RESUMO
BACKGROUND: Avenaciolide, a natural product isolated from Aspergillus avenaceus H. Smith, possesses several interesting biological properties, such as antifungal and antibacterial activities and inhibition of glutamate transport in mitochondria. In a study aiming to discover new compounds with antifungal activity, a bis-gamma-lactone analogous to avenaciolide was prepared and characterized by elemental analysis, mass spectrometry, and infrared and NMR spectroscopy. RESULTS: The absolute structures of this compound and of the synthetic precursor (also a bis-gamma-lactone) were determined by X-ray diffraction analysis. The bis-gamma-lactones synthesized crystallize in the orthorhombic space group P2(1)2(1)2(1), and the crystal packings are supported by C--H...O hydrogen bonds. The compound showed antifungal activity against Colletotrichum gloeosporioides (Penz.) Penz. & Sacc., while the synthetic precursor was inactive under the in vitro test conditions employed. CONCLUSION: The results indicate that it is not only the bis-gamma-lactone skeleton that is important to antifungal activity. The latter also depends on the presence of the exocyclic double bond possibly due to a Michael addition type reaction with the fungal enzymes.