Reassessment of the in vitro synergistic effect of fluconazole with the non-steroidal anti-inflammatory agent ibuprofen against Candida albicans

Ibuprofen as an adjuvant to conventional antimicrobials and essential oil compounds against skin pathogens

AIMS

Antimicrobial resistance continues to be a growing concern, resulting in increased use of drug combinations. Antibiotic adjuvants are an emerging strategy that may potentiate an antibiotics efficacy. Ibuprofen's polypharmacological properties have been investigated for their antimicrobial and host-modulating potential. This study aimed to investigate the potential of a novel multidrug combination involving ibuprofen, essential oil compounds (EOCs), and conventional antimicrobials against skin pathogens.

METHODS AND RESULTS

The minimum inhibitory concentrations of ibuprofen, conventional antimicrobials, and EOCs were determined and then combined and tested against 14 (reference and clinical) skin pathogens. The cytotoxicity was analysed using the MTT assay, whilst the anti-inflammatory effects were evaluated using lipopolysaccharide activated RAW264.7 murine macrophages. Four pairwise (Ibuprofen and antibiotic) (ΣFIC 0.33-0.50) and three triple (Ibuprofen and antibiotic with EOC) (ΣFIC 0.44-0.47) synergistic antimicrobial interactions were identified. These combinations demonstrated cell viability of 77.59%-100%. No combination significantly reduced nitric oxide production.

CONCLUSION

The results from this study provide insight into the potential of a multidrug combination involving ibuprofen with conventional antimicrobials and EOCs against common skin pathogens.

Novel aza-bicyclic 2-isoxazoline acylhydrazone hybrids and their synergistic potential with fluconazole against a drug-resistant Candida albicans strain

As the prevalence of drug-resistant Candida isolates continues to rise, the imperative for identifying novel compounds to enhance the arsenal of antifungal drugs becomes increasingly critical. Consequently, exploring new treatment strategies, including synthesizing molecular hybrids and applying combination therapy, is essential. For this reason, this study evaluated the efficacy of ten molecular hybrids of aza-bicyclic 2-isoxazoline-acylhydrazone belonging to two series 90 and 91 as possible anti-Candida agents. In addition, we also investigated the interaction between the hybrids and fluconazole, a commonly used antifungal drug. We evaluated the antifungal effect of aza-bicyclic 2-isoxazoline-acylhydrazone hybrid compounds against six Candida spp. strains that target planktonic cells. However, none of these new molecules were inhibitory active at the tested concentrations (2 to 1,024 µg/mL). Moreover, we analyzed the interaction between the ten new hybrid molecules and fluconazole using the checkerboard assay, employing two different methodologies for reading the plate. For this, one isolate fluconazole-resistant was selected. We observed that only one combination, 6-(4-tert-butylbenzoil)-4,5,6,6a-tetrahydro-3a-H-pirrole[3,2-d]isoxazole-3-carboxylic(furan-2-metilidene)-hydrazide (91e) and fluconazole, exhibited a synergistic interaction (FICI range 0.0781 to 0.4739). The combination successfully inhibited the growth of C. albicans CA2 fluconazole-resistant, and no interaction was observed in an isolate susceptible to fluconazole. Additionally, these results emphasize the continued need for research into new compounds and the importance of using combined approaches to increase their activity.

Pitavastatin Calcium Confers Fungicidal Properties to Fluconazole by Inhibiting Ubiquinone Biosynthesis and Generating Reactive Oxygen Species

Fluconazole (FLC) is extensively employed for the prophylaxis and treatment of invasive fungal infections (IFIs). However, the fungistatic nature of FLC renders pathogenic fungi capable of developing tolerance towards it. Consequently, converting FLC into a fungicidal agent using adjuvants assumes significance to circumvent FLC resistance and the perpetuation of fungal infections. This drug repurposing study has successfully identified pitavastatin calcium (PIT) as a promising adjuvant for enhancing the fungicidal activity of FLC from a comprehensive library of 2372 FDA-approved drugs. PIT could render FLC fungicidal even at concentrations as low as 1 μM. The median lethal dose (LD50) of PIT was determined to be 103.6 mg/kg. We have discovered that PIT achieves its synergistic effect by inhibiting the activity of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, thereby impeding ubiquinone biosynthesis, inducing reactive oxygen species (ROS) generation, triggering apoptosis, and disrupting Golgi function. We employed a Candida albicans strain that demonstrated a notable tolerance to FLC to infect mice and found that PIT effectively augmented the antifungal efficacy of FLC against IFIs. This study is an illustrative example of how FDA-approved drugs can effectively eliminate fungal tolerance to FLC.

