Antioxidant capacity of extracts from calyx fruits of roselle (<i>Hibiscus sabdariffa</i> L.)

Abstract

The antioxidant capacities of extracts of dried roselle (Hibiscus sabdariffa L.) calyx and fruit with distilled water ethanol (30, 60 and 95%) were determined by 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH), hydroxyl and 2-2’-azino-bis-(3-ethyl-benzthia-zoline-6-sulfonic acid) (ABTS) radical-scavenging assays. The results show that the extract in 30% ethanol always had the highest radical-scavenging activity, while the extract in 95% ethanol showed the lowest. Correlation analyses between antioxidant activities and contents of total phenols, anthocyanins and total saccharides indicated that the higher activity of 30% ethanol extract depends on its higher level of total phenol contents (20.25 mg GAE/g). The correlation coefficients R2 were 0.9615, 0.9089 and 0.9771, respectively. Hence, the 30% ethanol extract could be used as a good natural antioxidant with potent free radical scavenging activity.

Key words: Antioxidant, roselle, total phenol, anthocyanins, total saccharides.