Abstract
Leishmaniasis is one of the major tropical parasitic diseases, and the condition ranges in severity from self-healing cutaneous lesions to fatal visceral manifestations. There is no vaccine available against visceral leishmaniasis (VL) (also known as kala-azar in India), and current antileishmanial drugs face major drawbacks, including drug resistance, variable efficacy, toxicity and parenteral administration. We report here that n-hexane fractions of Artemisia annua leaves (AAL) and seeds (AAS) possess significant antileishmanial activity against Leishmania donovani promastigotes, with GI(50) of 14.4 and 14.6 µg ml(-1), respectively, and the IC(50) against intracellular amastigotes was found to be 6.6 and 5.05 µg ml(-1), respectively. Changes in the morphology of promastigotes and growth reversibility analysis following treatment confirmed the leishmanicidal effect of the active fractions, which presented no cytotoxic effect on mammalian cells. The antileishmanial activity was mediated via apoptosis, as evidenced by externalization of phosphatidylserine, in situ labelling of DNA fragments by terminal deoxynucleotidyltransferase-mediated dUTP nick end labelling (TUNEL) and cell-cycle arrest at the sub-G(0)/G(1) phase. High-performance thin-layer chromatography (HPTLC) fingerprinting showed that the content of artemisinin in crude bioactive extracts (~1.4 µg per 100 µg n-hexane fraction) was too low to account for the observed antileishmanial activity. Characterization of the active constituents by GC-MS showed that α-amyrinyl acetate, β-amyrine and derivatives of artemisinin were the major constituents in AAL and cetin, EINECS 211-126-2 and artemisinin derivatives in AAS. Our findings indicate the presence of antileishmanial compounds besides artemisinin in the n-hexane fractions of A. annua leaves and seeds.