Synthesis and antifungal activity of terpenyl-1,4-naphthoquinone and 1,4-anthracenedione derivatives

• Twenty seven 1,4-quinone derivatives were evaluated as antifungals.
• Five compounds showed fair wide antifungal spectra.
• Some of them showed MIC90 values < 10 μg/mL against dermatophytes, Candida spp. or Aspergillus fumigatus.
• The most potent compounds showed selectivity indexes SI > 9–50, with respect to Vero cells.
• Time-kill assays suggest a fungistatic behaviour.

The antifungal evaluation of twenty seven simple and heterocycle-fused prenyl-1,4-naphthoquinones and 1,4-anthracenediones was performed in vitro against human pathogenic yeasts (Candida spp.) and filamentous fungi (Aspergillus spp., Fusarium spp., and Trichophyton spp.). The synthetic strategy used to obtain the quinone derivatives was initially based on the Diels–Alder cycloaddition between myrcene and several p-benzoquinone derivatives, followed by cyclisation of the prenyl side chain in the case of anthracene-1,4-diones. The most promising compounds, displaying MIC values in the low μg/mL range, were those bearing one or two chlorine atoms attached to the quinone ring. Time-kill curves determined for the most potent compounds showed their fungistatic mode of action similar to that of itraconazole.

MIC in μg/mL (Tm: Trycophyton mentagrophytes; Tr: Trichophyton rubrum; Ck: Candida krusei; Cl: C. lusitaniae, Afu: Aspergillus fumigatus). HSI: Highest selectivity index.Figure optionsDownload as PowerPoint slide