2,9-Dimethylpicene: Synthesis, Mutagenic Activity, and Identification in Natural Samples

Abstract

Abstract 2,9-Dimethylpicene (2,9-DMPic) has been conveniently synthesized via a new route involving oxidative photocyclization of suitable substituted diarylethylenes and has been characterized by high-resolution 400-MHz 1H-NMR spectroscopy. Furthermore, 2,9-DMPic exhibits a typical line narrowed emission spectrum in n-decane matrix frozen at 15 K (Shpol'skii effect). Its unambiguous identification in a natural sample has been performed by this technique, providing strong evidence for the formation of this compound through aromatization of triterpenoid natural precursors. The mutagenicity of this naturally occurring methylated polycyclic aromatic hydrocarbon (PAH) has been examined in six his − strains of Salmonella typhimurium (TA 97, TA 98, TA 100, TA 102, TA 104, TA 1537) in the presence of a hepatic xenobiotic-metabolizing system. While carcinogenic PAH, used as positive controls, showed potent effects in this system, 2,9-DMPic proved completely inactive.