Toxicological evaluation of the aqueous whole plant extract of Aerva lanata (l.) Juss. ex Schult (Amaranthaceae).

BACKGROUND

Aerva lanata (L.) of the family Amaranthaceae is a Nigerian medicinal plant used traditionally for the management of lithiasis, headache, renal disorder, haematemesis, bronchitis, nasal bleeding, cough, scorpion stings, fractures and spermatorrhoea. Studies that show the pharmacological basis for some of such uses have been reported. There is, however, no scientific report on its toxicity profile to the best of our knowledge.

OBJECTIVE

This study was therefore aimed at investigating the toxicity profile of the aqueous extract of Aerva lanata.

METHODS

Acute toxicity tests for the extract administered orally at 1-30g/kg and intraperitoneally at 0.1-2g/kg were carried out in albino mice; while a sub-chronic toxicity test was done by daily oral administration of the extract at 40-1000mg/kg to albino rats for 90 days. Anthropometric, biochemical and haematological parameters' assessments as well as vital organs histological examinations were performed in the sub-chronic toxicity study.

RESULTS

The LD50 of the extract for oral and intraperitoneal acute toxicity tests were 22.62g/kg and 0.432g/kg respectively. The extract produced apparent changes in body weights of both male and female rats and significantly (p < 0.05) increased the weights of lungs, brain and pancreas of female rats while reducing the weight of testes in male rats. Haematological parameters were also altered with total leukocytes significantly (p < 0.05) increased and platelets significantly (p < 0.05) reduced in female rats; while neutrophils significantly (p < 0.05) increased in male rats. The extract (40-1000mg/kg) produced significant (p < 0.05) reduction of serum alanine transaminase concentration in both male and female rats. Aspartate transaminases and albumin were also significantly (p < 0.05) reduced in both male (at 1000mg/kg) and female (at 200mg/kg) rats. Alkaline phosphatase was also significantly (p < 0.05) reduced in female rats at 200mg/kg of the extract. Substantial alterations of creatinine, urea and uric acid were also observed. Triglyceride and cholesterol concentrations were significantly increased in male rats but decreased in female rats. At 1000mg/kg, the extract significantly elevated catalase and superoxide dismutase levels with no effect on malondialdehyde levels. It also reduced sperm count and motility of male rats. Mild to moderate cellular changes in the brain, kidney, liver, lungs, spleen and testes of treated rats were observed on histological examinations. Significant changes in biochemical and haematological parameters were also noted in treated animals when compared to control animals 30 days after cessation of treatment.

CONCLUSIONS

The overall findings of this study suggest that the aqueous extract of A. lanata is relatively safe on acute oral exposure, moderately toxic on acute intraperitoneal administration and is relatively safe with antioxidant actions on prolonged exposure. It however shows potentials for toxic effects such as cellular damage to organs, dyslipidaemia and reduction in male reproductive capacity. Caution must therefore be applied in its use on a long term basis.