Extraction and correlation of total phenolic and flavonoid contents in seaweeds collected from Rameshwaram during pre- and post- monsoon period using different solvent systems with their antioxidant activity

Abstract

The present study was carried out to compare and correlate the phenolic and flavonoid contents of Turbinaria sp., Sargassum sp . and Gracilaria sp . extracted using different solvents including methanol, isopropyl alcohol, acetone, acetonitrile, ethyl acetate and hexane, and elucidated for their anti-oxidant activity. The total phenolic and flavonoid contents of the solvent extracts were determined using the Folin-Ciocalteau assay and aluminium chloride colorimetric assay with gallic acid and quercetin as standards, respectively. The anti-oxidant activity in phenolic and flavonoid content was also estimated by phosphomolybdenum method and was compared with gallic acid and quercetin standard. The quantitative analysis of flavonoid content reveals that methanolic extract of Sargassum sp . (9.56±0.38 mg QE/g during pre-monsoon and 9.44±0.48 mg QE/g during post-monsoon season); acetone extract of Gracilaria sp . (2.16±0.11 mg QE/g during pre-monsoon and 2.12±0.07 mg QE/g during post-monsoon season) and methanolic extract of Turbinaria sp. (4.11±0.12 mg QE/g during pre-monsoon and 4.22±0.15 mg QE/g during post-monsoon season) had higher concentration of flavonoid content. However, the quantitative analysis of phenolic content was found to be lower in all the seaweed extracts as compared to flavonoids. The anti-oxidant activity of a phenolic content and flavonoid content were also found to be correlated. The findings of the current study conclusively demonstrate the content of phenolic and flavonoid compounds significantly correlate with antioxidant activity.