Sodium New Houttuyfonate Inhibits Candida albicans Biofilm Formation by Inhibiting the Ras1-cAMP-Efg1 Pathway Revealed by RNA-seq

Inhibition of Candida albicans Biofilm Formation and Attenuation of Its Virulence by Liriope muscari

(1) Background: Although Candida albicans accounts for the majority of fungal infections, therapeutic options are limited and require alternative antifungal agents with new targets; (2) Methods: A biofilm formation assay with RPMI1640 medium was performed with Liriope muscari extract. A combination antifungal assay, dimorphic transition assay, and adhesion assay were performed under the biofilm formation condition to determine the anti-biofilm formation effect. qRT-PCR analysis was accomplished to confirm changes in gene expression; (3) Results: L. muscari extract significantly reduces biofilm formation by 51.65% at 1.56 μg/mL use and therefore increases susceptibility to miconazole. L. muscari extract also inhibited the dimorphic transition of Candida; nearly 50% of the transition was inhibited when 1.56 μg/mL of the extract was treated. The extract of L. muscari inhibited the expression of genes related to hyphal development and extracellular matrix of 34.4% and 36.0%, respectively, as well as genes within the Ras1-cAMP-PKA, Cph2-Tec1, and MAP kinase signaling pathways of 25.58%, 7.1% and 15.8%, respectively, at 1.56 μg/mL of L. muscari extract treatment; (4) Conclusions: L. muscari extract significantly reduced Candida biofilm formation, which lead to induced antifungal susceptibility to miconazole. It suggests that L. muscari extract is a promising anti-biofilm candidate of Candida albicans since the biofilm formation of Candida albicans is an excellent target for candidiasis regulation.

Berberine inhibits Candida albicans growth by disrupting mitochondrial function through the reduction of iron absorption

AIMS

This study aimed to investigate whether berberine (BBR) can inhibit the iron reduction mechanism of Candida albicans, lowering the iron uptake of the yeast and perhaps having antimicrobial effects.

METHODS AND RESULTS

We determined that BBR may cause extensive transcriptional remodeling in C. albicans and that iron permease Ftr1 played a crucial role in this process through eukaryotic transcriptome sequencing. Mechanistic research showed that BBR might selectively inhibit the iron reduction pathway to lower the uptake of exogenous iron ions, inhibiting C. albicans from growing and metabolizing. Subsequent research revealed that BBR caused significant mitochondrial dysfunction, which triggered the process of mitochondrial autophagy. Moreover, we discovered that C. albicans redox homeostasis, susceptibility to antifungal drugs, and hyphal growth are all impacted by the suppression of this mechanism by BBR.

CONCLUSIONS

The iron reduction mechanism in C. albicans is disrupted by BBR, which disrupts mitochondrial function and inhibits fungal growth. These findings highlight the potential promise of BBR in antifungal applications.

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.

Shikonin Inhibits Candida albicans Biofilms via the Ras1-cAMP-Efg1 Signalling Pathway

Objective

To investigate the influence of shikonin (SK) on the formation of Candida albicans biofilms and discuss the possible mechanism.

Methods

The inhibition of the formation of C. albicans biofilms by SK was observed by scanning electron microscopy. A silicone film method and a water-hydrocarbon two-phase assay were performed to investigate the effects of SK on cell adhesion. Real-time reverse-transcription polymerase chain reaction was used to analyse the expression of genes related to cell adhesion and Ras1-cyclic adenosine monophosphate (cAMP) - enhanced filamentous growth protein 1 (Efg1) signalling pathway. Finally, the level of cAMP in C. albicans was detected and exogenous cAMP rescue experiment was conducted.

Results

The results showed that SK could destroy the typical three-dimensional structure of the biofilms, inhibit cell surface hydrophobicity and cell adhesion, downregulate the expression of Ras1-cAMP-Efg1 signalling pathway-related genes (ECE1, HWP1, ALS3, RAS1, CYR1, EFG1 and TEC1) and effectively reduce the production of key messenger cAMP in the Ras1-cAMP-Efg1 pathway. Meanwhile, exogenous cAMP reversed the inhibitory effect of SK on biofilms formation.

Conclusion

Our results suggest that SK exhibits potential anti-C. albicans biofilms effects related to the inhibition of Ras1-cAMP-Efg1 pathway.

