P-Terphenyl Compounds Possessing Antioxidative Activity from Japanese Inedible Mushrooms

Abstract

We are continuing to study biologically active substances from inedible mushrooms. In this paper, we report 36 new p-terphenyl compounds possessing antioxidative activity from fruit bodies of four Japanese inedible fungi named Thelephora aurantiotincta Corner, T. terrestris Ehrn., and Hydnellum caeruleum (Hornem.)P.Karst., belonging to Thelephoraceae; and Paxillus curtisii Berk., belonging to Coniophoraceae. Eight new p-terphenyl compounds, thelephantins A−H (1−8) (Quang et al., 2003a,b) and five known compounds—atro-mentin, 2-O-methylatromentin, gabajunins C and E, and thelephorin A—were isolated from T. aurantiotincta. Eight new p-terphenyl compounds—thelephantins I−P (9−16) (Quang et al., 2004) together with two known compounds, 2-O-methylatromentin and dihydroaurantiacin—were isolated from H. caeruleum, seven new p-terphenyl derivatives—terrestrins A−G (17−23) and two new pregnane-type steroids, terrestrones A and B (24, 25) from T. terrestris. In addition, 13 new p-terphenyl derivatives named curtisians E−Q(26−38) (Quang et al., 2003c−e) along with two known compounds—curtisians C and D—were also obtained from P. curtisii. These absolute structures were determined by 2D NMR, MS, IR, and UV spectra, X-ray crystallographic analysis, and chemical reactions. Antioxidative activities of these new p-terphenyl compounds were evaluated by diphenyl-p-picryhydrazyl (DPPH) radical scavenging effects. Some new p-terphenyl compounds showed equivalent or strong activities compared with vitamin C, α-tocopherol, and BHA (tert-butylhydroxyanisole).