Alpha‐terthienyl, a Non‐photodynamic Phototoxic Compound

Alpha‐terthienyl (αT), a natural product first isolated in the plant Tagetes erecta (family Compositae), is the first member of a new class of phototoxic compounds, whose activity is not based on the generation of singlet oxygen. Its maximum activity against Candida utilis was at 370 nm, and was not affected by the presence of sodium azide. Furthermore, its phototoxicity against E.coliB cells was expressed under nitrogen, but not under oxygen. In the presence of UVA, radioactive αT formed covalent bonds with calf thymus DNA, and was also incorporated into the DNA of C. utilis. Two different methods proved that the photochemical interaction of αT and DNA did not involve cross linking of double strands.