Abstract

Free radicals induce numerous diseases by lipid peroxidation, protein peroxidation and DNA damage. It has been reported that numerous plant extracts have antioxidant activities to scavenge free radicals. In the present study, the antioxidant properties of crude extract ofHibiscus rosasinensis were examined, using different in vitro analytical methodologies, such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS⁺ radical cation) radical cation scavenging activity and superoxide anion radical scavenging by riboflavin-methionine-illuminate system. Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and α-tocopherol were used as the reference antioxidant radical scavenger compounds. The crude extract inhibited 94.58% peroxidation of linoleic acid emulsion at 20 μg/ml concentration, while the standard antioxidants BHA, BHT and α-tocopherol indicated an inhibition of 93.75, 96.66 and 83.33% at 60 μg/ml concentration, respectively. The hydrogen peroxide radical, DPPH radical, ABTS⁺ radical cation(s) and superoxide anion radical scavenging activities of crude extract were also compared to BHA, BHT and α-tocopherol as references antioxidant compounds. The present study shows that the crude extract is an effective natural antioxidant component.

Key words: Hibiscus rosasinensis, antioxidant activity, free radical scavenging activity.