Antitumor in vitro evaluation of certain derivatives of pyrido-1,2-thiazines.

We report an antitumor in vitro evaluation of a small series of 3-phenyl(methyl)pyrazolo[4, 3-c] pyrido [3,2-e]-1,2-thiazines 4 and the related 3-benzoyl (acetyl)-4-hydroxypyrido [3,2-e]-1,2-thiazines 5 bearing a 3-(4-arylpiperazin-1-yl) propyl group at the nitrogen atom of the thiazine ring. Five of the seven pyridothiazines 5 tested and one compound from the series 4 (five compounds) exhibited in cell experiments a significant antitumor activity against several types of human tumor cells [GI50 values 3-54 mM/L]. The action of the most active compound 5f against some leukemia and melanoma cell lines was observed at sub mM/L doses at the GI50 level.