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MRSA infection is one of the alarming diseases in the current scenario. Identifying newer molecules to treat MRSA infection is of urgent need. In the present study, we have designed fluorinated thiazolidinone derivatives with various aryl/heteroaryl units at 5 th position of the thiazolidinone core as promising anti-MRSA agents. All the compounds were screened for antibacterial activity against four bacterial strains. Among the tested compounds, the halogenated compounds with simple arylidene ring, (5Z 4f) and (5Z)-5-[(3,5-difluorophenyl)methylidene]-2-[(1,3-thiazol-2-yl)amino]-1,3thiazol-4(5H)-one (4g) showed excellent activity with MIC 3.125 -6.25 μg/mL against S. aureus and P. aeruginosa organism. Furthermore, these potent compounds were screened against MRSA strains, ESKAPE panel organism, and H37Rv mycobacterium strain. Compounds 4c (MIC 0.39 μg/mL), and 4f (MIC 0.39 and 0.79 μg/mL) displayed promising activity against MRSA strains (ATCC and clinical isolates, respectively). The most potent compounds, 4c and 4f eradicated the growth of bacterial colonies in a time-kill assay indicated that these are bactericidal in nature. The preliminary toxicity study of the potent molecules revealed that these compounds are non-hemolytic in nature as they did not induce lysis in human RBCs. In addition, the molecular docking and dynamics studies of compounds 4b, 4c, 4f and 4g were carried out on MurB protein of S. aureus (PDB code: 1HSK). Docking results demonstrated remarkable hydrogen bonding interaction with key amino acids ARG310, ASN83, GLY79 and π-π interactions with TYR149 which confirm the mode of action of the molecules.

This study investigates the cytotoxic and antioxidant potential of crude leaf extracts of Pogostemon heyneanus (P. heyneanus) and Plectranthus amboinicus (P. amboinicus), medicinal plants from Lamiaceae family. Crude leaf extracts, with methanol, ethanol and chloroform were evaluated for cytotoxicity in two breast cancer cell lines of different grades, MCF-7 and MDA-MB-231, by MTT assay. The antioxidant activity of the extracts was evaluated by DPPH and H2O2 assays. The results of MTT assay revealed that chloroform extract of P. heyneanus and ethanol extract of P. amboinicus were effective against MCF-7 cells. The chloroform extract of P. heyneanus was more effective than P. amboinicus against MDA-MB-231. Effective antioxidant activity was shown by the ethanol extract of P. amboinicus which correlated positively with the total phenol content. The chloroform extract of P. heyneanus, was rich in steroids and saponins which correlated positively with the cytotoxic activity. In conclusion, chloroform soluble leaf extracts of P. heyneanus, which is rich in steroids and saponins shows effective cytotoxicity on both breast cancer lines studied and could be used for identification of a potential anticancer principle, while ethanol extract of P. amboinicus has better potential as an antioxidant.