DPPH (2,2-Diphenyl-1-picrylhydrazyl) is a cell-permeable, stable free radical that is commonly used to evaluate the ability of compounds to act as free radical scavengers or hydrogen donors and to measure the antioxidant activity of tissue extracts

DPPH shows a strong absorption band at 517nm. Due to its odd number of electrons, the solution presents a dark purple color, and the absorption disappears as the electron pairs are detached.The resulting decoloration is stoichiometric and depends on the number of electrons absorbed.Alcohol solutions of 0.5 mM are dense in color, and at this concentration, the Lambert-Beer law is followed within the effective range of absorption.DPPH is a fast, simple, inexpensive and widely used method for determining the ability of compounds to act as free radical scavengers or hydrogen donors and for evaluating the antioxidant activity of foods.It can also be used to quantify antioxidants in complex biological systems, solid or liquid samples.The method was simple and easy to determine the total antioxidant capacity and free radical scavenging activity of fruit and vegetable juice.The antioxidant properties of wheat grains and bran, vegetables, conjugated linoleic acid, herbal medicine, edible seed oil and flour in ethanol, acetone, methanol, ethanol and benzene were successfully studied.It is a simple method for the determination of the antioxidant properties of cysteine, glutathione, ascorbic acid, tocopherol and polyhydroxyaromatic compounds in olive oil, fruits, fruit juices and wines.