A majority of plant polyphenolics has antiradical and antioxidant features but the intensity of their activity strongly depends on the chemical structure of individual compounds. Plant extracts rich in phenol acids exhibit strong antioxidant and antiradical activity in vitro and in vivo.
Among the compounds with strong antiradical features, one could mention tannins, flavonoids, and phenolic acids. Tannins are high-molecular compounds with complicated and variable structure, exhibiting usually strong antiradical and antioxidant activity. Measurement of antiradical activity most commonly is performed using ABTS or DPPH tests.
In biochemistry, ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) is a chemical compound used to observe the reaction kinetics of specific enzymes. The ABTS method for free radical reduction is based on electron transfer between the bluish-green radical and the antioxidant agent.
DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assay was developed by Blois in 1958 with the viewpoint to determine the antioxidant activity based on electron-transfer that produces a violet solution in ethanol. DPPH is a free radical that is stabilized through the delocalization of its free electron over the entire molecule in such a manner that it does not dimerize, as can occur with other free radicals.
Antiradical activity