The potential role of plant secondary metabolites on antifungal and immunomodulatory effect

With the widespread use of antibiotic drugs worldwide and the global increase in the number of immunodeficient patients, fungal infections have become a serious threat to global public health security. Moreover, the evolution of fungal resistance to existing antifungal drugs is on the rise. To address these issues, the development of new antifungal drugs or fungal inhibitors needs to be targeted urgently. Plant secondary metabolites are characterized by a wide variety of chemical structures, low price, high availability, high antimicrobial activity, and few side effects. Therefore, plant secondary metabolites may be important resources for the identification and development of novel antifungal drugs. However, there are few studies to summarize those contents. In this review, the antifungal modes of action of plant secondary metabolites toward different types of fungi and fungal infections are covered, as well as highlighting immunomodulatory effects on the human body. This review of the literature should lay the foundation for research into new antifungal drugs and the discovery of new targets. KEY POINTS: • Immunocompromised patients who are infected the drug-resistant fungi are increasing. • Plant secondary metabolites toward various fungal targets are covered. • Plant secondary metabolites with immunomodulatory effect are verified in vivo.

Sodium New Houttuyfonate Induces Apoptosis of Breast Cancer Cells via ROS/PDK1/AKT/GSK3β Axis

BACKGROUND

Sodium new houttuyfonate (SNH) has been reported to have anti-inflammatory, anti-fungal, and anti-cancer effects. However, few studies have investigated the effect of SNH on breast cancer. The aim of this study was to investigate whether SNH has therapeutic potential for targeting breast cancer.

METHODS

Immunohistochemistry and Western blot analysis were used to examine the expression of proteins, flow cytometry was used to detect cell apoptosis and ROS levels, and transmission electron microscopy was used to observe mitochondria.

RESULTS

Differentially expressed genes (DEGs) between breast cancer-related gene expression profiles (GSE139038 and GSE109169) from GEO DataSets were mainly involved in the immune signaling pathway and the apoptotic signaling pathway. According to in vitro experiments, SNH significantly inhibited the proliferation, migration, and invasiveness of MCF-7 (human cells) and CMT-1211 (canine cells) and promoted apoptosis. To explore the reason for the above cellular changes, it was found that SNH induced the excessive production of ROS, resulting in mitochondrial impairment, and then promoted apoptosis by inhibiting the activation of the PDK1-AKT-GSK3β pathway. Tumor growth, as well as lung and liver metastases, were suppressed under SNH treatment in a mouse breast tumor model.

CONCLUSIONS

SNH significantly inhibited the proliferation and invasiveness of breast cancer cells and may have significant therapeutic potential in breast cancer.

The sodium new houttuyfonate suppresses NSCLC via activating pyroptosis through TCONS-14036/miR-1228-5p/PRKCDBP pathway

Several studies have suggested the potential value of Houttuynia cordata as a therapeutic agent in lung cancer, but direct evidence is still lacking. The study aimed to determine the regulatory impact of a major H. cordata constituent derivative (sodium new houttuyfonate [SNH]) on lncRNA networks in non-small cell lung cancer (NSCLC) to identify new potential therapeutic targets. After exposing NSCLC cells to SNH, we analysed the following: cell death (via flow cytometry, TUNEL and ASC speck formation assays), immune factors (via ELISA), gene transcription (via RT-qPCR), subcellular localisation (via FISH), gene-gene and gene-protein interactions (via dual-luciferase reporter and RNA immunoprecipitation assays, respectively) and protein expression and distribution (via western blotting and immunocytochemistry or immunohistochemistry). In addition, statistical analysis (via one-way ANOVA or unpaired t-tests) was performed. Exposure to SNH promoted NSCLC cell pyroptosis, concomitant with significant up-regulation of TCONS-14036, a novel lncRNA. Mechanistic research demonstrated that TCONS-14036 functions as a competing endogenous (ce)RNA by sequestering microRNA (miR)-1228-5p, thereby up-regulating PRKCDBP-encoding transcript levels. Indeed, PRKCDBP promoted pyroptosis by activating the NLRP3 inflammasome, resulting in CASP1, IL-1β and GSDMD cleavage. Our findings elucidate the potential molecular mechanisms underlying the ability of SNH to suppress NSCLC growth through activation of pyroptosis via the TCONS-14036/miR-1228-5p/PRKCDBP pathway. Thus, we identify a new potential therapeutic targets for NSCLC.

