Unusual Grignard Reaction of α-Arylcinnamonitriles [1]

Reaction of α-arylcinnamonitriles with excess of alkylmagnesium halide yielded predominantly the erythro isomer of α,β-dialkyl-α,β-diarylpropionitriles. PMR spectra of the diastereoisomers have been described.

Grignard Reaction of 2-Substituted-3-Cyanoquinolines

Grignard reactions of 2-morpholino and 2-methylthio-3-cyanoquinoline, 2-chloro-3-cyanoquinoline, 2-chloro-3-cyano-6-methoxyquinoline and 2-chloro-3-cyano-7-methylquinoline with alkyl or aryl magnesium halides have been studied. It was found that 2-morpholino and 2-methylthio- 3-cyanoquinolines gave 1,4-addition products followed by rapid aromatisation. 2-Chloro-3- cyanoquinoline with alkyl magnesium halides furnished 1,4-addition products but with aryl magnesium halides 1,4- and 1,2-addition products were obtained. The cyano group of 4-aryl-2-chloro- 3-cyano-1,4-dihydroquinolines was found to participate in the Grignard reaction to yield 1,2- addition products. 2-Chloro-3-cyano-6-m ethoxyquinoline with alkyl and phenyl magnesium halides yielded exclusively 1,4-addition products. Similarly with p-m ethoxyphenyl magnesium bromide, 1,4-addition products were isolated which participated in the Grignard reaction to yield the expected adducts. Unlike the other chloroquinoline derivatives, 2-chloro-3-cyano-7-methylquinoline with alkyl magnesium halide formed 1 ,2-addition products but with aryl magnesium halides, 1,4-addition products were isolated. The 4-alkyl-2-chloro-3-cyano-l,4-dihydroquinolines were unstable as compared to their 4-aryl analogs. A couple of the Grignard reaction products were found to be unstable on activated surface.

Studies on Enteric Anthelmintics: Impact of Single Point Structural Change on the Activity Profile

The impact of change only in one heteroatom in the substituent at position 5(6) of methyl benzimidazole-2-carbamates on the profile of anthelmintic activity against intestinal worms Ancylostoma ceylanicum (hookworm), Nippostrongylus brasiliensis (trichostrongylid), Syphacia obvelata (oxyurid) and Hymenolepis nana (cestode) has been studied. The observations made are likely to evoke interest for understanding the SAR in methyl benzimidazole-2-carbamates anthelmintics at a molecular level

Baldwin Rules for Ring Closure - a Re-examination of the Concept

The reaction of 5,5-diphenyl-γ-butyrolactone (3) with primary amines and ethyl γ-γ-diphenyl vinyl acetate with Aqu HBr in acetic acid served as examples for the exception to Baldwin rules for 5-exo-tet and 5-exo-trig ring closures. The structure of the reaction product of 3 with primary amines have been assigned on the basis of spectral data and conversion to γ-γ-diphenyl vinyl substituted acetamides, the authentic samples of which were prepared by an unambigous route of synthesis.

Emetine ditartrate: a possible lead for emergency contraception

Interception of pregnancy in its initial stage is an attractive and viable approach to contraception. A chemical agent, taken within the first few days of missed menses, intercepts the conception, which is expelled with menstrual flow. The main targets of such agents are the uterus, blastocyst and the growing trophoblasts, whose nutritional requirement is inhibited. Our previous work has identified several nonsteroidal chemical entities as pregnancy interceptives in rodents and infrahuman primates. However, none reached clinical stage due to their ineffectiveness by oral route. Nevertheless, parallel to these rationally designed synthetic compounds, a program was ongoing to identify natural product(s) that can be used as interceptives. We are reporting for the first time the detailed profile of emetine ditartrate, a compound whose pregnancy interceptive efficacy has been studied in mouse, rat, hamster, guinea pig and rabbit by oral and intravaginal routes of administration. By the oral route, the compound caused 100% resorption of the fetuses in rat, hamster and guinea pig at 6.0, 5.0 and 3.0 mg/kg, respectively, on administration during peri- and early postimplantation periods of pregnancy (depending upon the day of implantation in each species). By intravaginal route, the compound was administered once in the form of a vaginal pessary on the day of implantation in respective species; interception of pregnancy was not achieved completely in rat and hamster at doses four to five times the oral dose in multi-day schedule. However, in guinea pig and rabbit it was fully effective at 7.0 and 70.0 mg/animal, respectively. The compound was devoid of estrogenic, antiestrogenic and progestational activity but possessed mild antiprogestational activity at the high dose in vivo. In in vitro assay, however, it did not show any significant binding to estrogen and progesterone receptors. The mode of action of the compound was found to be mainly on the uterus and early embryos around implantation, possibly on the trophoblasts and endometrial cells at the attachment site. The absence of 100% efficacy in rat and hamster by intravaginal route, but not by oral route, is possibly due to poor absorption of the compound through the vagina in these species. The guinea pig and rabbit, therefore, seem the better species for evaluating the efficacy of the compound administered by the vaginal route.

