Antioxidant Potential of Polyphenol Rich Extract from Hibiscus sabdariffa.

ABSTRACT

Aims: Hibiscus sabdariffa is a medicinal plant species that is consumed for its health benefits in Africa, therefore this study investigated the antioxidant properties of Hibiscus polyphenolic rich extract (HPE), prepared from Hibiscus sabdariffa. Place and Duration of Study School of Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, United Kingdom, between June 2009 and December 2010. Methodology: The antioxidant assays evaluated the scavenging abilities of HPE Firstly against superoxide ions generated during the xanthine oxidase mediated breakdown of xanthine to uric acid. Secondly against ABTS (2,2-azino-bis-(3-ethylbenzthiazoline 6-sulfonic acid)) radical cation generated by filtering a solution of ABTS through manganese dioxide powder and potassium persulphate. Finally metal chelation ability of HPE against Iron ions (Fe2+) induced oxidative damage in cultured Jurkat-T cells was also assessed. Results: The results showed that 1.0% and 2.5% (v/v) diethyl ether extract of HPE significantly inhibited superoxide ions by 42.35 and 100.00% respectively. The extract also inhibited uric acid production, which suggest that components of HPE inhibit xanthine oxidase activity. In addition, it was found that HPE scavenge ABTS radical cations in dose dependent manner. HPE inhibited Fe2+-mediated lipid peroxidation in cultured Jurkat-T cells supplemented with 0.5 mg/ml and 1.0 mg/ml of HPE by 19.67% and 31.69% respectively, metal chelation ability was identified as a potential mechanism behind this observed reduction. Conclusions: HPE is rich in different phenolic compounds; therefore strong antioxidant potential of HPE observed in this study may be related to their polyphenolic constituents. This study demonstrated that Hibiscus sabdariffa is an efficient antioxidant plant species in vitro and may be beneficial in reducing oxidative damage to lipid and thus prevent or reduce the development and progression of free radical mediated diseases.