Effect of Gamma Irradiation on the Antimicrobial and Free Radical Scavenging Activities of Solvents-Based Extracts of Cucurbitaceae Seeds

Abstract

The effect of gamma irradiation upon the bioactive potentials of selected Cucurbitaceae seeds commonly known as Char Magaz was investigated. The seeds were irradiated in triplicate at doses of 1, 5, 10, and 20 kGy gamma rays in a cobalt-60 irradiator. These were extracted with n-hexane, chloroform, ethyl acetate and methanol and the extracts were concentrated by rotary evaporation. The antimicrobial effects of the irradiated and non-irradiated samples against bacterial strains and the fungal strains were assessed by the agar-well diffusion method and the minimal inhibitory concentration technique. The antioxidant activities were determined via 2, 2-diphenyl-1-picryl-hydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and ferric reducing antioxidant power (FRAP) methods. The chloroform extract of cucumber seeds exhibited the greatest zone of inhibition (18.0 mm) against S. aureus. Minimal inhibitory concentrations (MIC) for antibacterial and antifungal activities ranged from 320.0 to 1280 µg/mL, and 0.50 to 16.0 µg/mL, respectively. Seeds exposed up to 10 kGy gamma irradiation increased DPPH and ABTS scavenging activities. Comparatively, all seed extracts showed high antioxidant potentials in the FRAP assay at all doses. The results suggested that gamma irradiation up to 10 kGy enhances bioactivities of the analyzed seeds.