Hepatoprotective Effects of Daniellia oliveri Leaf Methanol Extract against Dimethylamine-induced Oxidative and Immunohistochemical Alterations in Rats

Dimethylamine (DMA) is commonly used in the manufacture of various products, including rubber, pharmaceuticals, pesticides, and herbicides, leading to several toxicological consequences. This study investigated the effect of Daniellia oliveri leaf methanol extract (DOLME) on DMA-induced liver toxicity in male Wistar rats. The extract was obtained using a Soxhlet extraction. Thirty-five male Wistar rats (average weight: 154 g) were used and divided into seven groups (A–G), with five rats per group. Group A served as the control, while Group B received intraperitoneal injections of DMA alone (10 mg/kg) twice weekly. Groups C, D, E, F, and G were treated orally with DOLME (50, 100, 150, 200, and 250 mg/kg, respectively) every other day, while a similar dose of DMA was administered twice per week. Rats were sacrificed, and liver tissues were harvested. One portion of liver was processed into a homogenate for biochemical assays, including superoxide dismutase (SOD), catalase, glutathione-S-transferase (GST), reduced glutathione (GSH), and glutathione peroxidase (GPx). The other portion was fixed for histological and immunohistochemical evaluations. The DMA treatment significantly (p < 0.05) reduced hepatic SOD and catalase activities, which were reversed by DOLME at most doses. Hepatic GST and GSH levels were also reduced (p < 0.05) by DMA but attenuated with DOLME treatment. Histological examination revealed hepatic portal triaditis in DMA-treated rats, which was ameliorated by DOLME. High expressions of EMA and cytokeratin were observed in the hepatocyte cytoplasm of DMA-treated rats, whereas mild to moderate expressions were noted in the DOLME-treated groups. These findings suggest that Daniellia oliveri leaf methanol extract mitigates DMA-induced liver damage through antioxidant mechanisms and by reducing the expression of epithelial membrane antigen and cytokeratin.