In Vitro Antibiofilm Activity of Eucarobustol E against Candida albicans

Abstract

Formyl-phloroglucinol meroterpenoids (FPMs) are important types of natural products with various bioactivities. Our antifungal susceptibility assay showed that one of the Eucalyptus robusta-derived FPMs, eucarobustol E (EE), exerted a strong inhibitory effect against Candida albicans biofilms at a concentration of 16 g/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 g/ml of EE resulted in marked reductions in the levels of expressions of genes involved in hyphal growth (EFG1, CPH1, TEC1, EED1, UME6, and HGC1) and cell surface protein genes (ALS3, HWP1, and SAP5). Interestingly, in response to EE, genes involved in ergosterol biosynthesis were downregulated, while the farnesol-encoding gene (DPP3) 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 (TUP1, NRG1), 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.

Kalopanaxsaponin A induces reactive oxygen species mediated mitochondrial dysfunction and cell membrane destruction in Candida albicans

“…The MIC 80 values of KPA against different Candida species were measured by the broth microdilution method. The results showed that KPA exerted a moderate antifungal effect (based on the previous reports [6,10,13,17]) against the five most common Candida species, including C. albicans, C. glabrata, C. parapsilosis, C. tropicalis and C. krusei, the MIC 80 value of which was all 16 μg/mL. The MIC 80 values of the positive control AMB were 0.5 or 1 μg/mL, respectively ( Table 1).…”

Essential Oils and Antifungal Activity

“…For example, mixed polymicrobial infections due to the presence of bacteria and pathogenic fungi, commonly found in patients with chronic infections, constitute a noteworthy health care burden. Citrus EOs are capable of preventing the polymicrobial biofilm formed by Pseudomonas aeruginosa and pathogenic fungi, in particular A. fumigatus and Scedosporium apiospermum , at concentration between 50 mg/L and 250 mg/L [ 120 ].These EOs showed a potential of inhibiting fungal growth with MIC in concentrations of 50 mg/L and 250 mg/L. Furthermore, Citrus EOs impeded formation of bacterial and fungal monomicrobial biofilms in concentrations of 50 mg/L.…”

Eucalyptal D Enhances the Antifungal Effect of Fluconazole on Fluconazole-Resistant Candida albicans by Competitively Inhibiting Efflux Pump

“…Our previous research also demonstrated that several novel FPMs exerted antifungal and antibiofilm activities against Candida spp. (Liu R. H. et al, 2017). Further investigations on FPMs showed that those FPMs with weak or without antifungal effects demonstrated enhanced activities when combined with other antifungal FPMs or azoles (data not shown).…”