Design, synthesis and activity evaluation of usnic acid monoesterification derivatives

Abstract

A new series of usnic acid (UA) monoesterified derivatives 2-15 were designed and synthesised using UA (1) as starting material. The structural characterisation of all compounds was elucidated using ¹H-NMR and ¹³C-NMR spectral data. In vitro studies demonstrated thatmost UA derivatives exhibited higher inhibitory activity against Candida albicans and Staphylococcus aureus. Among them, compound 7 displayed the highest inhibitory activity against C. albicans with a minimum inhibitory concentration (MIC) of 32 μg/mL. Compounds 5, 8, 9, 11and 13 demonstrated superior inhibition of S. aureus (MIC, 16 μg/mL) and biofilm formation in a concentration-dependent manner. With the exception of 11, compounds 5, 8, 9 and 13 were all more effective than UA in inhibiting S. aureus biofilms. This research highlights the potential of UA monoesterified derivatives for the development of dual antimicrobial and antibiofilm agents.

Graphical Abstract

Keywords:

• Usnic acid
• monoesterified derivatives
• Staphylococcus aureus
• Candida albicans
• biofilm

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by the National Key Research and Development Program of China (No. 2022YFC3502203).