Benzofuran derivatives with nerve growth factor-potentiating activity from Phellinus ribis

Three new benzofuran derivatives, namely ribisin E (1) ribisin F (2) along with ribisin G (3) were isolated from the MeOH extract of the fruiting bodies of Phellinus ribis. Their structures were elucidated based on the NMR analysis. Furthermore, the absolute configuration of ribisin E (1) and ribisin G (3) were deduced by the CD calculations, and the absolute configuration of ribisin F (2) was determined by comparing its CD spectrum and specific rotation with the data of known analogues. All compounds (1–3) exhibited the activity of promoting neurite outgrowth in nerve growth factor (NGF)-ediated PC 12 cell at concentrations ranging from 1 to 30 μM.