Polyphyllin I Effects Candida albicans via Inhibition of Virulence Factors

Paris polyphylla is often used in Chinese medicine to treat conditions such as carbuncles, trauma, snake bites, and mosquito bites. In the present study, we investigated the effect and mechanism of the morphological transition and extracellular phospholipase activity of Candida albicans treated with polyphyllin I (PPI). First, the minimum inhibitory concentration and antifungal activity of PPI were evaluated using the multiple microdilution method and time-killing assays. Then, the effect of PPI on the morphological transition of Candida albicans in Spider liquid medium and Sabouraud-dextrose liquid medium containing 10% fetal bovine serum was observed under an inverted microscope and by scanning electron microscopy. Finally, egg yolk agar plates were used to evaluate extracellular phospholipase activity. Gene expression was detected by real-time quantitative polymerase chain reaction analysis. Our results suggest that PPI inhibited the transition from the yeast to the hyphal stage and decreased secreted aspartyl proteinase activity. We further confirmed that PPI significantly downregulated the expression of extracellular phospholipase genes and cAMP-PKA signaling pathway-related genes. Taken together, our results suggest that PPI exerts anti-Candida albicans activity by inhibiting virulence characteristics, including the yeast-to-hyphal transition and the secretion of aspartyl proteases and phospholipases. The study results also indicated that PPI could be a promising therapeutic strategy for Candida albicans.

Hexyl-Aminolevulinate Ethosomes: a Novel Antibiofilm Agent Targeting Zinc Homeostasis in Candida albicans

Substantial drug resistance afforded by Candida albicans biofilms results in ineffective treatment with conventional drugs and persistent infection. Our previous study showed that hexyl-aminolevulinate ethosomes (HAL-ES) act against C. albicans biofilms and weaken their drug resistance and pathogenicity; however, the mechanism involved remains unclear. Here, we systematically evaluated the effects and mechanisms of HAL-ES on biofilm formation and drug resistance. We found that, in addition to mediating antifungal photodynamic therapy, HAL-ES inhibited the early, developmental, and mature stages of biofilm formation compared with fluconazole, HAL, or ES. Notably, adhesion and hyphal formation were significantly inhibited by postdrug effects even after brief exposure (2 h) to HAL-ES. Its therapeutic effect in vivo also has been demonstrated in cutaneous candidiasis. RNA sequencing and quantitative PCR showed that HAL-ES inhibited ribosome biogenesis by disrupting zinc homeostasis in C. albicans, thereby reducing the translation process during protein synthesis. Furthermore, HAL-ES downregulated the expression of multidrug resistance genes and increased fluconazole susceptibility in C. albicans. Our findings provide a novel and efficient method for the treatment of biofilm resistance in C. albicans infection as well as a basis for the application of HAL-ES. We also describe a new strategy for the treatment of biofilm-related infections via zinc restriction. IMPORTANCE Candida albicans is the most prevalent fungal species of the human microbiota. The medical impact of C. albicans on its human host depends on its ability to form biofilms. The intrinsic resistance conferred by biofilms to conventional antifungal drugs makes biofilm-based infections a significant clinical challenge. In this study, we demonstrate the attenuating effect of HAL-ES on C. albicans biofilm formation and drug resistance. Furthermore, we propose that HAL-ES inhibits protein translation by disrupting zinc homeostasis in C. albicans. This study not only provides a novel and effective therapeutic strategy against C. albicans biofilm but also proposes a new strategy to resolve C. albicans biofilm infection by disrupting zinc homeostasis.

In Silico and In Vitro Analysis of Sulforaphane Anti-Candida Activity

Oropharyngeal candidiasis/candidosis is a common and recurrent opportunistic fungal infection. Fluconazole (FLZ), one of the most used and effective antifungal agents, has been associated with a rise of resistant Candida species in immunocompromised patients undergoing prophylactic therapy. Sulforaphane (SFN), a compound from cruciferous vegetables, is an antimicrobial with yet controversial activities and mechanisms on fungi. Herein, the in silico and antifungal activities of SFN against C. albicans were investigated. In silico analyzes for the prediction of the biological activities and oral bioavailability of SFN, its possible toxicity and pharmacokinetic parameters, as well as the estimates of its gastrointestinal absorption, permeability to the blood-brain barrier and skin, and similarities to drugs, were performed by using different software. SFN in vitro anti-Candida activities alone and in combination with fluconazole (FLZ) were determined by the broth microdilution method and the checkerboard, biofilm and hyphae formation tests. Amongst the identified probable biological activities of SFN, nine indicated an antimicrobial potential. SFN was predicted to be highly absorbable by the gastrointestinal tract, to present good oral availability, and not to be irritant and/or hepatotoxic. SFN presented antifungal activity against C. albicans and prevented both biofilm and hyphae formation by this microorganism. SFN was additive/synergistic to FLZ. Overall, the data highlights the anti-Candida activity of SFN and its potential to be used as an adjuvant therapy to FLZ in clinical settings.

