Effect of single and combination therapy on methanol extracts of Khaya senegalensis stem bark, Vernonia amygdalina leaves and Garcinia kola seed in Leptospira interrogans-infected mice.

Ethnopharmacological Relevance: Pastoralists in Nigeria mix Garcinia kola seed (GK), Khaya senegalensis stem bark (KS), and Vernonia amygdalina leaves (VA) to treat leptospirosis.
Aim: To determine the in vitro and in vivo effect on single and combination therapy on Leptospira interrogans-infected mice.
Materials and Methods: Evaluation of in vitro assay for anti-leptospiral motility of the extracts was carried out in triplicates. For the in vivo assessment, 40 adult male mice inoculated with Leptospira were randomly allocated into 8 groups of 5 mice each. Groups IV-IX were treated with 800 mg/kg b.w. of KS, GK, VA, KS + GK, KS + VA, GK + VA for 5 days. Group I was negative control, II was model control, and III was treated with penicillin (3.7 mg/kg b.w.) intramuscularly.
Results: In vitro, at 90 min, all the extracts at 800, 400, and 200 mg/ml showed complete cessation of motility which was significantly (p < 0.05) different when compared to the negative control. A significant (p < 0.05) IC ₅₀ of 0.18 mg/ml was recorded with GK when compared to KS (0.40 mg/ml), VA (0.25 mg/ml), and procaine penicillin (0.31 mg/ml). Mean packed cell volume, haemoglobin concentration, and mean corpuscular haemoglobin concentration decreased significantly (p < 0.05) in all infected groups and returned to almost pre-infection values. However, significant leucocytosis (p < 0.05) was observed in group II. AST and ALP showed a significant increase (p < 0.001). Histopathological evaluation showed the extracts to prevent the distortion of normal architecture of the selected organs.
Conclusion: This study demonstrates the significant potential of Garcinia kola, Khaya senegalensis, and Vernonia amygdalina extracts singly and in combination to combat leptospirosis.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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