Efficacy of combination therapy using extracts of <i>Aloe secundiflora</i> Eng L and <i>Callistemon citrinus</i> William C. in <i>Leishmania major</i> infected BALB/c mice

Abstract

Background: Leishmania major causes cutaneous leishmaniasis which leads to painful skin sores in humans. In the current study, efficacy of combination therapy of A. secundiflora and C. citrinus against L. major infected mice treated intra-peritoneally and orally was studied. Pentostam administered intra-peritoneally and phosphate buffered saline intra-peritoneally and orally were used as a controls.
Objective: To determine the efficacy of combined therapy of C. citrinus and A. secundiflora extracts in Leishmania major infected BALB/c mice.
Design: Experimental-Laboratory based study
Setting: Kenya Medical Research Institute (Leishmania Department)
Subjects: Eight weeks Male BALB/c Mice
Results: The minimum inhibitory concentration (MICs) of aqueous extracts of A. secundiflora (A), and C. citrinus (B) were 2 mg/ml and 5 mg/ml respectively while the IC₅₀ for the same extracts were 467.09μg/ml and 457.88μg/ml respectively. The combination of these extracts at ratio (1:1) supported minimal growth of L. major promastigotes and had IC₅₀ of 58.45μg/ml as compared to MICs of 12.50μg/ml for Pentostam. The combination therapy had Infection rate (IR) of 19% and MI of 52.81% compared to Pentostam (IR=21% and MI=11.64%). The combination therapy reduced the footpad lesion size significantly (P < 0.05) just like the Pentostam control drug and no significant nitric oxide was stimulated. The oral and intra-peritoneal combination treatment reduced spleen amastigotes in mice by 73.46% and 78.12% corresponding to total LDUs of 10.87±0.64 and 8.96±0.82 respectively compared to Pentostam at 94.58% and LDU of 2.22±0.13. The difference between efficacy of Pentostam and that of combined extracts was almost significant (t= 2.653, P= 0.057).
Conclusion: The combination therapy was active against L. major parasite, reduced lesion size significantly and did not prevent visceralisation but reduced spleen parasite load significantly.