DPPH radical scavenging assay

Radical scavenging activity of jacquemont’s hazelnut 80 % ethanolic extracts, against stable DPPH radical, were evaluated by DPPH assay with slight modification (Kalia et al. 2008: Kant et al. 2013). The effect of antioxidants on DPPH-radical-scavenging test reflects the hydrogen donating capacity of a compound. When radical form of DPPH scavenged by an antioxidant through donation of hydrogen, DPPH becomes a stable molecule, which leads to a color change from purple to yellow and a decrease in absorbance was measured at 517 nm. Stock solution of 1 mg/ml for ascorbic acid, jacquemont’s hazelnut skin, hard shell and kernel were prepared in methanol, respectively. Different amount of concentration (20, 40, 60, 80, 100 μg/ml) for ascorbic acid, jacquemont’s hazelnut skin, hard shell and kernels were prepared in methanol having final volume 100 μl, to which 2 ml of the 0.100 mM DPPH solution prepared in methanol added. The mixtures were shaken vigorously, allowed to stand at 25 °C in the dark for 30 min, and a decrease in absorbance of the resulting solutions monitored at 517 nm (Shimadzu 2450) against a blank consisted of 100 µl of methanol and 2 ml of DPPH solution. All measurements were done in triplicate. Inhibition of free radical DPPH in percent I (%) was calculated as follows:

where, A _b was the absorbance of control reaction and A _s was absorbance of test compound. The sample concentration providing 50 % inhibitions (IC₅₀) were calculated by plotting inhibition percentages against concentrations of samples (Table 1).

DPPH and ABTS radical scavenging capacities of 80 % ethanolic extract of jacquemont’s hazelnut kernel and its byproducts

^aAscorbic acid