Can nonsteroidal anti-inflammatory drugs (NSAIDs) be repurposed for fungal infection?

Nonsteroidal anti-inflammatory drugs (NSAIDs) are an important class of anti-inflammatory drugs widely used for the treatment of musculoskeletal disorders, mild-to-moderate pain, and fever. This review aimed to explain the functional role and possible mechanisms of the antifungal effects of NSAIDs alone or in combination with antifungal drugs in vitro and in vivo. Several studies reported that NSAIDs such as aspirin, ibuprofen, diclofenac, indomethacin, ketorolac, celecoxib, flurbiprofen, and nimesulide had antifungal activities in vitro, either fungistatic or fungicidal, against different strains of Candida, Aspergillus, Cryptococcus, Microsporum, and Trichophyton species. These drugs inhibited biofilm adhesion and development, and yeast-to-hypha conversion which may be related to a prostaglandin E2 (PGE2)/PGEx-dependent mechanism. Modulating PGE2 levels by NSAIDs during fungal infection can be introduced as a possible mechanism to overcome. In addition, some important mechanisms of the antifungal activities of NSAIDs and their new derivatives on fungi and host immune responses are summarized. Overall, we believe that using NSAIDs along with classical antifungal drugs has the potential to be investigated as a novel therapeutic strategy in clinical studies. Furthermore, combination therapy can help manage resistant strains, increase the efficacy of antifungal drugs, and reduce toxicity.

Design, Synthesis, and Biological Evaluation of Dual-Target COX-2/CYP51 Inhibitors for the Treatment of Fungal Infectious Diseases

The design of novel dual-target (COX-2/CYP51) inhibitors was proposed in the study, and three series of compounds were constructed though the pathway of skeleton screening and combination; their molecular structures were synthesized and evaluated. Most of the compounds exhibited significant antifungal ability. Among them, potential compounds (10a-2, 16b-3) with excellent antifungal and anti-drug-resistant fungal ability (MIC₅₀, 0.125-2.0 μg/mL) were selected for the subsequent mechanistic study. On the one hand, these compounds could block the ergosterol biosynthesis pathway by inhibiting CYP51 and influence the internal physiological function of fungal cells, which included the increase of the ROS level, the anomaly of ΔΨ_m, and the emergence of an apoptotic state. On the other hand, these compounds also effectively showed COX-2 inhibition ability, eliminated the inflammatory reaction of the infected region, and activated the body's immune function. In summary, this study not only provided a novel antifungal drug design pathway but also discovered excellent target compounds.

Intestinal Infection of Candida albicans: Preventing the Formation of Biofilm by C. albicans and Protecting the Intestinal Epithelial Barrier

The large mortality and morbidity rate of C. albicans infections is a crucial problem in medical mycology. Because the generation of biofilms and drug resistance are growing concerns, the growth of novel antifungal agents and the looking for newer objectives are necessary. In this review, inhibitors of C. albicans biofilm generation and molecular mechanisms of intestinal epithelial barrier protection are elucidated. Recent studies on various transcription elements; quorum-sensing molecules; host responses to adherence; and changes in efflux pumps, enzymes, bud to hyphal transition, and lipid profiles have increased the knowledge of the intricate mechanisms underlying biofilm resistance. In addition, the growth of novel biomaterials with anti-adhesive nature, natural products, drugs, bioactive compounds, proteins, lipids, and carbohydrates are being researched. Recently, more and more attention has been given to various metal nanoparticles that have also appeared as antibiofilm agents in C. albicans. The intestinal epithelial obstacle exerts an crucial effect on keeping intestinal homeostasis and is increasingly associated with various disorders associated with the intestine such as inflammatory bowel disease (IBD), irritable bowel syndrome, metabolic syndrome, allergies, hepatic inflammation, septic shock, etc. However, whether their involvement in the prevention of other intestinal disorders like IBD are useful in C. albicans remains unknown. Further studies must be carried out in order to validate their inhibition functions in intestinal C. albicans. This provides innovates ideas for intestinal C. albicans treatment.

