Induction of reactive oxygen species by diphenyl diselenide is preceded by changes in cell morphology and permeability in Saccharomyces cerevisiae

Organoselenium compounds, such as diphenyl diselenide (PhSe)₂ and phenylselenium zinc chloride (PhSeZnCl), show protective activities related to their thiol peroxidase activity. However, depending on experimental conditions, organoselenium compounds can cause toxicity by oxidising thiol groups of proteins and induce the production of reactive oxygen species (ROS). Here, we analysed the toxicity of (PhSe)₂ and PhSeZnCl in yeast Saccharomyces cerevisiae. Cell growth of S. cerevisiae after 1, 2, 3, 4, 6, and 16?h of treatment with 2, 4, 6, and 10?μM of (PhSe)₂ was evaluated. For comparative purpose, PhSeZnCl was analysed only at 16?h of incubation at equivalent concentrations of selenium (i.e. 4, 8, 12, and 20?μM). ROS production (DCFH-DA), size, granularity, and cell membrane permeability (propidium iodide) were determined by flow cytometry. (PhSe)₂ inhibited cell growth at 2?h (10?μM) of incubation, followed by increase in cell size. The increase of cell membrane permeability and granularity (10?μM) was observed after 3?h of incubation, however, ROS production occurs only at 16?h of incubation (10?μM) with (PhSe)₂, indicating that ROS overproduction is a more likely consequence of (PhSe)₂ toxicity and not its determinant. All tested parameters showed that only concentration of 20?μM induced toxicity in samples incubated with PhSeZnCl. In summary, the results suggest that (PhSe)₂ toxicity in S. cerevisiae is time and concentration dependent, presenting more toxicity when compared with PhSeZnCl.     

和厚朴酚通过ROS的积累和破坏细胞膜杀死白色念珠菌

[目的]研究在体外情况下和厚朴酚对白色念珠菌的抑制作用及其可能机制。[方法]采用微量稀释法测定和厚朴酚对白色念珠菌的最低抑菌浓度（MIC₈₀）和最低杀菌浓度（MFC）;用透射电镜观察不同浓度和厚朴酚对白色念珠菌超微结构的影响;采用Annexin V-FITC/PI染色法分析不同浓度和厚朴酚对白色念珠菌细胞凋亡的影响;用DCFH-DA染色法测定不同浓度和厚朴酚对白色念珠菌细胞内活性氧积累的影响;用JC-1染色法分析不同浓度和厚朴酚对白色念珠菌线粒体膜电位的影响;用碘化丙啶染色、考马斯亮蓝G-250染色检测和厚朴酚对白色念珠菌细胞膜通透性的影响;通过测定加入麦角甾醇后,和厚朴酚对白色念珠菌的抑制作用的变化,检测和厚朴酚对白色念珠菌细胞膜的影响。[结果]和厚朴酚对白色念珠菌具有很强的抑制作用,MIC和MFC分别为16 μg/mL和32 μg/mL。对白色念珠菌细胞壁、细胞膜和胞浆均有明显的影响。和厚朴酚是通过增加活性氧的产生和破坏线粒体功能来诱导白念珠菌的细胞凋亡和坏死。它也影响细胞膜的通透性,这可能和细胞壁的破坏和与麦角固醇的结合有关。[结论]和厚朴酚通过产生活性氧并伴随着一系列的细胞损伤这种复杂的机制从而对白色念珠菌产生抑制作用,使和厚朴酚成为一种潜在的抗真菌药物。     

The Extracellular Matrix of Candida albicans Biofilms Impairs Formation of Neutrophil Extracellular Traps

Neutrophils release extracellular traps (NETs) in response to planktonic C. albicans. These complexes composed of DNA, histones, and proteins inhibit Candida growth and dissemination. Considering the resilience of Candida biofilms to host defenses, we examined the neutrophil response to C. albicans during biofilm growth. In contrast to planktonic C. albicans, biofilms triggered negligible release of NETs. Time lapse imaging confirmed the impairment in NET release and revealed neutrophils adhering to hyphae and migrating on the biofilm. NET inhibition depended on an intact extracellular biofilm matrix as physical or genetic disruption of this component resulted in NET release. Biofilm inhibition of NETosis could not be overcome by protein kinase C activation via phorbol myristate acetate (PMA) and was associated with suppression of neutrophil reactive oxygen species (ROS) production. The degree of impaired NET release correlated with resistance to neutrophil attack. The clinical relevance of the role for extracellular matrix in diminishing NET production was corroborated in vivo using a rat catheter model. The C. albicans pmr1Δ/Δ, defective in production of matrix mannan, appeared to elicit a greater abundance of NETs by scanning electron microscopy imaging, which correlated with a decreased fungal burden. Together, these findings show that C. albicans biofilms impair neutrophil response through an inhibitory pathway induced by the extracellular matrix.     

