Effects of Different Extraction Solvent Systems on Total Phenolic, Total Flavonoid, Total Anthocyanin Contents and Antioxidant Activities of Roselle (Hibiscus sabdariffa L.) Extracts

摘要

This study aims to investigate the variations in total phenolic content, total anthocyanin content, total flavonoid content and the antioxidant capacity of Roselle extracts in various extraction solvents. Extracts produced using three solvent systems (methanol, ethanol and acetone) at three different concentrations (50,70 and 90 % (v/v)) were compared roselle calyx extract produced using distilled water. The antioxidant capacities of roselle calyx extracts were evaluated using DPPH free radical-scavenging capacity, ferric reducing antioxidant power (FRAP) and reducing power. The extraction efficiencies of phenolics, anthocyanins and flavonoids from roselle calyx varied considerably. The results showed that at 50 %, ethanol was the appropriate solvent for extraction of flavonoids, which achieved 508.64 mg RE/L and phenolics, which achieved 762.11 mg GAE/L, while at 70 %, methanol was the effective solvent for extracting anthocyanins, which achieved 8.404 mg/L. For antioxidant activity, at 50 % for ethanol, 70 % for methanol, 50 and 70 % for acetone were solvents used to obtain the highest DPPH free radical scavenging activities, ranging from 869.47-927.60 umol TE/L. Thus, at 50 and 70 % for acetone were determined as solvents which gave extracts with the highest ferric reducing antioxidant power FRAP, ranging from 3493.52-3459.22 umol TE/L.