Antioxidant and free radical scavenging effect of black tea theaflavins has been shown in many epidemiological studies. In the present work we report the protective mechanism of tea theaflavins on biomarkers of oxidative stress, which are elevated during stress conditions. We hereby report the in vitro effect of theaflavins on erythrocyte malondialdehyde (MDA), intracellular reduced glutathione (GSH), and plasma membrane redox system (PMRS) of rats. The effect of theaflavin on PMRS has also been validated through an in silico docking simulation study using Molegro Virtual Docker (MVD). We report that theaflavins show significant protection to erythrocyte against oxidative stress induced by tert-butyl hydroperoxide (t-BHP). The findings suggest a possible protective role of theaflavins as antioxidant. 1. Introduction Tea is one of the ancient and most popularly consumed beverages worldwide. Mostly it is consumed as green and black tea. Among the types of tea, black tea accounts for approximately 80% of the global production. More research has been done on green tea, but in recent years black tea has attracted significant attention for its extensive health promotional effect . Black tea contains 30–40% polyphenols which include theaflavins (TFs), thearubigins (TRs), and bisflavonols. Theaflavins are mixture of theaflavin 3-gallate (TF3G), theaflavin 3′-gallate (TF3′G), and theaflavin 3,3′-digallate (TFDG), and the common feature of all these polyphenols is the presence of a seven-member benztropolone ring (Figure 1). Epidemiological studies and associated clinical observations indicate that black tea polyphenols possess many health beneficial properties including antioxidant, antimutagenic, anticancer, antipathogenic anti-inflammatory, and anticlastogenic effects [2–7]. Reports show that black tea consumption may reduce the risk of several diseases like cardiovascular disease, diabetes, osteoporosis, and neurodegenerative disease [8–11]. The exact mechanism underlying these properties remains speculative. Figure 1: Polyphenols of black tea. Oxidative stress has been shown to be coupled with altered homeostasis that leads to imbalance between oxidant production and/or antioxidant levels thus causing damage to biomolecules, dysregulation of normal physiology/metabolism coupled with neurodegeneration, cognitive impairment, immunosuppression, and ageing [12, 13]. The potential role of free radicals, reactive oxygen species, and antioxidants in the etiology of chronic diseases has stimulated extensive research in current years . In mammalian system,
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