Characterization of Candida albicans and Staphylococcus aureus polymicrobial biofilm on different surfaces

BackgroundStaphylococcus aureus and Candida albicans have been co-isolated from biofilm-associated diseases such as denture stomatitis, periodontitis, and burn wound infections, as well as from medical devices. However, the polymicrobial biofilm of both microorganisms has not been fully characterized.AimsTo characterize the polymicrobial biofilm of C. albicans and S. aureus in terms of microbial density, synergy, composition, structure, and stability against antimicrobials and chemical agents.MethodsCrystal violet assay was used to measure the biofilm formation. Scanning electron microscopy and confocal microscopy were used to analyze the structure and chemical composition of the biofilms, respectively.ResultsSupplemented media with fetal bovine serum (FBS) decreased the biofilm formation of S. aureus and the polymicrobial biofilm. For C. albicans, depending on the culture media, the addition of glucose or FBS had a positive effect in biofilm formation. FBS decreased the adhesion to polystyrene wells for both microorganisms. Supplementing the media with glucose and FBS enhanced the growth of C. albicans and S. aureus, respectively. It seems that C. albicans contributes the most to the adhesion process and to the general structure of the biofilms on all the surfaces tested, including a catheter model. Interestingly, S. aureus showed a great adhesion capacity to the surface of C. albicans in the biofilms. Proteins and β-1,6-linked polysaccharides seem to be the most important molecules in the polymicrobial biofilm.ConclusionsThe polymicrobial biofilm had a complex structure, with C. albicans serving as a scaffold where S. aureus adheres, preferentially to the hyphal form of the fungus. Detection of polymicrobial infections and characterization of biofilms will be necessary in the future to provide a better treatment.     

In vitro and in vivo effects of the combination of myricetin and miconazole nitrate incorporated to thermosensitive hydrogels,on C. albicans biofilms

BackgroundCandida albicans-related infections are common infections in clinic, among which biofilm-associated infections are most devastating and challenging to overcome. Myricetin (MY) is a plant-derived natural product with various pharmacological activities. Its anti-biofilm effect against C. albicans and its ability to increase the antifungal effect of miconazole nitrate (MN) were unclear and yet need to be explored.Hypothesis/PurposeIn this study the anti-biofilm effect of MY and its ability to increase the antifungal effect of MN were investigated in vitro and in vivo.Study design and methodsMY or/and MN were incorporated into a thermosensitive hydrogel (TSH) of poloxamer. The safety of MY or/and MN loaded TSHs towards human umbilical vein endothelial cells (HUVEC) was evaluated by a MTT assay and the in vivo safety towards mice knees was confirmed by histopathological examination. The anti-biofilm effect of MY and its ability to increase the antifungal effect of MN were investigated in vitro with C. albicans ATCC 10231 by broth microdilution method, crystal violet staining and scanning electron microscopy (SEM), as well as in vivo in an established mouse model of periprosthetic joint infection (PJI) by SEM, histological analysis, microorganism culture and detection of the serum levels of interleukin-6 (IL-6). The mechanism of action of MY was analyzed by qRT-PCR assay with C. albicans SC5314.ResultsOur results showed that MY and MN incorporated into TSHs exhibited good stability and safety, excellent temperature sensitivity and controlled drug release property. MY (5-640 µg/ml) exhibited no effect on C. albicans cell viability and MY (≥80 µg/ml) showed a significantly inhibitory effect on biofilm formation. MIC₅₀ (the lowest concentrations of drugs resulting in 50% decrease of C. albicans growth) and MIC₈₀ (the lowest concentrations of drugs resulting in 80% decrease of C. albicans growth) of MN were respectively decreased from 2 µg/ml to 0.5 µg/ml and from 4 µg/ml to 2 µg/ml when used in combination with MY (80 µg/ml). The mouse PJI was effectively prevented by MY and MN incorporated into TSH.ConclusionsLocal application of MY and MN incorporated into TSH might be useful for clinical biofilm-associated infections.     

Prostaglandin E2 from Candida albicans Stimulates the Growth of Staphylococcus aureus in Mixed Biofilms

Background

Previous studies showed that Staphylococcus aureus and Candida albicans interact synergistically in dual species biofilms resulting in enhanced mortality in animal models.

