In vitro and in vivo efficacy of combination therapy using allium sativum and aloe secundiflora against leishmania major infected balb/c mice

Abstract

Cutaneous leishmaniases (CL) is endemic in more than 88 countries worldwide. Zoonotic cutaneous leishmaniasis in Kenya is caused by Leishmania major. Currently used drugs like pentostam, Amphotericin B are expensive, toxic and require prolonged use. Combination therapy prevents drug resistance and reduces toxicity. In addition, herbal extracts can be safe and cheaper. Allium sativum and Aloe secundiflora water extracts have shown to have antileishmanial activities. In this study, the efficacy of combination therapy using A. sativum and A. secundiflora against L. major in BALB/c mice was studied using both intraperitoneal and oral routes of administration. The standard drug pentostam and phosphate buffered saline were used as positive and negative controls respectively. T-test and ANOVA were used for data analysis and P-value of < 0.05 was considered significant. Plant materials were dried, ground, soaked in water at 75oC for 1 hour, filtered then freeze dried. The minimum inhibitory concentrations (MICs) of aqueous extracts of A. secundiflora (AF) and A. sativum (AS) were 2000 μg/ml and 5000 μg/ml and IC50 were 467.09μg/ml and 457.88μg/ml respectively while the IC50 for their combination at ratio (1:1) was 391.79 μg/ml as compared to MICs of 12.5μg/ml and IC50 of 108.58μg/ml for pentostam. The combination therapy had Infection rate (IR) of 17% and multiplication index (MI) of 48.65% compared to pentostam with an IR=21% and MI=11.64%. The combination therapy reduced the footpad lesion size significantly (P < 0.05) like the pentostam control drug and no significant nitric oxide stimulated. The oral and intraperitoneal combination treatment reduced spleen amastigotes in mice by 55.48% and 64.13% corresponding to total Leishman Donovan Units (LDU) of 18.23 ± 0.90 and 14.69 ± 1.33 respectively compared to pentostam 94.58% and LDU of 2.22±0.13. In summary, the combination therapy was active against L. major parasite, by reducing spleen parasite load significantly but did not prevent visceralization as amastigotes were seen in spleen smears. This study recommends the health sector to consider developing therapeutic products from the test plants for the treatment of CL in poverty stricken leishmaniases endemic areas of Kenya.