Amphotericin B Polymer Nanoparticles Show Efficacy against Candida Species Biofilms

Purpose: Chronic infections of Candida albicans are characterised by the embedding of budding and entwined filamentous fungal cells into biofilms. The biofilms are refractory to many drugs and Candida biofilms are associated with ocular fungal infections. The objective was to test the activity of nanoparticulate amphotericin B (AmB) against Candida biofilms. Methods: AmB was encapsulated in the Molecular Envelope Technology (MET, N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan) nanoparticles and tested against Candida biofilms in vitro. Confocal laser scanning microscopy (CLSM) imaging of MET nanoparticles’ penetration into experimental biofilms was carried out and a MET-AmB eye drop formulation was tested for its stability. Results: MET-AmB formulations demonstrated superior activity towards C. albicans biofilms in vitro with the EC50 being ~30 times lower than AmB alone (EC50 MET-AmB = 1.176 μg mL−1, EC50 AmB alone = 29.09 μg mL−1). A similar superior activity was found for Candida glabrata biofilms, where the EC50 was ~10× lower than AmB alone (EC50 MET-AmB = 0.0253 μg mL−1, EC50 AmB alone = 0.289 μg mL−1). CLSM imaging revealed that MET nanoparticles penetrated through the C. albicans biofilm matrix and bound to fungal cells. The activity of MET-AmB was no different from the activity of AmB alone against C. albicans cells in suspension (MET-AmB MIC90 = 0.125 μg mL−1, AmB alone MIC90 = 0.250 μg mL−1). MET-AmB eye drops were stable at room temperature for at least 28 days. Conclusions: These biofilm activity findings raise the possibility that MET-loaded nanoparticles may be used to tackle Candida biofilm infections, such as refractory ocular fungal infections.

The Investigation of Thymol Formulations Containing Poloxamer 407 and Hydroxypropyl Methylcellulose to Inhibit Candida Biofilm Formation and Demonstrate Improved Bio-Compatibility

The aim of this study was to investigate the potential of thymol to inhibit Candida biofilm formation and improve thymol biocompatibility in the presence of hydroxypropyl methylcellulose (HPMC) and poloxamer 407 (P407), as possible drug carriers. Thymol with and without polymers were tested for its ability to inhibit biofilm formation, its effect on the viability of biofilm and biocompatibility studies were performed on HEK 293 (human embryonic kidney) cells. Thymol showed a concentration dependent biofilm inhibition; this effect was slightly improved when it was combined with HPMC. The Thymol-P407 combination completely inhibited the formation of biofilm and the antibiofilm effect of thymol decreased as the maturation of Candida biofilms increased. The effect of thymol on HEK 293 cells was a loss of nearly 100% in their viability at a concentration of 250 mg/L. However, in the presence of P407, the viability was 25% and 85% using neutral red uptake and sulforhodamine B assays, respectively. While, HPMC had less effect on thymol activity the thymol-P407 combination showed a superior inhibitory effect on biofilm formation and better biocompatibility with human cell lines. The combination demonstrates a potential medical use for the prevention of Candida biofilm formation.

The Effect of Resin-Based Dental Sealant Containing Vanillin on Biofilm Formation of Candida albicans

