ergosterol

Candida species are a leading cause of fungal infections worldwide. Candidiasis, the disease caused by Candida , represents a significant public health concern globally. Candida albicans is the most common causative agent, responsible for 50 - 90% of invasive candidiasis cases. Candida albicans employs various virulence factors to adhere to, invade host tissues, and cause disease.

This study aimed to detect and compare the virulence factors of C. albicans , including hydrophobicity, biofilm formation, ergosterol content, and secretory enzymes, in clinical and environmental samples.

A total of 105 clinical and 165 environmental samples suspected of containing C. albicans were collected from Imam Khomeini Hospital in Ahvaz, Iran. The isolates were evaluated for five potential virulence factors: Ergosterol content, cell surface hydrophobicity (CSH), biofilm formation, protease activity, and phospholipase activity.

Sixty C. albicans isolates were identified, consisting of 30 clinical and 30 environmental isolates. Biofilm production was observed in 100% of clinical isolates and 80% of environmental isolates (P < 0.001). Protease activity was detected in 66.6% of clinical isolates and 76.7% of environmental isolates (P = 0.008). Phospholipase activity was present in 60% of clinical isolates and 76.7% of environmental isolates (P = 0.262). Clinical isolates exhibited higher CSH (66.4 ± 9.8) compared to environmental isolates (47.7 ± 17.0) (P < 0.001). The ergosterol content was 1.2 ± 0.5 in clinical isolates and 1.1 ± 0.3 in environmental isolates.

Biofilm formation was a consistent characteristic of clinical isolates, while phospholipase and protease activity were more prevalent in environmental C. albicans isolates. The results suggest possible cross-contamination between patients and the environment, as the virulence factors of clinical and environmental isolates were similar.

Allium cepa L. as a traditional medicine is a rich source of beneficial bioactive metabolites. In the present study, the effect of A. cepa ethanolic extract (EAC) was studied on Aspergillus fumigatus growth, ergosterol synthesis, gliotoxin production, and gliP gene expression.

The minimum inhibitory concentration (MIC) of EAC (125-4000 µg/mL) was determined against A. fumigatus isolates according to Clinical and Laboratory Standards Institute (CLSI) guidelines (M-38). Protease activity, gliotoxin production, cell membrane ergosterol content, ultrastructure, and gliP gene expression were evaluated in the fungus exposed to 0.5× MIC concentrations of EAC (1000 μg/mL) and fluconazole (FCZ: 64 μg/mL).

Ergosterol content was significantly reduced to 0.53 and 0.45 µg/mg in FCZ- and EAC-treated fungal cells, respectively (p< .001). The protease activity was significantly inhibited in both EAC- and FCZ-treated groups. The gliotoxin production was inhibited by 51.55 and 68.75% in the treated groups with FCZ and EAC, respectively. The expression of gliP in both EAC- and FCZ-treated A. fumigatus groups was significantly reduced by 0.40 and 0.53-fold, respectively (p< .05).

This study finding revealed that A. cepa ethanolic extract (EAC) effectively suppressed the growth and virulence factors of A. fumigatus, which could be attributed in part to its bioactive metabolites. Further studies are recommended to isolate and identify these metabolites as potential candidates for the development of antifungal drugs.

Trametes species have been used for centuries in traditional medicine of Asian countries. Recently, some of the bioactive compound have been isolated and evaluated for therapeutic purposes from these species. The aim of this study was to report the isolation and structure elucidation of major sterols from fruiting bodies of Trametes gibbosa. Volatile compounds and antioxidant activities of the different mushroom extracts of mushroom were also examined.

The fruiting bodies of T. gibbosa were extracted with n-hexane, methanol, and hot water, respectively. For isolation of sterols, the n-hexane extract was subjected to column chromatography and fractionated by step gradient of n-hexane: ethyl acetate. The volatile oil was prepared by hydrodistillation and analyzed by GC-MS. For evaluation of the antioxidant activity, 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power assays were used. Moreover, the phenolic and carbohydrate contents were assessed using spectrophotometry methods.

The column chromatography of the n-hexane extract led to the isolation of three sterols. These compounds were identified for the first time in T. gibbosa as follows: ergosta-5,7,22-trien-3β-ol (ergosterol); 5,8-epidioxy-ergosta-6,22-dien-3-ol; 5,9-epidioxy-8,14-epoxy-ergosta-6,22-dien-3-ol. The most abundant volatile compounds were identified as aldehydes (29.01%), fatty acids (21.2%) and alcohols (12.07%). Based on antioxidant results, methanol and hot water extracts showed the highest activities in DPPH (EC50=588.56±36.37 µg/mL) and FRAP (432±6.6 mmol Fe2+/g DW) methods, respectively.

