Objective: The seeds of Nigella sativa locally known as "Kalonji" has been used in traditional medicine for the treatment of a variety of diseases including diarrhoea and asthma. The crude extract of N. sativa seeds (Ns.Cr) was studied in vitro for its possible spasmolytic and bronchodilator activities to rationalize the folkloric uses.
Methods: Isolated rabbit jejunum and guinea-pig tracheal preparations were set up in Tyrode's and Kreb's solutions respectively and aerated with 5% CO2 in oxygen. Isotonic and isometric responses were measured on Bioscience oscillograph and Grass polygraph respectively.
Results: The Ns.Cr caused a dose-dependent (0.1-3.0 mg/ml) relaxation of spontaneous contractions in rabbit jejunum. Ns.Cr also inhibited K(+)-induced contractions in a similar dose range, suggestive of calcium channel blockade (CCB). This effect was confirmed when pretreatment of the tissue with Ns.Cr, produced a dose-dependent shift in the Ca++ dose-response curves to the right similar to that of verapamil, a standard calcium channel blocker. In guinea-pig trachea, it caused relaxation of carbachol-, histamine- or K(+)-induced contractions indicating CCB. Activity-directed fractionation revealed that the CCB activity is concentrated in the petroleum ether fraction, which was found to be approximately 10 times more potent than the crude extract both in jejunum and tracheal preparations.
Conclusion: These data indicate that the crude extract of Nigella sativa seeds exhibits spasmolytic and bronchodilator activities mediated possibly through calcium channel blockade and this activity is concentrated in the organic fraction. Its usefulness for diarrhoea and asthma in traditional medicine, appears thus to be based on a sound mechanistic background.