Baylis–Hillman reaction assisted parallel synthesis of 3,5-disubstituted isoxazoles and their in vivo bioevaluation as antithrombotic agents

The solution-phase parallel synthesis involving reactions of Baylis-Hillman products of 3-substituted-5-isoxazolecarbaldehydes with nucleophiles and their in vivo antithrombotic evaluations are described along with the results of in vitro platelet aggregation inhibition assay of a few compounds. Results of the detailed evaluation of one of the compounds as an inhibitor of platelet aggregation are also presented.

Isoxazole-based derivatives from Baylis-Hillman chemistry: assessment of preliminary hypolipidemic activity

The synthesis of isoxazole-based derivatives utilizing Baylis-Hillman chemistry and results of their preliminary bioevaluation as hypolipidemic agents in triton model are described.

Purification and characterization of an alkaline lipase from a newly isolated Pseudomonas mendocina PK-12CS and chemoselective hydrolysis of fatty acid ester

Lipase isolated from a soil isolate, Pseudomonas mendocina (PK-12CS) chemoselectively hydrolyzed the fatty ester group in presence of arbamate of compound 5-amino-2,4-dihydro-3H-1,2,4-triazole-3 ones, a class of compounds which are attractive starting materials for the synthesis of triazole annealed heterocycles. The enzymatic method provides an easy access to the synthesis of N-substituted glycine. Under optimized fermentation conditions the culture produced 3510 Lipolytic Units/mL of cell free fermentation broth in 20 h of fermentation. The purified lipase exhibited molecular mass of 80 kDa on SDS polyacrylamide gel electrophoresis. The enzyme was stable at room temperature for more than a month and expressed maximum activity at 37 degrees C and pH 8.

Anilino-(2-bromophenyl) acetonitrile: a promising orally effective antileishmanial agent

Visceral leishmaniasis (VL) or kala-azar is a worldwide disseminated intracellular infection caused by the hemoflagellate protozoan parasites Leishmania donovani. Chemotherapeutic scenario presents a deplorable picture and demands an urgent search for a new and safe anti-VL drugs, preferably active by oral route. In search of new antileishmanial agents, a total of 16 compounds belonging to the anilino-(substituted phenyl)-acetonitrile class were tested in vitro in promastigote/macrophase-amastigote systems and in vivo in L. donvoani/hamster model for their antileishmanial activity. Compound 3, anilino-(2-bromophenyl)-acetonitrile, exhibited most promising activity both in vitro at a concentration of 100 microg/ml (82.33 and 94.36% in promastigote and macrophase-amastigote systems, respectively) and in vivo at a dose of 50 mg/kg for 5 days (82.11 and 80% by i.p. and p.o. routes, respectively), hence this compound was investigated in detail. To maximize its bioavailability, dissolution profile, absorption, the compound was also tested in vivo as its soluble form. But no enhancement in activity was observed. From the results of different parameters for example ED(50) and LD(50) etc. compound 3 appears to be a potent orally effective compound which could further be investigated to establish its potential as a candidate molecule of antileishmanial therapy.

Effect of different strains of yeast on stereocontrolled reduction of 5-acetylisoxazolines

The stereocontrolled reduction of 3-aryl-5-acetylisoxazolines (1) to the corresponding alcohols (2 and 3) in the presence of four different yeast strains, recognized as Baker's yeast (commercial), Candida krusei (ATCC 14243), Pichia farinosa (NRRL Y110) and Sacchromyces sp. (soil isolate) have been attempted. The C. krusei was found to be diastereoselective for the (R)-1 while the Sacchromyces sp. led to complete reduction to yield the RS- and SS-alcohol in 1:1 ratio at 10 g/L scale.

