Introduction: Moringa oleifera is a tropical tree whose leaves are rich in antioxidant compounds. Paracetamol hepatotoxicity is a significant public health concern.  Aim: The aim of this study was to investigate the possible protective role of Moringa oleifera leaves (MOL) aqueous extract on paracetamol induced liver injury in adult male albino rats.
Materials and Methods: Forty adult male albino rats were used in the current study and were divided into four equal groups,: Group I served as control; Group II were given MOL for 14 days; Group III were given water for 7 days followed by paracetamol for another seven days; Group IV were given MOL for 14 days and Paracetamol on the seventh day for 7days.All medications were given by nasogastric tube. Specimens of liver were excised and processed for histological and histochemical studies. Blood samples were collected for biochemical study. Statistical analysis of the results was done.
Results: MOL administration in group II didn't affect hepatic architecture or liver function tests. There was a significant increase in glutathione peroxidase and catalase activity and no significant difference in malondialdehyde level as compared to control. Paracetamol administration led to vacuolization of hepatocytes, cellular infiltrations and congestion in central and portal veins, with apparent increase in number of cholangiocytes. There were also significant decrease in the area percentage of PAS positive granules and significant decrease in area percentage of collagen fibers as compared to control. By electron microscope, distorted mitochondria, decrease of rough endoplasmic reticulum and increase of smooth endoplasmic reticulum & collagen fibrils were observed. Administration of Moringa before paracetamol ameliorated damaging effects of paracetamol. Minimal cellular infiltrations and apparent increase in number of cholangiocytes were still observed.  Conclusion: MOL extracts could protect the liver against paracetamol effects through inhibition of lipid peroxidation and enhancement of antioxidant enzymes.