In conclusion, the antioxidant assay basedon scavenging of DPPH radical at a DPPH concentration of 50 lM
in methanol or buffered methanol, depending upon the solubility
of the compound under investigation, is recommended. All operations
must be done in dark or dim light (Ozcelik et al., 2003). The
extent of inhibition is influenced by the solvent. This is evident
from the data for DPPH radical scavenging by BHT in methanolic
or buffered methanolic solution (Fig. 3). Besides, our data on the
comparative reaction of ascorbic acid, BHT and propyl gallate
(Fig. 5) indicates that the time course of inhibition also has to be
determined. The protocol described here, thus, takes care of the
spectrophotometric sensitivity range, besides sensitivity of DPPH
to light, pH and solubility of the compound.