Combinatorial synthesis and biological evaluation of isoxazole-based libraries as antithrombotic agents

The 3-substituted phenyl-5-isoxazolecarboxaldehydes have been identified as activated aldehydes for the generation of isoxazole-based combinatorial libraries on solid phase through automation. Three highly functionalized isoxazole-based libraries comprising of 32, 96 and 45 compounds each have been synthesized in parallel format using Baylis Hillman reaction, Michael addition, reductive amination and alkylation reactions. With an objective of lead generation all the three libraries were evaluated for their antithrombin activity in vivo.

Syntheses and anthelmintic activity of alkyl 5(6)-(substituted carbamoyl)- and 5(6)-(disubstituted carbamoyl)benzimidazole-2-carbamates and related compounds

A number of alkyl 5(6)-(substituted-carbamoyl)- and 5(6)-(disubstituted-carbamoyl)benzimidazole-2-carbamates and related compounds have been synthesized, and their anthelmintic activity against various intestinal helminths of experimental animals have been evaluated. A large percentage of the compounds synthesized showed noteworthy activity against Ancylostoma ceylanicum and at higher doses against Hymenolepsis nana infections. Compared to the alkyl 5(6)-(substituted-carbamoyl)benzimidazole-2-carbamates, the disubstituted carbamoyl analogues were found to exhibit better anthelmintic activity. The most active compound of the series, namely, methyl 5(6)-[(N-2-pyridylpiperazino)carbamoyl]benzimidazole-2-carbamate (90), has been screened against intestinal helminths in higher animals and as a micro- and macrofilaricidal agent. Compound 90 has been identified as a broad-spectrum anthelmintic agent. Compound 90 has been identified as a broad-spectrum anthelmintic in view of its efficacy against A. ceylanicum (hamsters and dogs), H. nana (rats), Nippostrongylus brasiliensis (rats), Syphacia obvelata (mice), A. tubaeformis (cat), Toxocara spp. (cat), and Litomosoides carinii (cotton rat).

Syntheses and biological evaluation of alkanediamines as antioxidant and hypolipidemic agents

A new series of compounds belonging to N,N'- [bis (1-aryl-6-hydroxy-hex-2-ene-1-one-3-yl)-1,n-alkanediamines (2-5a-f) have been synthesized and evaluated for antioxidant and hypolipidemic activities. Amongst all the synthesized compounds, seven compounds namely 2c, 2e, 4c, 5b, 5c, 5e and 5f exhibit potent antioxidant activity. These compounds have also been evaluated for hypolipidemic activity.

Modified iridoid glycosides as anti-implantation agents: inhibition of cell adhesion as an approach for developing pregnancy interceptive agents

Structural modifications in iridoid glycosides and evaluation of their efficacy on adhering capability (in vitro) of immature hamster uterine epithelial cells to the substratum have been studied. Out of 31, eight compounds in vitro, five compounds in utero and two in vivo showed adhesion/implantation preventing activity, respectively. The results provide an indication for further exploration in the line of development of anti-adhesive agents.

Cinnamoyl shikonin

The title compound, 1-(5,8-dihydro-1,4-dihydroxy-5,8-dioxo-2-naphthyl)-4-methylpent-3-en-1-yl cinnamate, C(25)H(22)O(6), crystallizes in space group P2(1). The phenyl ring of the cinnamate is anti to the carbonyl group of the same moiety [C-C-C-C = -175.6 (2) degrees] and is nearly parallel to the naphthyl ring system. Two six-membered rings formed by intramolecular hydrogen bonds, with O-H...O distances of 2.587 (2) and 2.589 (2) A, occur on either side of the fused ring system, creating a tetracyclic pyrene-shaped system. The phenyl ring forms an intermolecular stack with the benzoquinone ring, as a result of aromatic pi-pi interactions.

