Gastroprotective activity of Nigella sativa oil and its constituent, thymoquinone, against gastric mucosal injury induced by ischaemia/reperfusion in rats.

Ischaemia/reperfusion (I/R) induced gastric lesion, is known to be linked with free radical (FR) formation. Therefore, this model was used to assess the antioxidant effects of Nigella sativa oil (N.O) and thymoquinone (TQ) on gastric mucosal redox state and gastric lesions, 1 and 24 h after reperfusion. Male Wistar rats were subjected to I/R and were injected with either N.O (2.5 and 5 ml/kg, p.o) or TQ (5, 20, 50 and 100 mg/kg, p.o). The results showed that I/R elevated the levels of lipid peroxide (LPX) and lactate dehydrogenase (LDH), while decreased those of reduced glutathione (GSH) and superoxide dismutase (SOD). These biochemical changes were accompanied by an increase in the formation of gastric lesions, which was reduced by either treatment. N.O tended to normalize the level of LDH, GSH and SOD. However, its effect to restore LPX was only seen 24 h after reperfusion. Moreover, the aforementioned parameters were nearly reinstated by TQ. On the other hand, high doses of TQ (50 and 100 mg/kg) severely reduced the GSH content, 1 h after reperfusion. These results indicate that both N.O and TQ possess gastroprotective effect against gastric lesions which may be related to the conservation of the gastric mucosal redox state.