Biochemical and histological analysis of ethanol peel extract of Citrus sinensis on mercury chloride-induced prefrontal cortex damage in Wistar rats

Mercury is one of the heavy metals which is found extensively in many environmental and certain occupational settings. It is the third most dangerous heavy metal and its toxicity causes serious risks to health through unfavorable pathological and biochemical effects. Sweet orange is the fruit of the citrus species (Citrus sinensis) in the family Rutaceae.. Over time there has been increasing interest in the utilization of these peels for both nutritional and medicinal purposes. Studies have reported the antioxidant potential of orange peel oil in laboratory rodents, indicating its protective effect against oxidative stress-mediated ailments. The study evaluated the effect of ethanolic extract of Citrus sinensis peel on mercury chloride-induced changes in the prefrontal cortex of adult Wistar rats. Twenty-five Wistar rats were purchased and divided into five groups containing five animals in each group. Group 1 was administered with distilled water, Group 2, Group 3, Group 4, and Group 5 were administered with 5 mg/kg of mercury chloride only, 5 mg/kg of mercury chloride and 140 mg/kg Silymarin, 5 mg/kg mercury chloride and 1000 mg/kg of ethanoic extract of orange peel, and 5 mg/kg mercury chloride and 1500 mg/kg of ethanoic extract of orange peel. All administration was done orally and the administration lasted for 14 days. The animals were sacrificed humanely using 75 mg/kg ketamine intraperitoneally and prefrontal was dissected out. Part was homogenized in 0.1M phosphate buffered saline for the estimation of superoxide dismutase (SOD), and catalase (CAT) activities, and Malondialdehyde (MDA) level and the other part was fixed by immersion in 10 neutral buffered formal-saline for histological evaluation. The results indicate that the MDA level in control Group(13.29±1.183 μmol) is statistically significantly lower compared to the Group 2 (21.88±1.96 μmol), group 3 (27.44±3.52 μmol), Group 4 (22.20±1.16 μmol) and Group 5 (25.40±3.13 μmol). No statistically significant different that was observed in SOD activity. It CAT activities in control group (53.51±6.83 nmol/ml) is statistically significantly lower compared to the group 2 (26.21±3.70 nmol/ml), Group 3 (27.17±5.32 nmol/ml), Group 4 (25.30±4.24 nmol/ml) and Group5 (26.59±4.22 nmol/ml). Protective role of the extract was observed from the histological evaluation. This study suggests that ethanolic extract of Citrus sinensis peel have protective effects on mercury-induced changes in prelimbic part of the prefrontal cortex of adult Wistar rats.