Mechanistic Understanding of Candida albicans Biofilm Formation and Approaches for Its Inhibition

"Illuminated Glycoporphyrins": A photodynamic approach for Candida albicans inactivation

The continuous increase in the incidence of invasive mycoses, particularly those caused by Candida albicans, is a relevant health issue worldwide due to the lack of effective antifungals and the constant emergence of resistant strains. One of the most promising therapies to treat infections caused by resistant microorganisms is photodynamic inactivation (PDI). The development of novel photosensitizers (PSs) with suitable properties is a key factor to consider when optimizing this therapy. In this work, we designed, synthesized, and characterized four glycoporphyrins functionalized with S-galactose (acetylated and deacetylated) and varying the number of tertiary amino groups as precursors of cationic centers, which can be activated by protonation at physiological pH. The amino and glycosyl groups were introduced to enhance interaction with the microbial cell wall, increase hydrophilicity, and evaluate their combined effect on PS efficiency in photoinactivation. All derivatives presented the characteristic absorption and emission properties of the porphyrin macrocycle. Moreover, the glycoporphyrins were capable of generating singlet oxygen and superoxide anion radical. The photophysical and photodynamic properties were not affected by the different substitution patterns on the porphyrin core. PDI treatments of C. albicans cultures, treated with 5 μM of the PS and irradiated for 30 min, produced cellular inactivation of ∼3.5 log for glycoporphyrins with cationic centers. Furthermore, PDI of C. albicans mediated by glycoporphyrins was potentiated by the addition of KI. Under these conditions, a significant enhancement in cellular death was observed, achieving complete eradication of the treated cell suspensions. Moreover, glycoporphyrins containing pH-activable groups, combined with KI, showed outstanding efficacy against C. albicans pseudohyphae. These in vitro findings underscore the significant impact of substitution patterns on antimicrobial action. To our knowledge, this study marks the first application of glycosylated porphyrin derivatives containing pH-activatable cationic groups in the photoinactivation of C. albicans, paving the way for the development of novel derivatives with potential applications as effective antifungal PSs.

Biochemical insights into synergistic Candida biofilm disintegrating ability of p-cymene inclusion complex and miconazole

Phytoactive molecules emerge as a plentiful reservoir of adjuvant and antifungal agents. The resolution of solubility and stability issues has been facilitated by developing molecular complexes or inclusion complexes of phytoactive molecules. Miconazole (MCZ) is a favoured azole with low off-target impact, however, its pharmacological efficacy requires a revamp to enhance its suitability as an antifungal drug. Hence, the present investigation delves into the mechanism of action of the p-cymene/β-cyclodextrin inclusion complex (IC) along with MCZ against Candida albicans and Candidaglabrata biofilms. The synergy between IC and MCZ has been estimated at a concentration of 6.25 μg/mL IC + 0.5 μg/mL MCZ with a FICI of 0.19. The prepared IC + MCZ displayed remarkable antifungal properties against planktonic and sessile growth of Candida species. IC + MCZ exhibited a notable 80% biofilm eradication potential against both species, corroborated by morphological analysis using FE-SEM. The results indicated that IC/IC + MCZ acts by disrupting the biochemical composition of the ECM, altering the surface properties of the cells, reducing ergosterol, enhancing membrane permeability, and inducing oxidative stress. In conclusion, the study highlighted the synergistic antibiofilm activity of p-cymene IC with miconazole against Candida species. In summary, IC + MCZ has been established as a potent antifouling agent against Candida species, warranting further exploration for potential formulation with additional investigations.

Effect of polishing methods on Candida albicans adhesion and contributing factors in heat-cured acrylic dentures: an in-vitro comparative study

INTRODUCTION

Heat-polymerized acrylic resin is widely used in prosthodontics due to its various advantages. However, its susceptibility to microbial colonization, influenced by surface properties such as roughness, water sorption, and free surface energy, poses challenges in maintaining oral health. Microbial adhesion, particularly of Candida albicans, plays a significant role in the overall microbial load on the denture surface, predisposing several oral and health related complications. While polishing techniques improve surface smoothness, their effects on water sorption and free surface energy, which are critical to microbial adhesion, remain understudied. This study explores the impact of Mechanical Polishing (MP) and Chemical Polishing (CP) methods on these surface properties and their potential to reduce Candida albicans adhesion.

MATERIALS AND METHODS

Twenty-four square samples of heat-cured acrylic were fabricated and divided into two groups of 12 for MP and CP respectively. Surface roughness (Ra) was measured using a profilometer. Scanning Electron Microscopy (SEM) analysis was conducted on polished and unpolished specimens. Water sorption was assessed through weekly weighing, and free surface energy was determined using a goniometer. Candida albicans identification was done using Dichloran Rose-Bengal Chloramphenicol (DRBC) agar and confirmation was achieved through microscopy and growth on selective media. Adherence and viable assays were performed on both polished and non-polished specimens. Statistical analysis was performed using SPSS (Version 24.0). Mann-Whitney U test compared surface roughness, water sorption, free surface energy, and initial adherence between MP and CP groups. Linear regression analysis examined the influence of these factors on Candida albicans adherence.

RESULTS

Surface roughness did not significantly differ between the two polishing methods. However, CP resulted in significantly reduced water sorption, lower free surface energy, and decreased Candida albicans adhesion compared to MP. A significant negative association was observed between CP and Candida adherence.

CONCLUSION

Both polishing methods achieved the desired level of surface smoothness. However, CP demonstrated superior performance in reducing water sorption, free surface energy, and Candida albicans adhesion. This suggests its practical benefits in clinical settings, particularly intaglio surfaces where MP is impractical.

Sdd3 regulates the biofilm formation of Candida albicans via the Rho1-PKC-MAPK pathway

Candida albicans, the most frequently isolated fungal pathogen in humans, forms biofilms that enhance resistance to antifungal drugs and host immunity, leading to frequent treatment failure. Understanding the molecular mechanisms governing biofilm formation is crucial for developing anti-biofilm therapies. In this study, we conducted a genetic screen to identify novel genes that regulate biofilm formation in C. albicans. One identified gene is ORF19.6693, a homolog of the Saccharomyces cerevisiae SDD3 gene. The sdd3∆/∆ mutant exhibited severe defects in biofilm formation and significantly reduced chitin content in the cell wall. Overexpression of the constitutively active version of the Rho1 GTPase Rho1G18V, an upstream activator of the protein kinase C (PKC)-mitogen-activated protein kinase (MAPK) cell-wall integrity pathway, rescued these defects. Affinity purification, mass spectrometry, and co-immunoprecipitation revealed Sdd3's physical interaction with Bem2, the GTPase-activating protein of Rho1. Deletion of SDD3 significantly reduced the amount of the active GTP-bound form of Rho1, thereby diminishing PKC-MAPK signaling and downregulating chitin synthase genes CHS2 and CHS8. Taken together, our studies identify a new biofilm regulator, Sdd3, in C. albicans that modulates Rho1 activity through its inhibitory interaction with Bem2, thereby regulating the PKC-MAPK pathway to control chitin biosynthesis, which is critical for biofilm formation. As an upstream component of the pathway and lacking a homolog in mammals, Sdd3 has the potential to serve as an antifungal target for biofilm infections.IMPORTANCEThe human fungal pathogen Candida albicans is categorized as a critical priority pathogen on the World Health Organization's Fungal Priority Pathogens List. A key virulence attribute of this pathogen is its ability to form biofilms on the surfaces of indwelling medical devices. Fungal cells in biofilms are highly resistant to antifungal drugs and host immunity, leading to treatment failure. This study conducted a genetic screen to discover novel genes that regulate biofilm formation. We found that deletion of the SDD3 gene caused severe biofilm defects. Sdd3 negatively regulates the Rho1 GTPase, an upstream activator of the protein kinase C-mitogen-activated protein kinase pathway, through direct interaction with Bem2, the GTPase-activating protein of Rho1, resulting in a significant decrease in chitin content in the fungal cell wall. This chitin synthesis defect leads to biofilm formation failure. Given its essential role in biofilm formation, Sdd3 could serve as an antifungal target for biofilm infections.

Thiosemicarbazones and analogues as potential biofilm inhibitors of Candida albicans

Biofilms are a virulence factor for Candida albicans, a common pathogen in human fungal infections, making them resistant to many commercial antifungals. Therefore, the discovery of compounds that inhibit and eradicate biofilms is a priority. As thiosemicarbazones have had their effect on Candida biofilms little explored, this study investigated the inhibitory and eradication activity of 30 thiosemicarbazones and analogues against C. albicans biofilms. After initial screening, four compounds were selected and compound 28 emerged as the most potent with BIC50 at 31.55 ± 1.18 µM. By scanning electron microscopy analysis, blastoconidia adhered to the reduced surface and reduced formation of pseudohyphae and hyphae was revealed. Despite the inhibitory activity, the four compounds failed to eradicate the biofilm by more than 50%. Thus, the results suggest that the compounds evaluated are very promising for the development of effective antibiofilm compounds and open up new perspectives for elucidating the mechanism of action.

