Several different pharmacological effects have been described for Nigella sativa (Siah-Daneh), including an anti-inflammatory effect. In the present study, the effect of the extract of N. sativa on lung pathology and blood interleukin-4 (IL-4) and interferon-γ (IFN-γ) of sensitized guinea pigs was examined. Three groups (n=8 for each group) of guinea pigs sensitized to ovalbumin (OA) were given drinking water alone, and drinking water containing low and high concentrations of the plant extract, respectively. The animals of the control group (n=8) were treated with saline instead of OA and were given drinking water. The pathological changes of the lung, including infiltration of eosinophils and lymphocytes, local epithelial necrosis, the presence of oedema, thickening of the basement membrane, smooth muscle layer hypertrophy, mucosal secretion, and the presence of mucosal plug, and blood IL-4 and IFN-γ of sensitized guinea pigs were evaluated. The lungs of the sensitized group showed significant pathological changes (P<0.001). Blood IL-4 and IFN-γ were increased in sensitized animals compared to the controls (P<0.01 and P<0.001, respectively). Treatment of sensitized animals with the extract led to a significant decrease in pathological changes of the lung (P<0.01 to P<0.001), except for the oedema in the sensitized group treated with low concentration of the extract, but an increased IFN-γ. These results confirm a preventive effect of N. sativa extract on lung inflammation of sensitized guinea pigs.

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In previous studies, the relaxant, anticholinergic (functional antagonism) and antihistaminic, effects of Nigella sativa have been demonstrated on guinea pig tracheal chains. In the present study, the prophylactic effect of thymoquinone (one of the constituents of Nigella sativa) on tracheal responsiveness and white blood cell (WBC) count in lung lavage of sensitized guinea pigs was examined. Four groups of sensitized guinea pigs to ovalbumin (OA) were given drinking water alone (group S), drinking water containing low or high concentrations of thymoquinone (S + LTQ and S + HTQ groups) or inhaled fluticasone propionate (FP 250 microg) twice a day (positive control group) (n = 7, for all groups). Tracheal responses of control and four groups of sensitized animals to methacholine at an effective concentration causing 50 % of maximum response (EC(50) M) were measured. Tracheal responses to 0.1 % OA, relative to contraction induced by 10 microM methacholine were also examined. Total WBC and its differential count in lung lavage were also measured. The tracheal responsiveness to methacholine, OA and WBC of S guinea pigs was significantly higher than those of controls (p < 0.001 for all cases). Tracheal responsiveness in S + LTQ, S + HTQ, and FP groups to both methacholine (p < 0.05 to p < 0.001) and OA (p < 0.001 for all cases) was significantly decreased compared to that of the S group. Total WBC was also decreased in all experimental groups compared to that of the S group (p < 0.001 for all groups). There was an increase in eosinophils and a decrease in neutrophils, lymphocytes and monocytes in the S animals compared to the controls (p < 0.001 for all cases). Treatment with both concentrations of thymoquinone and FP variably improved differential WBC count changes compared to the S animals (nonsignificant to p < 0.001). The improvement in tracheal responsiveness, total WBC, eosinophils and lymphocytes changes in the S animals treated with both concentrations of TQ were significantly greater than those of FP (p < 0.05 to p < 0.001). These results showed a preventive effect of thymoquinone, one constituent of N. sativa, on tracheal responsiveness and inflammatory cells of lung lavage of sensitized guinea pigs which was comparable or even greater than that of the inhaled steroid.

Different pharmacological effects from Nigella sativa have been demonstrated in guinea pig tracheal chains in previous studies. In the present study, the prophylactic effects of thymoquinone on lung pathology as well as blood IL-4 and IFN-γ levels in sensitized guinea pigs were examined. Three groups of guinea pigs sensitized to ovalbumin were given drinking water alone (group S) or drinking water containing low (LTQ) or high (HTQ) concentrations of thymoquinone (groups S + LTQ and S + HTQ). The lung pathology as well as blood IL-4 and IFN-γ levels of the sensitized and the control guinea pigs were evaluated in three sensitized and one control group (n = 8, for all groups). The lungs of the S group showed significant pathological changes (p < 0.001). Blood IL-4 and IFN-γ levels were increased in the sensitized animals compared to those of controls (p < 0.01 and p < 0.001, respectively). Treatment of the S animals with thymoquinone significantly improved their pathological changes to the lung and decreased their IL-4 levels (p < 0.05 to p < 0.001) but increased their IFN-γ levels (p < 0.001). These results showed a preventive effect of thymoquinone on lung inflammation in sensitized guinea pigs.

OBJECTIVE:To examine the preventive effect of a hydro-ethanolic extract of Nigella sativa on the tracheal responsiveness and white blood cell count in the lung lavage fluid of sensitized guinea pigs.METHODS:Three groups of guinea pigs sensitized to intraperitoneally injected and inhaled ovalbumin were given drinking water alone (group S), drinking water containing a low concentration of N. sativa extract (group S+LNS) or drinking water containing a high concentration of N. sativa extract (group S+HNS). The tracheal responses of control animals (group C) and the three groups of sensitized guinea pigs (n = 7 for all groups) to methacholine were measured by the assessment of the tracheal smooth muscle response to increasing concentrations of methacholine, and the effective concentration causing 50% of the maximum response (EC50) was determined. Tracheal responses to 0.1% ovalbumin and white blood cell counts in the lung lavage fluid were also examined.RESULTS:The tracheal response of the group S guinea pigs to both methacholine and ovalbumin was significantly higher than the response of the controls (p<0.01 for both cases). The tracheal responses of the S+LNS and S+HNS groups to both methacholine and ovalbumin were significantly decreased compared to those of the S group (p<0.05 to p<0.01). The total white blood cell and eosinophil counts in the lung lavage fluid of group S were significantly higher than those of group C (p<0.01). The white blood cell counts in both treated groups showed significant improvements (p<0.01 for both cases).CONCLUSIONS:These results demonstrate the preventive effect of the N. sativa extract on the tracheal response and lung inflammation in sensitized guinea pigs.

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