2 2 diphenyl 2 picrylhydrazyl hydrate

The radical scavenging activity of mushroom extracts against the DPPH^• radical (2,2-diphenyl-2-picrylhydrazyl hydrate; Sigma-Aldrich, Steinheim, Germany) was determined by the method of Brand Williams modified by Dudonné et al. [40 , 41 (link)]. DPPH radicals have an absorption maximum at 515 nm; upon reduction by the antioxidant, the solution color fades and the reaction progress is easily monitored by a spectrophotometer (UVmini-1240, Shimadzu, Kyoto, Japan). Determination procedures were as follow: 3 mL of 6 × 10⁻⁵ M DPPH^• solution (prepared daily) was mixed with 100 μL of methanolic solutions of mushroom extracts (maximum dissolved concentration); after 20 min incubation for at 37°C, absorbance decrease of the mixture was monitored at 515 nm (A_s). Blank samples with 100 μL of methanol in the above DPPH^• solution were prepared and measured daily at same wavelength (A_b). The experiment was carried out in triplicate. Radical scavenging activity was calculated using the following formula. $\begin{array}{c}\text{Inhibition}\hspace{0.17em}\text{rate}\left(\%\right)=\left[\frac{A_b-A_s}{A_b}\right]\times \mathrm{100}.\end{array}$

Chemicals: 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH), 2,6-di-tert-butyl-4-methylphenol (BHT), 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ascorbic acid, dimethyl sulfoxide (DMSO), potassium persulfate, and all reagents were purchased from Sigma (St. Louis, MO, USA), Fluka Chemie (Buchs, Switzerland), and Merck (Nottingham, UK).