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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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 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.

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.

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).

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.

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.

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.

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.