In Vitro Antibiofilm Activity of Eucarobustol E against Candida albicans

Formyl-phloroglucinol meroterpenoids (FPMs) are important types of natural products with various bioactivities. Our antifungal susceptibility assay showed that one of the -derived FPMs, eucarobustol E (EE), exerted a strong inhibitory effect against biofilms at a concentration of 16 μg/ml. EE was found to block the yeast-to-hypha transition and reduce the cellular surface hydrophobicity of the biofilm cells. RNA sequencing and real-time reverse transcription-PCR analysis showed that exposure to 16 μg/ml of EE resulted in marked reductions in the levels of expressions of genes involved in hyphal growth ( , , , , , and ) and cell surface protein genes ( , , and ). Interestingly, in response to EE, genes involved in ergosterol biosynthesis were downregulated, while the farnesol-encoding gene ( ) was upregulated, and these findings were in agreement with those from the quantification of ergosterol and farnesol. Combined with the obvious elevation of negative regulator genes ( , ), we speculated that EE's inhibition of carbon flow to ergosterol triggered the mechanisms of the negative regulation of hyphal growth and eventually led to biofilm inhibition.