Synergistic Antifungal Activity of Terbinafine in Combination with Light-Activated Gelatin-Silver Nanoparticles Against Candida albicans Strains

The development of resistance to traditional antifungal therapies has necessitated the exploration of alternative treatment strategies to effectively manage fungal infections, particularly those induced by Candida albicans (C. albicans). This research investigates the possibility of integrating silver nanoparticles (AgNPs) with Terbinafine to improve antifungal effectiveness. Terbinafine, while potent, faces challenges with specific fungal strains, highlighting the need for strategies to enhance its treatment efficacy. Silver nanoparticles were produced through a light-activated, gelatin-based method, resulting in particle sizes ranging from 56.8 nm to 66.2 nm, confirmed by dynamic light scattering and scanning electron microscopy. Stability studies indicated that AgNPs produced with 30 mg of silver nitrate (AgNO₃) exhibited the greatest stability over 60 days across different temperature conditions. The analysis through UV-visible spectrophotometry revealed a notable shift in the absorption spectra as AgNO₃ concentrations increased, which was associated with a strengthening of plasmon resonance. The effectiveness of the AgNPs and Terbinafine combination was assessed against three strains of C. albicans (ATCC 10231, ATCC 90028, and ATCC 18804). Terbinafine demonstrated strong antifungal properties with minimum inhibitory concentrations (MIC) values ranging from 2-4 µg/mL, whereas AgNPs on their own displayed moderate effectiveness. The integrated formulation notably enhanced effectiveness, especially against strain ATCC 90028, revealing a synergistic effect (FIFi = 0.369). These results were complemented by the findings of the time-to-kill assay, where the same strain showed a 3.2 log₁₀ CFU/mL decrease in viable cell count. The process by which AgNPs boost activity entails the disruption of the fungal cell membrane and its internal components, probably as a result of silver ion release and the generation of free radicals. The results indicate that the combination of Terbinafine and AgNPs may act as a powerful alternative for addressing resistant fungal infections, presenting an encouraging direction for future antifungal treatments.

Mechanisms of Azole Potentiation: Insights from Drug Repurposing Approaches

The emergence of azole resistance and tolerance in pathogenic fungi has emerged as a significant public health concern, emphasizing the urgency for innovative strategies to bolster the efficacy of azole-based treatments. Drug repurposing stands as a promising and practical avenue for advancing antifungal therapy, with the potential for swift clinical translation. This review offers a comprehensive overview of azole synergistic agents uncovered through drug repurposing strategies, alongside an in-depth exploration of the mechanisms by which these agents augment azole potency. Drawing from these mechanisms, we delineate strategies aimed at enhancing azole effectiveness, such as inhibiting efflux pumps to elevate azole concentrations within fungal cells, intensifying ergosterol synthesis inhibition, mitigating fungal cell resistance to azoles, and disrupting biological processes extending beyond ergosterol synthesis. This review is beneficial for the development of these potentiators, as it meticulously examines instances and provides nuanced discussions on the mechanisms underlying the progression of azole potentiators through drug repurposing strategies.

Investigating the association between Candida albicans and early childhood dental caries: A comprehensive systematic review and meta-analysis

BACKGROUND

Early childhood caries (ECC) is a significant public health concern affecting children globally. Recent studies suggest a potential association between the presence of Candida albicans (C. albicans) in the oral cavity and the risk of ECC, but findings have been inconsistent. This systematic review and meta-analysis aimed to investigate the association between C. albicans and ECC.

METHODS

A comprehensive literature search was conducted across databases including PubMed, Web of Science, Cochrane Central Register of Controlled Trials, Embase, Google Scholar, and Scopus. Studies were included if they examined the presence of C. albicans and the occurrence or severity of dental caries in children. Data extraction and quality assessment were performed independently by two reviewers. Statistical analyses, including pooled odds ratios (OR) and 95% confidence intervals (CI), were conducted to synthesize the findings.

RESULTS

A total of 22 studies, involving 3301 participants, were included in the meta-analysis. The findings revealed a significant association between the presence of C. albicans and an increased likelihood of ECC, with a pooled odds ratio (OR) of 4.42 (95% CI: 3.14-6.24, p < 0.001). Subgroup analyses showed that factors such as geographic region, study design, and detection methods influenced the strength of this association. Studies conducted in Europe reported a stronger association (OR: 10.13, 95% CI: 6.01-17.09) compared to those in Asia (OR: 3.62, 95% CI: 2.53-5.20) and the Americas (OR: 3.98, 95% CI: 1.14-13.87). Case-control studies had a higher pooled OR (5.30, 95% CI: 1.72-16.31) compared to cross-sectional studies (4.30, 95% CI: 2.92-6.33). The odds of ECC in children with C. albicans were 4.08 (95% CI: 2.65-6.27) in dental plaque samples, 9.55 (95% CI: 2.17-42.01) in oral swab samples, and 4.70 (95% CI: 2.44-9.09) in saliva samples. No publication bias was observed based on Begg's test (P-value = 0.612) and Egger's test (P-value = 0.250).

CONCLUSIONS

The findings provide support for the hypothesis that C. albicans plays a role in the development of ECC. Moving forward, it is essential for future research to concentrate on comprehending the mechanisms that underlie this relationship and to develop specific strategies for prevention.

The Antifungal Potential of Ozonated Extra-Virgin Olive Oil Against Candida albicans: Mechanisms and Efficacy

The growing emergence of resistance mechanisms and side effects associated with antifungal agents highlight the need for alternative therapies. This study aims to investigate the antifungal potential of ozonated extra-virgin olive oil (EOO) against Candida albicans, with the goal of developing eco-friendly and highly effective treatments based on natural products. Antifungal activity was evaluated via cell viability and biofilm formation assays using Crystal Violet and Sytox green staining. The results showed that EOO reduced C. albicans viability in a dose-dependent manner, achieving over 90% cell death at a 3% (v/v) concentration. Transmission Electron Microscopy (TEM) revealed cell wall structural damage, and ROS levels increased by approximately 60% compared to untreated controls within 10 min of treatment. Additionally, the expression of autophagy-related genes atg-7 and atg-13was upregulated by 2- and 3.5-fold, respectively, after 15 min, suggesting a stress-induced cell death response. EOO also significantly inhibited hyphal formation and biofilm development, thus reducing C. albicans pathogenicity while preserving cell biocompatibility. EOO antifungal activity was also observed in the case of Candida glabrata. In conclusion, ozonated olive oil demonstrates potent antifungal activity against C. albicans by reducing cell viability, inhibiting hyphal and biofilm formation, and triggering oxidative stress and autophagy pathways. These findings position EOO as a promising alternative therapy for fungal infections.

Development and characterization of nanoemulsions containing Lippia origanoides Kunth essential oil and their antifungal potential against Candida albicans

AIMS

Nanoemulsions based on plant essential oils have shown promise as alternatives against fungal pathogens by increasing the solubility and bioavailability of the active compounds of essential oils, which can improve their efficacy and safety. In the present study, we aimed to prepare and characterize nanoemulsions of Lippia origanoides essential oil, and analyze their antifungal activity against C. albicans in planktonic and biofilm form. Additionally, we sought to verify their cytotoxicity.

METHODS AND RESULTS

Alginate nanoemulsions were prepared with different concentrations of essential oil, sunflower oil, and surfactant to investigate ideal formulations regarding stability and antifungal efficiency. The results showed the nanoemulsions remained stable for longer than 60 days, with acidic pH, particle sizes ranging from 180.17 ± 6.86 nm to 497.85 ± 253.50 nm, zeta potential from -60.47 ± 2.25 to -43.63 ± 12, and polydispersity index from 0.004 to 0.622. The photomicrographs revealed that the addition of sunflower oil influenced the formation of the particles, forming nanoemulsions. The antifungal results of the essential oil and nanoemulsions showed that the MIC ranged from 0.078 to 0.312 mg ml-1. The nanoemulsions were more effective than the free essential oil in eradicating the biofilm, eliminating up to 89.7% of its mass. With regard to cytotoxicity, differences were found between the tests with VERO cells and red blood cells, and the nanoemulsions were less toxic to red blood cells than the free essential oil.

CONCLUSIONS

These results show that nanoemulsions have antifungal potential against strains of C. albicans in planktonic and biofilm forms.

