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 activ ity in vivo, and differentiation and apoptosis in vitro. The relationship o f radical generation and pi-spin density or dipole moment was investigated, using quantum-chemical calculation with UHFIPM3. These data suggest that t he origin of radical generation by active benzo[a]phenothiazines, which aff ect such biological activities might be N-atom at position 12.