Keywords: Phyllanthus amarus; antiasthmatic activity; toxicity; phytochemicals

Abstract

Phyllanthus amarus (chanca piedra), plant family—Euphorbiaceae, have been used in the treatment of several ailments among traditional medicine practitioners. The plant after treatment and extraction with hexane solvent was screened for phytochemical constituents. Isolation of oil from the extract was done using vacuum liquid chromatography and characterized using gas chromatography-mass spectrometry. The acute toxicity test was determined to estimate the lethal dose (LD50) value of the extract in Balb/c albino mice. Bronchial asthma was induced into the guinea pigs in the test groups with 10% histamine dihydrochloride aerosols. Chloro-pheniranmine (8 mg/kg), saline (5 ml/kg) and the plant extract (10 mg/kg, 20 mg/kg and 30 mg/kg) were administered orally for 30 minutes prior to the exposure of histamine aerosols for 6 minutes. Phenolics, flavonoids, and alkaloids were present in the extract. The major components detected from the isolated yellow oil of P. amarus among others were 1, 14-tetradecandiol [retention time (Rt): 17.47, 14.86%], a dihydric alcohol and cholest-4-en-3-one (Rt:19.49, 15.01%), a reduced cholesterol. LD50 value of 28.18 mg of extract/kg body weight of the mice was derived from the regression graph. Upon exposure of the treated guinea pigs to the histamine aerosols, those which developed typical histamine asthma (characterised by dyspnoea: convulsions and asphyxia) within 6 minutes of exposure were removed from chamber for possible recovery while those which did not develop typical asthma after the 6th minute were taken as protected. The results of the study generally indicated that the plant extract exhibited significant bronchodilatory activity against histamine.