Fluconazole-COX Inhibitor Hybrids: A Dual-Acting Class of Antifungal Azoles

When used in combination with azole antifungal drugs, cyclooxygenase (COX) inhibitors such as ibuprofen improve antifungal efficacy. We report the conjugation of a chiral antifungal azole pharmacophore to COX inhibitors and the evaluation of activity of 24 hybrids. Hybrids derived from ibuprofen and flurbiprofen were considerably more potent than fluconazole and comparable to voriconazole against a panel of Candida species. The potencies of hybrids composed of an S-configured azole pharmacophore were higher than those with an R-configured pharmacophore. Tolerance, defined as the ability of a subpopulation of cells to grow in the presence of the drug, to the hybrids was lower than to fluconazole and voriconazole. The hybrids were active against a mutant lacking CYP51, the target of azole drugs, indicating that these agents act via a dual mode of action. This study established that azole-COX inhibitor hybrids are a novel class of potent antifungals with clinical potential.

Design, synthesis and biological evaluation of a series of iron and copper chelating deferiprone derivatives as new agents active against Candida albicans

Candida albicans, in specific conditions, is responsible of severe invasive systemic candidiasis that are related to its ability to produce biofilm on biological and artificial surfaces. Many studies reported the role of iron in fungal growth and virulence and the ability of metal chelating agents to interfere with C. albicans metabolism, virulence and biofilm formation. Here we report the activity of 3-hydroxy-1,2-dimethyl-4(1H)-pyridinone (deferiprone) derivatives against C. albicans planktonic cells and biofilm. Some of the studied compounds (2b and 3b) were able to chelate Fe(III) and Cu(II), and showed an interesting activity on planktonic cells (MIC₅₀ of 32 μg/mL and 16 μg/mL respectively) and on biofilm formation (BMIC₅₀ of 32 μg/mL and 16 μg/mL respectively) in cultured ATCC 10,231C. albicans; this activity was reduced, in a concentration dependent way, by the addition of Fe(III) and Cu(II) to the culture media. Furthermore, the most active compound 3b showed a low toxicity on Galleria mellonella larvae.

Candida albicans Antifungal Resistance and Tolerance in Bloodstream Infections: The Triad Yeast-Host-Antifungal

Candida albicans represents the most frequent isolated yeast from bloodstream infections. Despite the remarkable progress in diagnostic and therapeutic approaches, these infections continue to be a critical challenge in intensive care units worldwide. The economic cost of bloodstream fungal infections and its associated mortality, especially in debilitated patients, remains unacceptably high. Candida albicans is a highly adaptable microorganism, being able to develop resistance following prolonged exposure to antifungals. Formation of biofilms, which diminish the accessibility of the antifungal, selection of spontaneous mutations that increase expression or decreased susceptibility of the target, altered chromosome abnormalities, overexpression of multidrug efflux pumps and the ability to escape host immune defenses are some of the factors that can contribute to antifungal tolerance and resistance. The knowledge of the antifungal resistance mechanisms can allow the design of alternative therapeutically options in order to modulate or revert the resistance. We have focused this review on the main factors that are involved in antifungal resistance and tolerance in patients with C. albicans bloodstream infections.

Potential Antifungal Targets against a Candida Biofilm Based on an Enzyme in the Arachidonic Acid Cascade-A Review

Candida is an important opportunistic fungal pathogen, especially in biofilm associated infections. The formation of a Candida biofilm can decrease Candida sensitivity to antifungal drugs and cause drug resistance. Although many effective antifungal drugs are available, their applications are limited due to their high toxicity and cost. Seeking new antifungal agents that are effective against biofilm-associated infection is an urgent need. Many research efforts are underway, and some progress has been made in this field. It has been shown that the arachidonic acid cascade plays an important role in fungal morphogenesis and pathogenicity. Notably, prostaglandin E2 (PGE₂) can promote the formation of a Candida biofilm. Recently, the inhibition of PGE₂ has received much attention. Studies have shown that cyclooxygenase (COX) inhibitors, such as aspirin, ibuprofen, and indomethacin, combined with fluconazole can significantly reduce Candida adhesion and biofilm development and increase fluconazole susceptibility; the MIC of fluconazole can be decrease from 64 to 2 μg/ml when used in combination with ibuprofen. In addition, in vivo studies have also confirmed the antifungal activities of these inhibitors. In this article, we mainly review the relationship between PGE₂ and Candida biofilm, summarize the antifungal activities of COX inhibitors and analyze the possible antifungal activity of microsomal prostaglandin E synthase-1 (MPGES-1) inhibitors; additionally, other factors that influence PGE₂ production are also discussed. Hopefully this review can disclose potential antifungal targets based on the arachidonic acid cascade and provide a prevailing strategy to alleviate Candida albicans biofilm formation.

