Total Antioxidant Capacity, Total Phenolic Compounds and the Effects of Solvent Concentration on Flavonoid Content in Curcuma longa and Curcuma xanthorhhiza Rhizomes

Abstract

Natural products such as herbs, fruits, spices, beverages, vegetables are becoming more popular among scientific community and consumers because of their potential to arrest the effect of free radicals in human system. This study investigated the total antioxidant capacity of Curcuma longa and Curcuma xanthorrhiza use as spices and medicinal compound in Southeast Asia. Methanol was used as the extraction solvent, 2,2 – diphenyl -1- picrylhydrazil (DPPH) for free radical scavenging activity and ferric reducing antioxidant power (FRAP) assays. Phenolic acid and polyphenol content were both measured. Different concentrations of methanol were used for the extraction to determine flavonoid content and ascorbic acid was used as the control. The results revealed that C. longa had a higher values in all the assays including DPPH (270.1 mg TE/g dw), FRAP (231.7 mg TE/g dw), phenolic acid (42.7 mg GA/g dw) and polyphenols (39.4 mg GA/g dw). The 90% methanol extract showed the highest flavonoid content in both species of Zingiberaceae. This study provides evidence that the yield of extracts of C. longa and C. Xanthorrhiza obtained are directly proportional to solvent concentration and could be a source of natural antioxidant. Keywords: