A novel antioxidant activity index (AAU) for natural products using the DPPH assay

A novel antioxidant activity unit (AAU) was proposed as the antioxidation ability of natural products using the DPPH assay Based on the definition of MU using a combination of fitting curve equation for scavenging ratio of DPPH free radicals with the theoretical relation between DPPH concentration and absorbance the equation was deduced In this study eight - lignans and the standard samples of gallic acid vitamin C were used It was demonstrated that the concentration of DPPH was affected more by temperature than by time AAU showed its consistency and uniqueness between different concentrations of each lignan with a relative standard deviation (RSD) of less than 8 07% The antioxidant strength of plant extracts and pure compounds were compared Analysis of the antioxidant activity of lignans in relation with their structure factors was made (C) 2010 Elsevier Ltd All rights reserved