Synthesis and structure-activity relationships of pyridinyl-1H-1,2,3-triazolyldihydroisoxazoles as potent inhibitors of tubulin polymerization.

Three series of compounds; pyridinyl-1H-1,2,3-triazoles, pyridinyl-1H-1,2,3-triazolylisoxazoles and pyridinyl-1H-1,2,3-triazolyldihydroisoxazoles with TMP moiety were designed, synthesized and screened for their anti-cancer and anti-tubulin properties. By sequentially designing three series of compounds comprising of dihydroisoxazole in the linker, a small substituent like chlorine on one side (R(1)) and aromatic group (R) on the pyridine ring, we have optimized the anti-cancer as well as anti-tubulin activity. Pyridinyl-1H-1,2,3-triazolyldihydroisoxazoles 28b and 28c were found to be potent anti-cancer agents against all the cell lines tested with a concomitant accumulation of cells in the G2/M phase of the cell cycle. Molecular modeling suggests that the trimethoxyphenyl ring in 28b and 28c occupies the cholchicine binding domain of ß-tubulin, whereas, the dihydroisoxazole extends towards the interface of α,ß-tubulin.

Synthesis, anticancer activity and photophysical properties of novel substituted 2-oxo-2H-chromenylpyrazolecarboxylates.

2-Oxo-2H-chromenylpyrazolecarboxylates (8a-h and 12a-zb) have been synthesized by [3 + 2] cycloaddition of 2H-chromenophenylhydrazones (7a-h and 11a-w) with diethyl/dimethylbut-2-ynedioates. Phenylchromeno[4,3-c]pyrazol-4(1H)-ones (13i-n) were prepared from corresponding phenylhydrazones (7a-h) with catalytic amount of piperidine in presence of pyridine as a solvent at 100 °C. All the synthesized compounds (8a-h, 12a-zb and 13a-n) were screened for anticancer activity against three human cancer cell lines such as prostate (DU-145), lung adenocarcinoma (A549), and cervical (HeLa) by standard MTT assay method. Further, photophysical properties (UV and fluorescence) for these compounds were discussed.

Synthesis, structure-activity relationship of novel substituted 4H-chromen-1,2,3,4-tetrahydropyrimidine-5-carboxylates as potential anti-mycobacterial and anticancer agents.

Series of 4H-chromen-1,2,3,4-tetrahydropyrimidine-5-carboxylate derivatives 7a-7zb, 8a-8d and 9a-9d were synthesized and screened for their in vitro anti-mycobacterial activity against Mycobacterium tuberculosis H(37)Rv (MTB) and cytotoxicity against three human cancer cell lines including A549, SK-N-SH and HeLa. The results indicate that six compounds are more potent and 7za is most effective anti-mycobacterial derivative compared to the standard drugs Ethambutol and Ciprofloxacin. However, 12 compounds exhibited cytotoxicity against human neuroblastoma cell line; amongst them the compound 7v is most effective compared to the standard drug Doxorubicin. This is the first report assigning in vitro anti-mycobacterial, anticancer and structure-activity relationship for this new class of 4H-chromen-1,2,3,4-tetrahydropyrimidine-5-carboxylates.

alpha-Glucosidase inhibitory antihyperglycemic activity of substituted chromenone derivatives.

Series of 3,4- and 3,6-disubstituted chromenones including new chromenone derivatives were synthesized applying various synthetic strategies including Pechmann condensation, Knoevenagel condensation, Reimer-Tiemann reaction and Suzuki coupling in very good yields. Synthesized compounds (4a-z) were screened for in vitro alpha-glucosidase inhibitory and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activities. Majority of compounds displayed varying degrees of alpha-glucosidase inhibitory and DPPH scavenging activity. Compound 4x emerged as the most potent alpha-glucosidase inhibitor in present series of compounds owing to the presence of 3-acetyl-6-(6-methoxy-3-pyridyl) group on chromenone; however, it could not display DPPH scavenging activity and was found to be mixed non-competitive type inhibitor of rat intestinal alpha-glucosidase. When tested in vivo for antihyperglycemic activity in starch loaded Wistar rats, it displayed significant antihyperglycemic property. This is the first report assigning rat intestinal alpha-glucosidase inhibitory property for this class of new chromenones and presents new family of compounds possessing alpha-glucosidase inhibitory activities and antihyperglycemic property. Compound 4x may serve as an interesting new compound for the development of therapeutics targeted against diet-induced hyperglycemia in diabetes.

