COMPARATIVE STUDIES ON PHOSPHOMOLYBDENUM ASSAY, DPPH AND REDUCING POWER ANTIOXIDANT PROPERTIES IN MICROSHOOTS OF FIVE PERSIAN WALNUTS

Abstract

The present study was aimed to evaluate the comparative studies on in vitro antioxidant activity of five micropropagated axillary shoots (microshoots) of the walnut (Juglans regia L.) cultivars ‘Chandler’, ‘Howard’, ‘Kerman’, ‘Sunland’, and ‘Z63’. The antioxidant activity was assessed using three models: the phosphomolybdenum assay (PPM), reducing power assay, and 2,2- diphenyl-1-picrylhydrazyl-scavenging effect (DPPH) [1]. In all assays, the highest antioxidant activity was in microshoot extracts of ‘Kerman’ followed with ‘Sunland’. Walnut microshoots showed reducing powers at very low concentrations (less than 1 mg ml-1) that are in accordance with the results of Pereira et al. [2]. Results of DPPH scavenging of these walnut microshoots appeared to be concentration-dependent and increased with the increasing concentration of each extract. These results showed that with regard to standard antioxidant compounds, antioxidant activities of microshoots are high. Shoots and leaves of walnut contain considerable amounts of active components such as polyphenols, flavonoids, proanthocyanidins and tannins which are considered as potent scavengers of free radicals and reactive oxygen species. The present research program underlies that Persian walnut microshoots are as potential sources of natural antioxidants for medicinal and commercial uses and can be used as an easily accessible source of natural bioactive compounds.