Abstract
The toxicity of a methanol extract of roots of Lasiosiphon kraussianus (lg = 20 g dried root) was investigated in mice, rats, rabbits, dogs and isolated
rabbit ileum and heart. In acute toxicity studies carried out in mice, LD50 of the extract was 27.1 g/kg and 330 mg/kg after oral and intraperitoneal administrations
respectively. Clinical signs of peritoneal irritation, tachypnoea and listlessness
and post mortem lesions of haemorrhagic enteritis were observed. In chronic toxicity
studies with rats fed the extract at 2, 4 and 8 mg/kg/day for six months, no clinical
signs of toxicity were observed and no gross lesions were detected at post mortem
examinations. Haematological studies carried out in rabbits given 2 to 16 mg/kg of
the extract per os showed no significant changes in the blood parameters measured. There was also no
effect on blood pressure and respiration in the dog. On isolated rabbit ileum and
heart however, high concentrations of the extract (2-32 mg/ml) inhibited intestinal
rhythmic contractions and had negative inotropic and chronotropic effects on the heart.
It was concluded that a methanol extract of root of Lasiosiphon kraussianus when given at the dose of 2 mg (equivalent to 0.4 g dried root)/kg per os does not cause any toxic effects in mice, rats and rabbits.
A further study is required to confirm its efficacy in the treatment of leprosy and
viral diseases.
Key Word Index
Lasiosiphon kraussianus - Toxicity - Ileum - Heart
