Comparative Study of Total Phenol, Flavonoid Contents and Antioxidant Activity in Canna indica and Hibiscus rosa sinensis: Prospective Natural Food Dyes

Abstract

In the present study the comparative data of total phenol and total flavonoid contents along with antioxidant activity were assessed in native Canna indica. Total phenolic contents were analyzed by a Folin-Ciocalteu reagent and antioxidant activity was analyzed by DPPH assay and TEAC assay, in crude methanolic extracts of red, yellow varieties of Canna indica and red variety of Hibiscus rosa sinensis. DPPH assay of crude extracts taking pyrogallol as standard show that fresh red canna extract has best results for radical scavenging. Stability of color content of canna towards pH and its pKa were assessed. Colorimetric analysis of crude extracts showed red canna extract to be the best in terms of its tinctorial strength, a pre-requisite for a food dye. On the basis of the results obtained, red canna flowers were found to serve as a potential source of natural antioxidant and a natural food colorant.