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

The leaves and bark dichloromethane extracts of Ravensara anisata showed an tifungal activity against the yeast Candida albicans and the phytopathogeni c fungus Cladosporium cucumerinum in bioautographic TLC assays. Activity-gu ided fractionation afforded two new alpha-pyrones: 6R(*)-(4R(*)-acetoxy-2S( *)-hydroxy-8-phenyloctyl)-5, 6-dihydro-2-H-pyran-2-one and 6R(*)(2S(*)-acet oxy-4R(*)-hydroxy-8-phenyloctyl)-5,6-dihydro-2-H-pyran-2-one. Their structu res have been established by NMR spectroscopy, chemical methods and X-ray c rystallographic analysis. The antifungal activity against C. albicans and C . cucumerinum was determined for both compounds. (C) 1999 Elsevier Science Ltd. All rights reserved.