Sodium New Houttuyfonate Inhibits Cancer-Promoting Fusobacterium nucleatum (Fn) to Reduce Colorectal Cancer Progression

Colorectal cancer (CRC) is a major cause of morbidity and mortality worldwide. Recent studies showed that the common anaerobe Fusobacterium nucleatum (Fn) is closely associated with a higher risk for carcinogenesis, metastasis, and chemoresistance of CRC. However, there is no specific antimicrobial therapy for CRC treatment. Herbal medicine has a long history of treating diseases with remarkable effects and is attracting extensive attention. In this study, we tested six common phytochemicals for their antimicrobial activities against Fn and whether anti-Fn phytochemicals can modulate CRC development associated with Fn. Among these antimicrobials, we found that SNH showed the highest antimicrobial activity and little cytotoxicity toward cancer cells and normal cells in vitro and in vivo. Mechanistically, SNH may target membrane-associated FadA, leading to FadA oligomerization, membrane fragmentation and permeabilization. More importantly, SNH blocked the tumor-promoting activity of Fn and Fn-associated cancer-driven inflammation, thus improving the intestinal barrier damaged by Fn. SNH reduced Fn load in the CRC-cells-derived mice xenografts with Fn inoculation and significantly inhibited CRC progression. Our data suggest that SNH could be used for an antimicrobial therapy that inhibits Fn and cancer-driven inflammation of CRC. Our results provide an important foundation for future gut microbiota-targeted clinical treatment of CRC.

The Antimicrobial Peptide AMP-17 Derived from Musca domestica Inhibits Biofilm Formation and Eradicates Mature Biofilm in Candida albicans

The biofilm formation of C. albicans represents a major virulence factor during candidiasis. Biofilm-mediated drug resistance has necessitated the search for a new antifungal treatment strategy. In our previous study, a novel antimicrobial peptide named AMP-17 derived from Musca domestica was confirmed to have significant antifungal activity and suppress hyphal growth greatly in C. albicans. In the current work, we aimed to investigate the antibiofilm property of AMP-17 in C. albicans and explore the underlying mechanism. An antifungal susceptibility assay showed that AMP-17 exerted a strong inhibitory efficacy on both biofilm formation and preformed biofilms in C. albicans. Furthermore, AMP-17 was found to block the yeast-to-hypha transition and inhibit the adhesion of biofilm cells with a reduction in cellular surface hydrophobicity. A morphological analysis revealed that AMP-17 indeed suppressed typical biofilm formation and damaged the structures of the preformed biofilm. The RNA-seq showed that the MAPK pathway, biosynthesis of antibiotics, and essential components of the cell were mainly enriched in the biofilm-forming stage, while the citrate cycle (TCA cycle), phenylamine metabolism, and propanoate metabolism were enriched after the biofilm matured. Moreover, the co-expressed DEGs in the two pairwise comparisons highlighted the terms of transmembrane transporter activity, regulation of filamentation, and biofilm formation as important roles in the antibiofilm effect of AMP-17. Additionally, qRT-PCR confirmed that the level of the genes involved in cell adhesion, filamentous growth, MAPK, biofilm matrix, and cell dispersal was correspondingly altered after AMP-17 treatment. Overall, our findings reveal the underlying antibiofilm mechanisms of AMPs in C. albicans, providing an interesting perspective for the development of effective antifungal agents with antibiofilm efficacy in Candida spp.

