Novel stilbenoids isolated from the heartwood of Shorea laeviforia

Two novel stilbenoids, laevifonol (an epsilon-viniferin-ascorbic acid hybrid compound) and laevifoside (an O-glucoside of ampelopsin A) were isolated from the heartwood of Shorea laeviforia. Their structures were elucidated by nuclear magnetic resonance spectroscopic evidence including HMQC, HMBC, and NOESY. The novel compounds and other known stilbenoids from S. laeviforia were evaluated for inhibitory activity against rat liver 5alpha-reductase. Positive inhibitory activities were observed in resveratrol dimers and tetramers. No inhibitory activity was detected in laevifonol and ampelopsin A glucosides, laevifoside, or hemsleyanoside, whereas inhibitory activity was seen in their aglycon. These results suggest that the hydrophilic moiety in these compounds may inhibit action with the hydrophobic active site of the enzyme.