Antimicrobial activity of 3‐(substituted methyl)‐2‐phenyl‐4H‐l‐benzothiopyran‐4‐ones

A series of 3‐(substituted Methyl)‐2‐phenyl‐4H‐l‐benzothiopyran‐4‐ones (thioflavones) and thioflavone 1,1‐dioxides was prepared to test for antimicrobial activity and for antitumor activity. It was shown that an introduction of a substituted methyl group in the 3‐position of thioflavone resulted in significant antimicrobial activity against Trichophytons. 3‐(Acetoxymethyl)thioflavone shows the most antimicrobial potency in vitro against Trichophyton mentagrophytes. Most of the thioflavone 1,1‐dioxides showed antimicrobial activity against fungi. Five of the 40 related compounds demonstrated weak antitumor activity against P‐388 lymphocytic leukemia.