Trametes gibbosa is a valuable source of mycochemicals such as sterols, carbohydrate and phenolics. Further investigations are required for evaluation of the therapeutic potentials of the isolated compounds.

Candida albicans can cause various diseases, which might lead to various cases of life-threatening diseases. Biofilm is a specific feature of C. albicans formed on mucosal surfaces and medical devices. Moreover, biofilm protects Candida cells from antifungals and makes the treatment challenging. Here, we studied the effects of dehydrozingerone on C. albicans growth, ergosterol biosynthesis, biofilm formation, and the expression of an essential gene involved in yeast-hypha transition.

C. albicans cells were treated with serial two-fold concentrations of dehydrozingerone (0.125-2 mg/ml) for 48 h at 35 °C. The weights of the fungal cells were estimated as a sign of fungal growth. Biofilm formation was evaluated by a tetrazolium salt (XTT) reduction assay. The expression of the HWP1 gene was assayed by real-time PCR.

Dehydrozingerone inhibited C. albicans growth in the range of 3.57% to 84.28%, dose-dependently. The ergosterol content of yeast cells was reduced by 50% in the highest concentration. The biofilm formation was also inhibited by more than 50% at the highest concentration. The expression of the HWP1 gene was suppressed by dehydrozingerone at different concentrations.

Our results indicate that dehydrozingerone displayed effective activity against growth, biofilm formation, and ergosterol biosynthesis in C. albicans in vitro.

The increment in fungal infections, particularly due to Candida species, is alarming due to the emergence of multidrug resistance (MDR). Hence, the identification of novel drug targets to circumvent the problem of MDR requires immediate attention. The metabolic pathway, such as glyoxylate cycle (GC), which utilizes key enzymes (isocitrate lyase [ICL] and malate synthase [MLS]), enables C. albicans to adapt under glucose-deficient conditions. This study uncovers the effect of GC disruption on the major MDR mechanisms of C. albicans as a human pathogenic fungus.

For the purpose of the study, efflux pump activity was assessed by phenotypic susceptibilities in the presence of substrates rhodamine 6G (R6G) and Nile red, along with R6G extracellular concentration (527 nm). In addition, ergosterol content was estimated by the alcoholic potassium hydroxide hydrolysis method. The estimation of chitin was also accomplished by the absorbance (520 nm) of glucosamine released by acid hydrolysis.

The results revealed that the disruption of ICL enzyme gene (Δicl1) led to the impairment of the efflux activity of multidrug transporters belonging to the ATP-binding cassette superfamily. It was further shown that Δicl1 mutant exhibited diminished ergosterol and chitin contents. In addition, all abrogated phenotypes could be rescued in the reverting strain of Δicl1 mutant.

Based on the findings, the disruption of GC affected efflux activity and the synthesis of ergosterol and chitin. The present study for the first time revealed that metabolic fitness was associated with functional drug efflux, ergosterol and chitin biosynthesis and validated GC as an antifungal target. However, further studies are needed to comprehend and exploit this therapeutic opportunity.

Greatly increased use of antifungal therapies has resulted in the development of multidrug resistant. The phenolic compound carvacrol have been reported to have anti-Candida activity. This work is an attempt to examine effect of carvacrol on ergosterol synthesis against multidrug resistant Candida albicans.
This cross-sectional study has been conducted on 30 immune-compromised patients from vagina, mouth and skin surfaces during 2016-2017. Colonizing clinical isolates of C. albicans were identified and drug resistant isolates detected using WHONET software. The susceptibility tests for carvacrol were carried out in terms of disk diffusion, broth microdilution and time kill assays against multidrug resistant C. albicans. The ability to change from yeast to hyphal morphology exploited using a light microscopy. Ergosterol quantification has been investigated by spectrophotometric analysis. The expression profile of ERG11 gene was studied using quantitative real time RT-PCR to admit the possibility of further associated ergosterol pathway. Statistical analysis was performed with SPSS 21.0. Comparisons were performed using one-way ANOVA, with Tukey’s tests.
Ten colonizing clinical isolates of C. albicans were identified. Multidrug resistant isolates of C. albicans were detected. Carvacrol was found to have MIC90 of 100-200 µg/ml for multidrug drug resistant isolates of C. albicans. The time kill curve results show that carvacrol could significantly inhibit the growth of C. albicans (P≤0.05). In multidrug resistant C. albicans treated with carvacrol there was a marked reduction of the transition of yeast cells to hyphal cells. Significant decrease of ergosterol content was noted in multidrug resistant C. albicans treated with carvacrol. Furthermore, significant down-regulation was observed on ERG11 gene in multidrug resistant C. albicans treated with carvacrol (P≤0.05).
Carvacrol show strong antifungal activity against multidrug resistant C. albicans. These results provide proof of concept for the implementation of carvacrol that may have potential applications in the treatment of drug resistance C. albicans infections.