Anti-asthmatic activity of hydro alcoholic extract of Buddleja madagascariensis (Lam.) leaves in Guinea pig

The anti-asthmatic activity of the hydro alcoholic extract of Buddleja madagascariensis (Lam.) leaves was evaluated in vivo in guinea pigs and in vitro using the isolated guinea pig trachea. Administered orally at doses 50, 100, 200 and 400 mg/kg it protects animals from spasm of the air way caused by histamine aerosol 0.5 % pulverization. Dyspnoea starts at 68 ± 1.20 sec for control group animals, versus 120.25 ± 1.03, 156 ± 2.04, 240 ± 2.07 and 279 ± 1.68 sec for the animals treated with the extract at doses 50, 100, 200 and 400 mg/kg respectively (p<0.05). In vitro, the hydro alcoholic extract of B. madagascariensis leaves relaxes isolated guinea pig trachea pre contracted with histamine at 10-4 M with an EC50 of 0.037 mg/ml. These results indicate the bronchodilation activity of this plant. The pre-incubation of the isolated trachea in the bath containing the extract at concentrations of 40, 50 and 60 µl/ml increased the EC50 of histamine from 4.61 10-8 M to 5.58 10-7 M, 6.42 10-6 M and 8.32 10-5 M respectively (p<0.05). The maximal contraction induced by histamine decreases from 100 % to 92 ± 3, 83 ± 2 and 62 ± 3 %. This effect could be caused by the alkaloids and/or flavonoids present in the extract.