Relaxant effects of different fractions from<i> Nigella sativa L. </i>on guinea pig tracheal chains and its possible mechanism(s)

Abstract

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="metricconverter"> The relaxant effects of four cumulative concentrations of n-hexane, dichloromethane, methanol and aqueous fractions of <i>N. sativa</i> (0.8, 1.2, 1.6 and 2.0 g%) in comparison with saline as negative control and four cumulative concentrations of theophylline (0.2, 0.4, 0.6 and 0.8 m<i>M</i>) were examined by their relaxant effects on precontracted tracheal chains of guinea pig by 60 m<i>M</i> KCl (group 1) and 10 µ<i>M</i> methacholine (group 2). In group 1, all concentrations of only theophylline showed significant relaxant effects. However, in group 2, all concentrations of theophylline and methanol fraction, 1.2, 1.6 and 2.0 g% concentrations of dichloromethane and 1.2 and 2.0 g% concentrations of n-hexane fractions showed significant relaxant effects compared to that of saline. In addition, in group 1, the relaxant effect of most concentrations of all fractions except the low concentration (0.8 g%) of dichloromethane and methanol fraction were significantly less than those of theophylline. The relaxant effect of different concentrations of methanol and dichloromethane fraction and 1.2, 1.6 and 2.0 g% concentrations of n-hexane fraction were significantly greater in group 2 compared to group 1 experiments. There were significant positive correlations between the relaxant effects and concentrations for all fractions (except aqueous fraction) in group 2 and for theophylline in both groups but a negative correlation for n-hexane, dichloromethane and methanol fractions in group 1. The results showed relaxant effect of most fractions from <i>N. sativa</i> on tracheal chains of guinea pigs which was more potent for methanol and dichloromethane fractions. </smarttagtype>