Antioxidative Activity of Green Tea Treated with Radical Initiator 2,2‘-Azobis(2-amidinopropane) Dihydrochloride

• Published in: Journal of agricultural and food chemistry Vol. 48; no. 10; pp. 5068 - 5073
• Main Authors: Yokozawa, Takako, Cho, Eun Ju, Hara, Yukihiko, Kitani, Kenichi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-10-2000
• Subjects: Amidines - pharmacology; Animals; Antioxidants - chemistry; Antioxidants - pharmacology; Biological and medical sciences; Coffee, tea and other stimulative beverage industries; Food industries; Free Radicals - chemistry; Free Radicals - metabolism; Fundamental and applied biological sciences. Psychology; General pharmacology; LLC-PK1 Cells; Medical sciences; Oxidants - pharmacology; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Swine; Tannins - chemistry; Tannins - pharmacology; Tea - chemistry; Catechin; Pharmacognosy; Stimulant plant; Foodstuff; Extract; Plant leaf; Antioxidant; Radical scavenger; Biological activity; Free radical; Camellia sinensis; Dicotyledones; Angiospermae; Plant origin; Spermatophyta; Oxidation; Protection; Green tea; Theaceae; Vegetal tannin
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf000253b

This study investigated the antioxidative activity of green tea extract, and a green tea tannin mixture and its components, under conditions of radical generation using the hydrophilic azo compound, 2,2‘-azobis(2-amidinopropane) dihydrochloride (AAPH) to generate peroxyl radicals at a constant and measurable rate in the cultured renal epithelial cell line, LLC−PK1, which is susceptible to oxidative damage. Treatment with AAPH decreased cell viability and increased the formation of thiobarbituric acid-reactive substances. However, green tea extract, and the tannin mixture and its components, comprising (−)-epigallocatechin 3-O-gallate (EGCg), (−)-gallocatechin 3-O-gallate (GCg), (−)-epicatechin 3-O-gallate (ECg), (−)-epigallocatechin (EGC), (+)-gallocatechin (GC), (−)-epicatechin (EC), and (+)-catechin (C), showed protective activity against AAPH-induced cellular damage. The tannin mixture and its components exhibited higher antioxidative activity than the green tea extract. Furthermore, EGCg and GCg had higher activity than EGC and GC, respectively. In particular, EGCg exerted the most significant cellular protective activity against AAPH. These results indicate that green tea tannin may inhibit cellular loss and lipid peroxidation resulting from the peroxyl radical generated by AAPH, and that the chemical structure of tannin is also involved in the activity, suggesting that the O-dihydroxy structure in the B ring and the galloyl groups are important determinants for radical scavenging and antioxidative potential. Keywords: Antioxidative activity; 2,2‘-azobis(2-amidinopropane) dihydrochloride; green tea; tannin; (−)-epigallocatechin 3-O-gallate; LLC−PK 1