Serotonin reuptake inhibitors effect on fluconazole activity against resistant Candida glabrata strains

Sertraline exhibits in vivo antifungal activity against Candida auris and enhances the effect of voriconazole in combination

Candida auris is a global health threat due to its multidrug-resistant nature, particularly in intensive care units, where outbreaks are associated with high mortality rates. The urgency for alternative effective strategies has led to the exploration of combination therapy and drug repurposing Out of the possible drugs known with a potential antifungal effect, sertraline, a selective serotonin reuptake inhibitor widely used on clinical settings has shown promising results. This study aimed to evaluate the antifungal activity of sertraline and voriconazole alone and in combination in a murine model of candidaemia due to C. auris. Immunosuppressed BALB/c mice were infected via intravenous injection with C. auris and then received experimental treatments intraperitoneally for 7 days. The therapeutic efficacy was assessed by determining fungal tissue burden and animal survival. Sertraline exhibited a dose-dependent decrease in fungal burden, with the kidneys showing the most substantial reduction. Combination therapy of sertraline + voriconazole demonstrated an enhanced antifungal effect compared to the monotherapy of both drugs. As far as we know, this preclinical study is the first to evaluate the antifungal activity of sertraline, alone and in combination with an antifungal, against C. auris, representing a possible promissory option for adjuvant treatment of candidaemia due to this organism.

The antidepressant drug sertraline is a novel inhibitor of yeast Pah1 and human lipin 1 phosphatidic acid phosphatases

Phosphatidic acid phosphatase (PAP) is an evolutionarily conserved eukaryotic enzyme that catalyzes the Mg2+-dependent dephosphorylation of phosphatidic acid to produce diacylglycerol. The product and substrate of PAP are key intermediates in the synthesis of triacylglycerol and membrane phospholipids. PAP activity is associated with lipid-based cellular defects indicating the enzyme is an important target for regulation. We identified that the antidepressant sertraline is a novel inhibitor of PAP. Using Saccharomyces cerevisiae Pah1 as a model PAP, sertraline inhibited the activity by a noncompetitive mechanism. Sertraline also inhibited the PAP activity of human lipin 1 (α, β, and γ), an orthologue of Pah1. The inhibitor constants of sertraline for the S. cerevisiae and human PAP enzymes were 7-fold and ∼2-fold, respectively, lower than those of propranolol, a commonly used PAP inhibitor. Consistent with the inhibitory mechanism of sertraline and propranolol, molecular docking of the inhibitors predicts that they interact with non-catalytic residues in the haloacid dehalogenase-like catalytic domain of Pah1. The Pah1-CC (catalytic core) variant, which lacks regulatory sequences, was inhibited by both drugs in accordance with molecular docking data. That Pah1 is a physiological target of sertraline in S. cerevisiae is supported by the observations that the overexpression of PAH1 rescued the sertraline-mediated inhibition of pah1Δ mutant cell growth, the lethal effect of overexpressing Pah1-CC was rescued by sertraline supplementation, and that a sublethal dose of the drug resulted in a 2-fold decrease in TAG content.

Exploring the Antibiofilm Effect of Sertraline in Synergy with Cinnamomum verum Essential Oil to Counteract Candida Species

The emergence and spread of drug-resistant pathogens, resulting in antimicrobial resistance, continue to compromise our capability to handle commonly occurring infectious diseases. The rapid global spread of multi-drug-resistant pathogens, particularly systemic fungal infections, presents a significant concern, as existing antimicrobial drugs are becoming ineffective against them. In recent decades, there has been a notable increase in systemic fungal infections, primarily caused by Candida species, which are progressively developing resistance to azoles. Moreover, Candida species biofilms are among the most common in clinical settings. In particular, they adhere to biomedical devices, growing as a resilient biofilm capable of withstanding extraordinarily high antifungal concentrations. In recent years, many research programs have concentrated on the development of novel compounds with possible antimicrobial effects to address this issue, and new sources, such as plant-derived antimicrobial compounds, have been thoroughly investigated. Essential oils (EOs), among their numerous pharmacological properties, exhibit antifungal, antibacterial, and antiviral activities and have been examined at a global scale as the possible origin of novel antimicrobial compounds. A recent work carried out by our research group concerned the synergistic antibacterial activities of commercially available and chemically characterized Cinnamomum verum L. essential oil (C. verum EO) in association with sertraline, a selective serotonin reuptake inhibitor whose repositioning as a non-antibiotic drug has been explored over the years with encouraging results. The aim of this work was to explore the synergistic effects of C. verum EO with sertraline on both planktonic and sessile Candida species cells. Susceptibility testing and testing of the synergism of sertraline and C. verum EO against planktonic and sessile cells were performed using a broth microdilution assay and checkerboard methods. A synergistic effect was evident in both the planktonic cells and mature biofilms, with significant reductions in fungal viability. Indeed, the fractional inhibitory concentration index (FICI) was lower than 0.5 for all the associations, thus indicating significant synergism of the associations with the Candida strains examined. Moreover, the concentrations of sertraline able to inhibit Candida spp. strain growth and biofilm formation significantly decreased when it was used in combination with C. verum EO for all the strains considered, with a reduction percentage in the amount of each associated component ranging from 87.5% to 97%.