Glucosinolate derivatives as antifungals: A review

Fungal infections are becoming a severe threat to the security of global public health due to the extensive use of antibiotic medications and the rise in immune-deficient patients globally. Additionally, there is an increase in the development of fungus resistance to available antifungal medications. It is necessary to focus on the development of new antifungal medications in order to address these problems. The wide range of chemical structures, low cost, high availability, high antimicrobial action, and lack of adverse effects are the characteristics of plant secondary metabolites. In order to find and develop new antifungal medications, plant secondary metabolites like glucosinolate (GSL) derivatives are crucial sources of information. These natural compounds are enzymatically transformed into isothiocyanates (ITCs), nitriles, epithionitriles, oxazolidin-2-thion, and thiocyanate when they get mechanically damaged. The current review offers a thorough understanding of how isothiocyanates affect fungi with detailed mechanism. Along with this antifungal activity of nitriles, epithionitriles, oxazolidin-2-thion, and thiocyanate are mentioned. The review summarizes our present understanding of the following subjects: role of isothiocyanate by inhibiting aflatoxin biosynthesis, effect of isothiocyanate on transcriptomes, isothiocyanate targets cell membrane, role of isothiocyanate in efflux, and the role of isothiocyanate in synergistic activity. Antifungal activity of nitrile, epithionitrile, oxazolidine-2-thion, and thiocyanate is mentioned. Cytotoxicity study and clinical trials data were also added. More extensive studies will be needed in this field to assess safety concerns and clinical efficacies of GSL derivatives.

The effect of soaking heat-polymerized acrylic resin denture base in avocado seed extract ( Persea americana Mill.) on the inhibition of denture-plaque microorganisms biofilm growth

Background

Heat polymerized acrylic (HPA) resins are known to have high porosity that contributes to increased surface roughness and microcrack formation in stress areas. This facilitates the attachment and growth of polymicrobial biofilms contributing to increased antimicrobial resistance. Many research had been carried out on avocado seeds, but no research that studies avocado seeds effect on denture-plaque microorganism biofilm on HPA resin has been found.

Methods

This study used 144 samples (n=144), namely HPA resin discs covered with mono-species and polymicrobial biofilms. The discs were soaked for 8 hours in the 5%, 10%, 15%, 20% avocado seed extract, positive control (alkaline peroxide), and negative control (aquadest). Each disc was shaken with a vortex mixer for 1 minute, and 100 μL was added into 96-well microplates with three times repetition and incubated for 24 hours. A microtiter plate biofilm formation assay was then conducted The inhibition values were determined from the percentage inhibition value formula which required absorption values from a microplate reader (595 nm). The research data were analyzed using a univariant test, and a one-way ANOVA test, accompanied by Welch ANOVA on non-homogenous data.

Results

In this research, it was found that the MBIC 50 of avocado seed extract against the mono-species of C. albicans (5%), C. glabrata (5%), A. odontolyticus (15%), S. gordonii (15%), S. aureus (10%), while against polymicrobial was 20%. There was a significant effect of soaking HPA resin in avocado seed extract on the inhibition of mono-species and polymicrobial biofilms with a value of p<0.001 (p<0.05).

Conclusion

The MBIC 50 of avocado seed extract in polymicrobial biofilm group was higher than that in the mono-species biofilm groups. Although alkaline peroxide showed higher inhibition value than that of the MBIC 50 in polymicrobial biofilm group, 20% avocado seed extract was concluded effective as it inhibited >50% polymicrobial biofilm.

Anti-fungal peptides: an emerging category with enthralling therapeutic prospects in the treatment of candidiasis

Candida infections, particularly invasive candidiasis, pose a serious global health threat. Candida albicans is the most prevalent species causing candidiasis, and resistance to key antifungal drugs, such as azoles, echinocandins, polyenes, and fluoropyrimidines, has emerged. This growing multidrug resistance (MDR) complicates treatment options, highlighting the need for novel therapeutic approaches. Antifungal peptides (AFPs) are gaining recognition for their potential as new antifungal agents due to their diverse structures and functions. These natural or recombinant peptides can effectively target fungal virulence and viability, making them promising candidates for future antifungal development. This review examines infections caused by Candida species, the limitations of current antifungal treatments, and the therapeutic potential of AFPs. It emphasizes the importance of identifying novel AFP targets and their production for advancing treatment strategies. By discussing the therapeutic development of AFPs, the review aims to draw researchers' attention to this promising field. The integration of knowledge about AFPs could pave the way for novel antifungal agents with broad-spectrum activity, reduced toxicity, targeted action, and mechanisms that limit resistance in pathogenic fungi, offering significant advancements in antifungal therapeutics.

Anti-biofilm effect of clove oil against Candida albicans: A systematic review

In recent years, Candida albicans has emerged as a significant opportunistic pathogen, causing various infections, particularly in immunocompromised geriatric individuals. One of the major hindrances in managing Candida infections lies in its potential to develop and survive in biofilms, which demonstrate resistance to conventional antifungal therapies, thereby complicating treatment strategies. While clove oil has shown promising results as a potential antifungal agent, its specific anti-biofilm effects against Candida albicans biofilms remain relatively underexplored. Therefore, there is a need for a comprehensive review to evaluate the existing literature on the anti-biofilm properties of clove oil and its mechanisms of action against Candida albicans biofilms. Such a review will provide valuable insights into the potential therapeutic applications of clove oil in combating biofilm-associated Candida infections. This review will enable us to infer and understand the potential effects of clove oil against Candida albicans. This systematic review aims to determine the anti-biofilm efficacy of clove oil against Candida albicans. This systematic review was registered in 'PROSPERO' (CRD42024524134) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The literature searches used Google Scholar, PubMed, and Science Direct databases. All original studies published in English from 2004 to 2023 were included. From 37 studies found online, only four were reviewed. Results showed that clove oil had significant anti-biofilm activity when assessed against Candida albicans. Our systematic review provides insights into clove oil's potential as a therapeutic agent against Candida albicans biofilms. Clove oil also represents a promising avenue for future research and development in managing Candida biofilms.

ASLdC3: A Derivative of Acidic Sophorolipid Disrupts Mitochondrial Function, Induces ROS Generation, and Inhibits Biofilm Formation in Candida albicans

Fungal infections account for more than 140 million cases of severe and life-threatening conditions each year, causing approximately 1.7 million deaths annually. Candida albicans and related species are the most common human fungal pathogens, causing both superficial (mucosal and cutaneous) and life-threatening invasive infections (candidemia) with a 40-75% mortality rate. Among many virulence factors of Candida albicans, morphological transition from yeast to hyphae, secretion of hydrolytic enzymes, and formation of biofilms are considered to be crucial for pathogenicity. However, the arsenals for the treatment against these pathogens are restricted to only a few classes of approved drugs, the efficacy of which is being compromised by host toxicity, fungistatic activity, and the emergence of drug resistance. In this study, we have described the development of a molecule, exhibiting excellent antifungal activity (MIC 8 μg/mL), by tailoring acidic sophorolipids with aryl alcohols via enzyme catalysis. This novel derivative, ASLdC3, is a surface-active compound that lowers the surface tension of the air-water interface up to 2-fold before reaching the critical micelle concentration of 25 μg/mL. ASLdC3 exhibits excellent antibiofilm properties against Candida albicans and other nonalbicans Candida species. The molecule primarily exhibits its antifungal activity by perturbing mitochondrial function through the alteration of the mitochondrial membrane potential (MMP) and generation of reactive oxygen species (ROS). The ROS damages fungal cell membrane function and cell wall integrity, eventually leading to cell death. ASLdC3 was found to be nontoxic in in vitro assay and nonhemolytic. Besides, it does not cause toxicity in the C. elegans model. Our study provides a valuable foundation for the potential of acidic sophorolipid as a nontoxic, biodegradable precursor for the design and synthesis of novel molecules for use as antimicrobial drugs as well as for other clinical applications.

Chitosan and liposomal delivery systems for epicatechin or propyl gallate targeting localized treatment of vulvovaginal candidiasis

Natural polyphenols are promising alternatives to antifungals for novel treatments of vulvovaginal candidiasis (VVC) in an era of antimicrobial resistance. However, polyphenols are poorly soluble and prone to degradation. To overcome their limitations, we propose incorporation in liposomes. The study aimed to develop chitosan and liposome comprising delivery systems for epicatechin (EC) or propyl gallate (PG) as treatment of VVC. EC was selected for its antioxidative properties and PG as an ester of antifungal gallic acid. To improve formulation retention at vaginal site, mucoadhesive chitosan was introduced into formulation as liposomal surface coating or hydrogel due to intrinsic antifungal properties. These polyphenol-loaded liposomes exhibited an average size of 125 nm with a 64 % entrapment efficiency (for both polyphenols). A sustained in vitro polyphenol release was seen from liposomes, particularly in chitosan hydrogel (p < 0.01 or lower). Viscosity was evaluated since increased viscosity upon mucin contact indicated adhesive bond formation between chitosan and mucin confirming mucoadhesiveness of formulations. Antifungal activity was evaluated by the broth microdilution method on Candida albicans CRM-10231. Unlike PG, incorporation of EC in liposomes enabled antifungal activity. Fungicidal activity of chitosan was confirmed both when used as liposomal coating material and as hydrogel vehicle.

