Labdane diterpenoids from Aframomum sceptrum: NMR study and antiparasitic activities

Two novel labdane diterpenoids, 15ξ-methoxy-labdan-8(17),11(E),13(14)-trien-15,16-olide (1) and 12(S)-hydroxy-15ξ-methoxy-labdan-8(17),13(14)-dien-15,16-olide (2) were isolated from the rhizomes of Aframomum sceptrum K. Schum (Zingiberaceae). Their structures were established on the basis of their spectroscopic data. Stigmast-4-en-6β-ol-3-one and caryophylene oxide were also obtained. In vitro trypanocidal and leishmanicidal activities of labdanes 1 and 2 were evaluated. Compound 2 exhibited activity similar to that of reference drugs against Leishmania donovani.

From the rhizoma of Aframomum sceptrum (Zingiberaceae), which is traditionally used against infectious diseases in Ivory Coast, two new labdanes (1 and 2) were obtained, consistently with chemotaxonomical data of the genus. During structural elucidation, interesting solvent effects were observed in NMR. Labdane 2 proved to be strongly active against Leishmania donovani promastigotes in vitro.Highlights► Composition of the rhizoma of A. sceptrum was previously unknown. ► 2 undescribed labdanes were obtained, consistently with chemotaxonomical data. ► During structural elucidation, interesting solvent effects were observed in NMR. ► 2 is strongly active against Leishmania donovani promastigotes in vitro.