Kinetic study of the DPPH antiradical activity of lipophilic tomato waste extracts

Abstract

In this study, lipophilic tomato waste extracts (obtained from the Knjaz, Bačka, Saint Pierre, Rutgers and Novosadski niski genotypes) were analyzed to determine their lycopene and p-carotene content, as well as their kinetics of antiradical activity. The kinetic behaviour of lipophilic tomato waste extracts and standard antioxidant compound (BHA) were investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical test. In addition, correlations between the contents of lycopene and p-carotene content and antiradical activity of lipophilic tomato waste extracts were also sought. The content of lycopene in tomato waste extracts ranged from 4.29 ± 0.14 mg/g for Rutgers waste exract to 22.64 ± 0.86 mg/g for Knjaz waste extract, while the content of p-carotene varied from 2.48 ± 0.09 mg/g for Novosadski niski waste exract to 15.93 ± 0.56 mg/g for Knjaz waste extract. Based on the time required for the DPPH radical-extract reaction to reach steady state, the investigated lipophilic extracts, as well as BHA can be classified as the antioxidants with slow (steady state > 150 min) antiradical behaviour. A comparison of the efficient concentrations at different kinetic times (EC 50t) for the lipophilic tomato waste extracts and BHA showed that the DPPH antiradical activity decreased in the order of BHA > Knjaz > Bačka > Saint Pierre > Rutgers > Novosadski niski. The results of the correlation analysis suggest that lycopene is the main individual carotenoid responsible for the EC50t values of the tomato waste extracts towards the stable DPPH radical.