A 5-month toxicity study of the ethanol extract of the leaves of Heliotropium indicum in Sprague Dawley rats after oral administration.

Background: Heliotropium indicum Linn. (Boraginaceae) is used in Nigerian traditional medicine to treat tuberculosis with treatment lasting for 3 months; however, information on its toxicity is scarce.

Objective: This study investigated the safety of the leaves of Heliotropium indicum after a 5 month oral administration.

Methods: The leaves of H. indicum were dried; extracted in 70% ethanol and concentrated to dryness. Swiss mice were administered orally with single doses of the extract (0.5 to 12.0 g/kg b.wt /day); mortality was examined for up to 14 days. In another study, the plant material (0.5 to 2.0 g/kg b.wt /day) were administered daily by oral gavage to Sprague Dawley rats. Body weight was monitored weekly, hematological, biochemical and organ parameters were determined at the end of the 1st, 2nd and 5th months of extract administration.

Results: The oral administration of the ethanol extract of H. indicum caused dose-dependent mortality. The LD50 was 9.78 g/kg b.wt for the Swiss mice; no harmful effect was observed on the liver and kidney except the testes which exhibited considerable inflammatory changes at the highest dose of 2.0 g/kg b.wt./day after the 5th month treatment. No significant difference (P>0.05) was shown in the enzyme study, marginal increase occurred in some haematological parameters. The increase in body weight of the treated rats after its initial reduction was consistent and significantly different (P<0.05) from their initial body weight.

Conclusion: Prolonged administration of the crude leaf extract of H. indicum is considered to be safe and nontoxic at the doses studied. However, there is a probability of a negative effect on the testes at a higher dose of the extract.