Abstract:
Background & objectives: Several plant products have been tested and found to possess anti-
leishmanial activity. The present study was undertaken to establish whether methanolic extract of
Allium sativum Linn has antileishmanial activity in comparison to standard drugs.
Methods: Methanolic extract of A. sativum bulbs was screened for in vitro and in vivo antileishmanial
activity against Leishmania major strain (NLB 145) and L. donovani strain (NLB 065). Pentostam®
and Amphotericin B® were used as standard drugs. BALB/c mice and golden hamsters
(Mesocricetus auratus) were used in in vivo studies on L. major and L. donovani respectively.
Results: The extract exhibited very low cytotoxicity (IC50 >450 μg/ml) against Vero cells. The
extract had significantly better (p <0.001) leishmanicidal activity against both species (IC50 34.22
μg/ml to L. major, 37.41 μg/ml to L. donovani) than Pentostam. However, the activity was
significantly lower (p <0.001) than that of Amphotericin B against both the species. At a
concentration of 250 μg/ml, the extract induced the production of 60 μM of nitric oxide, a ten-fold
up-regulation in activated macrophages. The multiplication indices for L. major amastigotes treated
in 100 μg/ml were significantly different (p <0.05). Treatment with the extract, daily for 28 days
led to a significant reduction (p <0.05) in footpad swelling in BALB/c mice; similar activity
noticed in the treatment with standard drugs. The Leishman-Donovan Units (LDU) for the extract
treated animals were significantly higher (p <0.05) than those of standard drugs, but lower compared
to the negative control.
Interpretation & conclusion: Since the mechanism of action for the methanolic extract is apparently
immunomodulatory, garlic compounds could be purified and tried as complementary medicine in
the management of leishmaniases.