Antifungal activity of β-lapachone against a fluconazole-resistant Candida auris strain

Candida spp. can be found in the human microbiome. However, immunocompromised patients are likely to develop invasive Candida infections, with mortality rates higher than 50%. The discovery of C. auris, a species that rapidly acquire antifungal resistance, increased the concern about Candida infections. The limited number of antifungal agents and the high incidence of resistance to them make imperative the development of new antifungal drugs. β-lapachone is a biological active naphthoquinone that displays antifungal activity against C. albicans and C. glabrata. The aim of this study was to evaluate if this substance affects C. auris growth and elucidate its mechanism of action. A fluconazole-resistant C. auris isolate was used in this study. The antifungal activity of β-lapachone was determined through microbroth dilution assays, and its mechanism of action was evaluated using fluorescent probes. Interaction with fluconazole and amphotericin B was assessed by disk diffusion assay and checkerboard. β-lapachone inhibited planktonic C. auris cell growth by 92.7%, biofilm formation by 84.9%, and decrease the metabolism of preformed biofilms by 87.1% at 100 µg/ml. At 100 µg/ml, reductions of 30% and 59% of Calcofluor White and Nile red fluorescences were observed, indicating that β-lapachone affects cell wall chitin and neutral lipids content, respectively. Also, the ratio 590 nm/529 nm of JC-1 decreased 52%, showing that the compound affects mitochondria. No synergism was observed between β-lapachone and fluconazole or amphotericin B. Data show that β-lapachone may be a promising candidate to be used as monotherapy to treat C. auris resistant infections.

Effects of Sucrose and Farnesol on Biofilm Formation by Streptococcus mutans and Candida albicans

Candida albicans (C. albicans) and Streptococcus mutans (S. mutans) are frequently detected in the plaque biofilms of children with early childhood caries. This study investigated the effects of sucrose and farnesol on biofilm formation by the oral pathogens S. mutans and C. albicans, including their synergistic interactions. Biofilm formation dynamics were monitored using the Cell Index (CI). The CI for S. mutans increased in the brain-heart infusion medium, peaking at 10 h; however, the addition of sucrose reduced the CI. For C. albicans yeast cells, the CI increased at sucrose concentrations > 0.5%, peaking at 2 h. Mixed cultures of S. mutans and C. albicans yeast cells showed significantly higher CI values in the presence of sucrose, suggesting a synergistic effect on biofilm formation. Farnesol consistently suppressed biofilm formation by C. albicans yeast cells, even in the presence of sucrose, and higher farnesol concentrations resulted in greater inhibition. Regarding C. albicans hyphal cells, sucrose did not enhance biofilm formation, whereas farnesol significantly reduced biofilm formation at all concentrations tested. These findings elucidate the complex roles of sucrose and farnesol in biofilm formation by S. mutans and C. albicans and emphasize the potential of farnesol as an effective oral biofilm inhibitor.

Evaluation of mixed biofilm production by Candida spp. and Staphylococcus aureus strains co-isolated from cystic fibrosis patients in northwest Algeria

Cystic fibrosis patients' lungs are chronically colonized by multiple microbial species capable of forming biofilms. This study aimed to characterize the polymicrobial biofilm formed by Candida spp. and S. aureus, co-isolated from sputum samples of cystic fibrosis patients regarding microbial density, metabolic activity, and structure. 67 samples from 28 patients were collected with a 96% alteration rate. 34% showed alterations by both Candida spp. and Gram-positive bacteria, predominantly Candida spp. and S. aureus in 77% of cases, accounting for 6 associations. Biofilm biomass was quantified using the crystal violet assay, and metabolic activity was assessed using the MTT reduction assay. Scanning electron microscopy analyzed the C. tropicalis/S. aureus24 biofilm architecture. Candida spp. isolates demonstrated the ability to form mixed biofilms with S. aureus. The C. tropicalis/S. aureus24 association exhibited the highest production of biofilm and metabolic activity, along with the C. albicans17/C. rugosa/S. aureus7 in both single and mixed biofilms.

Butyl isothiocyanate exhibits antifungal and anti-biofilm activity against Candida albicans by targeting cell membrane integrity, cell cycle progression and oxidative stress

The prevalence of Candida albicans infection has increased during the past few years, which contributes to the need for new, effective treatments due to the increasing concerns regarding antifungal drug toxicity and multidrug resistance. Butyl isothiocyanate (butylITC) is a glucosinolate derivative, and has shown a significant antifungal effect contrary to Candida albicans. Additionally, how butylITC affects the virulence traits of C. albicans and molecular mode of actions are not well known. Present study shows that at 17.36 mM concentration butylITC inhibit planktonic growth. butylITC initially slowed the hyphal transition at 0.542 mM concentration. butylITC hampered biofilm development, and inhibits biofilm formation at 17.36 mM concentration which was analysed using metabolic assay (XTT assay) and Scanning Electron Microscopy (SEM). In addition, it was noted that butylITC inhibits ergosterol biosynthesis. The permeability of cell membranes was enhanced by butylITC treatment. Moreover, butylITC arrests cells at S-phase and induces intracellular Reactive Oxygen Species (ROS) accumulation in C. albicans. The results suggest that butylITC may have a dual mode of action, inhibit virulence factors and modulate cellular processes like inhibit ergosterol biosynthesis, cell cycle arrest, induces ROS production which leads to cell death in C. albicans.

Application of cuminaldehyde and ciprofloxacin for the effective control of biofilm assembly of Pseudomonas aeruginosa: A combinatorial study

Pseudomonas aeruginosa is widely associated with biofilm-mediated antibiotic resistant chronic and acute infections which constitute a persistent healthcare challenges. Addressing this threat requires exploration of novel therapeutic strategies involving the combination of natural compounds and conventional antibiotics. Hence, our study has focused on two compounds; cuminaldehyde and ciprofloxacin, which were strategically combined to target the biofilm challenge of P. aeruginosa. The minimum inhibitory concentration (MIC) of cuminaldehyde and ciprofloxacin was found to be 400 μg/mL and 0.4 μg/mL, respectively. Moreover, the fractional inhibitory concentration index (FICI = 0.62) indicated an additive interaction prevailed between cuminaldehyde and ciprofloxacin. Subsequently, sub-MIC doses of cuminaldehyde (25 μg/mL) and ciprofloxacin (0.05 μg/mL) were selected for an array of antibiofilm assays which confirmed their biofilm inhibitory potential without exhibiting any antimicrobial activity. Furthermore, selected doses of the mentioned compounds could manage biofilm on catheter surface by inhibiting and disintegrating existing biofilm. Additionally, the test combination of the mentioned compounds reduced virulence factors secretion, accumulated reactive oxygen species and increased cell-membrane permeability. Thus, the combination of cuminaldehyde and ciprofloxacin demonstrates potential in combating biofilm-associated Pseudomonal threats.

Impact of multiscale surface topography characteristics on Candida albicans biofilm formation: From cell repellence to fungicidal activity

While there has been significant research conducted on bacterial colonization on implant materials, with a focus on developing surface modifications to prevent the formation of bacterial biofilms, the study of Candida albicans biofilms on implantable materials is still in its infancy, despite its growing relevance in implant-associated infections. C. albicans fungal infections represent a significant clinical concern due to their severity and associated high fatality rate. Pathogenic yeasts account for an increasing proportion of implant-associated infections, since Candida spp. readily form biofilms on medical and dental device surfaces. In addition, these biofilms are highly antifungal-resistant, making it crucial to explore alternative solutions for the prevention of Candida implant-associated infections. One promising approach is to modify the surface properties of the implant, such as the wettability and topography of these substrata, to prevent the initial Candida attachment to the surface. This review summarizes recent research on the effects of surface wettability, roughness, and architecture on Candida spp. attachment to implantable materials. The nanofabrication of material surfaces are highlighted as a potential method for the prevention of Candida spp. attachment and biofilm formation on medical implant materials. Understanding the mechanisms by which Candida spp. attach to surfaces will allow such surfaces to be designed such that the incidence and severity of Candida infections in patients can be significantly reduced. Most importantly, this approach could also substantially reduce the need to use antifungals for the prevention and treatment of these infections, thereby playing a crucial role in minimizing the possibility contributing to instances of antimicrobial resistance. STATEMENT OF SIGNIFICANCE: In this review we provide a systematic analysis of the role that surface characteristics, such as wettability, roughness, topography and architecture, play on the extent of C. albicans cells attachment that will occur on biomaterial surfaces. We show that exploiting bioinspired surfaces could significantly contribute to the prevention of antimicrobial resistance to antifungal and chemical-based preventive measures. By reducing the attachment and growth of C. albicans cells using surface structure approaches, we can decrease the need for antifungals, which are conventionally used to treat such infections.

