Theaflavins antioxidative effects

Yoshino, K., Kara, Y, Sano, M., and Tomita, I. 1994. Antioxidative effects of black tea theaflavins and thearubigins on lipid peroxidation of rat liver homogenates induced by less butylhydroperoxide. Biol. Pharm. Bull. 17 146-49. 

Certain natural compounds possess anti-apoptotic effects. For example, ascorbic acid and a-tocopherol prevent apoptosis caused by serum withdrawal in HL-60 cells with the antioxidative effects (76). Caffeic acid inhibits ceramide-induced apoptosis in U937 cells through the inhibition of protein tyrosine kinase activity 17). Quercetin inhibits hydrogen peroxide-induced apoptosis via intervention in the activator protein 1 (AP-1) -mediated apoptotic pathway 18). Epigallocatechin-3-gallate and theaflavins inhibits arsenite-induced apoptosis through the decrease in phosphorylation of Erks and JNKs (79). Therefore, it is important to know whether these natural compounds show inhibitory effects on Trp-P-1-induced apoptosis. In this study, we demonstrated that Trp-P-1 induced caspase-8-initiated apoptosis in rat MNCs, and that certain food components inhibited Trp-P-l-induced apoptosis. 

Flavonoids exhibit protective action against LDL oxidation. It has been shown [145] that the pretreatment of macrophages and endothelial cells with tea flavonoids such as theaflavin digallate diminished cell-mediated LDL oxidation probably due to the interaction with superoxide and the chelation of iron ions. Quercetin and epicatechin inhibited LDL oxidation catalyzed by mammalian 15-lipoxygenase, and are much more effective antioxidants than ascorbic acid and a-tocopherol [146], Luteolin, rutin, quercetin, and catechin suppressed copper-stimulated LDL oxidation and protected endogenous urate from oxidative degradation [147]. Quercetin was also able to suppress peroxynitrite-induced oxidative modification of LDL [148],... 

CS071 Shiraki, M., Y. Hara, T. Osawa, H. CS082 Kumon, T. Nakayama and S. Kawa-kishi. Antioxidative and antimu-tagenic effects of theaflavins from black tea. Mutat Res 1994 323 (1/2) ... 

The inhibitory effects of tea polyphenols on xanthine oxidase (XO) were investigated. Theaflavins and EGCG inhibit XO to produce uric acid and also act as scavengers of superoxide. Theaflavin 3,3 -digaUate (TE-3) acts as a competitive inhibitor and is the most potent inhibitor of XO among these compounds. TE-3 also inhibited the superoxide production in HL-60 cells. Therefore, the antioxidative activity of tea polyphenols is due not only to their ability to scavenge superoxides but also to their ability to block XO and relative oxidative signal transducers. ... 

Shiraki, M., Kara, Y, Osawa, T., Kumon, H., Nakayama, T., and Kawakishi, S. 1994. Antioxidative and antimutagenic effects of theaflavins from black tea. Mutat. Res. 323 29-34. 

Considerable interest has developed in the past decade in unraveling the beneficial health effects of tea, particnlarly in its polyphenolic components and its antioxidant activity. Catechins, theaflavins, and thearnbigins are three important gronps of polyphenols present in tea. The formation mechanism of these componnds dnring tea processing as well as their respective biological activities are of great importance and of scientific and commercial interest. 

Green and black teas have been reported to inhibit human LDL oxidation in vitro and ex vivo (13,15-18). However, at least one study has indicated tiiat black tea is not effective to protect LDL from oxidative modification (19). Current study demonstrated that the aqueous extracts of Pu-Erh tea (PET) scavenged DPPH radical and inhibited Cu -induced LDL oxidation in vitro. The antioxidant potency of PET was similar to that of green and black tea extracts but the content of EGCG in Pu-Erh tea was lower than that of the green tea. It is suggested that the antioxidant activity of PET is due to the oligomeric phenolic compounds and theaflavins. 

---