Acute oral toxicity and in vitro leukotriene inhibitory property of hydroalcoholic extract of Nicotiana tabacum in guinea pig lung strips

Abstract

Objective: The present study investigates acute toxicity and leukotriene inhibitory property of Nicotiana tabacum. Materials and Methods: Leaves of N. tabacum were extracted with aqueous ethanol (1:1) by cold percolation method. The extract was administered orally at the limit dose of 2000 mg/kg to evaluate the toxic potential of the plant. In vitro leukotriene inhibitory property of extract was examined on isolated lung strips of guinea pigs contracted with leukotriene D4 (10 μMol). The relaxation response was observed at six cumulative concentrations (6.25, 12.5, 25, 50, 100, and 200 mg/ml) of extract and standard, Montelukast, (0.15, 0.3, 0.45, 0.6, 0.75, and 0.9 mM). One-way ANOVA followed by Tukey’s test was used for statistical analysis of data using GraphPad Prism 7. Results: Crude extract of N. tabacum administered orally at the dose of 2000 mg/kg did not cause any mortality indicating safety of the plant. The LD50 of the plant was found to be >2000 mg/kg. Increasing concentrations of N. tabacum showed a decrease in muscle tone induced by LTD4 in a dose-dependent manner (105.12 ± 1.03% at 200 mg/kg and EC50 = 22.22 mg/ml). However, the relaxant effect of extract at highest concentration was non-significant (P > 0.05) compared to Montelukast. The relaxant effects of all concentrations of montelukast were significantly higher (P < 0.001) than saline. On the other hand, at the lowest concentration, the relaxant effect of N. tabacum was not significant (P > 0.05) compared to saline. Montelukast showed maximum relaxation of 112.82 ± 2.16 % at highest concentration (EC50 = 0.20 mM).