Methodology/Principal Findings

The aim of the current study was to test possible candidate molecules which might mediate this synergistic interaction in an in vitro model of mixed biofilms, such as farnesol, tyrosol and prostaglandin (PG) E₂. In mono-microbial and dual biofilms of C.albicans wild type strains PGE₂ levels between 25 and 250 pg/mL were measured. Similar concentrations of purified PGE₂ significantly enhanced S.aureus biofilm formation in a mode comparable to that observed in dual species biofilms. Supernatants of the null mutant deficient in PGE₂ production did not stimulate the proliferation of S.aureus and the addition of the cyclooxygenase inhibitor indomethacin blocked the S.aureus biofilm formation in a dose-dependent manner. Additionally, S. aureus biofilm formation was boosted by low and inhibited by high farnesol concentrations. Supernatants of the farnesol-deficient C. albicans ATCC10231 strain significantly enhanced the biofilm formation of S. aureus but at a lower level than the farnesol producer SC5314. However, C. albicans ATCC10231 also produced PGE₂ but amounts were significantly lower compared to SC5314.

Conclusion/Significance

In conclision, we identified C. albicans PGE₂ as a key molecule stimulating the growth and biofilm formation of S. aureus in dual S. aureus/C. albicans biofilms, although C. albicans derived farnesol, but not tyrosol, may also contribute to this effect but to a lesser extent.     

Inhibition of Candida albicans biofilm formation and yeast-hyphal transition by 4-hydroxycordoin

Candida albicans distinguishing features such as dimorphism and biofilm formation are thought to play a key role in oral tissue invasion and resistance to host defences and antifungal agents. In this study, we investigated the effect of 4-hydroxycordoin, a natural isopentenyloxychalcone, on growth, biofilm formation and yeast-hyphal transition of C. albicans. Serial dilutions of 4-hydroxycordoin in YNB medium were prepared in microplates to determine minimal inhibitory concentrations (MIC) and effects on biofilm formation for two strains of C. albicans. 4-Hydroxycordoin at up to 200 μg/ml had no effect on growth of C. albicans. Biofilm formation was strongly inhibited (>85%) by 4-hydroxycordoin at 20 μg/ml, while concentrations ranging from 50 to 200 μg/ml caused a significant inhibition of yeast-hyphal transition, as determined by microscopic observation. In conclusion, 4-hydroxycordoin exerts inhibitory effects on two important virulence factors of C. albicans: biofilm formation or yeast-hyphal transition. This suggests that 4-hydroxycordoin may have a therapeutic potential for C. albicans infections.     

Histatin 5 Resistance of Candida glabrata Can Be Reversed by Insertion of Candida albicans Polyamine Transporter-Encoding Genes DUR3 and DUR31

Candida albicans and Candida glabrata are predominant fungi associated with oral candidiasis. Histatin 5 (Hst 5) is a small cationic human salivary peptide with high fungicidal activity against C. albicans, however many strains of C. glabrata are resistant. Since Hst 5 requires fungal binding to cell wall components prior to intracellular translocation, reduced Hst 5 binding to C. glabrata may be the reason for its insensitivity. C. glabrata has higher surface levels of β-1,3-glucans as compared with C. albicans; however these differences did not account for reduced Hst 5 uptake and killing in C. glabrata. Similarly, the biofilm matrix of C. glabrata contained significantly higher levels of β-1,3-glucans compared with C. albicans, but it did not reduce the percentage of Hst 5 positive fungal cells in the biofilm. Hst 5 enters C. albicans cell through polyamine transporters Dur3p and Dur31p that are uncharacterized in C. glabrata. C. glabrata strains expressing CaDur3 and CaDur31 had two-fold higher killing and uptake of Hst 5. Thus, neither C. glabrata cell surface or biofilm matrix β-1,3-glucan levels affected Hst 5 toxicity; rather the crucial rate limiting step is reduced uptake that can be overcome by expression of C. albicans Dur proteins in C. glabrata.     