Biomaterials coated with zwitterionic polymer brush demonstrated significant resistance to bacterial adhesion and biofilm formation in comparison to brush coatings incorporated with antibiotics

A critical problem with the use of biomaterial implants is associated with bacterial adhesion on the surface of implants and in turn the biofilm formation. Among different strategies that have been reported to resolve this dilemma, surface design combined with both antiadhesive and antimicrobial properties has proven to be highly effective. Physiochemical properties of polymer brush coatings possess non-adhesive capability against bacterial adhesion and create a niche for further functionalization. The current study aims to evaluate the effect of antibiotics incorporated into the polymer brush on bacterial adhesion and biofilm formation. Brushes made of zwitterionic polymers were synthesized, functionalized with vancomycin via both physical and chemical conjugation, and grafted onto the silicon rubber surfaces. Antibacterial and antiadhesive measurements of designed coated biomaterials were mediated through the use of a parallel plate flow chamber against biofilm growth developed by Staphylococcus aureus and Escherichia coli over a period of 24 h. The analysis of biofilm growth on designed coated biomaterials showed that the pristine coated zwitterionic brushes are significantly resistant to bacterial adhesion and biofilm formation but not in the polymer brush coating incorporated with antibiotics.

In vitro inhibition of biofilm and virulence factor production in azole-resistant strains of Candida albicans isolated from diabetic foot by Artemisia vulgaris stabilized tin (IV) oxide nanoparticles

The advent of nanotechnology has been instrumental in the development of new drugs with novel targets. Recently, metallic nanoparticles have emerged as potential candidates to combat the threat of drug-resistant infections. Diabetic foot ulcers (DFUs) are one of the dreadful complications of diabetes mellitus due to the colonization of numerous drug-resistant pathogenic microbes leading to biofilm formation. Biofilms are difficult to treat due to limited penetration and non-specificity of drugs. Therefore, in the current investigation, SnO2 nanoparticles were biosynthesized using Artemisia vulgaris (AvTO-NPs) as a stabilizing agent and were characterized using ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Furthermore, the efficacy of AvTO-NPs against biofilms and virulence factors of drug-resistant Candida albicans strains isolated from DFUs was assessed. AvTO-NPs displayed minimum inhibitory concentrations (MICs) ranging from 1 mg/mL to 2 mg/mL against four strains of C. albicans. AvTO-NPs significantly inhibited biofilm formation by 54.8%-87%, germ tube formation by 72%-90%, cell surface hydrophobicity by 68.2%-82.8%, and exopolysaccharide (EPS) production by 69%-86.3% in the test strains at respective 1/2xMIC. Biosynthesized NPs were effective in disrupting established mature biofilms of test strains significantly. Elevated levels of reactive oxygen species (ROS) generation in the AvTO-NPs-treated C. albicans could be the possible cause of cell death leading to biofilm inhibition. The useful insights of the present study could be exploited in the current line of treatment to mitigate the threat of biofilm-related persistent DFUs and expedite wound healing.

Update on fungal lipid biosynthesis inhibitors as antifungal agents

Fungal diseases today represent a world-wide problem. Poor hygiene and decreased immunity are the main reasons behind the manifestation of this disease. After COVID-19, an increase in the rate of fungal infection has been observed in different countries. Different classes of antifungal agents, such as polyenes, azoles, echinocandins, and anti-metabolites, as well as their combinations, are currently employed to treat fungal diseases; these drugs are effective but can cause some side effects and toxicities. Therefore, the identification and development of newer antifungal agents is a current need. The fungal cell comprises many lipids, such as ergosterol, phospholipids, and sphingolipids. Ergosterol is a sterol lipid that is only found in fungal cells. Various pathways synthesize all these lipids, and the activities of multiple enzymes govern these pathways. Inhibiting these enzymes will ultimately impede the lipid synthesis pathway, and this phenomenon could be a potential antifungal therapy. This review will discuss various lipid synthesis pathways and multiple antifungal agents identified as having fungal lipid synthesis inhibition activity. This review will identify novel compounds that can inhibit fungal lipid synthesis, permitting researchers to direct further deep pharmacological investigation and help develop drug delivery systems for such compounds.

Real-time monitoring of biofilm growth identifies andrographolide as a potent antifungal compound eradicating Candida biofilms

Candida species cause life-threatening infections with high morbidity and mortality rates and their resistance to conventional therapy is closely linked to biofilm formation. Thus, the development of new approaches to study Candida biofilms and the identification of novel therapeutic strategies could yield improved clinical outcomes. In the current study, we have set up an impedance-based in vitro system to study Candida spp. biofilms in real-time and to evaluate their sensitivity to two conventional antifungal groups used in clinical practice - azoles and echinocandins. Both fluconazole and voriconazole were unable to inhibit biofilm formation in most strains tested, while echinocandins showed biofilm inhibitory capacity at relatively low concentrations (starting from 0.625 mg/L). However, assays performed on 24 h Candida albicans and C. glabrata biofilms revealed that micafungin and caspofungin failed to eradicate mature biofilms at all tested concentrations, evidencing that once formed, Candida spp. biofilms are extremely difficult to eliminate using currently available antifungals. We then evaluated the antifungal and anti-biofilm effect of andrographolide, a natural compound isolated from the plant Andrographis paniculata with known antibiofilm activity on Gram-positive and Gram-negative bacteria. Optical density measures, impedance evaluation, CFU counts, and electron microscopy data showed that andrographolide strongly inhibits planktonic Candida spp. growth and halts Candida spp. biofilm formation in a dose-dependent manner in all tested strains. Moreover, andrographolide was capable of eliminating mature biofilms and viable cell numbers by up to 99.9% in the C. albicans and C. glabrata strains tested, suggesting its potential as a new approach to treat multi-resistant Candida spp. biofilm-related infections.

Biofilm development of Candida boidinii and the effect of tyrosol on biofilm formation

OBJECTIVES

The applicability of a simple and high-throughput method for quantitative characterization of biofilm formation by Candida boidinii was tested in order to evaluate the effects of exogenous tyrosol on yeast growth and biofilm formation capacity.

RESULTS

Significant concentration-, temperature and time-dependent effect of tyrosol (2-(4-hydroxyphenyl)ethanol) was demonstrated, but it differentially affected the growth and biofilm formation (characterized by crystal violet staining and XTT-reduction assay) of Candida boidinii. Testing biofilm based on metabolic activity displayed sensitively the differences in the intensity of biofilm in terms of temperature, tyrosol concentration, and exposure time. At 22 °C after 24 h none of the tyrosol concentrations had significant effect, while at 30 °C tyrosol-mediated inhibition was observed at 50 mM and 100 mM concentration. After 48 h and 72 h at 22 °C, biofilm formation was stimulated at 6.25-25 mM concentrations, meanwhile at 30 °C tyrosol decreased the biofilm metabolic activity proportionally with the concentration.

CONCLUSIONS

The research concludes that exogenous tyrosol exerts unusual effects on Candida boidinii growth and biofilm formation ability and predicts its potential application as a regulating factor of various fermentations by Candida boidinii.

Exploring the Potential Mechanism of Action of Piperine against Candida albicans and Targeting Its Virulence Factors

Plant-derived compounds have proven to be a source of inspiration for new drugs. In this study, piperine isolated from the fruits of Piper nigrum showed anti-Candida activity. Furthermore, the mechanisms of action of piperine and its impact on virulence factors in Candida albicans, which have not been comprehensively understood, were also assessed. Initially, piperine suppressed the hyphal transition in both liquid and solid media, hindered biofilm formation, and resulted in observable cell distortions in scanning electron microscope (SEM) samples, for both fluconazole-sensitive and fluconazole-resistant C. albicans strains. Additionally, the morphogenetic switches triggered by piperine were found to rely on the activity of mutant C. albicans strains. Secondly, piperine treatment increased cell membrane permeability and disrupted mitochondrial membrane potential, as evidenced by propidium iodine and Rhodamine 123 staining, respectively. Moreover, it induced the accumulation of intracellular reactive oxygen species in C. albicans. Synergy was obtained between the piperine and the fluconazole against the fluconazole-sensitive strain. Interestingly, there were no hemolytic effects of piperine, and it resulted in reduced cytotoxicity on fibroblast cells at low concentrations. The results suggest that piperine could have a dual mode of action inhibiting virulence factors and modulating cellular processes, leading to cell death in C. albicans.

