Therapeutic Potential And Toxicity Levels Of Solanum Aculeastrum Dunal. Plant Extracts Against Leishmania Major Infection In Balb/C Mice

ABSTRACT Solanum acueastrum Dunal. plant (Solanaceae family), growing in most parts of tropical Africa down to South Africa, has been shown to have some chemotherapeutic value. The fruit and leaf of S. aculeastrum is used for treating various diseases like jigger wounds, swelling joints in fingers, bronchitis, enlarged spleen, rheumatism, gangrene, gonorrhea, and other inflammatory-related ailments. Scientific studies conducted in S. Africa have also validated that S. aculeastrum fruit extracts can be used for the treatment of breast cancer. The current study evaluated S. acueastrum leaf and fruit water and methanol extracts for possible antileishmanial activity in BALB/c mice and toxicity levels in vero cells (lineage of cells isolated from kidney epithelial cells of an African Green monkey). Air dried S. aculeastrum fruit and leaf were extracted in methanol and water and stored at 40C in air tight bottles. In in vitro bioassays, L. major parasites were exposed to varying concentrations of S. aculeastrum fruit and leaf extracts and the inhibitory concentration (IC50) on the promastigotes, percentage infection rate of macrophages by amastigotes and the toxicological effect on vero cells determined. In in vivo bioassays, BALB/c mice were infected subcutaneously with 1 × 106 promastigotes and kept for 4 weeks to allow for disease establishment. Infected mice were treated with fruit and leaf methanol and water extracts, amphotericin B (AmB) drug, and sterile phosphate buffered saline (PBS) intraperitoneally at 100 μg/ml for 4 weeks. The mice were sacrificed by ether euthanasia and splenic impression smears made on slides, fixed in methanol, stained with Giemsa and parasites quantified. Fruit methanol extracts were most effective in inhibiting the growth of promastigotes with lowest IC5078.62 μg/ml. Fruit water showed the best activity in inhibiting infection of macrophages by amastigotes. Fruit methanol were most toxic to health vero cells at Ld50 = 8.06 mg/ml while AmB antileishmanial control drug showed the highest toxicity of 1.25 mg/ml in killing 50% of vero cells. Analysis of variance computation indicated a statistically significant difference in lesion sizes between experimental and control mice groups (P = 0.0001). Based on splenic impression smears, it was evident that either water or methanol extracts significantly protected the mice against splenic parasites as compared to the control (P = 0.0001). Findings from this study demonstrate that S. aculeastrum extracts have potential anti-leishmanial activities and that the medicinal use of the plant also poses considerable health risks exhibited by its toxicity against dividing vero cells.