Candida albicans, a polymorphic opportunistic pathogen of humans, can exist in different morphological forms like yeast, hyphae, pseudohyphae, chlamydospores and white and opaque cells. Proteomic analysis of opaque form of C. albicans ATCC 10231 is carried out in the present study using micro-LC-MS/MS and validated using expression analysis of selected genes using RT-qPCR and mitochondrial membrane potential (MMP) assay. This is the first report identifying opaque cell-specific proteins of C. albicans. A total of 188 proteins were significantly modulated under opaque form compared to white cells, of which 110 were up-regulated, and 78 were down-regulated. It was observed that oxidative phosphorylation (OxPhos) and oxidative stress are enhanced in C. albicans cells growing under opaque form as proteins involved in OxPhos (Atp1, Atp3, Atp16, Atp7, Cox6, Nuc2, Qcr7 and Sdh12) and oxidative stress response (Gcs1, Gtt11, Gpx2, Sod1, Ccp1 and Lys7) were significantly up-regulated. The maximum up-regulation of 23.16 and 13.93-fold is observed in the case of Ccp1 and Nuc2, respectively. The down-regulation of proteins viz. Als1, Csh1, Sap9 and Rho1 determining cell surface chemistry indicates modulation in cell wall integrity and reduced adhesion of opaque cells compared to white cells. This study is significant as it is the first draft of the proteomic profile of opaque cells that suggests enhanced OxPhos, oxidative stress, and modulation in cell surface chemistry that indicates reduced adhesion and cell wall integrity that could be associated with reduced virulence in opaque form. However, a deeper investigation is needed to explore it further.

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Inclusion of Candida albicans in the list of pathogens with potential drug resistance threat in recent years has compelled scientists to explore novel and potent antifungal agents. In this study, we have evaluated anti-Candida potential of menthol against different growth forms and synergistic potential with fluconazole. Menthol inhibited planktonic growth of all the isolates completely at ≤3.58 mM and killed 99.9% inoculum at MIC, indicating that menthol is fungicidal. Menthol inhibited hyphal form growth completely at 0.62 mM. It has inhibited developing a biofilm by 79% at 3.58 mM, exhibiting excellent activity against recalcitrant biofilms. FIC index values of 0.182 and 0.093 indicate excellent synergistic activity between fluconazole and menthol against planktonic and biofilm growth, respectively. Menthol enhanced rate of OxPhos among 22% cells; arrested 71% cells at G2-M phase of cell cycle and induced apoptosis in 15% cells. Thus, menthol exhibits excellent anti-Candida activity against differentially susceptible isolates as well as various growth and morphological forms of C. albicans. Menthol affects membrane integrity thereby inducing oxidative stress followed by cell cycle arrest and apoptosis. Considering the excellent anti-Candida potential and as it is Generally Recognized as Safe by the Food and Drug Administration, it may find use in antifungal chemotherapy, alone or in combination.

Objectives The ability to form biofilm is considered as one of major virulence factors of Candida albicans, as biofilms form growth confers antifungal resistance and facilitate immune evasion. It is intriguing to understand morphophysiological modulations in the C. albicans cells growing under biofilm form growth. Data description In present study, we have profiled biofilm-specific proteins using LC-MS/MS analysis. Whole cell proteins of C. albicans cells grown under biofilm form growth (test) and planktonic (control) growth for 24 h were extracted, digested and identified using micro-Liquid Chromatography-Mass Spectrometry (LC-MS/MS). The present data represents proteomic profile (SWATH Spectral Libraries) of C. albicans biofilm intended to be useful to scientific community as it exhibits reuse potential.