Antifungal activity of a prenylated flavonoid from Dalea elegans against Candida albicans biofilms

BackgroundThe continuing emergence of infections with antifungal resistant Candida strains requires a constant search for new antifungal drugs, with the plant kingdom being an important source of chemical structures.PurposeThe present study investigated the antifungal effect of 2′,4′-dihydroxy-5′-(1′′′,1′′′-dimethylallyl)-8-prenylpinocembrin (8PP, formerly 6PP), a natural prenylflavonoid, on Candida albicans biofilms, and compared this with an azole antifungal (fluconazole) by studying the cellular stress and antioxidant response.Study design/methodsThe fluconazole sensitive (SCa) and azole-resistant (RCa) C. albicans strains were used, with biofilm formation being studied using crystal violet (CV) and confocal scanning laser microscopy (CSLM). The minimal inhibitory concentration for sessile cells (SMIC) was defined as the concentration of antifungal that caused a 50% (SMIC 50) and 80% (SMIC 80) reduction of treated biofilms. The reactive oxygen species (ROS) were detected by the reduction of nitro blue tetrazolium (NBT), and reactive nitrogen intermediates (RNI) were determined by the Griess assay. The activities of the superoxide dismutase (SOD) and catalase (CAT) antioxidant enzymes and the total antioxidant capacity of the biofilms were measured by spectrophotometric methods. ROS accumulation was also detected inside biofilms by using the fluorogenic dye 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA), which was visualized by CSLM.ResultsThe SCa and RCa biofilms were strongly inhibited by 8PP at 100 µM (SMIC 80). We observed that cellular stress affected biofilms growth, resulting in an increase of ROS and also of reactive nitrogen intermediates (RNI), with SOD and CAT being increased significantly in the presence of 8PP. The basal level of the biofilm total antioxidant capacity was higher in RCa than SCa. Moreover, in SCa, the total antioxidant capacity rose considerably in the presence of both 8PP and fluconazole.ConclusionOur data suggest that 8PP may be useful for the treatment of biofilm-related Candida infections, through an accumulation of endogenous ROS and RNI that can induce an adaptive response based on a coordinated increase in antioxidant defenses. 8PP may also have a therapeutic potential in C. albicans infections.     

Plagiochin E,an antifungal bis(bibenzyl), exerts its antifungal activity through mitochondrial dysfunction-induced reactive oxygen species accumulation in Candida albicans

Background

Plagiochin E (PLE) is an antifungal macrocyclic bis(bibenzyl) isolated from liverwort Marchantia polymorpha L. Its antifungal mechanism is unknown. To elucidate the mechanism of action, its effect on mitochondria function in Candida albicans was studied.

Methods

We assayed the mitochondrial membrane potential (mtΔψ) using rhodamine 123, measured ATP level in mitochondria by HPLC, and detected the activities of mitochondrial F₀F₁-ATPase and dehydrogenases. Besides, the mitochondrial dysfunction-induced reactive oxygen species (ROS) production was determined by a fluorometric assay, and the effects of antioxidant L-cysteine on PLE-induced ROS production and the antifungal effect of PLE on C. albicans were also investigated.

Results

Exposure to PLE resulted in an elevation of mtΔψ, and a decrease of ATP level in mitochondria. The ATP depletion owed to PLE-induced enhancement of mitochondrial F₀F₁-ATPase and inhibition of the mitochondrial dehydrogenases. These dysfunctions of mitochondria caused ROS accumulation in C. albicans, and this increase in the level of ROS production and PLE-induced decrease in cell viability were prevented by addition of L-cysteine, indicating that ROS was an important mediator of the antifungal action of PLE.

Conclusions

PLE exerts its antifungal activity through mitochondrial dysfunction-induced ROS accumulation in C. albicans.

General significance

The effect of PLE on the mitochondria function in C. albicans was assayed for the first time. These results would conduce to elucidate its underlying antifungal mechanism.     

Lipopeptides from Bacillus strain AR2 inhibits biofilm formation by Candida albicans

The ability of the human fungal pathogen Candida albicans to reversibly switch between different morphological forms and establish biofilms is crucial for establishing infection. Targeting phenotypic plasticity and biofilm formation in C. albicans represents a new concept for antifungal drug discovery. The present study evaluated the influence of cyclic lipopeptide biosurfactant produced by Bacillus amyloliquefaciens strain AR2 on C. albicans biofilms. The biosurfactant was characterized as a mixture of iturin and fengycin by MALDI-TOF and amino acid analysis. The biosurfactant exhibited concentration dependent growth inhibition and fungicidal activity. The biosurfactant at sub-minimum growth inhibition concentration decreased cell surface hydrophobicity, hindered germ tube formation and reduced the mRNA expression of hyphae-specific gene HWP1 and ALS3 without exhibiting significant growth inhibition. The biosurfactants inhibited biofilm formation in the range of 46–100 % depending upon the concentration and Candida strains. The biosurfactant treatment dislodged 25–100 % of preformed biofilm from polystyrene plates. The biosurfactant retained its antifungal and antibiofilm activity even after exposure to extreme temperature. By virtue of the ability to inhibit germ tube and biofilm formation, two important traits of C. albicans involved in establishing infection, lipopeptides from strain AR2 may represent a potential candidate for developing heat stable anti-Candida drugs.     

