Quantification, Antioxidant and Free Radical Scavenging Potentials of Polyphenols from Crude Extracts of <i>Phyllanthus amarus</i> leaves

Abstract

This work examined the quantity of Polyphenols (tannins, flavonoids and phenolic acids) and their antioxidant and radical scavenging activities in five solvent extracts of P. amarus leaf using assay methods such as DPPH, ABTS, OH, NO and FRAP. Solvents of varying polarity (hexane, chloroform ethyl acetate, acetone, methanol and aqueous) were used for extraction. Results revealed various extraction yields; the highest was aqueous, methanol and ethyl acetate in this order compared to acetone, chloroform and hexane, indicating that extraction efficiency favors high polar solvents. The solvents extract various phytochemicals with ethyl acetate, aqueous and methanol showed better phytochemical distribution. The result also showed that, acetone extract has more of flavonoids followed by ethyl acetate; the least was found to be hexane and chloroform extract while tannin and phenolic acids were higher in ethyl acetate extract. Investigating the fifty percent inhibitory concentration (IC₅₀) of the tested extracts demonstrated that, the ethyl acetate extract which generally gave the highest percentage inhibition, showed the lowest IC₅₀ for ABTS, NO and OH at p=0.05. The correlation between IC₅₀ values and polyphenol content were analyzed for each extract using Pearson’s correlation analysis. It was found that the ethyl acetate extract showed positive and significant correlation between ON∙, ABTS, FRAP and phenolic acids with coefficient of 0.993, 0.996, and 0.920 respectively and OH radical to flavonoids and tannins with coefficient of 0.875 and 0.866 respectively. DPPH to tannins has a coefficient of 0.854. An evaluation on the correlation analysis revealed that ethyl acetate extract is the best. Conclusively, the richer the polyphenol content, the better the antioxidant potential of plant and ethyl acetate is the best solvent for extraction of polyphenols to address diseases that relate to oxidative stress.