Synthesis, photochemical E (trans)-->Z (cis) isomerization and antimicrobial activity of 2-chloro-5-methylpyridine-3-olefin derivatives.

2-Chloro-5-methylpyridine-3-olefin derivatives (3a-e) have been synthesized from 2-chloro-5-methylnicotinaldehyde (1) and studied their photochemical E (trans)-->Z (cis) isomerization upon direct irradiation and triplet sensitized excitation for the first time. The triplet sensitized excitations of the compounds yielded high Z (4a-e) isomer composition, whereas the direct excitation results in less Z (4a-e) isomer composition, indicating triplet pathway is very efficient in converting the E (trans)-->Z (cis) isomer. Thus synthesized E (3a-c and 3e) and generated Z (4a-c and 4e) isomers were tested for antimicrobial activity. Antifungal activity of these pyridine derivatives are closely comparable to the standard used.

Rats with unilateral median forebrain bundle, but not striatal or nigral, lesions by the neurotoxins MPP+ or rotenone display differential sensitivity to amphetamine and apomorphine.

Rotenone and 1-methyl-4-phenyl pyridinium (MPP+) are two mitochondrial neurotoxins known to produce Parkinson's disease (PD) in experimental animals. In the present study, we compared drug-induced rotational asymmetry in rats lesioned using these neurotoxins at three distinct basal ganglia sites, the striatum, substantia nigra pars compacta (SNpc) and median forebrain bundle (MFB). The levels of dopamine (DA) in the ipsilateral striata of these hemiparkinsonian animals were assayed employing an HPLC-electrochemical procedure 2 days after the final rotational study. Rats infused with rotenone or MPP+ into the SNpc, but not into the striatum or MFB, exhibited contralateral rotations immediately after recovery from anesthesia. Irrespective of the lesion site or the toxin used, all the animals exhibited ipsilateral rotations when challenged with D-amphetamine. Apomorphine administration caused contralateral circling behavior in MFB-lesioned animals, but ipsilateral rotations in rats that received rotenone or MPP+ in the striatum or SNpc. Stereotaxic administration of rotenone into the MFB, SNpc or striatum caused a significant loss of DA in the ipsilateral striatum to varying degrees (96%, 62% and 30%, respectively, as compared to the contralateral side). However, unilateral MPP+ administration into the MFB, SNpc or striatum caused respectively about 98%, 74% and 59% loss of striatal DA. Behavioural observations and the neurochemical results indicate that, among the three anatomically distinct loci-lesioned, MFB-lesioned animals mimicked behavioral aberrations similar to nigral lesions caused by 6-hydroxydopamine, a classical parkinsonian neurotoxin. Moreover, the results point out that while both d-amphetamine and apomorphine-induced rotations could be considered as valuable behavioral indices to test novel drugs against PD, yet apomorphine-induced contralateral bias proves to be a more reliable indicator of specific destruction in the nigrostriatal pathway and development of post-synaptic DA receptor supersensitivity.

Antibacterial constituents from the berries of Piper nigrum.

Piper nigrum finds an extensive application in antibacterial preparations belonging to Ayurvedic system of medicine. A bioguided extraction and fractionation of the petroleum ether extract of the berries of P. nigrum afforded 2E, 4E, 8Z-N-isobutyleicosatrienamide (1), pellitorine (2), trachyone (3), pergumidiene (4) and isopiperolein B (5). Pergumidiene and trachyone are isolated for the first time from P. nigrum. All the isolated compounds were active against Bacillus subtilis, Bacillus sphaericus, and Staphylococcus aureus amongst Gram + ve bacteria, and Klebsiella aerogenes and Chromobacterium violaceum among Gram -ve bacterial strains.