Characterization of Mucosal Candida albicans Biofilms

C. albicans triggers recurrent infections of the alimentary tract mucosa that result from biofilm growth. Although the ability of C. albicans to form a biofilm on abiotic surfaces has been well documented in recent years, no information exists on biofilms that form directly on mucosal surfaces. The objectives of this study were to characterize the structure and composition of Candida biofilms forming on the oral mucosa. We found that oral Candida biofilms consist of yeast, hyphae, and commensal bacteria, with keratin dispersed in the intercellular spaces. Neutrophils migrate through the oral mucosa and form nests within the biofilm mass. The cell wall polysaccharide β-glucan is exposed during mucosal biofilm growth and is more uniformly present on the surface of biofilm organisms invading the oral mucosa. We conclude that C. albicans forms complex mucosal biofilms consisting of both commensal bacterial flora and host components. These discoveries are important since they can prompt a shift of focus for current research in investigating the role of Candida-bacterial interactions in the pathogenesis of mucosal infections as well as the role of β-glucan mediated signaling in the host response.     

In vitro activity of eugenol against <Emphasis Type="Italic">Candida albicans</Emphasis> biofilms

Most manifestations of candidiasis are associated with biofilm formation occurring on the surfaces of host tissues and medical devices. Candida albicans is the most frequently isolated causative pathogen of candidiasis, and the biofilms display significantly increased levels of resistance to the conventional antifungal agents. Eugenol, the major phenolic component of clove essential oil, possesses potent antifungal activity. The aim of this study was to investigate the effects of eugenol on preformed biofilms, adherent cells, subsequent biofilm formation and cell morphogenesis of C. albicans. Eugenol displayed in vitro activity against C. albicans cells within biofilms, when MIC₅₀ for sessile cells was 500 mg/L. C. albicans adherent cell populations (after 0, 1, 2 and 4 h of adherence) were treated with various concentrations of eugenol (0, 20, 200 and 2,000 mg/L). The extent of subsequent biofilm formation were then assessed with the tetrazolium salt reduction assay. Effect of eugenol on morphogenesis of C. albicans cells was observed by scanning electron microscopy (SEM). The results indicated that the effect of eugenol on adherent cells and subsequent biofilm formation was dependent on the initial adherence time and the concentration of this compound, and that eugenol can inhibit filamentous growth of C. albicans cells. In addition, using human erythrocytes, eugenol showed low hemolytic activity. These results indicated that eugenol displayed potent activity against C. albicans biofilms in vitro with low cytotoxicity and therefore has potential therapeutic implication for biofilm-associated candidal infections.     

Heparin-benzyl alcohol enhancement of biofilms formation and antifungal susceptibility of vaginal Candida species isolated from pregnant and nonpregnant Saudi women

Biofilm formation by Candida species is a major contribute to their pathogenic potential.The aim of this study was to determine in vitro effects of EDTA, cycloheximide, and heparin-benzyl alcohol preservative on C. albicans (126) and non-albicans (31)vaginal yeast isolates biofilm formations and their susceptibility against three antifungal Etest strips. Results of the crystal violet-assay, indicated that biofilms formation were most commonly observed [100%] for C. kefyr, C. utilis, C. famata, and Rhodotorula mucilaginosa, followed by C. glabrata [70%], C. tropicalis [50%], C. albicans [29%], Saccharomyces cerevisiae [0.0%]. EDTA (0.3mg/ml) significantly inhibited biofilm formation in both C. albicans and non-albicans isolates (P=0.0001) presumably due to chelation of necessary metal cations for the process-completion. In contrast, heparin (-benzyl alcohol preservative) stimulated biofilm formation in all tested isolates, but not at significant level (P=0.567). Conversely, cycloheximide significantly (P=0.0001) inhibited biofilm formation in all C. albicans strains(126) and its effect was even 3 fold more pronounced than EDTA inhibition, probably due to its attenuation of proteins (enzymes) and/or complex molecules necessary for biofilm formation. Results also showed that all nonalbicans yeasts isolates were susceptible to 5-flucytosine (MIC₅₀, 0.016 µg/ml; MIC₉₀, 0.064 µg/ml), but 14% of C. albicans isolates were resistant (MIC₅₀, 0.064 µg/ml; MIC₉₀ >32 µg/ml). The MIC₅₀ value of amphotricin B for all C. albicans and non-albicans isolates was at a narrow range of 0.023 µg /ml, and the MIC₉₀ values were 0.047 µg/ml and 0.064 µg/ml respectively, thereby confirming its efficacy as a first line empiric- treatment of Candida spp infections.     

