The authors isolated four olefinic catechols, commonly referred to as urushiol, from the sap of Korean lacquer tree (Rhus vernicifera STOKES) with stronger antioxidative activities than α-tocopherol. The hexane extract with a free radical scavenging activity was purified by silica and ODS gel column chromatography. The active compounds were identified by MS and H-NMR as 3-[8 (Z), 11 (Z), 14 -pentadecatrienyl]catechol, 3-[8 (Z), 11 (Z)-pentadecadienyl]catechol, 3-[8 (Z)-pentadecenyl] catechol, and 3-pentadecylcatechol. All of these compounds showed strong free radical scavenging activities on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical, in which 3-pentadecylcatechol exhibited the highest activity (IC50: 1.2 ㎍/㎖). They also showed a significant inhibitory activity on lipid peroxidation (IC50: 2.1 - 3.5 ㎍/㎖). The antioxidative activity of 3-pentadecylcatechol on DPPH radical and lipid peroxidation is approximately two times greater than that of α-tocopherol. The results suggest that the urushiol derivatives may contribute to the preservative characteristics effective against oxidative stress and could be a good source for industrial applications including a coating material.
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