Determination of Antioxidant Property, Total Phenolics Content, and α-Glucosidase Inhibitory Activity of Different Solvent Extracts of Defatted and Non-Defatted Peanut Skins

Peanut skins are by-product with little economic
value. The effect of different solvents, on the total phenolic content
(TPC), antioxidant property and in vitro antidiabetic activity of
defatted and non-defatted peanut skins was determined. TPC was
estimated using Folin-Ciocalteau reagent. Antioxidant property
was evaluated using ferric reducing antioxidant power (FRAP)
and 2, 2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging
capacity methods, α-glucosidase inhibition was evaluated using 4-
nitrophenyl α-D-glucopyranoside (pNPG) method. Peanut skin of
the defatted extracted with ethanol had the much of the content of
total phenolics (391.76 mg/g GAE). Highest DPPH scavenging
property was found in the methanolic extract of defatted peanut
skins with IC50 value of 15.00 ± 1.00 μg/mL, while highest FRAP
value was found in the aqueous extract of non-defatted extracts.
Aqueous extracts demonstrated stronger inhibitory property
against α-glucosidase and had IC50 of 16.33 ± 1.15 and 16.33 ± 8.50
μg/mL for defatted and non-defatted extracts, respectively. The
finding of the present shows that peanut skins are important by
product for utilization as natural antioxidant and α-glucosidase
inhibitors.