New Therapeutic Approach: Diphenyl Diselenide Reduces Mitochondrial Dysfunction in Acetaminophen-Induced Acute Liver Failure

The acute liver failure (ALF) induced by acetaminophen (APAP) is closely related to oxidative damage and depletion of hepatic glutathione, consequently changes in cell energy metabolism and mitochondrial dysfunction have been observed after APAP overdose. Diphenyl diselenide [(PhSe)₂], a simple organoselenium compound with antioxidant properties, previously demonstrated to confer hepatoprotection. However, little is known about the protective mechanism on mitochondria. The main objective of this study was to investigate the effects (PhSe)₂ to reduce mitochondrial dysfunction and, secondly, compare in the liver homogenate the hepatoprotective effects of the (PhSe)₂ to the N-acetylcysteine (NAC) during APAP-induced ALF to validate our model. Mice were injected intraperitoneal with APAP (600 mg/kg), (PhSe)₂ (15.6 mg/kg), NAC (1200 mg/kg), APAP+(PhSe)₂ or APAP+NAC, where the (PhSe)₂ or NAC treatment were given 1 h following APAP. The liver was collected 4 h after overdose. The plasma alanine and aspartate aminotransferase activities increased after APAP administration. APAP caused a remarkable increase of oxidative stress markers (lipid peroxidation, reactive species and protein carbonylation) and decrease of the antioxidant defense in the liver homogenate and mitochondria. APAP caused a marked loss in the mitochondrial membrane potential, the mitochondrial ATPase activity, and the rate of mitochondrial oxygen consumption and increased the mitochondrial swelling. All these effects were significantly prevented by (PhSe)₂. The effectiveness of (PhSe)₂ was similar at a lower dose than NAC. In summary, (PhSe)₂ provided a significant improvement to the mitochondrial redox homeostasis and the mitochondrial bioenergetics dysfunction caused by membrane permeability transition in the hepatotoxicity APAP-induced.     

D319 induced antifungal effects through ROS-mediated apoptosis and inhibited isocitrate lyase in Candida albicans

BackgroundCandida albicans (C. albicans) is an opportunistic pathogen that can cause superficial and life-threatening systemic infections in immunocompromised patients. However, the available clinically antifungals are limited. Therefore, the development of effective antifungal agents and therapies is urgently needed. Quinoline type of compounds were reported to possess potent anti-fungal effect. A series of quinoline derivatives were synthesized. Moreover their inhibitory activities and mechanisms on C. albicans were evaluated in this study.MethodsThe structure of D319 was identified by extensive spectroscopic analysis. The antifungal activity of D319 on C. albicans was evaluated using conventional methods, including the inhibition zone diameters with filter paper, Clinical Laboratory Standard Institute (CLSI) broth microdilution method in vitro, and in a murine model in vivo. Flow cytometry, fluorescence microscopy, western blot, knockout mutant and revertant strain techniques, and molecular modeling were applied to explore the mechanism of action of D319 in anti-Candida.ResultsD319 exhibited potent anti-Candida activity with Minimum Inhibitory Concentration value of 2.5 μg/mL in vitro. D319 significantly improved survival rate and reduced fungal burden compared to vehicle control in a murine model in vivo. The treatment of C. albicans with D319 resulted in fungal apoptosis through reactive oxygen species (ROS) accumulation in C. albicans. Furthermore, D319 inhibited the glyoxylate enzyme isocitrate lyase (ICL) of C. albicans, which was also confirmed by docking analysis.ConclusionsQuinoline compound D319 exhibited strong anti-Candida activities in vitro and in vivo models through inhibiting ICL activity and ROS accumulation in C. albicans.General significanceThis study showed that compound D319 as a novel isocitrate lyase inhibitor, would be a promising anti-Candida lead compound, which provided a potential application of this type of compounds in fighting clinical fungal infections. Furthermore, this study also supported ICL as a potential target for anti-Candida drug discovery.