Study on antioxidant activity of different polar extracts from walnut kernel pellicle in vitro

Using ethyl acetate,n-butanol,chloroform,petroleum ether extracted polyphenols from walnut kernel pellicle. Preliminary evaluation the antioxidant activities of different polarity extract from walnut kernel pellicle by DPPH free radical scavening assay,OH free radical scavenging assay,ABTS free radical scavening assay and iron ion reduction capacity. The results showed that the extraction capacity of polyphenols from walnut kernel pellicle was ethyl acetate>n-butanol>chloroform>petroleum ether. The ethyl acetate extract has the strongest DPPH free radical and ABTS free radical scavenging ability,the IC₅₀ values were 5.004 μg/mL and 29.654 μg/mL,followed by the n-butanol(9.596,23.681 μg/mL),chloroform extract(62.719,144.475 μg/mL)and petroleum ether extract(48.316,146.424 μg/mL). The n-butanol extract has the strongest OH free radical scavenging capacity,the IC₅₀ value was 393.578 μg/mL,followed by ethyl acetate(510.186 μg/mL),chloroform extract(627.003 μg/mL)and petroleum ether extract(840.315 μg/mL). When the sample concentration was 100 μg/mL,the absorbance of the different polarity extracts were ethyl acetate extracts(0.821)>n-butanol extracts(0.509)>chloroform extracts(0.406)>petroleum ether extracts(0.142)in the iron ion reduction reaction. In conclusion,the antioxidant activity of different polar extracts was different,followed by acetic ether>n-butanol>chloroform>petroleum ether,and positively correlated with the mass concentration.