Antitumor activity of benzo[a]phenothiazines

We have previously reported on the diverse biological activities of benzo[a]phenothiazines, such as the induction of antitumor and antimutagenic activity in vivo, and differentiation and apoptosis in vitro. The relationship of radical generation and pi-spin density or dipole moment was investigated, using quantum-chemical calculation with UHF/PM3. These data suggest that the origin of radical generation by active benzo[a]phenothiazines, which affect such biological activities might be N-atom at position 12.