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.

The effect of Nigella sativa oil against the liver damage induced by Schistosoma mansoni infection in mice

It has been reported that Nigella sativa oil possesses anticestode and antinematode actions. Besides, it produced a hepatoprotective effect in some models of liver toxicity. Therefore, our aim in this work was to study the effect of the Nigella oil (N.O) on Schistosomiasis mansoni infected mice. The oil was given in two dose levels (2.5 and 5 ml/kg, orally for two weeks) either alone or in combination with praziquantel (PZQ), the drug of choice for the treatment of schistosomiasis. Three aspects of drug action were investigated, the effect on Schistosomiasis mansoni infection, the effect on liver functions, and on redox state. The parasitological investigation included worm distribution, oogram pattern and ova count. Furthermore, liver granuloma diameters were measured. The biochemical parameters were the serum level of L-alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (AP), albumin (Alb) and total protein. Moreover, to assess the antioxidant capability of the Nigella oil, four parameters were studied, viz., liver lipid peroxide (LPD) and reduced glutathione (GSH) contents and the activity of the defence enzyme superoxide dismutase (SOD) and lactate dehydrogenase (LDH). When the oil was given alone, it reduced the number of S. mansoni worms in the liver and decreased the total number of ova deposited in both the liver and the intestine. Furthermore, it increased the number of dead ova in the intestinal wall and reduced the granuloma diameters markedly. When N.O was administered in combination with PZQ, the most prominent effect was a further lowering in the dead ova number over that produced by PZQ alone. Concerning the biochemical parameters, infection of mice with S. mansoni produced a pronounced elevation in the serum activity of ALT, GGT, with a slight increase in AP level. However, it tended to reduce serum albumin level. These changes were accompanied with an alteration in the liver contents of LPD and GSH along with a significant decline in the activity of the cytosolic SOD and LDH. Administration of Nigella sativa oil succeeded partially to correct the previous changes in ALT, GGT, AP activity, as well as the Alb content in serum. However, it failed in the liver to restore either LPD and GSH content or LDH and SOD activities to normal level. These results suggest that Nigella sativa oil may play a role against the alterations caused by S. mansoni infection, an effect which may be induced partly by improving the immunological host system and to some extent with its antioxidant effect.