Synthesis and antitumor activity of 5-substituted-2-(pyridyl)benzothiazole compounds

Fifteen novel 5-substituted-2-(pyridyl)benzothiazole compounds were designed and synthesized by simple hydrolization and condensation reaction of the 2-amino-5-substituent benzothiazole.  Activities of these synthesized compounds were evaluated on Bcap-37, HCT-15 and HepG2 tumor cells in vitro by standard MTT assay.  5-Fluorouracil (5-FU) was used as the positive control.  The results revealed that most of the new compounds had potent effects on Bcap-37, HCT-15 and HepG2 tumor cells, and had no or less effect on 293T and L02 normal cells.  Particularly, compounds 1c and 2e exhibited better activities on HCT-15 and HepG2 cells with IC₅₀ values of 41.59 and 38.65 μmol·L⁻¹, and 1i showed excellent activities on Bcap-37 and HepG2 cells with IC₅₀ values of 46.63 and 23.51 μmol·L⁻¹, respectively.  The structure-activity relationship of 5-substituted-2-(pyridyl)benzothiazole compounds were also discussed preliminarily.