A note to the biological activity of benzoxazine derivatives containing the thioxo group.

New 3-benzyl-4-thioxo-2H-1,3-benzoxazine-2(3H)-ones and 3-benzyl-2H-1,3-benzoxazine-2,4(3H)-dithiones were synthesized. The compounds were tested for in vitro antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium kansasii and Mycobacterium avium. The replacement of the carbonyl group by the thiocarbonyl group increased the antimycobacterial activity. The most active derivatives were more active than isonicotinhydrazide (INH). The cytotoxicity and the antiproliferative activity were studied as well.