Epicatechin and its in vivo metabolite, 3′-O-methyl epicatechin, protect human fibroblasts from oxidative-stress-induced cell death involving caspase-3 activation

Abstract

There is considerable current interest in the cytoprotective effects of natural antioxidants against oxidative stress. In particular, epicatechin, a major member of the flavanol family of polyphenols with powerful antioxidant properties in vitro, has been investigated to determine its ability to attenuate oxidative-stress-induced cell damage and to understand the mechanism of its protective action. We have induced oxidative stress in cultured human fibroblasts using hydrogen peroxide and examined the cellular responses in the form of mitochondrial function, cell-membrane damage, annexin-V binding and caspase-3 activation. Since one of the major metabolites of epicatechin in vivo is 3'-O-methyl epicatechin, we have compared its protective effects with that of epicatechin. The results provide the first evidence that 3'-O-methyl epicatechin inhibits cell death induced by hydrogen peroxide and that the mechanism involves suppression of caspase-3 activity as a marker for apoptosis. Furthermore, the protection elicited by 3'-O-methyl epicatechin is not significantly different from that of epicatechin, suggesting that hydrogen-donating antioxidant activity is not the primary mechanism of protection.

Bioguided extraction of polyphenols from grape marc by using an alternative supercritical-fluid extraction method based on a liquid solvent trap

“…gallic acid, quercetin) induced apoptosis in transformed cells (which is consistent with previous results of Romero et al [31]), whereas others (e.g. catechin, epicatechin) rescued cells from apoptosis (by effect of their potent antioxidant activity, which was previously observed by Spencer et al [32]). This finding was confirmed by using 25 mM C 6 ceramide or even 10 µM H 2 O 2 as apoptotic prooxidant inducers, which resulted in 44 and 38%, respectively, of cells being rescued with 1 mM epicatechin.…”

Flavonoids and brain health: multiple effects underpinned by common mechanisms

“…1). There is abundant evidence that flavonoids are effective in blocking this oxidantinduced neuronal injury, although their potential to do so is thought not to rely on direct radical or oxidant scavenging activity [63,64]. Instead, they are believed to act by modulating a number of protein kinase and lipid kinase signalling cascades, such as the PI3 kinase (PI3K)/Akt, tyrosine kinase, protein kinase C (PKC) and MAPK signalling pathways [58,78].…”

Biosynthesis and genetic engineering of proanthocyanidins and (iso)flavonoids

“…Green tea is a rich source of catechin derivatives, particularly (-)-epigallocatechin gallate, and both this compound and (-)-epicatechin protect mammalian cells from free radical-mediated oxidative stress and cause apoptosis of cancer cells (Zhan et al 1997;Ahmad et al 2000;Spencer et al 2001). …”