Five New Phenolic Compounds with Antioxidant Activities from the Medicinal Insect Blaps rynchopetera

Five new phenolic compounds rynchopeterines A-E (1-5), in addition to thirteen known phenolics, were isolated from Blaps rynchopetera Fairmaire, a kind of medicinal insect utilized by the Yi Nationality in Yunnan Province of China. Their structures were established on the basis of extensive spectroscopic analyses (1D and 2D NMR, HR-MS, IR) along with calculated electronic circular dichroism method. Rynchopeterines A-E (1-4) exhibited significant antioxidant activities with IC50 values of 7.67-12.3 μg/mL measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Besides, rynchopeterines B (2) and C (3) showed mild cytotoxicity against tumor cell Caco-2 and A549.