Antifungal activity of selective serotonin reuptake inhibitors against Cryptococcus spp. and their possible mechanism of action

Fungal infections caused by Cryptococcus spp. pose a threat to health, especially in immunocompromised individuals. The available arsenal of drugs against cryptococcosis is limited, due to their toxicity and/or lack of accessibility in low-income countries, requiring more therapeutic alternatives. Selective serotonin reuptake inhibitors (SSRIs), through drug repositioning, are a promising alternative to broaden the range of new antifungals against Cryptococcus spp. This study evaluates the antifungal activity of three SSRIs, sertraline, paroxetine, and fluoxetine, against Cryptococcus spp. strains, as well as assesses their possible mechanism of action. Seven strains of Cryptococcus spp. were used. Sensitivity to SSRIs, fluconazole, and itraconazole was evaluated using the broth microdilution assay. The interactions resulting from combinations of SSRIs and azoles were investigated using the checkerboard assay. The possible action mechanism of SSRIs against Cryptococcus spp. was evaluated through flow cytometry assays. The SSRIs exhibited in vitro antifungal activity against Cryptococcus spp. strains, with minimum inhibitory concentrations ranging from 2 to 32 μg/mL, and had synergistic and additive interactions with azoles. The mechanism of action of SSRIs against Cryptococcus spp. involved damage to the mitochondrial membrane and increasing the production of reactive oxygen species, resulting in loss of cellular viability and apoptotic cell death. Fluoxetine also was able to cause significant damage to yeast DNA. These findings demonstrate the in vitro antifungal potential of SSRIs against Cryptococcus spp. strains.

Sertraline has fungicidal activity against Candida spp. and acts by inhibiting membrane and cell wall biosynthesis

Aim: Our study evaluated the activity of sertraline (SER) alone and associated with antifungal drugs in planktonic Candida spp. strains, and investigated its mechanism of action. Materials & methods: Broth microdilution method and minimum fungicidal concentration/MIC ratio were used to assess SER anticandidal activity, and the interaction with antifungals was determined by fractional inhibitory concentration index. The mechanism of action was investigated by flow cytometry and in silico tests. Results: SER inhibited Candida spp. strains at low concentrations by the fungicidal effect and showed no loss of effectiveness when combined. Its action seemed to be related to the membrane and cell wall biosynthesis inhibition. Conclusion: SER has activity against Candida spp. isolated and associated with antifungals, and acts by causing cell wall and membrane damage.

Anti-Candidal Activity of Reboxetine and Sertraline Antidepressants: Effects on Pre-Formed Biofilms

Reboxetine (REB) and sertraline (SER) are antidepressants. The antifungal potential of these drugs against planktonic Candida has been recently reported with limited data about their effects on Candidal biofilms. Biofilms are self-derived extracellular matrixes produced by the microbial population that is attached to biotic surfaces, such as vaginal and oral mucosa, or abiotic surfaces, such as biomedical devices, resulting in persistent fungal infections. The commonly prescribed antifungals, azoles, are usually less effective when biofilms are formed, and most of the prescribed antifungals are only fungistatic. Therefore, the current study investigates the antifungal potentials of REB and SER, alone and in combination with fluconazole (FLC) and itraconazole (ITR) against Candidal biofilms. Using proper controls, Candida species (Candida albicans, C. albicans; Candida krusei, C. krusei; and Candida glabrata, C. glabrata) were used to form biofilms in 96-well microplates. Serial dilutions corresponding to concentrations ranging from 2 to 4096 µg/mL of the target drugs (REB, SER, FLC, ITR) were prepared and added to the plates. Impairment of the biofilm biomass and biofilm metabolic viability was detected using the crystal violet (CV) assay and 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, respectively. In the checkerboard assay, the sessile fractional inhibitory concentration index (SFICI) was calculated to evaluate the effects of drug combinations. SER was more effective in reducing the biomass than REB for C. albicans and C. glabrata, but both were equal for C. krusei. For the reduction in metabolic activity in C. albicans and C. glabrata, SER had a slight advantage over REB. In C. krusei, REB was slightly more potent. Overall, FLC and ITR were almost equal and produced more significant reductions in metabolic activity when compared to SER and REB, except for C. glabrata, where SER was almost equal to FLC. Synergism was detected between REB + FLC and REB + ITR against biofilm cells of C. albicans. Synergism was detected between REB + ITR against biofilm cells of C. krusei. Synergism was detected between REB + FLC and REB + ITR against biofilm cells of C. albicans, C. krusei, and C. glabrata. The results of the present study support the potential of SER and REB as anti-Candidal biofilm agents that are beneficial as a new antifungal to combat Candidal resistance.