Antileishmanial Activity of Labdane Diterpenes Isolated from Alpinia nigra Seeds

Background: Alpinia nigra is a well-known ethnomedicinally important plant used to treat many diseases in the folks. Objective: It has been investigated for its antileshmanial activity in this study. Method: Mature aromatic seeds were subjected to organic solvent (n-hexane, ethylaceate and methanol) extraction. All the extracts were tested against Leishmania donovoni promastigotes in vitro. The active extracts were subjected to column chromatography for further separation and purification of compounds. The purified compounds were characterized by standard spectroscopic techniques and tested against the promastigotes. Results: Two of the extracts along with the purified compound A and B were found significantly active against the leishmania promastigotes. MTT assay revealed remarkable leshmanicidal efficacy of compound A (IC50 – 63.0 nM) and B (IC50 - 90.5 nM) against the promastigotes. Human red blood cells hemolysis experiment suggests both the compounds to be fairly safe. Conclusion: These diterpene compounds could be used as potential hit molecules for further drug development against Leishmaniasis. This is the first report of antileshmanial activities of two isolated labdane diterpenes from A. nigra.