Inhibition of Biofilm Formation by Candida albicans and Polymicrobial Microorganisms by Nepodin via Hyphal-Growth Suppression

Abstract

Candida albicans is an opportunistic pathogenic yeast and is responsible for candidiasis. It readily colonizes host tissues and implant devices, and forms biofilms, which play an important role in pathogenesis and drug resistance. In this study, the antibiofilm, antihyphal, and antivirulence activities of nepodin, isolated from Rumex japonicus roots, were investigated against a fluconazole-resistant C. albicans strain and against polymicrobial-microorganism-biofilm formation. Nepodin effectively inhibited C. albicans biofilm formation without affecting its planktonic cell growth. Also, Rumex-root extract and nepodin both inhibited hyphal growth and cell aggregation of C. albicans. Interestingly, nepodin also showed antibiofilm activities against Candida glabrata, Candida parapsilosis, Staphylococcus aureus, and Acinetobacter baumannii strains and against dual biofilms of C. albicans and S. aureus or A. baumannii but not against Pseudomonas aeruginosa. Transcriptomic analysis performed by RNA-seq and qRT-PCR showed nepodin repressed the expression of several hypha- and biofilm-related genes (ECE1, HGT10, HWP1, and UME6) and increased the expression of several transport genes (CDR4, CDR11, and TPO2), which supported phenotypic changes. Moreover, nepodin reduced C. albicans virulence in a nematode-infection model and exhibited minimal cytotoxicity against the nematode and an animal cell line. These results demonstrate that nepodin and Rumex-root extract might be useful for controlling C. albicans infections and multispecies biofilms.

Synergistic Effect of Berberine Hydrochloride and Fluconazole Against Candida albicans Resistant Isolates

“…The drug-monotherapy groups could not effectively inhibit hyphal-specific gene expression, such as ECE1 upregulation after FLC exposure, or HWP1 , ALS3 , and ECE1 upregulation after BBH exposure, indicated by numerous hyphae or pseudohyphae. Hyphae are physical scaffolds for yeast cell adhesion and aggregation, which enable increased biofilm strength, integrity, and maturation ( Haque et al, 2016 ; Lee et al, 2019 ). HWP1 mutants produce a thin biofilm with less hyphae in vitro , but display serious biofilm defects in vivo , only forming yeast microcolonies ( Nobile et al, 2006b ).…”

Plant-Derived Substances in the Fight Against Infections Caused by Candida Species

“…The inhibition of Candida spp. biofilm formation by nepodin, a phenolic compound that diminished the hypha- and biofilm-related genes ( ECE1, HGT10, HWP1, UME6 ) was also confirmed [ 92 ]. Furthermore, a flavonoid belonging to the chalcone group―loureirin A, the major active component of Draconis sanguis , down-regulated the expression of adhesion-related genes and hypha/biofilm-related genes ( HWP1 , IFF4 , EAP1 , ECE1 , RAS1 , GPR1 , CYR1 , EFG1 , CEK1 , CPH1 , UME6 , PGA10 ) [ 120 ].…”

“…Furthermore, another study demonstrated increased expression of IFD6 gene in Candida spp. caused by neopodin, an anthraquinone from Rumex crispus [ 92 ]. IFD6 encodes an aryl alcohol dehydrogenase considered to be an inhibitor of biofilm matrix production through quorum-sensing aryl and acyl alcohols [ 39 ].…”

Microbial Interkingdom Biofilms and the Quest for Novel Therapeutic Strategies

“…An example is citral, that shows strong activity against MRSA, where it targets biofilm specific pathways and also shows activity against different Candida species [119][120][121]. Recently, citral, as well as lemongrass, which is rich in citral and nepodin, were shown to have strong activity against dual-species C. albicans-S. aureus biofilms [83,84]. Citral resulted in lower biofilm biomass as well as in the number of viable cells of both species.…”

“…The authors also showed that citral was interfering with the expression of Candida adhesins, as well as downregulating the expression of genes involved in the production of QS molecules, peptidoglycan, and fatty acids in S. aureus [84]. Nepodin, isolated from Rumex crispus, was shown to reduce the expression of hypha-specific genes and upregulated the expression of several transport genes [83]. Whereas citral was only tested in vitro, nepodin also affected C. albicans virulence in a nematode infection model system, but dual-species infections were not performed.…”