Search for new chemical entities as menses inducing agents

In continuation of an ongoing program on developing nonsteroidal pregnancy interceptives to be used as a menses regulating agent, a new class of compounds belonging to 3-substituted amino-1-aryl-6-hydroxy-hex-2-ene-1-ones series has been investigated for pregnancy interceptive activity in the hamster and rat. The compounds were administered (subcutaneous) on days 4-8 (hamster) and 5-9 (rat) post coitum (PC). The animals were laparotomized on days 12 (hamster) and 16 (rat) PC. To derive percent efficacy, the total number of implantation was divided by the number of normal and resorbed implantations. Among the 14 compounds evaluated, three were found to intercept pregnancy by 100%. Another compound was active by 75%, whereas the rest were inactive. None of the active compounds were, however, active in rat with this schedule. Results indicate that the observed species- and schedule-specific activity owes its origins to differences in the implantation physiology and early post-implantation development between the two species. The study, nevertheless, offers an insight to the new class of compounds for this activity.

Identification of Inhibitors of DNA Topoisomerase II from a Synthetic Library of Glycoconjugates

A library of 24 glycoconjugates related to glycosylated beta-amino acid derivative (I) was been prepared and screened against DNA topoisomerase-II of the filarial parasite S. cervi. Among these, compound 6 was found to be a potent inhibitor of DNA topoisomerase-II with 95% inhibition at 1.09 microM. Furthermore, compound 6 was at least three times more potent than the lead compound, glycosylated beta-amino acid derivative I.

Syntheses and immunomodulatory activity of 3-O-[2'-hydroxy-3'-N,N-disubstituted aminopropan-1'-yl]-alpha-D-glucofuranoses

A number of 3-O-[2'-hydroxy-3'-N,N-aminopropan-1'-yl]-alpha-D-glucofuranoses were synthesised by regioselective oxirane ring opening in compound 2 with different secondary amines followed by selective deacetalisation. All the compounds were tested for their immunomodulatory potential in vitro; seven of them expressed significant immunostimulant activity.

Antifilarial activity of some 2H-1-benzopyran-2-ones (coumarins)

Six synthetic 2H-1-benzopyran-2-one (cournarin) derivatives (CDRI compounds # 1, 2, 3, 4, 5 and 6) were evaluated for filaricidal activity against Litomosoides carinii and Acanthocheilonema viteae infections in cotton rats (Sigmodon hispidus) and Mastomys coucha respectively. Significant effects on macrofilariae (>80% death/sterilisation) were detected with compounds #2, 3 and 6 against L. carinii and/or A. viteae. Thus detection of filaricidal activity in benzopyrones, which are so far known for anti-inflammatory activity, provides a new lead for development of better filaricidal agents for combating filariasis.

A new class of potential chloroquine-resistance reversal agents for Plasmodia: syntheses and biological evaluation of 1-(3'-diethylaminopropyl)-3-(substituted phenylmethylene)pyrrolidines

1-(3'-Diethylaminopropyl)-3-(substituted phenylmethylene)pyrrolidines were synthesized and evaluated for CQ-resistant reversal activity. In general the compounds of the series elicit better biological response than their phenylmethyl analogues. The most active compound 4b has been evaluated in vivo in detail, and the results are presented. The possible mode of action of the compounds of this series is by inhibition of the enzyme heme oxygenase, thereby increasing the levels of heme and hemozoin, which are lethal to the parasite.

Syntheses and biological evaluation of 3-substituted amino-1-aryl-6-hydroxy-hex-2-ene-1-ones as antioxidant and hypolipidemic agents

A new series of compounds belonging to 3-substituted amino-1-aryl-6-hydroxy-hex-2-ene-1-ones (4-12a-e) have been synthesized and evaluated for antioxidant and hypolipidemic activities. Amongst all the synthesized compounds, seven compounds, namely 5b, 5d, 6e, 8a, 8b, 10b and 11a, exhibit better antioxidant activity than probucol. Two compounds, 5d and 10b, have been evaluated in detail for antioxidant and hypolipidemic activities and show comparable activity profile to that of probucol and guggulipid. From the present study it may be postulated that the mechanism of action of these compounds could be through activation of lecithin cholesterol acyltransferase (LCAT), liver lipolytic activity, increased faecal bile acid secretion and inhibition of hepatic cholesterol biosynthesis.

Syntheses and antifilarial profile of 7-chloro-4-(substituted amino) quinolines: a new class of antifilarial agents

The syntheses of 7-chloro-4-(substituted amino) quinolines (2-22) and their antifilarial activities are delineated. Some of the screened compounds have shown promising filarial response and sterilization effect on female Acanthocheilonema viteae in rodents.