Natural products from traditional medicine as promising agents targeting at different stages of oral biofilm development

Oral cavity is an ideal habitat for more than 1,000 species of microorganisms. The diverse oral microbes form biofilms over the hard and soft tissues in the oral cavity, affecting the oral ecological balance and the development of oral diseases, such as caries, apical periodontitis, and periodontitis. Currently, antibiotics are the primary agents against infectious diseases; however, the emergence of drug resistance and the disruption of oral microecology have challenged their applications. The discovery of new antibiotic-independent agents is a promising strategy against biofilm-induced infections. Natural products from traditional medicine have shown potential antibiofilm activities in the oral cavity with high safety, cost-effectiveness, and minimal adverse drug reactions. Aiming to highlight the importance and functions of natural products from traditional medicine against oral biofilms, here we summarized and discussed the antibiofilm effects of natural products targeting at different stages of the biofilm formation process, including adhesion, proliferation, maturation, and dispersion, and their effects on multi-species biofilms. The perspective of antibiofilm agents for oral infectious diseases to restore the balance of oral microecology is also discussed.

Antifungal activity and potential mechanism of berberine hydrochloride against fluconazole-resistant Candida albicans

Introduction. The emergence of resistance to fluconazole in Candida albicans has made the clinical treatment of this microbe difficult. A potential strategy to address this problem involves diminishing fungal resistance to antimicrobial drugs.Hypothesis. Berberine hydrochloride (BH), the primary active ingredient of the traditional Chinese medicine (TCM) Coptis, inhibits the growth of fluconazole-resistant C. albicans through its action on the high-osmolarity glycerol mitogen-activated protein kinase (HOG-MAPK) pathway.Aim. To examine the effect of BH on the HOG-MAPK pathway to assess the potential molecular mechanism by which BH inhibits fluconazole-resistant C. albicans.Methodology. The minimum inhibitory concentration (MIC) of BH to fluconazole-resistant C. albicans was measured using the broth microdilution approach to determine the concentration of effective drug intervention. Changes in physiological functions regulated by the HOG-MAPK pathway in response to BH treatment were measured, as well as the expression of central signalling pathway genes and key downstream factors by qRT-PCR and Western blotting, respectively.Results. BH inhibited fluconazole-resistant C. albicans and the sensitivity to fluconazole increased after BH treatment. At a concentration of 256 and 64 μg ml^-1 BH may affect key downstream factors that regulate several physiological functions of C. albicans by upregulating the core genes expression of SLN1, SSK2, HOG1, and PBS2 in the HOG-MAPK pathway. Upregulation of GPD1, the key gene for glycerol synthesis, increased cell osmotic pressure. BH treatment increased the accumulation of reactive oxygen species by upregulating the expression of the key respiratory metabolism gene ATP11 and downregulating the expression of the superoxide dismutase gene SOD2. Furthermore, downregulation of mycelial-specific HWP1 hindered the morphological transformation of C. albicans and inhibition of the chitin synthase gene CHS3 and the β-(1,3) glucan synthase gene GSC1 impaired cytoderm integrity.Conclusion. BH affects multiple target genes in diminishing the resistance of C. albicans strains to fluconazole. This effect may be related to the action of BH on the HOG-MAPK pathway.

Antifungal Activity of Sodium New Houttuyfonate Against Aspergillus fumigatus in vitro and in vivo

Aspergillus fumigatus is an important pathogen causing invasive aspergillosis, which is associated with high morbidity and mortality in immunocompromised people. However, the treatment of A. fumigatus infection is a growing challenge, owing to the limited availability antifungal agents and the continual emergence of drug-resistant strains. Drug repurposing is a potential strategy to solve this current problem. Sodium new houttuyfonate (SNH), derived from houttuynin, extracted from Houttuynia cordata, has anti-bacterial and anti-Candida albicans effects. However, whether it has anti-A. fumigatus activity had not been reported. In this study, the antifungal properties of SNH against A. fumigatus, including the standard strain AF293, itraconazole resistant clinical strains, and voriconazole resistant clinical strains, were evaluated in vitro and in vivo. Moreover, the potential mechanism of SNH was characterized. SNH exhibited significant fungicidal activity toward various A. fumigatus strains. SNH also inhibited fungal growth, sporulation, conidial germination and pigment formation, and biofilm formation. Further investigations revealed that SNH interfered with the A. fumigatus cell steroid synthesis pathway, as indicated by transcriptomic and quantitative real-time polymerase chain reaction analyses, and inhibited ergosterol synthesis, as indicated by cell membrane stress assays and ergosterol quantification. Moreover, daily gastric gavage of SNH significantly decreased the fungal burden in mice with disseminated infection (kidney, liver, and lung) and local tissue damage. In addition, the application of SNH downregulated the production of IL-6 and IL-17A. Together, these findings provided the first confirmation that SNH may be a promising antifungal agent for the treatment of A. fumigatus infection.

