Antioxidant and cancer cell proliferation inhibition effect of citrus pectin-oligosaccharide prepared by irradiation

Pectin was dissolved in deionized distilled water (2%, vol/vol) and irradiated at 20 kGy using a Co-60 gamma ray irradiator. The resulting solution was dialyzed and lyophilized. The samples were separated into three groups to estimate their antioxidant and cancer cell proliferation effects: non-irradiated (0 kGy), irradiated (20 kGy), and dialyzed (20 kGy-F, mol wt < 10,000) samples. Antioxidant properties of each treatment was tested by a beta-carotene-linoleic acid bleaching assay and electron donating ability and compared for antioxidant index, which indicated that the activity was higher in the order of 20 kGy-F > 20 kGy > 0 kGy. Spleen cell survival effect of the irradiated pectin (20 kGy) and dialyzed (20 kGy-F) samples was higher than the non-irradiated control (0 kGy). The pectins inhibited growth of the cancer cell in the order of 20 kGy-F > 20 kGy > 0 kGy. The Ames test revealed that none of the fractions was mutagenic, and there was no indication of a dose-dependent response for any of the samples. These results suggest that a functional pectin oligosaccharide can be produced by irradiation for the food industry without any chemical treatment.