Inhibition of growth and regulation of IGFs and VEGF in human prostate cancer cell lines by shikonin analogue 93/637 (SA)

BACKGROUND

Insulin-like growth factors (IGFs) are important mitogens and are involved in normal and malignant cellular proliferation. IGFs and IGF binding proteins (IGFBPs) regulate the prostatic cell growth and reduction/blocking of IGFs has been suggested to be of therapeutic value in prostate cancer. beta,beta-dimethyl acryl shikonin, an extract from the roots of plant Arnebia nobilis has been shown to have anticancer properties but was found to be toxic. Subsequently, several analogoues of beta,beta-dimethyl acryloyl shikonin were synthesized and one of them shikonin analogue 93/637 (SA) was significantly less toxic compared to beta,beta-dimethyl acryloyl shikonin.

MATERIALS AND METHODS

We have investigated the effect of SA on prostate cancer cell (DU 145, LNCaP and PC-3) growth and expression of IGFs (IGF-I, IGF-II and IGF-I receptor (IGF-IR)), IGFBP-3 and vascular endothelial growth factor (VEGF).

RESULTS

SA had growth inhibitory effect on PC-3 cells in a dose dependent manner. It also showed slight inhibitory effect on the growth of DU 145 and LNCaP cells at low doses ranging from 250 nM to 1 microM and has moderate inhibitory effect at concentrations 2.5 microM and above. Lactate dehydrogenase (LDH) activity assays indicated cellular damage, only at higher concentrations of SA that are greater than 1 microM. Gene expression studies by RT-PCR have demonstrated a decrease in mRNAs of IGF-II in DU 145, IGF-I, and IGF-IR in LNCaP, and IGF-II and VEGF in PC-3 cells and an increase in IGFBP-3 in both DU 145 and PC-3 cells by treatment with SA.

CONCLUSIONS

The results demonstrate the inhibitory effect of SA on cellular growth and IGFs specifically in PC-3 cells and suggest a potential therapeutic use in treatment of prostate cancer.

Effect of metal cationization on the low-energy collision-induced dissociation of loganin, epi-loganin and ketologanin studied by electrospray ionization tandem mass spectrometry

The effect of alkali metal and silver cationization on the collision-induced dissociation (CID) of loganin (1), epi-loganin (2) and ketologanin (3) is discussed. Their protonated molecular ions fragment mainly by glycosidic cleavages. The epimeric pairs (1 and 2) show differences in the abundances of the resulting fragment ions. Lithium cationization induces new dissociation pathways such as the retro-Diels-Alder (RDA) fragmentation followed by rearrangement. Unlike the dissociation of protonated molecular ions, the dissociation of lithiated molecules also provides lithiated sugar fragments. The CID of dilithiated molecules is substantially different from that of the monolithiated precursors. RDA reaction appears to be favoured by the presence of the additional lithium atom in the molecule. In addition, other ring cleavages are also induced. The abundances of the various fragment ions are different in the CID spectra of the epimeric pairs. Extensive D labelling and (6)Li labelling experiments confirmed many of the ion structures proposed. The CID spectra of the sodiated ions are generally weaker, although similar to those of the corresponding lithiated species. Higher alkali metal ion (K(+), Rb(+) and Cs(+)) adducts generated only the corresponding metal ions as products of CID. Similar fragmentations were also observed in the CID of the [M + Ag](+) ions of these compounds, the epimeric pairs showing characteristic differences in their CID behaviour. Copyright 2000 John Wiley & Sons, Ltd.

Quinolones: novel probes in antifilarial chemotheraphy

Quinolones have been discovered in our laboratory as a new class of antifilarial agents. This has led to the design, synthesis, and antifilarial evaluation of a number of N-substituted quinol-4(1H)-one-3-carboxamide derivatives 4-6. The macrofilaricidal activity of the target compounds was initially evaluated in vivo against Acanthoeilonema viteae by oral administration of 200 mg/kg x 5 days. Among all the synthesized compounds, 13 displayed activity, with the most potent compound (4a) exhibiting 100% macrofilaricidal and 90% microfilaricidal activities. Compound 4e elicited significant macrofilaricidal (80%) response while compound 5c showed 100% sterilization of female worms. Finally, the two most potent macrofilaricidal compounds, namely 4a and 4e, have been screened for their potency against DNA topoisomerase II, and it has been observed that both have the capability to interfere with this enzyme at 10 micromol/mL concentration. The structure-activity relationship (SAR) associated with position-3 and aryl ring substituents is discussed.

