The protective effect of olive cake treatment on oxidant/antioxidant biomarkers, on serum, red blood cells and liver, in streptozotocin-induced diabetic rats fed cholesterol-enriched diet

Abstract

PurposeThe purpose of this study is to determine the effect of olive cake (OC) on lipid peroxidation as well as antioxidant enzymes activities of serum, red blood cells (RBCs) and liver, in streptozotocin (STZ)-induced-diabetic rat fed cholesterol-enriched diet.Design/methodology/approachHypercholesterolemic male rats were rendered diabetic (HC-D) by a single intraperitoneal injection dose of STZ (35 mg/kg BW). HC-D rats were divided into two groups fed for 28d a diet supplemented with OC at 7.5 percent (HC-D-OC) or not (HC-D). A control group (C) was submitted to standard diet containing 20 per cent casein for the same experimental period.FindingsRBCs, serum and liver thiobarbituric acid reactive substances (TBARS) contents were significantly increased in HC-D, compared to C group (p = 0.04, p = 0.02 and 0.03). These values were significantly decreased (48 per cent and 64 per cent; p = 0.02 and p = 0.0007) in serum and liver of HC-D-OC vs HC-D group. In RBCs, superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) activities were, respectively, 1.5, 2- and 1.7-fold higher (p = 0.03, p = 0.008 and p = 0.03) in HC-D group compared to HC group. In serum and liver, SOD, CAT and GST activities were, respectively, 1.3-, 2.6- and 1.6-fold increased (p = 0.03, p = 0.007 and p = 0.02). In HC-D-OC compared to HC-D group, RBCs glutathione peroxidase (GSH-Px), CAT and GST activities were, respectively, 2.1-, 3.3- and 2.1-fold higher (p = 0.04, p = 0.0009 and p = 0.03). In serum, SOD and CAT activities were, respectively, 1.5- and 1.9-fold increased (p = 0.02, p = 0.02). In liver, SOD, GSH-PX, CAT and GST activities were significantly increased (p = 0.005, p = 0.03, p = 0.02 and p = 0.04).Originality/valueIn diabetic rats-fed cholesterol-enriched diet, OC was able to reduce oxidative stress by decreasing lipid peroxidation and increasing antioxidant enzymes activities in serum, RBCs and liver.