SOME PHENOLIC COMPOUNDS FROM STEM BARK OF MELINJO (GNETUM GNEMON) AND THEIR ACTIVITY TEST AS ANTIOXIDANT AND UV-B PROTECTION

Abstract

Isolation and structure elucidation of three phenolic compounds, namely 3,4-dimethoxychlorogenic acid (1), resveratrol (2), and 3-methoxyresveratrol (3) from stem bark of Melinjo (Gnetum gnemon) had been done. The isolation of those compounds was carried out by chromatographyc method and structure elucidation was performed by interpretation of spectroscopic data, including UV, IR, 1H and 13C NMR 1D and 2D, and FABMS. The result of this study showed that activity each compounds as radical hydroxyl scavenger of 3,4-dimethoxychlorogenic acid (3), resveratrol (2), and 3-methoxyresveratrol (3), with an IC50 523,7; 45,17; and 60,12; g/ml respectively. Each compound showed significant activity as UV-B protection. Activity test as UV-B protection showed that resveratrol and methoxyresveratrol have maximum protections (SPF 8,03 and 12,34 respectively), and 3,4-dimethoxychlorogenic acid has minimum protection (SPF 2,55), each compounds on 50 g/ml. Key word : melinjo; Gnetum gnemon; natural antioxidant; UV-B protection FMIPA, 2007 (PEND. KIMIA