Characterization of iridoids by fast atom bombardment mass spectrometry followed by collision-induced dissociation of

Fast atom bombardment mass spectra of a series of naturally occurring and synthetically modified iridoid glycosides were studied using lithium cationization and collision-induced dissociation of the resulting [M+Li]+ ions. Lithium cationization leads to the unambiguous determination of the molecular masses of these compounds. Collision-induced dissociation of the lithiated molecular ions give valuable structural information regarding the nature of the substituent on both the aglycone and the sugar moieties. The characteristic fragmentation pathways identified are (1) elimination of neutral molecules comprising the substituents on either the aglycone or sugar moieties, (2) formation of lithiated aglycone and their fragment ions, (3) formation of lithiated sugar and their fragment ions, (4) fragmentation corresponding to the cleavage of the aglycone or sugar ring and (5) fragmentation characteristic of the substituents present in either the aglycone or sugar parts of the molecule. Elimination of two acyloxy radicals from the lithiated molecular ion is a characteristic fragmentation in the case of acyloxy derivatives.

Secondary amines as new pharmacophores for macrofilaricidal drug design

Several secondary amines exhibit promising macrofilaricidal response in vivo through oral route of administration against Acanthocheilonema viteae in which N-hexylcyclohexylamine (1) shows 100% macrofilaricidal activity while a tertiary amine such as 9 elicits predominantly microfilaricidal (93%) response.

Effects of 2-deoxy-D-glucose on Acanthocheilonema viteae: rodent filariids as studied by multinuclear NMR spectroscopyt

A well known glucose antimetabolite, 2-deoxy glucose (2DG) widely used in chemotherapy of cancer along with radiation, was evaluated as an antifilarial agent by nuclear magnetic resonance. The uptake and metabolism of 2DG in the experimental filarial infection Acanthocheilonema viteae was studied by in vivo multinuclear NMR. An unusually long retention time of 2DG6P within these parasites was observed on continuous 31P NMR monitoring, along with a decrease in ATP levels. These results led to therapeutic investigation in A. viteae infected host Mastomys coucha. 2DG showed a remarkable adulticidal activity (73.6%) with 50% sterilization of surviving female worms at a dose of 250 mg/kg x 5, p.o. NMR observations and activity profile substantiate the findings of one another, directed towards the hitting of bioenergetic machinery of A. viteae by macrofilaricidal agent (2DG).

Effect of alkali metal cationization and multiple alkali metal exchange on the collision-induced dissociation of loganic acid studied by electrospray ionization tandem mass spectrometry

Under electrospray ionization conditions loganic acid undergoes alkali metal (Li, Na and K) exchange and alkali metal cationization. Multiple exchanges of up to four alkali metal ions are observed. Different populations of metal exchanged species are produced during electrospray ionization. Collision-induced dissociation of ammonium cationized species is compared with that of metal cationized species to study the effect of metal cationization. Glycosidic cleavage and ring cleavages of aglycone and sugar moieties are the major fragmentation pathways observed during collision-induced dissociation. The fragmentations of the highly metal exchanged species indicate the opening of the pyran ring. Collision-induced dissociation of the various metal exchanged and metal cationized species also reveals the nature of the different populations. Copyright 2000 John Wiley & Sons, Ltd.

In search of new chemical entities with spermicidal and anti-HIV activities

Several compounds belonging to 2-isoxazolines (4,5a-c), isoxazoles (3,6a-c) and 1-amino-1-cycloalkyl-2-substituted phenyl ethanes (16-18,a-e) have been synthesised and found to possess spermicidal activity. Out of these a couple of compounds (5a and 6a) exhibit anti-HIV activity.

