Background: Drug resistance in Candida species, has emerged as a major problem in the public health system worldwide. Application of nanoparticles is proposed as a novel and potential agent for reduction of drug resistance burdens. Objectives: The current study was conducted to evaluate the effects of zinc oxide nanoparticles (ZnO NPs containing chitosan and linoleic acid) on hyphae cell wall proteins (Hwp1) gene expression, a crucial gene in pathogenicity of Candida albicans, and cytotoxicity on human hepatocyte carcinoma (HepG2) cells as well as the production of Reactive Oxygen Species (ROS). Methods: The effects of novel ZnO NPs on expression of Hwp1 gene of C. albicans was analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) in comparison to fluconazole as a standard drug. Reactive Oxygen species production was examined in macrophages treated with ZnO NPs relative to non-treated cells. Also, the cytotoxicity effects of ZnO NPs were assessed using the MTT assay against HepG2 cell line. Results: The findings indicated that ZnO NPs significantly decreased the level of Hwp1 gene expression in standard and clinical isolates of C. albicans. Increased level of ROS production in macrophages was found in the presence of ZnO NPs in concentrationdependent manner compared to the control group without exposure of ZnO NPs (P = 0.001). Furthermore, ZnO NPs did not show cytotoxicity activity on HepG2 cells at different concentrations (P > 0.05). Conclusions: Taken together, the newly synthesized ZnO NPs may be a suitable candidate for inhibition of the critical gene responsible for biofilm dispersion and the control of Candida infection with limited cytotoxicity on human cells. However, more studies are required for support of its effect in vitro and in vivo.
The number of Candida spp. infections and drug resistance are dramatically increasing worldwide, particularly among immunosuppressed patients, and it is urgent to find novel compounds with antifungal activity. In this work, the antifungal and antibiofilm activity of thymoquinone (TQ), a key bioactive constituent of black cumin seed Nigella sativa L., was evaluated against Candida glabrata, a WHO ‘high-priority’ pathogen. Then, its effect on the expression of C. glabrata EPA6 and EPA7 genes (related to biofilm adhesion and development, respectively) were analyzed. Swab samples were taken from the oral cavity of 90 hospitalized patients in ICU wards, transferred to sterile falcon tubes, and cultured on Sabouraud Dextrose Agar (SDA) and Chromagar Candida for presumptive identification. Next, a 21-plex PCR was carried out for the confirmation of species level. C. glabrata isolates underwent antifungal drug susceptibility testing against fluconazole (FLZ), itraconazole (ITZ), amphotericin B (AMB), and TQ according to the CLSI microdilution method (M27, A3/S4). Biofilm formation was measured by an MTT assay. EPA6 and EPA7 gene expression was assessed by real-time PCR. From the 90 swab samples, 40 isolates were identified as C. glabrata with the 21-plex PCR. Most isolates were resistant to FLZ (n = 29, 72.5%), whereas 12.5% and 5% were ITZ and AMB resistant, respectively. The minimum inhibitory concentration (MIC50) of TQ against C. glabrata was 50 µg/mL. Importantly, TQ significantly inhibited the biofilm formation of C. glabrata isolates, and EPA6 gene expression was reduced significantly at MIC50 concentration of TQ. TQ seems to have some antifungal, antibiofilm (adhesion) effect on C. glabrata isolates, showing that this plant secondary metabolite is a promising agent to overcome Candida infections, especially oral candidiasis.
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