Molecular Mechanisms Associated with Antifungal Resistance in Pathogenic Candida Species

Candidiasis is a highly pervasive infection posing major health risks, especially for immunocompromised populations. Pathogenic Candida species have evolved intrinsic and acquired resistance to a variety of antifungal medications. The primary goal of this literature review is to summarize the molecular mechanisms associated with antifungal resistance in Candida species. Resistance can be conferred via gain-of-function mutations in target pathway genes or their transcriptional regulators. Therefore, an overview of the known gene mutations is presented for the following antifungals: azoles (fluconazole, voriconazole, posaconazole and itraconazole), echinocandins (caspofungin, anidulafungin and micafungin), polyenes (amphotericin B and nystatin) and 5-fluorocytosine (5-FC). The following mutation hot spots were identified: (1) ergosterol biosynthesis pathway mutations (ERG11 and UPC2), resulting in azole resistance; (2) overexpression of the efflux pumps, promoting azole resistance (transcription factor genes: tac1 and mrr1; transporter genes: CDR1, CDR2, MDR1, PDR16 and SNQ2); (3) cell wall biosynthesis mutations (FKS1, FKS2 and PDR1), conferring resistance to echinocandins; (4) mutations of nucleic acid synthesis/repair genes (FCY1, FCY2 and FUR1), resulting in 5-FC resistance; and (5) biofilm production, promoting general antifungal resistance. This review also provides a summary of standardized inhibitory breakpoints obtained from international guidelines for prominent Candida species. Notably, N. glabrata, P. kudriavzevii and C. auris demonstrate fluconazole resistance.

Natural Compounds with Antifungal Properties against Candida albicans and Identification of Hinokitiol as a Promising Antifungal Drug

Candida albicans is an opportunistic yeast that causes most fungal infections. C. albicans has become increasingly resistant to antifungal drugs over the past decade. Our study focused on the identification of pure natural compounds for the development of antifungal medicines. A total of 15 natural compounds from different chemical families (cinnamic derivatives, aromatic phenols, mono- and sesquiterpenols, and unclassified compounds) were screened in this study. Among these groups, hinokitiol (Hi), a natural monoterpenoid extracted from the wood of the cypress family, showed excellent anti-C. albicans activity, with a MIC value of 8.21 µg/mL. Hi was selected from this panel for further investigation to assess its antifungal and anti-inflammatory properties. Hi exhibited significant antifungal activity against clinically isolated fluconazole- or caspofungin-resistant C. albicans strains. It also reduced biofilm formation and hyphal growth. Treatment with Hi protected Caenorhabditis elegans against infection with C. albicans and enhanced the expression of antimicrobial genes in worms infected with C. albicans. Aside from its antifungal activities against C. albicans, Hi challenge attenuated the LPS-induced expression of pro-inflammatory cytokines (IL-6, IL-1β, and CCL-2) in macrophages. Overall, Hi is a natural compound with antifungal and anti-inflammatory properties, making Hi a promising platform with which to fight against fungal infections.

In-vivo efficiency of the novel azole compounds (ATTAF-1 and ATTAF-2) against systemic candidiasis in a murine model

BACKGROUND

Antifungal resistance is the main health concern in the control of invasive fungal infections. This research was designed to further assess the antifungal activity of aryl-1,2,4-triazole-3-ylthio analogs of fluconazole (ATTAFs) against Candida albicans systemic candidiasis in the murine model.

MATERIALS & METHODS

The murine model of systemic candidiasis was designed via the inoculation of 1 × 106 CFU of Candida albicans. The treatment dosages of 3.5 and 35 mg/kg per day were selected for ATTAFs and fluconazole, respectively. The median survival time (MST) was assayed for 30 days post-infection. The quantitative and qualitative (via histopathology staining) fungal burden was also assessed. Furthermore, immunohistochemistry and biochemistry assays were performed to monitor anti-inflammatory activity using the Cyclooxygenase-2 (Cox-2) marker and changes in serum protein levels.

RESULTS

ATTAFs considerably improved the survival of the murine model (P < 0.003). Compared with fluconazole, the antifungal activity of ATTAFs and their MST showed no difference (P > 0.05). However, these compounds decreased the fungal burden in the kidneys, spleen, and liver.

CONCLUSION

Our research indicates that ATTAF-1 and ATTAF-2 are effective therapeutic agents due to their fungal clearing and increasing the MST in the murine model of systemic candidiasis. Although we concluded that these components are novel and promising candidates for the management of invasive candidiasis, further studies are warranted to correlate these findings with clinical outcomes.

Phenotypic Investigation of Virulence Factors, Susceptibility to Ceragenins, and the Impact of Biofilm Formation on Drug Efficacy in Candida auris Isolates from Türkiye

Candida auris has emerged as a significant fungal threat due to its rapid worldwide spread since its first appearance, along with its potential for antimicrobial resistance and virulence properties. This study was designed to examine virulence characteristics, the efficacy of ceragenins, and biofilm-derived drug resistance in seven C. auris strains isolated from Turkish intensive care patients. It was observed that none of the tested strains exhibited proteinase or hemolysis activity; however, they demonstrated weak phospholipase and esterase activity. In addition, all strains were identified as having moderate to strong biofilm formation characteristics. Upon determining the minimum inhibitory concentrations (MIC) of ceragenins, it was discovered that CSA-138 exhibited the highest effectiveness with a MIC range of 1-0.5 µg/mL, followed by CSA-131 with a MIC of 1 µg/mL. Also, antimicrobial agents destroyed mature biofilms at high concentrations (40-1280 µg/mL). The investigation revealed that the strains isolated from Türkiye displayed weak exoenzyme activities. Notably, the ceragenins exhibited effectiveness against these strains, suggesting their potential as a viable treatment option.

Molecular association of Candida albicans and vulvovaginal candidiasis: focusing on a solution

Candida albicans-mediated vulvovaginal candidiasis (VVC) is a significant challenge in clinical settings, owing to the inefficacy of current antifungals in modulating virulence, development of resistance, and poor penetration into the biofilm matrix. Various predisposition factors are molecular drivers that lead to the dysbiosis of normal microflora of the vagina, upregulation of central metabolic pathways, morphogenesis, hyphal extension, adhesion, invasion, and biofilm formation leading to chronic infection and recurrence. Hence, it is crucial to understand the molecular mechanism behind the virulence pathways driven by those drivers to decode the drug targets. Finding innovative solutions targeting fungal virulence/biofilm may potentiate the antifungals at low concentrations without affecting the recurrence of resistance. With this background, the present review details the critical molecular drivers and associated network of virulence pathways, possible drug targets, target-specific inhibitors, and probable mode of drug delivery to cross the preclinical phase by appropriate in vivo models.

Biofilm Formation in Medically Important Candida Species

Worldwide, the number of infections caused by biofilm-forming fungal pathogens is very high. In human medicine, there is an increasing proportion of immunocompromised patients with prolonged hospitalization, and patients with long-term inserted drains, cannulas, catheters, tubes, or other artificial devices, that exhibit a predisposition for colonization by biofilm-forming yeasts. A high percentage of mortality is due to candidemia caused by medically important Candida species. Species of major clinical significance include C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. krusei, and C. auris. The association of these pathogenic species in the biofilm structure is a serious therapeutic problem. Candida cells growing in the form of a biofilm are able to resist persistent therapy thanks to a combination of their protective mechanisms and their ability to disseminate to other parts of the body, thus representing a threat from the perspective of a permanent source of infection. The elucidation of the key mechanisms of biofilm formation is essential to progress in the understanding and treatment of invasive Candida infections.

Antibiofilm Effect of Lavandula multifida Essential Oil: A New Approach for Chronic Infections

Fungal infections are associated with high morbidity and mortality rates, being highly prevalent in patients with underlying health complications such as chronic lung disease, HIV, cancer, and diabetes mellitus. To mitigate these infections, the development of effective antifungals is imperative, with plants standing out as promising sources of bioactive compounds. In the present study, we focus on the antibiofilm potential of Lavandula multifida essential oil (EO) against dermatophyte strains and Candida albicans. The EO was characterized using GC and GC-MS, and its antifungal effect was assessed on both biofilm formation and disruption. Biofilm mass, extracellular matrix, and viability were quantified using crystal violet, safranin, and XTT assays, respectively, and morphological alterations were confirmed using optical and scanning electron microscopy. L. multifida EO showed very high amounts of carvacrol and was very effective in inhibiting and disrupting fungal biofilms. The EO significantly decreased biofilm mass and viability in all tested fungi. In addition, a reduction in dermatophytes' extracellular matrix was observed, particularly during biofilm formation. Morphological alterations were evident in mature biofilms, with a clear decrease in hypha diameter. These promising results support the use of L. multifida EO in the development of effective plant-based antifungal products.