Ibuprofen-mediated reversal of fluconazole resistance in clinical isolates of Candida

INTRODUCTION

In view of the increasing prevalence of invasive Candidiasis in today's health-care scenario and the emergence of fluconazole resistance among clinical isolates of Candida, we sought to determine if Ibuprofen could elicit a reversal of fluconazole resistance and thereby offer a potential therapeutic breakthrough in fluconazole-resistant Candidiasis.

MATERIALS AND METHODS

We selected 69 clinical isolates of Candida, which demonstrated an MIC of >32 μg/ml for fluconazole, and subjected them to broth microdilution in presence and absence of Ibuprofen.

RESULTS

Forty two of the 69 isolates (60.9%) demonstrated reversal of Fluconazole resistance with concomitant use of Ibuprofen. This was characterized by significant species-wise variation (p=0.00008), with all the C. albicans isolates and none of the C. glabrata isolates demonstrating such reversal. Only 22.2% and 37.7% of C. krusei and C. tropicalis isolates respectively showed Ibuprofen-mediated reversal of Fluconazole resistance.

CONCLUSION

Since Ibuprofen is a known efflux pump inhibitor, our findings hint at the possible mechanism of Fluconazole resistance in most of our Candida isolates and suggest a potential therapeutic alternative that could be useful in the majority of Fluconazole-resistant clinical isolates of Candida.

Potent drugs that attenuate anti-Candida albicans activity of fluconazole and their possible mechanisms of action

Fluconazole (FLCZ) is a first-line drug for treating Candida albicans infections, but clinical failure due to reduced sensitivity is a growing concern. Our previous study suggested that certain drug combinations pose a particular challenge in potently reducing FLCZ's anti-C. albicans activity, and cyclooxygenase inhibitors formed the major group of these attenuating drugs in combination with FLCZ. In this study, we examined the effects of diclofenac sodium (DFNa) and related compounds in combination with FLCZ against C. albicans, and investigated their possible mechanisms of interaction. DFNa, ibuprofen, and omeprazole elevated the minimum inhibitory concentration (MIC) of FLCZ by 8-, 4-, and 4-fold, respectively; however, loxoprofen sodium and celecoxib did not. An analogue of DFNa, 2,6-dichlorodiphenylamine, also elevated the MIC by 4-fold. Gene expression analysis revealed that diclofenac sodium induced CDR1 efflux pump activity, but not CDR2 activity. In addition, an efflux pump CDR1 mutant, which was manipulated to not be induced by DFNa, showed less elevation of MIC compared to that shown by the wild type. Therefore, DFNa and related compounds are potent factors for reducing the sensitivity of C. albicans to FLCZ partly via induction of an efflux pump. Although it is not known whether such antagonism is relevant to the clinical treatment failure observed, further investigation of the molecular mechanisms underlying the reduction of FLCZ's anti-C. albicans activity is expected to promote safer and more effective use of the drug.

Combinatory effect of fluconazole and FDA-approved drugs against Candida albicans

Candida albicans is the primary cause of systemic candidiasis, which has a high mortality rate. Unfortunately, the number of antifungal drugs available for treatment of Candida infections is limited, and there is an urgent need for development of new drugs and alternative therapeutic options. We investigated the combinatory effect of fluconazole (FLCZ) and 640 FDA-approved drugs in vitro. Ten drugs enhanced and 77 drugs attenuated the antifungal activity of FLCZ. Other drugs did not appear to alter the antifungal activity of FLCZ, although 17 drugs displayed potency equivalent to or greater than that of FLCZ. The 10 FLCZ-enhancing drugs included three inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA reductase, whose synergistic activity had been reported previously. However, the antifungal effects of 3 FLCZ enhancers-artesunate, carvedilol, and bortezomib-were previously unknown. In addition, many drugs were found to attenuate the antifungal activity of FLCZ, including 17 cyclooxygenase (COX) inhibitors, 15 estrogen-related agents, vitamin A- and D-related compounds, antihypertensive drugs, and proton pump inhibitors. Although the clinical significance remains to be determined, analyses of molecular events responsible for synergy or antagonism could provide insight into more efficient use of existing antifungals and lead to novel therapies.

