Acute toxicity and histopathological assessment of methanol extract of Cleome viscosa (Linn.) whole plant.

Cleome viscosa Linn (Cleomaceae) is a medicinal plant used widely in Nigeria for the management of various ailments.  This research appraised the toxic potential of the plant with a view to validating or contesting its safety. Acute oral toxicity of the methanolic whole plant extract of Cleome viscosa was evaluated in mice using modified Lorke’s method. Signs accompanying toxicity and possible death of animals were investigated for a period of two weeks to determine the median lethal dose (LD50) of the extract. After two weeks observation period, all the animals in the respective dose groups 10, 100, 1000, 1600, 2900 and 5000 mg/kg were euthanized by cervical dislocation. The weight gained, absolute organ weight, and mean organ-body weight ratios (OBR) were determined and compared with values from those of the control group. The oral median lethal dose of the extract was found to be greater than 5000 mg/kg. There was a significant difference in weight gained on day 7 (P=0.052) among dose groups up to 1000 mg/Kg body weight. There was however, no significant difference in the relative organ weights between treated and control animals except for the Liver (p=0.048).  Histopathological analysis showed mild congestion of the pulmonary vessels at dose 1600 mg/kg and above, mild diffuse vacuolar degeneration of hepatocytes across all tested dose as well as mild renal cortical congestion especially at high dose. The oral median lethal dose results indicate that the methanol extract of Cleome viscosa whole plant is non- toxic by oral administration at the tested doses.   Key words: Cleome viscosa, methanol extract, acute toxicity, histopathology