Comparative analysis of free radical scavenging potential of several fruit peel extracts by in vitro methods

We studied the radical scavenging potential of several fruit peel extracts using various standard chemical and biochemical in vitro methods. Peel extracts of C. sinensis (CS), P. granatum (PG), M. paradisiaca (MP), C. vulgaris (CV), C. melo (CM), M. indica (MI), and C. papaya (CP) were used in the present study and butylated hydroxyl anisole (BHA) was used as a standard. Marked 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was observed with 25 μg/mL of CS and MP and 50 μg/mL of PG, while all the studied doses of CP were found to be pro-oxidative. β-Carotene bleaching revealed a higher singlet oxygen scavenging potential of all the peel extracts except MI. High NO-radical scavenging activity was observed at 25 μg/mL of PG and MP. Inhibition test of H2O2-induced LPO in erythrocytes or in liver tissue showed that all the peels tested were effective on peroxy-radicals at one or other doses. The present study revealed the radical scavenging activity of the test peel extracts in a manner that was dose- and radical/methodspecific. Therefore, evaluation of the efficacy of herbal extracts should be carried out using different methods and not merely a single in vitro method.