Early childhood caries (ECC), or baby bottle tooth decay is one of the most common chronic diseases that affect young children at 6 years of age or younger. The disease is resulted from complex interactions between tooth structures and cariogenic microorganisms in dental biofilm after exposure to fermentable carbohydrates through improper feeding practices. This leads to a rapid development of demineralization of teeth shortly after they erupt in the oral cavity. Candida albicans have been reported recently to be associated with the pathogenesis of ECC. One of the general approaches currently used for the prevention of ECC is the application of dental sealant to occlusal (chewing surface) pits and fissures of caries-susceptible teeth. Many types of dental sealants have been extensively used and various antimicrobial agents were introduced to dental sealants to increase their caries preventive effect. The aim of the present study was to evaluate the antimicrobial effect of vanillin incorporated resin-based dental sealant on C. albicans biofilm. Resin-based dental sealants (Clinpro; 3M ESPE, USA) containing different concentrations of vanillin (0%, 0.5%, 1% and 5% w/v) were prepared in 96-well plate. The suspension (107 colony forming unit/mL) of each strain of Candida albicans (ATCC 10231, ATCC 18804 and 2 clinical isolates) was added to saliva-coated sealant resin samples and incubated at 37°C in 5% CO2 atmosphere for 24 h to allow the Candida biofilm formation. The quantity of vital biofilm was determined by WST Microbial Cell Counting Kit (Dojindo Molecular Technologies, USA) at 460 nm. All tests were done in triplicate and repeated three times. Kruskal-Wallis test followed by Dunn’s method were used to account for multiple comparisons. Statistical significance was set at p-value less than 0.05. The results showed that 0.5-5% vanillin-incorporated dental sealant resins showed a significant suppressive effect against all strains of Candida. No significant differences of anti-biofilm effects were found among Candida strains. Approximately 30-50% Candida biofilm reduction was noticed in sealant resins containing vanillin compared with controls without vanillin. In conclusion, the adding of vanillin (0.5-5% w/v) to dental sealant resins is effective in inhibiting biofilm formation of fungus related to early childhood caries, C. albicans. Therefore, the use of dental sealants containing vanillin has the potential to prevent this type of dental caries in young children and biofilm formation by oral Candida. Further clinical studies are required to investigate physical properties of this sealant and clinical evaluation in the patients.

Adenophora triphylla var. japonica Inhibits Candida Biofilm Formation, Increases Susceptibility to Antifungal Agents and Reduces Infection

(1) Background: Candida is the most common cause of fungal infections worldwide, but due to the limited option of antifungal therapies, alternative strategies are required. (2) Methods: Adenophora triphylla var. japonica extract was used for the biofilm formation assay using RPMI1640. The combinatorial antifungal assay, the dimorphic transition assay, and the adherence assay were done to see the influence of inhibition of biofilm formation. qRT-PCR analysis were performed to check the gene expression. (3) Results: Adenophora triphylla var. japonica extract inhibited the Candida biofilm formation. Treatment of extract increased the antifungal susceptibility of miconazole from a 37% reduction in fungal growth to 99.05%, and also dose-dependently reduced the dimorphic transition of Candida and the attachment of Candida to HaCaT cells. The extract blocked the expression of hyphal-related genes, extracellular matrix genes, Ras1-cAMP-PKA pathway genes, Cph2-Tec1 pathway gene, and MAP kinase pathway gene. (4) Conclusions: In this study, the treatment of Adenophora triphylla var. japonica extract showed inhibition of fungal biofilm formation, activation of antifungal susceptibility, and reduction of infection. These results suggest that fungal biofilm formation is a good target for the development of antifungal adjuvants, and Adenophora triphylla var. japonica extract should be a good candidate for biofilm-associated fungal infections.

Composition and Biological Activity of Vitis vinifera Winter Cane Extract on Candida Biofilm

Vitis vinifera canes are waste material of grapevine pruning and thus represent cheap source of high-value polyphenols. In view of the fact that resistance of many pathogenic microorganisms to antibiotics is a growing problem, the antimicrobial activity of plant polyphenols is studied as one of the possible approaches. We have investigated the total phenolic content, composition, antioxidant activity, and antifungal activity against Candida biofilm of an extract from winter canes and a commercially available extract from blue grapes. Light microscopy and confocal microscopy imaging as well as crystal violet staining were used to quantify and visualize the biofilm. We found a decrease in cell adhesion to the surface depending on the concentration of resveratrol in the cane extract. The biofilm formation was observed as metabolic activity of Candida albicans, Candida parapsilosis and Candida krusei biofilm cells and the minimum biofilm inhibitory concentrations were determined. The highest inhibition of metabolic activity was observed in Candida albicans biofilm after treatment with the cane extract (30 mg/L) and blue grape extract (50 mg/L). The composition of cane extract was analyzed and found to be comparatively different from blue grape extract. In addition, the content of total phenolic groups in cane extract was three-times higher (12.75 gGA/L). The results showed that cane extract was more effective in preventing biofilm formation than blue grape extract and winter canes have proven to be a potential source of polyphenols for antimicrobial and antibiofilm treatment.

