Estimation of Total Phenolics, Total Flavonoids Content and In Vitro Antioxidant Activities of Extract and Fractions of <i>Asplenium platyneuron</i> (Carl Linnaeus)

Abstract

Phenolic compounds possess the potential to function as antioxidants, hence the growing interest in ethnomedicine to use them for treatment or prevention of diseases associated with oxidative stress. This study measured the total phenolics and flavonoid contents (TPC and TFC) and in vitro antioxidant activity of Asplenium platyneuron extract and its fractions. The methanol extract was partitioned successively in n-hexane, ethyl acetate (EtOAc) and n-butanol. Thereafter, the EtOAc soluble was fractionated using vacuum liquid chromatography (VLC) in gradients of n-hexane/ EtOAc and dichloromethane/methanol. The free radical scavenging activity was determined by using diphenyl-picrylhydrazyl (DPPH), and the reducing power by ferric reducing antioxidant power (FRAP) and the total antioxidant capacity assays. The TPC of EtOAc fraction was 9.31 ± 0.76 mg GAE/g extract compared with 1.33 ± 0.61 mg GAE/g extract of n-hexane fraction. The TFC for EtOAc was 139.73 ± 8.03 mg QE/g extract higher than 35.73 ± 15.01 mg QE/g extract of n-butanol fraction. The ethylacetate fraction exhibited the highest DPPH free radical scavenging capacity of 80.50%, and FRAP of 413.00 ± 1.28 mg GAE/g extract with IC50 of 1.31 ± 0.68mg/mL. There was a strong correlation between the antioxidant activity and the TFC/TPC. The VLC fractions, AP2 and AP7 (IC50 1.43 ± 1.34 and 1.41± 1.11 mg/mL respectively) elicited antioxidant activity higher than other fractions. Dereplication analysis identified three phenolics; apigenin 6-C-hexoside-8-C-pentoside, kaempferol 3-O-caffeoylsophoroside and schaftoside from A. platyneuron. The high TPC/TFC and its strong antioxidant properties makes A. platyneuron a promising source of novel lead antioxidants.