Antioxidant capacity of extracts from calyx fruits of roselle (Hibiscus sabdariffa 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.