Effects of catechins and green tea extract on the photosensitized singlet oxygen oxidation of linoleic acid in a model system as compared with α-tocopherol
2011
Jung, M.Y., Woosuk University, Wanju, Republic of Korea | Jung, D.M., Woosuk University, Wanju, Republic of Korea | Wu, J.W., Woosuk University, Wanju, Republic of Korea | Choi, D.S., Woosuk University, Wanju, Republic of Korea
Effects of catechins and green tea extract (GTE) on the photosensitized singlet oxygen oxidation of linoleic acid were studied. Epigallocatechin gallate (EGCG) showed the highest antioxidant activity, followed by gallocatechin gallate, epigallocatechin, and epicatechin in a decreasing order. α-Tocopherol showed strong antioxidative activity at the initial oxidation stage, but its antioxidative property rapidly decreased with illumination time. EGCG showed significantly stronger antioxidative activity than α-tocopherol at the later oxidation stage (p less than 0.05) due to the higher stability of EGCG. Unlike α-tocopherol, GTE possessed strong antioxidative activity even at the later oxidation stage. Overall, GTE was a better antioxidant than α-tocopherol for the protection of linoleic acid from singlet oxygen oxidation. Electron spin resonance (ESR) spectroscopy and visible-spectroscopic data showed unambiguous evidences that the protective activity of GTE against the photosensitized oxidation of linoleic acid was due to the singlet oxygen quenching mechanism.
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