Antioxidant Potential by Arabinoxylan Rice Bran, MGN-3/biobran, Represents a Mechanism for Its Oncostatic Effect Against Murine Solid Ehrlich Carcinoma

We have recently examined the oncolytic effect of arabinoxylan rice bran, MGN-3/biobran, against solid Ehrlich carcinoma (SEC)-bearing mice via immune-modulation and apoptosis [N.K. Badr El-din, E. Noaman, M. Ghoneum, In vivo tumor inhibitory effects of nutritional rice bran supplement MGN-3/biobran on Ehrlich carcinoma-bearing mice, Nutr. Cancer 60 (2) (2008) 235-244]. In the present study, we examined the antioxidant system as another possible mechanism through which MGN-3 exerts its oncostatic potential. Female albino mice were inoculated intramuscularly in the right thigh with Ehrlich ascites carcinoma (EAC) cells. MGN-3 (25 mg/kg body weight) was injected intraperitoneally (i.p.) six times a week for 25 days into mice at either day 4 or day 11 post-EAC cell inoculation. Tumor growth, lipid peroxidation (LPx), glutathione (GSH) contents, the activity of the antioxidant scavenger enzymes, and alterations in gene expression were examined. MGN-3 efficiently suppressed the growth of tumors, which was associated with normalization of the LPx levels and augmentation of GSH contents. MGN-3 enhanced the activity of the endogenous antioxidant scavenging enzymes -- superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and glutathione-S-transferase (GST) -- in blood, liver, and tumor tissue. Similarly it up-regulated the expression of GPx, SOD1 and CAT mRNA in the liver. The effect of MGN-3 was more pronounced when treated early, at day 4 of tumor cell inoculation, as compared to later treatment at 11 days. In conclusion, MGN-3-induced oncostatic activity by modulating lipid peroxidation, augmenting the antioxidant defense system and protecting against oxidative stress.