In vitro synergy of pseudolaric acid B and fluconazole against clinical isolates of Candida albicans

Candida albicans is the most common fungal pathogen in humans. The emergence of resistance to azole antifungals has raised the issue of using such antifungals in combination to optimise therapeutic outcome. The objective of this study was to evaluate in vitro synergy of pseudolaric acid B (PAB) and fluconazole (FLC) against clinical isolates of C. albicans. The in vitro antifungal activity of PAB, a diterpene acid from Pseudolarix kaempferi Gordon, was evaluated alone and in combination with FLC against 22 FLC-resistant (FLC-R) and 12 FLC-susceptible (FLC-S) C. albicans using the chequerboard microdilution method and time-killing test assays. Synergism was observed in all 22 (100%) FLC-R strains tested as determined by both fractional inhibitory concentration index (FICI) with values ranging from 0.02 to 0.13 and bliss independence (BI) models. Synergism was observed in two of 12 (17%) FLC-S strains as determined by FICI model with values ranging from 0.25 to 0.5 and in three of 12 (18%) FLC-S strains as determined by BI model. For FLC-R strains, the drug concentrations of FLC and PAB, where synergistic interactions were found, ranged from 0.06 to 4 μg ml(-1) and 0.5 to 4 μg ml(-1) respectively. For FLC-S strains, the drug concentrations of FLC and PAB were 1-8 μg ml(-1) and 0.5-4 μg ml(-1) respectively. The BI model gave results consistent with FICI, but no antagonistic activity was observed in any of the strains tested. These interactions between PAB and FLC were confirmed using the time-killing test for the selected strains. Fluconazole and PAB exhibited a good synergism against azole-R isolates of C. albicans.

In vitro activity of terbinafine associated to amphotericin B, fluvastatin, rifampicin, metronidazole and ibuprofen against Pythium insidiosum

We evaluated the in vitro activities of terbinafine alone and in combination with amphotericin B, fluvastatin, rifampicin, metronidazole or ibuprofen against 17 clinical isolates of Pythium insidiosum. The assays were based on technique M38-A2, as well as the checkerboard microdilution method. The main synergism observed was by combination of terbinafine plus amphotericin B (41.18%). Antagonisms were observed in combinations of terbinafine with fluvastatin (35.30%) or rifampicin (5.88%).

Paradoxical growth effects of the echinocandins caspofungin and micafungin, but not of anidulafungin, on clinical isolates of Candida albicans and C. dubliniensis

OBJECTIVES

To analyze the effects of a high concentration of three antifungal substances, the echinocandins anidulafungin, caspofungin, and micafungin, on the growth of Candida spp.

METHODS

The growth of 127 C. dubliniensis isolates and 103 C. albicans isolates cultured in medium containing anidulafungin, caspofungin, or micafungin was analyzed using a broth microdilution test according to the guidelines of the CLSI M27-A2 [NCCLS (1997), Wayne, PA]. The final concentrations of all three echinocandins ranged from 0.125 to 64 microg/L.

RESULTS

The different effects of these three antifungal substances on C. albicans cells in comparison to C. dubliniensis cells were quite distinct. When both Candida species were grown in the presence of anidulafungin only a trailing effect was observed. Micafungin induced an Eagle effect in C. dubliniensis only (63%), while caspofungin induced this effect in the majority of C. dubliniensis isolates (90%) and in only a few C. albicans isolates (14%).

CONCLUSIONS

Based on our observations, anidulafungin has effects that are different from the ones produced by micafungin and caspofungin. Whether this different response to high concentrations of echinocandins is based on genetic or phenotypic differences between C. albicans and C. dubliniensis has to be determined in future experiments.

Stochastic detection of enantiomers

The rapid quantification of the enantiomers of small chiral molecules is very important, notably in pharmacology. Here, we show that the enantiomers of drug molecules can be distinguished by stochastic sensing, a single-molecule detection technique. The sensing element is an engineered alpha-hemolysin protein pore, fitted with a beta-cyclodextrin adapter. By using the approach, the enantiomeric composition of samples of ibuprofen and thalidomide can be determined in less than 1 s.