Trimer and Tetramer Resveratrols from Shorea macroptera

Four oligomer resveratrols have been isolated from the stembark of Shorea macroptera Dyer by using various chromatographic techniques. The dried and ground bark of Shorea macroptera (6kg) was soaked with acetone for 72 hours. The acetone extract was concentrated in vacuo to yield a crude extract (300g) that was partitioned further using diethyl ether. The diethyl extract was concentrated (115g) and subjected to vacuum liquid chromatography (VLC) using gradient system of Hexane: Ethylacetate (Ea) and seven fractions were afforded. Fraction 4 was further purified by second VLC (CHCl3-acetone system), and repeated radial chromatography (CHCl₃-MeOH system) to yield compound 1. Fraction 5 was subjected to VLC (Hex: Ea: Ac system) and purified by radial chromatography repeatedly (CHCl₃:Ea:MeOH system) to give compound 2, 3 and 4.The structures of compounds 1–4 were determined based on spectroscopic data including UV, IR, 1D an 2D NMR and comparison with those previously reported. The similarity to these published data from Tanaka et al, 2000 [1], Ito et al, 1997 [2] and Tanaka et al, 2001 [3] suggested compound 1 as davidiol A, a trimer resveratrol and compound 2, 3 and 4 as tetramer resveratrols namely hopeaphenol, isohopeaphenol and hemsleyanol D, respectively.

Acknowledgement: Scholarship of one of the authors was financed by the National Science Fellowship (NSF) from Ministry of Science, Technology and Innovation Malaysia (MOSTI).

References: [1] Tanaka T et al. (2000) Phytochemistry 53: 1009–1014.

[2] Tukiran AS et al. (2005) Biochemical Systematics & Ecology 33: 631–634.

[3] Tanaka T et al. (2001) Heterocycles 55:729–740.