Two 6-substituted 5,6-dihydro-alpha-pyrones from Ravensara anisata.

The leaves and bark dichloromethane extracts of Ravensara anisata showed antifungal activity against the yeast Candida albicans and the phytopathogenic fungus Cladosporium cucumerinum in bioautographic TLC assays. Activity-guided fractionation afforded two new alpha-pyrones: 6R*-(4R*-acetoxy-2S*-hydroxy- 8-phenyloctyl)-5,6-dihydro-2-H-pyran-2-one and 6R*-(2S*-acetoxy-4R*- hydroxy-8-phenyloctyl)-5,6-dihydro-2-H-pyran-2-one. Their structures have been established by NMR spectroscopy, chemical methods and X-ray crystallographic analysis. The antifungal activity against C. albicans and C. cucumerinum was determined for both compounds.