A Cecropin-4 Derived Peptide C18 Inhibits Candida albicans by Disturbing Mitochondrial Function

Global burden of fungal infections and related health risk has accelerated at an incredible pace, and multidrug resistance emergency aggravates the need for the development of new effective strategies. Candida albicans is clinically the most ubiquitous pathogenic fungus that leads to high incidence and mortality in immunocompromised patients. Antimicrobial peptides (AMPs), in this context, represent promising alternatives having potential to be exploited for improving human health. In our previous studies, a Cecropin-4-derived peptide named C18 was found to possess a broader antibacterial spectrum after modification and exhibit significant antifungal activity against C. albicans. In this study, C18 shows antifungal activity against C. albicans or non-albicans Candida species with a minimum inhibitory concentration (MIC) at 4∼32 μg/ml, and clinical isolates of fluconazole (FLZ)-resistance C. tropicalis were highly susceptible to C18 with MIC value of 8 or 16 μg/ml. Additionally, C18 is superior to FLZ for killing planktonic C. albicans from inhibitory and killing kinetic curves. Moreover, C18 could attenuate the virulence of C. albicans, which includes damaging the cell structure, retarding hyphae transition, and inhibiting biofilm formation. Intriguingly, in the Galleria mellonella model with C. albicans infection, C18 could improve the survival rate of G. mellonella larvae to 70% and reduce C. albicans load from 5.01 × 107 to 5.62 × 104 CFU. For mechanistic action of C18, the level of reactive oxygen species (ROS) generation and cytosolic Ca2 + increased in the presence of C18, which is closely associated with mitochondrial dysfunction. Meanwhile, mitochondrial membrane potential (△Ψm) loss and ATP depletion of C. albicans occurred with the treatment of C18. We hypothesized that C18 might inhibit C. albicans via triggering mitochondrial dysfunction driven by ROS generation and Ca2 + accumulation. Our observation provides a basis for future research to explore the antifungal strategies and presents C18 as an attractive therapeutic candidate to be developed to treat candidiasis.

Berberine Inhibits the Adhesion of Candida albicans to Vaginal Epithelial Cells

Vulvovaginal candidiasis (VVC) is an inflammatory disease of the vagina mainly caused by Candida albicans (C. albicans), which affects around three-quarters of all women during their reproductive age. Although some antifungal drugs such as azoles have been applied clinically for many years, their therapeutic value is very limited due to the emergence of drug-resistant strains. Previous studies have shown that the adhesion of C. albicans to vaginal epithelial cells is essential for the pathogenesis of VVC. Therefore, preventing the adhesion of C. albicans to vaginal epithelial cells may be one of the most effective strategies for the treatment of VVC. Berberine (BBR) is a biologically active herbal alkaloid that was used to treat VVC. However, so far, its mechanism has remained unclear. This study shows BBR significantly inhibits the adhesion of C. albicans to vaginal epithelial cells by reducing the expressions of ICAM-1, mucin1, and mucin4 in vaginal epithelial cells, which play the most important role in modulating the adhesion of C. albicans to host cells, and balancing IL-2 and IL-4 expressions, which play a key effect on regulating the inflammatory response caused by C. albicans infection. Hence, our findings demonstrate that BBR may be a potential therapeutic agent for VVC by interfering with the adhesion of C. albicans to vaginal epithelial cells and represents a new pathway for developing antifungal therapies agents from natural herbs.

Antifungal Activity and Potential Mechanism of 6,7, 4'-O-Triacetylscutellarein Combined With Fluconazole Against Drug-Resistant C. albicans

