Scavenging Assays of the DPPH Radical

2,2–diphenyl–1–picrylhydrazyl is a stable radical in organic solvents, which has an electron and can accept an electron or a hydrogen ion. In the presence of the free radical scavenger, the single electron of DPPH is captured, making the color of DPPH become lighter and the absorbance value at the maximum light absorption wavelength decrease linearly.

2,2–diphenyl–1–picrylhydrazyl radical scavenging activity was determined using the slightly modified method of (Rozi et al., 2020). To be specific, the freshly prepared DPPH–methanol solution (.2 mmol/L) was added with 100 μl different concentration of APP40, APP60, and APP80. Next, the absorbance at 517 nm was measured with a microplate reader, while V_c was used as a reference material. All tests were performed in triplicate. Besides, the scavenging activity was calculated as follows:

where A₁, A₂, and A₀ represent the absorbance of samples with DPPH–methanol solution, samples with methanol, and distilled water with DPPH–methanol solution, respectively.