Potent 1,3-disubstituted-9H-pyrido[3,4-b]indoles as new lead compounds in antifilarial chemotherapy

Substituted 9H-pyrido[3,4-b]indoles (beta-carbolines) identified in our laboratory as potential pharmacophore for designing macrofilaricidal agents, have been explored further for identifying the pharmacophore responsible for high order of adulticidal activity. This has led to syntheses and macrofilaricidal evaluations of a number of 1-aryl-9H-pyrido[3,4-b]indole-3-carboxylate derivatives (3-7). The macrofilarical activity was initially evaluated in vivo against Acanthoeilonema viteae. Amongst all the synthesized compounds, only twelve compounds namely 3a, 3c, 3d, 3f, 4c, 4d, 4f, 5a, 6f, 6h, 6i and 7h have exhibited either > 90% micro- or macrofilaricidal activity or sterilization of female worms. These compounds have also been screened against Litomosoides carinii and of these only 3f and 5a have also been found to be active. Finally these two compounds have been evaluated against Brugia malayi. The structure activity relationship (SAR) associated with position-1 and 3 substituents in beta-carbolines have been discussed. It has been observed that the presence of carbomethoxy at position-3 and an aryl substituent at position- in beta-carbolines effectively enhance antifilarial activity particularly against A. viteae. Amongst the various compounds screened, methyl 1-(4-methylphenyl)-9H-pyrido[3,4-b]indole-3-carboxylate (4c) has shown highest adulticidal activity and methyl 1-(4-chlorophenyl)-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole-3-carboxyla te (3a) has shown highest microfilaricidal action against A. viteae at 50 mg/ kg x 5 days (i.p.). Another derivative of this compound namely 1-(4-chlorophenyl)-3-hydroxymethyl-9H-pyrido[3,4-b]indole (5a) exhibited highest activity against L. carinii at 30 mg/kg x 5 days (i.p.) and against B. malayi at 50 mg/kg x 5 days (i.p.) or at 200 mg/kg x 5 days (p.o.).

Potent 1,3-disubstituted-9H-pyrido[3,4-b]indoles as new lead compounds in antifilarial chemotherapy

Substituted 9H-pyrido[3,4-b]indoles (beta-carbolines), identified in our laboratory as potential pharmacophores for designing macrofilaricidal agents, have been explored further for identifying the pharmacophore responsible for the high order of adulticidal activity. This has led to syntheses and macrofilaricidal evaluations of a number of 1-aryl-9H-pyrido[3,4-b]indole-3-carboxylate derivatives (3-7). The macrofilaricidal activity was initially evaluated in vivo against Acanthoeilonema viteae. Among all the synthesized compounds, only 12 compounds, namely 3a, 3c, 3d, 3f, 4c, 4d, 4f, 5a, 6f, 6h, 6i, and 7h, have exhibited either >90% micro- or macrofilaricidal activity or sterlization of female worms. These compounds have also been screened against Litomosoides carinii, and of these only 3f and 5a have also been found to be active. Finally these two compounds have been evaluated against Brugia malayi. The structure-activity relationship (SAR) associated with position 1 and 3 substituents in beta-carbolines has been discussed. It has been observed that the presence of a carbomethoxy at position 3 and an aryl substituent at position 1 in beta-carbolines effectively enhances antifilarial activity particularly against A. viteae. Among the various compounds screened, methyl 1-(4-methylphenyl)-9H-pyrido[3,4-b]indole-3-carboxylate (4c) has shown the highest adulticidal activity and methyl 1-(4-chlorophenyl)-1,2,3,4-tetrahydro-9H-pyrido[3, 4-b]indole-3-carboxylate (3a) has shown the highest microfilaricidal action against A. viteae at 50 mg/kg x 5 days (ip). Another derivative of this compound, namely 1-(4-chlorophenyl)-3-(hydroxymethyl)-9H-pyrido[3,4-b]indole (5a), exhibited the highest activity against L. carinii at 30 mg/kg x 5 days (ip) and against B. malayiat 50 mg/kg x 5 days (ip) or at 200 mg/kg x 5 days (po).

Chemoselective Hydrolysis of Esters by Fungal Lipase

Lipase, isolated from Aspergillus niger, exhibits chemoselectivity towards hydrolysis of fatty acid esters and does not hydrolyse carbamates; this has been demonstrated with substrates such as 5 ( N-methoxycarbonyl- N-ethoxycarbonylmethylamino)-2-aryl-2,4-dihydro-3 H-1,2,4-triazol-3-ones.

