Studies on synthesis of novel pyrido[2,3-d]pyrimidine derivatives, evaluation of their antimicrobial activity and molecular docking.

A series of novel pyrido[2,3-d]pyrimidine derivatives 6 were prepared starting from 2-amino-3-cyano-4-trifluoromethyl-6-phenyl pyridine 3 via Grignard's reaction, cyclization followed by coupling with aliphatic and cyclic amines. All the compounds 6 were screened for antibacterial, minimum bactericidal concentration (MBC), biofilm inhibition activity as well as antifungal and minimum fungicidal concentration (MFC) activities. Among the screened compounds, the compounds 6e, 6f, and 6m which showed exhibiting promising activity have been identified. The results reveal that the compound pyrido[2,3-d]pyrimidine derivative 6e altered the sterol profile which may exert its antifungal activity through inhibition of ergosterol biosynthesis and could be an ideal candidate for antifungal therapy. The molecular docking results also validated the antifungal results.

Synthesis of novel pyrazolo[3,4-b]quinolinyl acetamide analogs, their evaluation for antimicrobial and anticancer activities, validation by molecular modeling and CoMFA analysis.

A series of novel alkyl amide functionalized 2,3-pyrazole fused quinoline derivatives 5, 6 and 7 have been prepared starting from quinoline-2(1H)one 1 in a series of steps. All the final products were screened for antibacterial activity, the promising lead compound 5r was identified with MIC values ranging between 3.9 and 7.8 µg/mL against different bacterial strains. Compound 5r also showed good antifungal and anti-biofilm activities against the tested panel of various fungal and bacterial strains. Compound 5r when treated on mature biofilms of S. aureus strain MLS16, showed increased levels of intracellular ROS accumulation suggesting its contribution to the bactericidal activity. All the compounds were also screened for anticancer activity against a panel of four human cancer cell lines. Based on these studies, compounds 5c, 5d, 5r and 7f were considered as promising and exhibited significant cytotoxicity with IC50 values of <15 µM. The biological activity data was further validated by molecular modeling and CoMFA studies.

Osmotin: a plant sentinel and a possible agonist of mammalian adiponectin.

Osmotin is a stress responsive antifungal protein belonging to the pathogenesis-related (PR)-5 family that confers tolerance to both biotic and abiotic stresses in plants. Protective efforts of osmotin in plants range from high temperature to cold and salt to drought. It lyses the plasma membrane of the pathogens. It is widely distributed in fruits and vegetables. It is a differentially expressed and developmentally regulated protein that protects the cells from osmotic stress and invading pathogens as well, by structural or metabolic alterations. During stress conditions, osmotin helps in the accumulation of the osmolyte proline, which quenches reactive oxygen species and free radicals. Osmotin expression results in the accumulation of storage reserves and increases the shelf-life of fruits. It binds to a seven-transmembrane-domain receptor-like protein and induces programmed cell death in Saccharomyces cerevisiae through RAS2/cAMP signaling pathway. Adiponectin, produced in adipose tissues of mammals, is an insulin-sensitizing hormone. Strangely, osmotin acts like the mammalian hormone adiponectin in various in vitro and in vivo models. Adiponectin and osmotin, the two receptor binding proteins do not share sequence similarity at the amino acid level, but interestingly they have a similar structural and functional properties. In experimental mice, adiponectin inhibits endothelial cell proliferation and migration, primary tumor growth, and reduces atherosclerosis. This retrospective work examines the vital role of osmotin in plant defense and as a potential targeted therapeutic drug for humans.