Comparative Study on the Antioxidant Capacity of Aqueous Extract of Costus spicatus (jacq.) Leaf and Rhizomes

Antioxidants play an important role in inhibiting and scavenging free radicals, thus providing protection to humans against infection and degenerative diseases. Modern research is directed towards "natural antioxidants" from herbal plants due to their safe therapeutic. Costus spicatus is an herbaceous plant whose parts- leaves, rhizome, stem and roots are used locally because of its medicinal properties. The specific objective of the study was to determine and compare the antioxidant capacity of aqueous extracts of Costus spicatus leaf and rhizome for their antioxidant activity and radical scavenging potential. The in vitro antioxidant status of the aqueous extract of Costus spicatus leaf and rhizome was compared using 2,2-diphenyl-1-picrylhydrazyl (DPPH), H2O2, Nitric Oxide (NO), 2,2-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS), Total Antioxidant Capacity (TAC) and Ferric Ion Reducing Antioxidant Power Assay (FRAP). The total phenolics and flavonoid contents were also estimated quantitatively. The aqueous extract of Costus spicatus leaf and rhizome both have notable flavonoid content. However the rhizome had slightly higher phenolic content compared to the leaf. Both the leaf and rhizome of aqueous extract of Costus spicatus have notable antioxidant capacity when compared with the standard used. The aqueous extract of Costus spicatus rhizome showed higher antioxidant activity than the leaf in a concentration dependent manner. These results revealed that the aqueous extract of Costus spicatus leaf and rhizome has antioxidant capacity and scavenging potential, with the rhizome having the most notable capacity and therefore can be further explored in antioxidant research and in management of diseases related to oxidative stress.