharmaceutically suitable salts of the compound of the invention can be prepared by reacting the free acid precursor or base forms of the compound with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent, or in a mixture of the two; generally, non-aqueous media like ether, ethyl acetate, ethanol, isopropanol, or acetonitrile are preferred. Lists of suitable salts are found in Remington&#39;s Pharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa., 1985, p. 1418, the disclosure of which is hereby incorporated by reference in its entirety.  
      As described above, the compounds of the present invention are generally useful in the treatment of indications including, but not limited to:  
      Preventative and therapeutic indications, including, but not limited to, inflammatory, degenerative, genetic, free-radical mediated, neoplastic (malignant or pre-malignant), age-related or age-associated, traumatic or infectious diseases affecting an organ or system or the whole organism, human or animal including, but not limited to: systemic illnesses including central nervous system disorders (e.g., atherosclerosis, degenerative joint disease, Alzheimer&#39;s disease, Parkinson&#39;s disease and other neurodegenerative conditions including, but not limited to, amyotrophic lateral sclerosis, Huntington&#39;s disease, Lewy body disease, epilepsy) and trauma to any bodily area including the head; promotion of neuronal or cellular regeneration in acute, subacute or chronic injuries or conditions afflicting humans or animals including, but not limited to, the nervous system; inflammatory and free-radical mediated disorders including, but not limited to, aging and age-associated conditions such as those mentioned above, and including other disorders such as atherosclerosis or osteoporosis; vascular or ischemic diseases of the nervous system that include, but are not limited to, stroke, vascular (ischemic) dementia and migraine; proliferative disorders and related conditions affecting humans or animals including cellular atypia, dysplasia, pre-malignant and malignant stages of acute, subacute or chronic conditions; and prevention of degeneration of nerve cells (neurodegeneration) in the acute, subacute or chronic phase of cerebral injuries including, but not limited to, trauma or acute, subacute or chronic disorders of the nervous system such as neurodegenerative or ischemic disorders and epilepsy. The method of treatment comprising administering an effective amount of IPAM or salts thereof as an active ingredient and may include an suitable carrier thereof to a human or animal subject in need thereof to prevent or treat the above mentioned disorders that specifically include, but are not limited to, the mentioned conditions; Inhibiting or treating normal or pathological aging and age related conditions comprising administering an effective amount of IPAM to a live multi or unicellular organism including human, animal or plant; Administering or adding an effective amount of IPAM or salts thereof as an active ingredient with or without a suitable carrier to nutritional products or derivatives of nutritional products for the prevention, inhibition or treatment of the disorders or injuries listed above afflicting unicellular or multicellular life or life-like form including, but not limited to, bacteria, fungi, or plants; and administering or adding of an effective amount of IPAM or salts thereof as an active ingredient with or without a suitable carrier to nutritional products or derivatives of nutritional products, including but not limited to foodstuffs and nutritional supplements, or agricultural products for enhancing the health promoting properties of such products, for the preservation of the products themselves, or for the treatment or prevention of conditions or injuries affecting the products or the intended consumer of the products.  
     EXAMPLE 1  
      An important feature of IPAM, as compared to other neuroprotective indoles such as melatonin or indolepropionic acid is the combination of both, longer half life and lipophilic properties as demonstrated in the following example:  
      Time dependent changes in indole levels in brain tissue (pg/mg protein) after administration of 0.5 mg/kg i.p. of drug in phosphate buffered saline to one month old male Sprague-Dawley rats (N=4 animals, mean+SD). Endogenous levels of melatonin in saline treated control animals were 25+10 pg/mg protein, endogenous levels of indolepropionate were 80+20 pg/mg protein. Significant amounts of endogenous IPAM in rat brain could not be detected. Brain tissue was homogenized 1:10 in phosphate buffer and extracted 1:1 with ethylacetate. Recovery for melatonin, indolepropionate and IPAM were 57+6, 69+12 and 80+4%. Indoles were measured by HPLC with electrochemical detection (20% methanol eluent, 990 mV oxidation potential, IPAM elutes at 18 minutes, melatonin at 21 minutes, indolepropionate at 36 minutes).  
                                           Treatment   30 minutes   60 minutes   120 minutes                  Melatonin   450 + 30   200 + 15   73 + 6       Indolepropionate   160 + 11   210 + 18   230 + 25       IPAM   480 + 46   520 + 50   570 + 69                  
 
     EXAMPLE 2  
     Inhibition of Hydroxyl Radical Mediated Oxidative Damage to DNA By IPAM in Rat Forebrain Homogenate  
      Rat forebrain homogenate was incubated for sixty minutes with 3 mM hydrogen peroxide, 4 mM ferrous sulfate and 2 mM ADP to generate hydroxyl radicals. The concentrations of each indole compound to reduce oxidative DNA damage by 50%, the IC 50 values, are given as means+standard deviations for N=6 different determinations. The IC 50 values were calculated by running six experiments each at 10 increasing concentrations ranging from 0.01 to 100 micromolar of melatonin, indole-3-propionic acid and indole-3-propionamide. DNA damage was examined by measuring the formation of 8-hydroxydeoxyguanosine with HPLC and electrochemical detection in the presence and absence of the hydroxyl radical scavengers.  
                                                   Treatment   IC 50                          Melatonin   1.40 + 0.16 μM           Indole-3-propionic acid   7.46 + 0.80 μM           IPAM   0.18 + 0.03 μM                      
 
     EXAMPLE 3  
     Inhibition of the Aging Process in a Rotifer Model (Philodina) By Melatonin, Indolepropionate and IPAM  
      Free-radicals are involved in the aging process and since IPAM is a powerful cytoprotective agent, we tested IPAM for its property to inhibit the aging process. The following experiments illustrate that not only was IPAM devoid of toxicity, but it dramatically extended the life span of rotifers, an established model of aging. The potency of IPAM exceeded that of melatonin and IPA and was far superior to any other compound thus far described in the literature. (*=p&lt;0.05, statistically significant difference to control).  
                                                   Median life       Maximum life               span in days   Increase in %   span in days   Increase in %       Treatment   (50% survival)   of control   (90% survival)   of control                                                        Control (0.1% DMSO)   23.4 +− 0.6           27           0.5 μM melatonin   28.0 +− 1.5   +19%   (N.S.)   35   +30%       0.5 μM   30.0 +− 1.7   +28%   (*)   39   +37%       indolpropionic acid       0.5 μM IPAM   31.8 +− 1.7   +31%   (*)   42   +55%       Control (0.1% DMSO)   25.9 +− 0.8           30       5 μM melatonin   33.5 +− 1.5   +29%   (*)   42   +40%       5 μM   33.8 +− 1.2   +30%   (*)   41   +37%       indolpropionic acid       5 μM IPAM   36.3 +− 1     +40%   (*)   45   +50%       Control (0.1% DMSO)   25.0 +− 0.9           30       50 μM melatonin   28.1 +− 0.7   +12%   (N.S.)   31   +3%       50 μM   24.3 +− 1.0   −3%   (N.S.)   30   +−0%       indolpropionic acid       50 μM IPAM   28.8 +− 1.5   +15%   (*)   34   +13%                  
 
     EXAMPLE 4  
     Synergistic Effects on Longevity of Rotifers (Philodina) By Melatonin, Indolepropionate and IPAM with Ascorbate and Trolox  
      Ascorbate and trolox were administered at a concentration of 100 micromolar, the indoles were given at a concentration of 5 micromolar. Presented is the mean and the SD of ten experiments on individual rotifers with * being significantly different at a p level of less than 0.05 and N.S. being not statistically significant.  
                                                   Medium   Increase in %   Maximum   Increase in %       Treatment   Life Span   of control   Life Span   of control                                                        Control (0.1% DMSO)   24.5 +− 0.8           30           100 μM Ascorbate   24.3 +− 0.6   −1%   (N.S.)   28    −7%       100 μM Trolox   26.4 +− 0.7   +8%   (N.S.)   30   +−0%       Ascorbate and Trolox   28.9 +− 1.1   +18%   (*)   36   +20%       Ascorbate in 0.1% DMSO   26.4 +− 0.7           30       Ascorbate and Melatonin   37.7 +− 1.8   +43%   (*)   48   +60%       Ascorbate and   39.7 +− 1.5   +50%   (*)   48   +60%       Indolpropionate       Ascorbate and IPAM   44.6 +− 1.7   +68%   (*)   54   +80%       Trolox in 0.1% DMSO   29.3 +− 1.1           34       Trolox and Melatonin   38.4 +− 1.7   +31%   (*)   48   +41%       Trolox and   42.4 +− 1.5   +45%   (*)   51   +50%       Indolpropionate       Trolox and   46.1 +− 1.6   +57%   (*)   57   +67%       Indolpropionamide       Ascorbate and Trolox   28.8 +− 0.9           34       Ascorbate, Trolox and   42.4 +− 2.0   +47%   (*)   54   +59%       Melatonin       Ascorbate, Trolox and   44.0 +− 2.0   +53%   (*)   56   +65%       Indolpropionate       Ascorbate, Trolox and   50.4 +− 1.7   +75%   (*)   60   +77%       IPAM                  
 
     EXAMPLE 5  
     Inhibition of Aβ Aggregation By IPAM and IPA  
      Like melatonin and IPA, IPAM was a potent inhibitor of Aβ aggregation.  FIG. 1  illustrates the results of thioflavin T fluorescence experiments performed with Aβ1-40 showing the effects of IPAM as compared with melatonin and IPA.  
      The ThT was performed as previously described. Briefly, 5 μl were obtained from each sample after incubation and added to 2 ml of a glycine-NaOH buffer (50 mM), pH 9.2, containing 2 μM thioflavin T. Fluorescence intensities were measured at excitation 435 nm and emission 485 nm in a Hitachi F-2000 fluorescence spectrophotometer. A time scan of fluorescence intensity was performed and three measurements were obtained after the decay reached a plateau at 200, 220, and 240 seconds. These measurements were averaged after subtracting the background fluorescence of 2.0 μM thioflavin T in the blank buffers. The compounds used in the experiments did not exhibit significant fluorescence within the regions of interest at any time-point. All measurements were done in triplicate. Aqueous stock solutions of 1 mM of each compound were made by first preparing a 10 mM suspension in 1 N HCl and then by completely dissolving them in 100 mM phosphate buffered saline at pH 7.4 (1:10, v:v) and re-adjusting the pH to 7.4 with 1 N NaOH. Solutions of Aβ were prepared by dissolving 2.2 mg of the peptide in 1 ml of 50 mM bicarbonate buffer at pH 9.6. 50 μl aliquots of this solution were lyophilized and stored at −80° C. until needed. Working stock solutions of the peptide (500 μM concentration) were prepared in HPLC-grade water immediately prior to the experiments. In the experimental samples, Aβ was further diluted 1:1 with phosphate buffered saline (pH 7.4, 100 mM) to which each of the compounds or equivalent volumes of buffer solution were added. The final concentration of Aβ in each sample was 250 μM and the compound:Aβ molar ratios were 1:1.  
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      Although the present invention has been described in terms of specific embodiments, it is anticipated that alterations and modifications thereof will no doubt become apparent to those skilled in the art. It is therefore intended that the following claims be interpreted as covering all alterations and modifications that fall within the true spirit and scope of the invention.