New α-glucosidase inhibitors with p-terphenyl skeleton from the mushroom Hydnellum concrescens.

The purpose of this study is to elucidate the bioactive components responsible for the the α-glucosidase inhibitory activity detected in the EtOAc extract of the mushroom Hydnellum concrescens . Two new p -terphenyl derivatives, concrescenins A ( 1 ) and B ( 2 ), in along with six known compounds thelephantins L ( 3 ), I ( 4 ), J ( 5 ), K ( 6 ), dihydroauran-tiacin dibenzoate ( 7 ), and curtisian A ( 8 ) were isolated from the fruiting bodies of H. concrescens . Their chemical structures were elucidated by NMR experiments. Compounds 1 – 4 and 6 – 8 showed the inhibitory activity against α-glucosidase with the IC 50 of 0.99, 3.11, 4.53, 18.77, 2.98, 5.16, and 8.34 μM, respectively. Kinetic analysis of α-glucosidase indicated that compounds 1 and 2 inhibited the activity of α-glucosidase in a noncompetitive fashion with a Ki value of 0.02 and 0.21 μM, respectively. In antioxidant evaluation, compounds 1 and 4 showed weak DPPH scavenging activity (EC 50 = 82.50 and 161.75 μM) and weak reducing ability (EC 50 = 193.57 and 152.94 μM). The current research supports the potential use of mushroom-derived p -terphenyl derivatives for the treatment of diabetes. [ABSTRACT FROM AUTHOR]