Total phenolic, flavonoid contents and free radical scavenging capacity of extracts from tubers of Stachys affinis

We extracted the metabolites from Stachys affinis tubers (SAT) using the 70% of ethanol followed by the extracts were concentrated using the rotary evaporator and then it were fractionated as n-hexane fraction (NHF), dichloromethane fraction (DCMF), ethyl acetate fraction (EAF), n-butanol fraction (NBF) and water fraction (WF). Afterward, the antioxidant activity of these fractions was evaluated. Among fractions, the highest antioxidant activity including 1, 1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, superoxide radical scavenging, superoxide radical scavenging, reducing power, metal-chelating activity and total antioxidant activity were exhibited in EAF and lowest in NHF. Moreover, the nitrite scavenging activity was found the minimum in WE whereas maximum in EAF. The biochemical content of phenol (587.33 ± 4.18 mg TAE/g) and flavonoid (60.00 ± 0.58 mg QE/g) was exhibited higher in EAF than the other extracted were tested. Overall the present results indicated that higher concentration of the phenol and flavonoid from the EAF might be increased the antioxidant activity and further studies deserve to identify the compound specificity on the enhanced antioxidant activity of EAF.