The increased resistance of Candida albicans to conventional antifungal drugs poses a huge challenge to the clinical treatment of this infection. In recent years, combination therapy, a potential treatment method to overcome C. albicans resistance, has gained traction. This study assessed the effect of 6,7,4′-O-triacetylscutellarein (TA) combined with fluconazole (FLC) on C. albicans in vitro and in vivo. TA combined with FLC showed good synergistic antifungal activity against drug-resistant C. albicans in vitro, with a partial inhibitory concentration index (FICI) of 0.0188–0.1800. In addition, the time-kill curve confirmed the synergistic effect of TA and FLC. TA combined with FLC showed a strong synergistic inhibitory effect on the biofilm formation of resistant C. albicans. The combined antifungal efficacy of TA and FLC was evaluated in vivo in a mouse systemic fungal infection model. TA combined with FLC prolonged the survival rate of mice infected with drug-resistant C. albicans and reduced tissue invasion. TA combined with FLC also significantly inhibited the yeast-hypha conversion of C. albicans and significantly reduced the expression of RAS-cAMP-PKA signaling pathway-related genes (RAS1 and EFG1) and hyphal-related genes (HWP1 and ECE1). Furthermore, the mycelium growth on TA combined with the FLC group recovered after adding exogenous db-cAMP. Collectively, these results show that TA combined with FLC inhibits the formation of hyphae and biofilms through the RAS-cAMP-PKA signaling pathway, resulting in reduced infectivity and resistance of C. albicans. Therefore, this study provides a basis for the treatment of drug-resistant C. albicans infections.

Paeonol assists fluconazole and amphotericin B to inhibit virulence factors and pathogenicity of Candida albicans

This study aimed to evaluate the mono- and dual- antifungal activities of paeonol (PAE) and fluconazole (FLZ)/amphotericin B (AmB). To this end, the effects of PAE and FLZ/AmB on cell surface hydrophobicity, hydrolase activity, morphological transition were investigated in vitro and in a Galleria mellonella infection model. The results showed a relatively high minimum inhibitory concentration (MIC) and sessile MIC (SMIC) of PAE alone. However, compared with the single drug, the combined use of PAE and FLZ/AmB had a potent synergistic potential to inhibit the virulence factors for Candida. The concomitant use of two drugs was consistently more effective than either drug alone for increasing survival rate, decreasing the fungal burden, and alleviating the pathological features of G. mellonella infected by the fungus. Taken together, these findings demonstrate the anti-Candida effects of PAE plus FLZ/AmB and their potential to increase the sensitivity of C. albicans to FLZ/AmB of PAE.

Inhibitory effects of sodium new houttuyfonate on growth and biofilm formation of Streptococcus mutans

The present study aimed to assess the impact of sodium new houttuyfonate (SNH) on growth and biofilm formation of Streptococcus mutans, and the combinatorial effects of SNH with cariostatic agents. The effects of SNH on S. mutans planktonic cultures were assessed by growth curve assay. The effects of SNH on S. mutans biofilm and extracellular polysaccharides (EPS) production were observed via crystal violet (CV) assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, colony-forming unit (CFU) counting assay, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Quantitative real-time polymerase chain reaction (qPCR) was applied to investigate the regulatory effects of SNH on the expression of virulence genes of S. mutans. Checkerboard microdilution assay was performed to investigate the combinatorial effects of SNH with two common cariostatic agents. SNH acted as an inhibitor on planktonic cell growth, biofilm formation and EPS production of S. mutans. SNH also downregulated the expression of gtfBCD and comDE systems and exhibited synergism with chlorhexidine (CHX). In conclusion, this study indicated a possibility for SNH to become an anticaries agents by its antimicrobial activity and synergistic effects with CHX against S. mutans.

Sodium New Houttuyfonate Affects Transcriptome and Virulence Factors of Pseudomonas aeruginosa Controlled by Quorum Sensing

As a major opportunistic pathogen, Pseudomonas aeruginosa can produce various virulence factors and form biofilms. These processes are controlled by the quorum sensing (QS) system. Sodium new houttuyfonate (SNH) is an adduct of houttuyfonate, the main component of the common Chinese medicine plant Houttuynia cordata, which has antibacterial and anti-inflammatory effects. We evaluated the effect of SNH on P. aeruginosa biofilms, virulence factors, and transcription. Transcriptome analysis showed that the key rhlI and pqsA genes of the P. aeruginosa QS system were down-regulated after SNH treatment. SNH reduces proteases and pyocyanin production and inhibits biofilm formation by regulating the P. aeruginosa QS system. SNH also changes the expression of genes related to virulence factors and biofilms (lasA, lasB, lecA, phzM, pqsA, and pilG). These results suggested that the mechanism of SNH against P. aeruginosa by affecting the expression of biofilm and virulence factors controlled by quorum sensing.