Synthesis and Antimicrobial Activity of Methoxy- Substituted γ-Oxa-ε-lactones Derived from Flavanones

摘要

Six γ-oxa-ε-lactones, 4-phenyl-3,4-dihydro-2 -1,5-benzodioxepin-2-one ( ) and its five derivatives with methoxy groups in different positions of A and B rings ( – ), were synthesized from corresponding flavanones. Three of the obtained lactones ( , , ) have not been previously described in the literature. Structures of all synthesized compounds were confirmed by complete spectroscopic analysis with the assignments of signals on H and C-NMR spectra to the corresponding atoms. In most cases, lactones – exerted an inhibitory effect on the growth of selected pathogenic bacteria ( , , and ), filamentous fungi ( , , and sp.), and yeast ( ). The broadest spectrum of activity was observed for unsubstituted lactone , which was particularly active against filamentous fungi and yeast. Lactones with methoxy groups in the 3′ ( ) and 4′ ( ) position of B ring were more active towards bacteria whereas lactone substituted in the 7 position of the A ring ( ) exhibited higher antifungal activity. In most cases, the introduction of lactone function increased the activity of the compound compared to its flavonoid precursors, chalcones – , and flavanones – .