Antioxidative Effects of Green Tea Polyphenols on Free Radical Initiated and Photosensitized Peroxidation of Human Low Density Lipoprotein

Chem Phys Lipids. 2000 Jun;106(1):53-63. doi: 10.1016/s0009-3084(00)00133-x.

Abstract

Antioxidative effects of the main polyphenolic components extracted from green tea leaves, i.e. (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG) and gallic acid (GA), against free radical initiated peroxidation of human low density lipoprotein (LDL) were studied. The peroxidation was initiated either thermally by a water-soluble initiator 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH), or photochemically by a triplet sensitizer benzophenone (BP). The reaction kinetics was monitored by the uptake of oxygen and the depletion of alpha-tocopherol (TOH) presented in the native LDL. Kinetic analysis of the antioxidation process demonstrates that these green tea polyphenols are effective antioxidants against both AAPH-initiated and BP-photosensitized LDL peroxidation. The antioxidative action of the green tea polyphenols includes trapping the initiating and/or propagating peroxyl radicals with the activity sequence EC>EGCG>ECG>EGC>GA for the AAPH initiated peroxidation, and reducing the alpha-tocopheroxyl radical to regenerate alpha-tocopherol with the activity sequence of ECG>EC>EGCG>EGC>GA and ECG>EGCG>GA>EC>EGC for the AAPH-initiated and BP-photosensitized peroxidations respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / pharmacology*
  • Catechin / analogs & derivatives
  • Catechin / pharmacology
  • Flavonoids / pharmacology
  • Free Radicals / metabolism
  • Gallic Acid / pharmacology
  • Humans
  • In Vitro Techniques
  • Kinetics
  • Lipid Peroxidation / drug effects*
  • Lipid Peroxidation / radiation effects
  • Lipoproteins, LDL / blood
  • Lipoproteins, LDL / drug effects*
  • Lipoproteins, LDL / metabolism
  • Phenols / chemistry
  • Phenols / isolation & purification
  • Phenols / pharmacology*
  • Photochemistry
  • Polymers / chemistry
  • Polymers / isolation & purification
  • Polymers / pharmacology*
  • Tea / chemistry*

Substances

  • Antioxidants
  • Flavonoids
  • Free Radicals
  • Lipoproteins, LDL
  • Phenols
  • Polymers
  • Tea
  • Gallic Acid
  • Catechin
  • epicatechin gallate
  • epigallocatechin gallate
  • gallocatechol