In vitro, antioxidant and scavenging activities of Hibiscus rosa sinensis crude extract

The objective of this study is to ascertain the potency of, Hibiscus rosa sinensis leaves extract,with 70% ethanol/ water, as potential natural antioxidant. The phytochemical screening identified the bioactive compounds of the dry extract; carbohydrates and/or glycosides, steroids and/or triterpenes, flavonoids and tannins.The total phenolic and the total flavonoids contents reached 48.4 mg catechol equivalent and 24.26 mg quercetin equivalent /g dry weight, respectively.We assayed in vitro total antioxidant capacity and reducing power ofH. rosa extract (HRE), using butylated hydroxytoluene (BHT) and ascorbic acid (ASA) as references, respectively.HRE recorded two-fold stronger antioxidant capacity than that of BHT while its reducing power was less than that of ASA, with reaction time and extract concentration dependent manner. In addition we evaluated the scavenging activities of HRE for O2•−, H2O2 and NO compared to that of butylated hydroxyanisole (BHA). BHA recorded up to (61.6%), (65.8%), and (37.3%), respectively, at 500 μg/ml. Scavenging ability of HRE was very closed to that of BHA, in case of O2•− ( 60.4%) and NO ( 36.3%) while it was lower in case of H2O2 (48.5%). Finally, we investigate the protection effect of HRE against lipid peroxidation (LPO) and protein oxidation(PO) using Fe+3/ ascorbate oxidizing system. LPO shwed 2.5-fold increase while PO reduced 56% of –SH groups. The co-incubation of Fe+3/ascorbate with Hibiscus extract inhibited lipid and protein oxidative damage nearly with 31%, at 500 μg/ml. So, we can conclude that the in vitro study emphasized HRE effective antioxidant and scavenging activities which may be due to its phenolics and flavonoids contents.