Mechanistic Insights in Biofilm Eradication Potential of Tyrosol Functionalized Chitosan Gold Nanoparticles against Candida spp.

In the present study, tyrosol functionalized chitosan gold nanoparticles (Chi-TY-AuNPs) were prepared as an alternative treatment strategy to combat fungal infections. Various biophysical techniques were used to characterize the synthesized Chi-TY-AuNPs. The antifungal and antibiofilm activities of Chi-TY-AuNPs were evaluated against C. albicans and C. glabrata and efforts have been made to elucidate the possible mechanism of action. Chi-TY-AuNPs showed a high fungicidal effect against both sessile and planktonic cells of Candida spp. Additionally, Chi-TY-AuNPs completely eradicated (100%) the mature biofilms of both the Candida spp. FESEM analysis highlighted the morphological alterations in Chi-TY-AuNPs treated Candida biofilm cells. Effect of Chi-TY-AuNP's on the ECM components showed significant reduction in protein content in C. glabrata biofilm and substantial decrease in extracellular DNA (eDNA) content of both the Candida spp. ROS generation analysis using DCFDA-PI staining showed high ROS levels in both the Candida spp., whereas pronounced ROS production was observed in Chi-TY-AuNPs treated C. glabrata biofilm. Biochemical analysis revealed decreased ergosterol content in Chi-TY-AuNP's treated C. glabrata cells, while inconsequential changes were observed in C. albicans. Furthermore, the transcriptional expression of selected genes (ergosterol biosynthesis, efflux, sterol importer, and glucan biogenesis) was reduced in C. glabrata in response to Chi-TY-AuNP's except ERG11 and CDR1. Conclusively the result showed the biofilm inhibition and biofilm eradication efficacy of Chi-TY-AuNPs in both the Candida spp. Findings of the present study manifest Chi-TY-AuNP's as a potential therapeutic solution to Candida biofilm-related chronic infections and overcome biofilm antifungal resistance.

Eradication of Candida albicans Biofilm Viability: In Vitro Combination Therapy of Cationic Carbosilane Dendrons Derived from 4-Phenylbutyric Acid with AgNO3 and EDTA

Candida albicans is a human pathogen of significant clinical relevance. This pathogen is resistant to different drugs, and most clinical antifungals are not effective against the prevention and treatment of C. albicans infections. As with other microorganisms, it can produce biofilms that serve as a barrier against antifungal agents and other substances, contributing to infection in humans and environmental tolerance of this microorganism. Thus, resistances and biofilm formation make treatment difficult. In addition, the complete eradication of biofilms in implants, catheters and other medical devices, is challenging and necessary to prevent relapses of candidemia. Therefore, it is a priority to find new molecules or combinations of compounds with anti-Candida biofilm activity. Due to the difficulty of treating and removing biofilms, the aim of this study was to evaluate the in vitro ability of different generation of cationic carbosilane dendrons derived from 4-phenylbutyric acid, ArCO2Gn(SNMe3I)m, to eradicate C. albicans biofilms. Here, we assessed the antifungal activity of the second generation dendron ArCO2G2(SNMe3I)4 against C. albicans cells and established biofilms since it managed to seriously damage the membrane. In addition, the combinations of the second generation dendron with AgNO3 or EDTA eradicated the viability of biofilm cells. Alterations were observed by scanning electron microscopy and cytotoxicity was assessed on HeLa cells. Our data suggest that the dendritic compound ArCO2G2(SNMe3I)4 could represent an alternative to control the infections caused by this pathogen.