Free radical scavenging by ethanol extract of propolis.

The free radical scavenging ability of an ethanolic extract of propolis (EEP) was demonstrated by electron spin resonance spectroscopy, when 2,2-diphenyl-1-picrylhydrazyl (DPPH) was treated with increasing concentrations of EEP. It was shown that the DPPH signal intensity was inversely related to the EEP concentration and to the reaction time. It is assumed that the ability of components in EEP to donate a hydrogen atom is responsible for the lowering of the DPPH-EEP signal, and reflect the anti-oxidative nature of EEP.