Antioxidative activities of galloyl glucopyranosides from the stem-bark of Juglans mandshurica
2008
Ngoc, T.M.(Chungnam National Univ., Daejon (Korea R.)) | Hung, T.M. | Thuong, P.T. | Kim, J.C. | Choi, J.S. | Bae, K.H. | Hattori, M. | Choi, C.S. | Lee, J.S. | Min, B.S.
Two phenolics, 1,2,6-trigalloylglucose (1) and 1,2,3,6-tetragalloylglucose (2), isolated from the stem-bark of Juglans mandshurica were evaluated for their antioxidative activities. The results showed that compounds 1 and 2 exhibited strong scavenging activities against 1,1'-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzenthiazoline-6-sulphonic) acid (ABTSsup(+)radical), and superoxide radicals (O2sup(-)radical), and also had a significant inhibitory effect on lipid peroxidation and low-density lipoprotein (LDL) oxidation. The strong superoxide radical scavenging of 1 and 2 resulted from the potential competitive inhibition with xanthine at the active site of xanthine oxidase (OX). In addition, compounds 1 and 2 displayed significant lipoxygenase inhibitory activity, the mode of inhibition also being identified as competitive. In comparison, the antioxidative activities of compounds 1 and 2, together with gallic acid, indicated that the number of galloyl moieties could play an important role in the antioxidative activity.
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