In vitro antioxidant analysis and quantitative determination of phenolic and flavonoid contents of Emilia sonchifolia (L) D.C (Asteraceae) leaf extract and fractions

Emilia sonchifolia (L.) D.C. is a medicinal plant from the family Asteraceae known for a wide range of ethnomedicinal uses such as management of inflammatory diseases, pains, cancer, diabetes, cataract, asthma and liver disease. This research was aimed at assessing the antioxidant potential and quantitative determination of phenolic and flavonoid contents of the extract and fractions of Emilia sonchifolia leaves. The leaves of the plant were processed, extracted and partitioned successively and exhaustively with dichloromethane (DCM) and ethyl acetate. Phytochemical screening was carried out on the methanol extract using standard methods. Antioxidant evaluation of the methanol extract and fractions of Emilia sonchifolia leaves was carried out using Ferric Reducing Antioxidant Power (FRAP) assay and 2, 2, diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Quantitative determination of total phenolic content and total flavonoid content was done. The extraction and partitioning yielded the crude extract and respective fractions. The phytochemical screening revealed the presence of tannins, saponins, flavonoids, alkaloids and cardiac glycosides. Antioxidant evaluation of the crude extract and fractions of the plant exhibited significant (p<0.001) antioxidant activity in both assay though not comparable with the standard agent, ascorbic acid. In DPPH assay, the highest percentage inhibition was observed in ethyl acetate fraction (62%) followed by the extract (61%), DCM fraction (55%) and aqueous fractions (54%) at 100 µg/mL. In FRAP assay, the highest reducing power was exhibited by ethyl acetate fraction (0.457 nm) followed by the extract (0.444 nm), DCM fraction (0.441 nm) and aqueous fraction (0.439 nm). Although these activities were significant, they were not comparable to that of the standard drug ascorbic acid (0.914 nm). In total phenolic content assay ethyl acetate fraction had the highest phenolic content (5.804 mg/g), followed by crude extract (2.500 mg/g). The total flavonoid content was observed to be highest in ethyl acetate fraction (10.556 mg/g), followed by crude extract (4.444 mg/g). From this research work it was observed that Emilia sonchifolia leaves have a good antioxidant activity which could be responsible for its wide range of ethnomedicinal activities and this lends scientific credence for the use of this plant in the management of disease conditions.