Smart chitosan-PLGA nanocarriers functionalized with surface folic acid ligands against lung cancer cells

Lung cancer is the second most prevalent and first killer cancer worldwide, and conventional approaches do not have enough ability to suppress it. Therefore, a novel targeted chitosan (CS)-poly lactic-co-glycolic acid (PLGA)-folic acid (FA) nanocarrier was developed for delivery of sorafenib (Sor) to lung cancer cells. The nanocarrier (CPSF) had a size of 30-40 nm with globular shapes. Surface charge and drug content of CPSF were ascertained at about 1.1 mV and 15 %, respectively. Controlled (4 % within 2 h) and pH-sensitive (18 % within 2 h at pH = 5.0) Sor release were observed for the nanocarrier. The MTT assay demonstrated a cell viability of 13 % after 24 h treatment with 400 nM CPSF in A549 cancer cells while it was 78 % in MSC normal cells. The qRT-PCR revealed >8 folds and 11 folds increase for Caspase9 and P53 genes after 5 h treatment with 100 nM (IC₅₀) CPSF; but a reduction of 5 folds was observed for the Bcl2 gene. Besides, 57 % and 20 % apoptosis were attained in cell cycle arrest and apoptosis assays for CPSF, respectively. CPF indicated about 88 % internalization in cancer cells. These data prove that CPSF is a promising nanodelivery system for lung cancer suppression.

Microbiological evaluation in invisible aligner chemical cleaning methods against Candida albicans and Streptococcus mutans

INTRODUCTION

This study aimed to assess the efficacy of chemical agents in removing Candida albicans and Streptococcus mutans biofilm from invisible aligners.

METHODS

The samples were made of EX30 Invisalign trays, biofilm was cultured by standardized suspensions of C. albicans ATCC strain and S. mutans clinical strain on the sample. The treatments used were 0.5% sodium hypochlorite (NaClO) (20 minutes), 1% NaClO (10 minutes), chlorhexidine (5 minutes), peroxide (15 minutes), and orthophosphoric acid (15 seconds). The control group received phosphate-buffered saline for 10 minutes. The colony-forming units per milliliter of each microorganism were determined by serial dilutions seeded in plates with selective culture mediums for each one. Data were analyzed by the Kruskal-Wallis and Conover-Iman tests at an α of 0.05.

RESULTS

For the C. albicans biofilm group, the control group had 9.7 Log10 of microorganism growth, and all treatment groups had statistically significant biofilm reduction, in which chlorhexidine presented the highest inhibition of 3 Log10, followed by alkaline peroxide and orthophosphoric acid both with 2.6 Log10, 1% NaClO (2.5 Log10), and 0.5% NaClO (2 Log10). As for S. mutans, the control group had 8.9 Log10 of growth, and a total microorganism inhibition was reached by chlorhexidine, 1% NaClO, and orthophosphoric acid, whereas alkaline peroxide inhibited growth to 7.9 Log10 and 0.5% NaClO 5.1 Log10.

CONCLUSIONS

Within the limitations, chlorhexidine and orthophosphoric acid had greater efficacy in both biofilms. In addition, 1% NaClO and alkaline peroxide also had significant effects; therefore, their incorporation aligners disinfection protocols are valid.

Phenyl Pentyl Ketone and m-isobutyl Methoxy Benzoate Produced by Streptomyces Chrestomyceticus ADP4 are Potent Antimicrobial Agents Displaying Broad Spectrum Activities

Isolation and identification of two antimicrobial compounds, a phenyl pentyl ketone (CP1) and m-isobutyl methoxy benzoate (CP2), from Streptomyces chrestomyceticus ADP4 have been reported. Structure of the compounds were elucidated from analyses of spectral data that included LCMS/MS, NMR, FTIR and UV spectroscopies. Both the compounds displayed significant inhibition of albicans and non-albicans species of Candida (NAC) pathogens including C. auris, which is currently a pathogen of global concern. Also, the compounds showed potent antagonistic activity against Staphylococcus aureus, another significant human pathogen. No in-vitro cytotoxicity against HePG2 cells was observed with either of the compounds. Both displayed favourable drug likeness properties as determined by in-silico ADME and toxicological studies. Also, this is the first report on production of these anti-microbial compounds by an actinobacterium.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01068-7.

A Putative Role of Candida albicans in Promoting Cancer Development: A Current State of Evidence and Proposed Mechanisms

Candida albicans is a commensal fungal species that commonly colonizes the human body, but it is also a pervasive opportunistic pathogen in patients with malignant diseases. A growing body of evidence suggests that this fungus is not only coincidental in oncology patients, but may also play an active role in the development of cancer. More specifically, several studies have investigated the potential association between C. albicans and various types of cancer, including oral, esophageal, and colorectal cancer, with a possible role of this species in skin cancer as well. The proposed mechanisms include the production of carcinogenic metabolites, modulation of the immune response, changes in cell morphology, microbiome alterations, biofilm production, the activation of oncogenic signaling pathways, and the induction of chronic inflammation. These mechanisms may act together or independently to promote cancer development. Although more research is needed to fully grasp the potential role of C. albicans in carcinogenesis, the available evidence suggests that this species may be an active contributor and underscores the importance of considering the impact of the human microbiome on cancer pathogenesis. In this narrative review, we aimed to summarize the current state of evidence and offer some insights into proposed mechanisms.

Antifungal activity of Allyl isothiocyanate by targeting signal transduction pathway, ergosterol biosynthesis, and cell cycle in Candida albicans

Background and Purpose

In recent years, the inclusion of Candida albicans on the list of infections that pose a threat due to drug resistance has urged researchers to look into cutting-edge and effective antifungal medications. In this regard, the current study investigated the probable mode of action of allyl isothiocyanate (AITC) against Candida albicans.

Materials and Methods

In this study, planktonic assay, germ tube inhibition assay, adhesion, and biofilm formation assay were performed to check the growth and virulence factors. Furthermore, ergosterol assay, reactive oxygen production analysis, cell cycle analysis, and quantitative real-time polymerase chain reaction analysis were performed with the aim of finding the mode of action. A biomedical model organism, like a silkworm, was used in an in vivo study to demonstrate AITC anti-infective ability against C. albicans infection.

Results

Allyl isothiocyanate completely inhibited ergosterol biosynthesis in C. albicans at 0.125 mg/ml. Allyl isothiocyanate produces reactive oxygen species in both planktonic and biofilm cells of C. albicans. At 0.125 mg/ml concentration, AITC arrested cells at the G2/M phase of the cell cycle, which may induce apoptosis in C. albicans. In quantitative real-time polymerase chain reaction analysis, it was found that AITC inhibited virulence factors, like germ tube formation, at 0.125 mg/ml concentration by downregulation of PDE2, CEK1, TEC1 by 2.54-, 1.91-, and 1.04-fold change, respectively, and upregulation of MIG1, NRG1, and TUP1 by 9.22-, 3.35-, and 7.80-fold change, respectively. The in vivo study showed that AITC treatment successfully protected silkworms against C. albicans infections and increased their survival rate by preventing internal colonization by C. albicans.

Conclusion

In vitro and in vivo studies revealed that AITC can be an alternative therapeutic option for the treatment of C. albicans infection.

Antimicrobial Peptides: Challenging Journey to the Pharmaceutical, Biomedical, and Cosmeceutical Use

Antimicrobial peptides (AMPs), or host defence peptides, are short proteins in various life forms. Here we discuss AMPs, which may become a promising substitute or adjuvant in pharmaceutical, biomedical, and cosmeceutical uses. Their pharmacological potential has been investigated intensively, especially as antibacterial and antifungal drugs and as promising antiviral and anticancer agents. AMPs exhibit many properties, and some of these have attracted the attention of the cosmetic industry. AMPs are being developed as novel antibiotics to combat multidrug-resistant pathogens and as potential treatments for various diseases, including cancer, inflammatory disorders, and viral infections. In biomedicine, AMPs are being developed as wound-healing agents because they promote cell growth and tissue repair. The immunomodulatory effects of AMPs could be helpful in the treatment of autoimmune diseases. In the cosmeceutical industry, AMPs are being investigated as potential ingredients in skincare products due to their antioxidant properties (anti-ageing effects) and antibacterial activity, which allows the killing of bacteria that contribute to acne and other skin conditions. The promising benefits of AMPs make them a thrilling area of research, and studies are underway to overcome obstacles and fully harness their therapeutic potential. This review presents the structure, mechanisms of action, possible applications, production methods, and market for AMPs.

