Ochraceopyronide, a Rare α-Pyrone-C-lyxofuranoside from a Soil-Derived Fungus <i>Aspergillus ochraceopetaliformis</i>

Abstract

The fungal strain was isolated from a soil sample collected in Giza province, Egypt, and was identified as Aspergillus ochraceopetaliformis based on phenotypic and genotypic data. The ethyl acetate extract of the fungal strain exhibited promising activity levels against several pathogenic test organisms and through a series of 1H NMR guided chromatographic separations, a new α-pyrone-C-lyxofuranoside (1) along with four known compounds (2–5) were isolated. The planar structure of the new metabolite was elucidated by detailed analysis of its 1D/2D NMR and HRMS/IR/UV spectroscopic data, while the relative configuration of the sugar moiety was determined by a combined study of NOESY and coupling constants data, with the aid of theoretical calculations. The structures of the known compounds—isolated for the first time from A. ochraceopetaliformis—were established by comparison of their spectroscopic data with those in the literature. All isolated fungal metabolites were evaluated for their antibacterial and antifungal activities against six Gram-positive and Gram-negative bacteria as well as against three human pathogenic fungi.

Keywords

• <i>Aspergillus</i> <i>ochraceopetaliformis</i>
• α-pyrones
• C-lyxofuranosides
• sugar conformations
• triterpenoids
• polyketides