Protective Effects of Aqueous Extract of Bay Leaf (Laurus Nobilis) on Endotoxin-Induced Oxidative Stress in Rabbits

ABSTRACT The protective effect of oral co-administration of Laurus nobilis on Escherichia coli endotoxin-exposed rabbits was studied. Twenty-five (25) rabbits were randomized into five groups containing five rabbits each – Group A, 500 Endotoxin Unit (EU) kg−1 bw, Group B, 500 EU kg−1 bw + 6.6 mg kg−1 bw extract, Group C, 500 EU kg−1 bw + 3.3 mg kg−1 bw extract, Group D, 500 EU kg−1 bw + Ascorbic acid (100 mg kg−1 bw) and Group E (0 EU kg−1 bw). The rabbits were pre-administered with the bay leaf extract in the first 7 days, then endotoxin oral administration was started and repeated daily for 21 d. At the end of days 7 and 21, assays for the serum superoxide dismutase, glutathione S-transferase, reduced glutathione, catalase, and malondialdehyde were done. The animals were sacrificed to collect kidneys and liver. Histopathological analysis of the liver and kidneys showed that exposure to 500 EU kg−1 bw endotoxin for 21 d + bay leaf extract at 6.6 and 3.3 mg kg−1 bw increased specific activities of superoxide dismutase, glutathione S-transferase, and reduced glutathione and catalase compared to the negative control. There was a decrease in the concentration of malondialdehyde in groups treated with the aqueous extract of bay leaf.