On the Use of Triarylsilanols as Catalysts for Direct Amidation of Carboxylic Acids.

Triarylsilanols have been reported as the first silicon-centered molecular catalysts for direct amidation of carboxylic acids with amines as identified after a screen of silanols, silanediols, disiloxanediols, and incompletely condensed silsesquioxanes as potential homogeneous catalysts. Subsequent synthesis and testing of various electronically differentiated triarylsilanols have identified tris(p-haloaryl)silanols as more active than the parent triarylsilanol, where the bromide congener is found to be the most active. Catalyst decomposition can be observed by NMR methods, but RPKA methods reveal that product inhibition is operative, where tertiary amides are more inhibitory than secondary amides. Studies using an authentically synthesized triaryl silylester as a putative intermediate in the catalytic system enable a plausible mechanism to be proposed as supported by computationals.

In vivo pharmacological investigation of Monotheca buxifolia and Bosea amherstiana using animal models.

Experimental based evidence suggests that most of the medicinal plants possess wide-ranging pharmacological and biological activities that may possibly use in treatment of inflammation-related diseases. The current study was aimed to explore the acute toxicity, analgesic, sedative and antipyretic activities of Monotheca buxifolia and Bosea amherstiana in mices. In vivo experimental models were used in this study. Acute toxicity was evaluated for 24 h' interval at concentration of 500, 1000, 1500 and 2000 mg/kg. The analgesic activity was estimated by acetic acid induced writhing test. White wood apparatus enclosed in stainless steel was used for sedative experiment and antipyretic activity was evaluated in brewer's yeast induced hyperthermic at 50, 100 and 150 mg/kg i.p. Both plants were found safe at all tested doses. Monotheca buxifolia and Bosea amherstiana dose-dependently reduced abdominal constrictions in mice. Both plants exhibited significant (P < 0.0001) sedative effects in dose of 50, 150 and 150 mg/kg. Both plants markedly (P < 0.0001) reduced yeast induced hyperthermia. The inhibitions were dose-dependent and remained significant up to five hours of administration. These investigational results have linked a pharmacological indication for the traditional claim of the drugs to be used as an anti-inflammatory, analgesics and antipyretic agents.

Novel 1,3-oxazine-tetrazole hybrids as mushroom tyrosinase inhibitors and free radical scavengers: Synthesis, kinetic mechanism, and molecular docking studies.

A variety of 5-(2H-tetrazol-5-yl)-4-thioxo-2-(substituted phenyl)-4,5-dihydro-1,3-oxazin-6-ones (3a-k) have been synthesized from 1,3-oxazine-5-carbonitriles (2a-k). The protocol represents an efficient, facile, and novel route from easily available precursors to unprecedented structures that share 1,3-oxazine and tetrazole motifs of utmost value. All the synthesized compounds (3a-k) were evaluated for their inhibitory potential against mushroom tyrosinase. Results revealed that all examined 1,3-oxazine-tetrazole hybrids exhibited significant tyrosinase inhibitory activity while compound 3d having 2-bromophenyl moiety was the most potent among the series with IC50 value 0.0371 ± 0.0018 µM as compared to the reference kojic acid (IC50  = 16.832 ± 0.73 µM). Inhibitory kinetics showed that compound 3d behaves as a competitive inhibitor. The molecular docking analysis was performed against target protein to investigate the binding mode. Moreover, compounds 3j and 3k displayed superior DPPH radical scavenging activity than other analogues.

Synthesis, carbonic anhydrase inhibitory activity and antioxidant activity of some 1,3-oxazine derivatives.

Hit, Lead & Candidate Discovery A series of 1-(6-methyl-2-substituted phenyl-4-thioxo-4H-1,3-oxazin-5-yl)ethanones (3a-n) were synthesized by the reaction of benzoyl isothiocyanates with active methylene compound acetylacetone in the presence of triethyl amine in a one-pot process. The structures of the products were elucidated by elemental analyses, FT-IR, 1 H NMR, 13 C NMR, and mass spectroscopy. These new 1,3-oxazine derivatives were evaluated for their inhibitory activity against carbonic anhydrase II. Results for in vitro assay revealed that compound 3b having 4-methoxy phenyl moiety was the most potent inhibitor with IC50 value of 0.144 ± 0.008 µM. It exhibited higher enzyme inhibitory activity as compared to the standard acetazolamide (IC50 = 0.997 ± 0.061 µM). The compounds 3c, 3h, and 3n also displayed superior inhibitory activities compared to the rest of the synthesized oxazine derivatives. The radical scavenging activity of oxazine derivatives was also performed and it was found that compounds showed moderate antioxidant activity. Lipinski rule confirmed the therapeutic potential of the synthesized compounds. Molecular docking studies were also performed to further understand the binding affinity of these compounds with PDBID 1V9E which confirmed that the synthesized derivatives bind in the active binding site of the target protein. Based upon our results, it is proposed that compound 3b may serve as a lead structure to design more potent carbonic anhydrase inhibitors.