Synthesis of bisquinolines and their in vitro ability to produce methemoglobin in canine hemolysate

Synthesis of a number of derivatives of bisquinolines (3-9) have been reported here. Effect of these compounds on in vitro methemoglobin formation and methemoglobin reductase activity has resulted in the identification of two potential compounds (5 & 7), showing negligible methemoglobin toxicity.

Synthesis and antileishmanial activity of alpha-cyano ethyl propenoates--a new class of antileishmanials

A number of alpha-cyano-beta-substituted ethyl propenoates were synthesised by condensation of appropriate aldehydes with ethyl cyanoacetate in basic medium. These compounds have been studied for their antileishmanial activities in vivo in hamsters. Two compounds exhibited 70-77% activities both by intramuscular and oral routes.

Synthesis and methemoglobin toxicity of the amides of 6/7 mono or disubstituted quinolone

A series of 6/7-mono and disubstituted quinolone-3-carboxamide derivatives (1-12) were synthesized and their in vitro methemoglobin producing capacity have been delineated. The compounds 5, 6, 9 and 10 showed minimum methemoglobin toxicity.

Potential inhibitors of plasmodial heme oxygenase; an innovative approach for combating chloroquine resistant malaria

Syntheses of imidazo-pyridines and substituted prolines and their effect on heme oxygenase activity of Plasmodium yoelii and corresponding infected host have been studied. Six compounds in vitro and one in vivo showed selective inhibition of parasite enzyme which may be further exploited in the development of resistant reversal agents.

Finger printing of Mycobacterium tuberculosis in patients with intracranial tuberculomas by using in vivo, ex vivo, and in vitro magnetic resonance spectroscopy

In vivo, ex vivo, and in vitro proton magnetic resonance spectroscopy was performed in 12 patients with intracranial tuberculomas with an aim of detecting the biochemical constituents of Mycobacterium tuberculosis in a granuloma. One dimensional (1D) single pulse and spin-echo sequences and 2D correlative spectroscopy were used for the ex vivo study to confirm the resonances seen on in vivo study. Spectroscopic studies of the perchloric acid and lipid extract of granuloma and M. tuberculosis were performed to look for similarity of resonance. In vivo study showed the presence of lipids at 0.9, 1.3, 2.0, 2.8 ppm, and phosphoserine at 3.7 ppm. All these resonances were confirmed on ex vivo study. In addition, distinct resonances of serine and phenolic lipids were seen on ex vivo and in vitro study of tuberculous granuloma, which have not been observed in other intracranial tumors. Lipid extract of granuloma and M. tuberculosis showed phenolic lipids at 7.1 and 7.4 ppm, a constituent of the cell wall of the bacteria in a tuberculoma. It appears that it may be possible to finger print the biochemicals of the cell wall of M. tuberculosis in a tuberculous granuloma and thus may help in detection and diagnosis of such lesions.

Correlation between inhibition of growth and arginine transport of Leishmania donovani promastigotes in vitro by diamidines

Diamidines are known to possess potent antiprotozoal activity due to their property of binding with DNA minor groove. Pentamidine or 1,5-bis-(4'-amidinophenoxy)pentane, is the most known aromatic diamidine and is used to treat cases of antimony resistant leishmaniasis. Yet, it suffers from limited clinical application due to its adverse and toxic side effects. A set of four structural analogs of pentamidine along with the known antileishmanial diamidines viz., pentamidine, berenil and dibromopropamidine, were tested for their effect on growth of Leishmania donovani promastigotes in vitro using 3H-thymidine incorporation as the growth parameter. In view of structural similarity between amidino moiety of diamidines and guanidino group of L-arginine and also the previous report from this laboratory regarding presence of a novel arginine transporter in Leishmania donovani promastigotes, a parallel study was also conducted with the analogs and standard diamidines for their inhibitory effect on leishmanial arginine transport function. Bisbenzyl pentamidine and biscyclopropyl pentamidine were identified as considerably more potent inhibitors of growth and arginine transport function of leishmania promastigotes in vitro than the parent drug, pentamidine. A linear correlation was established between inhibition of parasite growth and arginine transport with regard to standard diamidines as well as novel analogs. Inhibition of arginine transport by dibromopropamidine and Pentamidine was competitive. The diamidines possibly gain entry into leishmania cells through arginine transporter.