Novel substituted 1,2,4-dithiazolylchromones 3a–j were synthesized by the reaction of 3-formylchromones (1a–j) with two equivalents of p-chlorothiobenzamide (2) in dry xylene and characterized spectroscopically (IR, 1H and 13C NMR, mass) and elemental analysis. All synthesized compounds were screened for in vitro antimicrobial activity against various pathogenic bacterial and fungal strains and were found to possess good to moderate inhibitory potential against all tested strains. Antimicrobial results reveal that compounds bearing lipophilic electron withdrawing groups such as chloro and bromo displayed significant inhibitory potential against both bacterial and fungal strains. Particularly, compound 3c displayed significant inhibitory against bacterial strains and compound 3h exhibits significant inhibitory potential in comparison to standard drug fluconazole against fungal strain S. cerevisiae. 1. Introduction Fungal and bacterial infections are affecting millions of people worldwide, and are associated with high rates of mortality and morbidity [1]. Resistance to antimicrobial agents is becoming a major problem; microbes acquire the ability to resist antimicrobial drugs by undergoing genetic changes either by mutation or gene transfer within or between species that allow microbes to defend themselves against the antimicrobial agents [2]. Therefore, the discovery of new antimicrobials has assumed critical importance to combat the fungal and bacterial infections. Heterocycles containing N and S are found to display variety of biological activities; amongst them, dithiazoles both 1,2,3- and 1,2,4- are endowed with interesting biological activities, in particular, antimicrobial activity [3]. Similarly, chromone moiety constitutes the basic nucleus of flavones, which are most important and widespread natural product of plants and display a large number of biological activities such as antifungal [4], antibacterial [5], anticancer [6], antiviral [7], antioxidant [8] antimalarial [9] neuroprotective [10], and HIV inhibitory [11]. Recently, we have reported the synthesis of 3-(5-phenyl-3H-[1,2,4]-dithiazol-3-yl) chromen-4-ones with significant inhibitory potential against microbial strains; particularly, compound having both electron withdrawing groups such as chloro and fluoro linked with chromone ring showed more inhibitory potential against fungal strains than standard drug [12]. Therefore, it was decided in the present study to incorporate chloro group at the phenyl ring of the 1,2,4-dithiazolylchromones in order to observe the effect of novel
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