Antifungal liposomes: Lipid saturation and cholesterol concentration impact interaction with fungal and mammalian cells

Liposomes are lipid-based nanoparticles that have been used to deliver encapsulated drugs for a variety of applications, including treatment of life-threatening fungal infections. By understanding the effect of composition on liposome interactions with both fungal and mammalian cells, new effective antifungal liposomes can be developed. In this study, we investigated the impact of lipid saturation and cholesterol content on fungal and mammalian cell interactions with liposomes. We used three phospholipids with different saturation levels (saturated hydrogenated soy phosphatidylcholine (HSPC), mono-unsaturated 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC), and di-unsaturated 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine (PLPC)) and cholesterol concentrations ranging from 15% to 40% (w/w) in our liposome formulations. Using flow cytometry, >80% of Candida albicans SC5314 cells were found to interact with all liposome formulations developed, while >50% of clinical isolates tested exhibited interaction with these liposomes. In contrast, POPC-containing formulations exhibited low levels of interaction with murine fibroblasts and human umbilical vein endothelial cells (<30%), while HSPC and PLPC formulations had >50% and >80% interaction, respectively. Further, PLPC formulations caused a significant decrease in mammalian cell viability. Formulations that resulted in low levels of mammalian cell interaction, minimal cytotoxicity, and high levels of fungal cell interaction were then used to encapsulate the antifungal drug, amphotericin B. These liposomes eradicated planktonic C. albicans at drug concentrations lower than free drug, potentially due to the high levels of liposome-C. albicans interaction. Overall, this study provides new insights into the design of liposome formulations towards the development of new antifungal therapeutics.

Biofilm-associated genes as potential molecular targets of nano-Fe3O4 in Candida albicans

BACKGROUND

There are few effective treatments for Candida biofilm-associated infections. The present study demonstrated changes in the expression of biofilm-associated genes in Candida albicans treated with magnetic iron oxide nanoparticles (denoted as nano-Fe₃O₄).

METHODS

Nano-Fe₃O₄ was biologically synthesized using Bacillus licheniformis, Bacillus cereus, and Fusarium oxysporum. Additionally, the biologically synthesized nano-Fe₃O₄ was characterized by visual observation; ultraviolet-visible spectroscopy, scanning electron microscopy, X-ray diffraction spectroscopy, and Fourier transform infrared spectroscopy. The biologically synthesized nano-Fe₃O₄ was tested for growth and biofilm formation in C. albicans. Furthermore, quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was used to study the inhibition of biofilm-associated genes in C. albicans treated with nano-Fe₃O₄.

RESULTS

The production of biologically synthesized nano-Fe₃O₄ was confirmed using extensive characterization methods. The nano-Fe₃O₄ inhibited growth and biofilm formation. Nano-Fe₃O₄ exhibited growth inhibition with minimum inhibition concentrations (MICs) of 50 to 200 μg mL^-1. The anti-biofilm effects of nano-Fe₃O₄ were shown by 2,3-bis (2-methoxy-4-nitro-5 sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT) reduction assay, crystal violet staining, and light field microscopy. The gene expression results showed that the downregulation of BCR1, ALS1, ALS3, HWP1, and ECE1 genes inhibited the biofilm formation in C. albicans. ALS1 reduction was greater than others, with downregulation of 1375.83-, 1178.71-, and 768.47-fold at 2 × MIC, 1 × MIC, and ½ × MIC of nano-Fe₃O₄, respectively.

CONCLUSION

Biofilm-associated genes as potential molecular targets of nano-Fe₃O₄ in C. albicans may be an effective novel treatment strategy for biofilm-associated infections.

Candida albicans antibiofilm molecules: analysis based on inhibition and eradication studies

Biofilms are communities of microbial cells surrounded by an extracellular polysaccharide matrix, recognized as a fungal source for local and systemic infections and less susceptible to antifungal drugs. Thus, treatment of biofilm-related Candida spp. infections with popular antifungals such as fluconazole is limited and species-dependent and alternatively demands the use of expensive and high toxic drugs. In this sense, molecules with antibiofilm activity have been studied but without care regarding the use of important criteria such as antibiofilm concentration lower than antifungal concentration when considering the process of inhibition of formation and concentrations equal to or lower than 300 µM. Therefore, this review tries to gather the most promising molecules regarding the activity against the C. albicans biofilm described in the last 10 years, considering the activity of inhibition and eradication. From January 2011 to July 2021, articles were searched on Scopus, PubMed, and Science Direct, combining the keywords "antibiofilm," "candida albicans," "compound," and "molecule" with AND and OR operators. After 3 phases of selection, 21 articles describing 42 molecules were discussed in the review. Most of them were more promising for the inhibition of biofilm formation, with SM21 (24) being an interesting molecule for presenting inhibitory and eradication activity in biofilms with 24 and 48 h, as well as alizarin (26) and chrysazine (27), with concentrations well below the antifungal concentration. Despite the detection of these molecules and the attempts to determine the mechanisms of action by microscopic analysis and gene expression, no specific target has been determined. Thus, a gap is signaled, requiring further studies such as proteomic analyses to clarify it.

An Unconventional Oral Candidiasis in an Immunocompetent Patient

Oral candidiasis (OC) is an opportunistic fungal infection of the oral mucosae, sustained by Candida albicans or other non-albican Candida species (NAC), usually eradicated by conventional antifungals of the classes of azoles, polyenes, or derivative from echinocandins. OC usually occurs under predisposing local or systemic factors. C. lusitaniae is an opportunistic strain that is rarely responsible for human infection and occurs mainly in severe immunocompromised states. The present work reported an unconventional case of OC in an otherwise healthy immunocompetent woman sustained by C. lusitaniae and a multi-resistant strain of C. albicans.

Effects of TiS2 on Inhibiting Candida albicans Biofilm Formation and Its Compatibility with Human Gingival Fibroblasts in Titanium Implants

Titanium is widely used in medical devices, such as dental and orthopedic implants, due to its excellent mechanical properties, low toxicity, and biocompatibility. However, the titanium surface has the risk of microbial biofilm formation, which results in infections from species such as Candida albicans (C. albicans). This kind of biofilm prevents antifungal therapy and complicates the treatment of infectious diseases associated with implanted devices. It is critical to developing a feasible surface to decrease microbial growth while not interfering with the growth of the host cells. This study reports the influence of titanium surface modification to titanium disulfide (TiS₂) on inhibiting C. albicans biofilm formation while allowing the attachment of human gingival fibroblasts (HGFs) on their surface. The surface of titanium parts is directly converted to structured titanium and TiS₂ using direct laser processing and crystal growth methods. C. albicans adhesion and colonization are then investigated on these surfaces by the colony counting assay and reactive oxygen species (ROS) assay, using 2',7'-dichlorofluorescin diacetate (DCFH-DA) and microscopy images. Also, the viability and adhesion of HGFs on these surfaces are investigated to show their adhesion and biocompatibility. Titanium samples with the TiS₂ surface show both C. albicans biofilm inhibition and HGF attachment. This study provides insight into designing and manufacturing titanium biomedical implants.

Nanoparticle-Based Photodynamic Inhibition of Candida albicans Biofilms with Interfering Quorum Sensing

Biofilm formation is a critical event in the pathogenesis and virulence of fungal infections caused by Candida albicans, giving rise to about a 1000-fold increase in the resistance to antifungal agents. Although photodynamic treatment (PDT) has been excellently implicated in bacterial infections, studies on its potential against fungal infection through the clearance of fungal biofilm formation remain at its infancy stage. Here, we have designed photodynamic nanoparticles with different sizes, modifications, and the ability of generating reactive oxygen species (ROS) to examine their effects on inhibiting biofilm formation and destructing mature biofilms of C. albicans. We found that the nanoparticles modified with oligo-chitosan exhibited a better binding efficiency for planktonic cells, leading to stronger inhibitory efficacy of the filamentation and the early-stage biofilm formation. However, for mature biofilms, the nanoparticles with the smallest size (∼15 nm) showed the fastest penetration speed and a pronounced destructing effect albeit conferring the lowest ROS-producing capability. The inhibitory effect of photodynamic nanoparticles was dependent on the disruption of fungal quorum sensing (QS) by the upregulation of QS molecules, farnesol and tyrosol, mediated through the upregulation of ARO 8 and DPP 3 expression. Our findings provide a powerful strategy of nanoparticulate PDT to combat fungal infections through the inhibition of both hyphal and biofilm formation by disrupting QS.

Asian Ancistrocladus Lianas as Creative Producers of Naphthylisoquinoline Alkaloids

This book describes a unique class of secondary metabolites, the mono- and dimeric naphthylisoquinoline alkaloids. They occur in lianas of the paleotropical Ancistrocladaceae and Dioncophyllaceae families, exclusively. Their unprecedented structures include stereogenic centers and rotationally hindered, and thus likewise stereogenic, axes. Extended recent investigations on six Ancistrocladus species from Asia, as reported in this review, shed light on their fascinating phytochemical productivity, with over 100 such intriguing natural products. This high chemodiversity arises from a likewise unique biosynthesis from acetate-malonate units, following a novel polyketidic pathway to plant-derived isoquinoline alkaloids. Some of the compounds show most promising antiparasitic activities. Likewise presented are strategies for the regio- and stereoselective total synthesis of the alkaloids, including the directed construction of the chiral axis.