Lipid peroxidation gallate

TERAO J, PiSKULA M and YAO Q (1994) Protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation in phospholipid bilayers , Arch Biochem Biophys, 308, 278-84. 

The effects of flavonoids on in vitro and in vivo lipid peroxidation have been thoroughly studied [123]. Torel et al. [124] found that the inhibitory effects of flavonoids on autoxidation of linoleic acid increased in the order fustin < catechin < quercetin < rutin = luteolin < kaempferol < morin. Robak and Gryglewski [109] determined /50 values for the inhibition of ascorbate-stimulated lipid peroxidation of boiled rat liver microsomes. All the flavonoids studied were very effective inhibitors of lipid peroxidation in model system, with I50 values changing from 1.4 pmol l-1 for myricetin to 71.9 pmol I 1 for rutin. However, as seen below, these /50 values differed significantly from those determined in other in vitro systems. Terao et al. [125] described the protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation of phospholipid bilayers. 

We found that tannins such as (-)-epigallocatechin, (-) epicatchin gallate and (-)-epigalloylcatechin gallate "Fig. (30)" contained in green tea inhibited ADP plus NADPH-induced lipid peroxidation in rat liver microsomes.[16] Therefore, we examined the effects of tannin fractions of green tea on peroxidized oil-induced liver injury. As shown in "Table (10) and Table (11)", the oral administration of extracts of green tea reduced the elevation of serum FFA, LPO and GPT, and liver TG in rats fed peroxidized oil for 7 days. 

Terao, J., Pisukla, M., and Yao, Q. 1994. Protective effects of epicatechin, epicatechin gallate and quercetin on lipid peroxidation in phospholipids bilayers. Arch. Biochem. Biophys. 308 278-84. 

Epigallocatechin-3-O-gallate (ECCC) HepG2 cells Suppress lipid peroxidation and to protect cells from oxidative damages. [75] ... 

Quercetin (7), morin (39), myricetin (8), and fisetin (40) (Fig. 11.18) were active inhibitors of induced lipid peroxidation in the presence of ferrous ion. Isovitexin (24) is an effective antioxidant—being more effective than BHA (bu-tylated hydroxyanisole) and a-tocopherol. Epicatechin 3-0-gallate (41) is a potent oxygen free-radical scavenger (Beier and Nigg, 1992). 

Although phospholipid bilayers are better mimics of biomembranes than are micelles, there are few reliable quantitative data on flavonoid antioxidant activities in lipid bilayers. Terao and coworkers compared the antioxidant efficiency of quercetin and catechins (epicatechin and epicatechin gallate) with that of a-Toc in egg yolk PC liposomes using initiation by the water-soluble initiator, ABAP, and analysis of hydroperoxide formation and antioxidant consumption by HPLC. Based on the length of the induction periods and the profile of suppressed hydroperoxide formation, they concluded that quercetin and the catechins were more efficient antioxidants than a-Toc in these bilayers. Apparently the unique behavior of a-Toc in bUayers is responsible for these results (vide supra). In hexane and alcohols solution during suppressed peroxidation of methyl linoleate, the relative antioxidant activities reversed so that the flavonoids were 5-20 times less active... 

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