Study on antibacterial and antioxidant activities against dimer, trimer and tetramer resveratrol from Malaysian's Dipterocarpus verrucosus

Dipterocarpus verrucosus Foxw. ex Slooten, known as „keruing merah“ by the local is a species of tree in the family Dipterocarpaceae (Symington, 1974). The stem bark was collected from Jengka, Pahang, Malaysia and extracted in acetone and methanol. The phytochemical investigation of this plant led to the isolation of three types of resveratrol compound, laevifonol (dimer), α-viniferin (trimer) and vaticanol B (tetramer). The compound structure was determined by NMR spectra and also in comparison with the previously reported data. Biological activities of the compounds were evaluated against six strains of bacteria; Pseudomonas aeruginosa, Klebsiella pneunomonia, Salmonella paratyphi, Bacillus subtilis, Stapylococcus aureus and E.coli by disc diffusion method (Barry at el., 1994) while antioxidant were evaluated by DPPH (Blois, 1958), TPC (Velioglu et al., 1999), FTC (Osawa and Namiki 1981 and TBA (Kikuzaki and Nakatani 1993). The DPPH radical scavenger test showed that tetramer gave better result (36.6%) as compared to the dimer and trimer. TPC evaluations showed that the tetramer and dimer contain the same amount of phenolics which is 616.15mg/g of GAEs while trimer displayed lower amount of 340mg/g of GAEs. FTC and TBA methode revealed that the trimer showed better inhibition among the others with the value of 77.77 and 86.47% each. Antibacterial activity, trimer resveratrol with concentration of 50mg/ml showed to be the most active with inhibition toward Stapylococcus aureus (8.8mm), Pseudomonas aeruginosa (8.5mm) and E.coli (17mm). These biological data suggested that no regular pattern is observed between molecular size and biological properties.

Keywords: Dipterocarpus verrucosus, Dipterocarpaceae, oligostilbenoid, antibacterial, antioxidant

Acknowledgement: We wish to thank to Ministry of Higher Education Malaysia for financial support via FRGS grant 600-RMI/ST/FRGS 5/3/Fst(3/2008) and for Phd study leave as well as UiTM for all the support

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