Five New Oligostilbenes with One or Two Dihydrofurans from the Stem Bark of Vatica rassak

Abstract

From the stem bark of Vatica rassak, five new stilbenoids (vaticanols E, F and vaticasides A-C) were isolated.The structures including the relative configuration were established on the basis of spectroscopic analysis.Plants belonging to the family Dipeterocarpaceae are known to abundant source of stilbenoids. 1, 2 Various biological effects such as chemopreventive, 3 anti-inflammatory activity, 4 and inhibitory activity of histamine release 5 and gastric ATPase 6 have been recently found in the stilbene derivatives.Stilbenoids are then regarded as useful candidates for drug development.In continuation of our phytochemical studies [7][8][9][10][11] of Dipterocarpaceous plants oriented to search for biological active principles, the structures of stilbenoids in some plants of Hopea, 7 Vatica, 8, 9 and Shorea 10, 11 were characterized and their distinctive cytotoxicty was disclosed. 12n our preceding papers dealt with oligostilenes in the stem bark of Vatica rassak, the structures of a stilbene trimer (vaticanol A), 8 two tetramers (vaticanols B and C) 8 and a hexamer (vaticanol D), 9 were described.They are commonly composed of a 3,5,4'-trihydroxystilbene (resveratrol).Further investigation of the acetone extract resulted in isolation of two new oligostilbenoids, vaticanols E (1) and F (2), together with three new O-glucosyl oligostilbenoids, vaticasides A-C (3-5).This paper deals with their structure elucidation including the relative configuration.Vaticanol E (1), a pale yellow amorphous powder, showed a positive reaction to the Gibbs test.The absorption band in the UV spectra showed the presence of aromatic rings (284 nm).The [M-H] -ion peak at m/z 679.1971 in the high-resolution (HR) FABMS corresponds to the molecular formula of C 42 H 32 O 9 .The 1 H NMR spectrum (Table ) showed the presence of three 4-hydroxyphenyl groups [δ 7.77,