Azole affinity of sterol 14α-demethylase (CYP51) enzymes from Candida albicans and Homo sapiens. Antimicrob Agents Chemother. 2013;57:1352-1360. [PMID: 23274672 DOI: 10.1128/aac.02067-12]

The fungicide propiconazole induces hepatic steatosis and activates PXR in a mouse model of diet-induced obesity

Propiconazole is a triazole fungicide previously shown to induce triglyceride accumulation in human liver HepaRG cells, potentially via activation of the Pregnane X Receptor (PXR). However, whether propiconazole can disrupt hepatic and whole-body metabolism in vivo is currently unknown. Therefore, we aimed to examine the metabolic effects of propiconazole in the context of metabolic dysfunction-associated steatotic liver disease (MASLD), obesity, and insulin resistance. To this end, male C57BL/6J mice were fed a high-fat diet for 20 weeks. During the last 10 weeks, mice additionally received vehicle, 0.04, 30, or 100 mg/kg body weight (bw)/day propiconazole via oral gavage. High-dose propiconazole, but not low or intermediate dose, reduced body weight gain and adipose tissue weight in obese mice. Mice receiving high-dose propiconazole displayed improved glucose tolerance and reduced levels of plasma triglycerides and cholesterol. Propiconazole dose-dependently increased liver weight and triglyceride levels and at high dose caused signs of hepatic inflammation. RNA sequencing on the liver revealed that propiconazole mainly induced PXR target genes. At intermediate and high dose, propiconazole induced pathways related to cell-cell interactions and inflammation, while oxidative phosphorylation was repressed by propiconazole. Comparison of gene regulation in wildtype and PXR knockout primary hepatocytes as well as gene reporter assays confirmed the activation of PXR by propiconazole. All in all, our data underscore the capacity of propiconazole to activate PXR in the liver and thereby promote the development of hepatic steatosis in vivo.

Novel yeast-based biosensor for environmental monitoring of tebuconazole

Due to increasing demand for high and stable crop production, human populations are highly dependent on pesticide use for growing and storing food. Environmental monitoring of these agrochemicals is therefore of utmost importance, because of their collateral effects on ecosystem and human health. Even though most current-use analytical methods achieve low detection limits, they require procedures that are too complex and costly for routine monitoring. As such, there has been an increased interest in biosensors as alternative or complementary tools to streamline detection and quantification of environmental contaminants. In this work, we developed a biosensor for environmental monitoring of tebuconazole (TEB), a common agrochemical fungicide. For that purpose, we engineered S. cerevisiae cells with a reporter gene downstream of specific promoters that are expressed after exposure to TEB and characterized the sensitivity and specificity of this model system. After optimization, we found that this easy-to-use biosensor consistently detects TEB at concentrations above 5 μg L-1 and does not respond to realistic environmental concentrations of other tested azoles, suggesting it is specific. We propose the use of this system as a complementary tool in environmental monitoring programs, namely, in high throughput scenarios requiring screening of numerous samples. KEY POINTS: • A yeast-based biosensor was developed for environmental monitoring of tebuconazole. •The biosensor offers a rapid and easy method for tebuconazole detection ≥ 5 μg L-1. •The biosensor is specific to tebuconazole at environmentally relevant concentrations.

Advancements in the nanodelivery of azole-based fungicides to control oil palm pathogenic fungi

The cultivation of oil palms is of great importance in the global agricultural industry due to its role as a primary source of vegetable oil with a wide range of applications. However, the sustainability of this industry is threatened by the presence of pathogenic fungi, particularly Ganoderma spp., which cause detrimental oil palm disease known as basal stem rot (BSR). This unfavorable condition eventually leads to significant productivity losses in the harvest, with reported yield reductions of 50-80 % in severely affected plantations. Azole-based fungicides offer potential solutions to control BSR, but their efficacy is hampered by limited solubility, penetration, distribution, and bioavailability. Recent advances in nanotechnology have paved the way for the development of nanosized delivery systems. These systems enable effective fungicide delivery to target pathogens and enhance the bioavailability of azole fungicides while minimising environmental and human health risks. In field trials, the application of azole-based nanofungicides resulted in up to 75 % reduction in disease incidence compared to conventional fungicide treatments. These innovations offer opportunities for the development of sustainable agricultural practices. This review highlights the importance of oil palm cultivation concerning the ongoing challenges posed by pathogenic fungi and examines the potential of azole-based fungicides for disease control. It also reviews recent advances in nanotechnology for fungicide delivery, explores the mechanisms behind these nanodelivery systems, and emphasises the opportunities and challenges associated with azole-based nanofungicides. Hence, this review provides valuable insights for future nanofungicide development in effective oil palm disease control.

Design, Synthesis, Investigation, and Biological Activity Assessments of (4-Substituted-Phenyl)-N-(3-morpholinopropyl)-3-phenylthiazol-2(3H)-imine Derivatives as Antifungal Agents

In this study, a series of novel thiazol-2(3H)-imine (2a-2j) were designed, synthesized, and characterized by means of 1H NMR, 13C NMR, and HRMS spectral analyses. In vitro antifungal activity was performed using a modified EUCAST protocol. Two of the synthesized compounds (2d and 2e) showed activity against Candida albicans and Candida parapsilosis. Compound 2e showed activity against C. parapsilosis (MIC50 = 1.23 μg/mL) for 48 h. This value is very similar to ketoconazole. The dynamic analysis of the potential compounds 2d and 2e revealed notable stability while interacting with the 14α-demethylase enzyme substrate. The absorption, distribution, metabolism, and excretion (ADME) studies of the candidate compound showed acceptable ADME parameter data and verified their drug-likeness characteristics. According to the results of this study, compound 4-(4-fluorophenyl)-N-(3-morpholinopropyl)-3-phenylthiazol-2(3H)-imine (2e) and its derivatives as 14α-demethylase inhibitors can be used as a new antifungal for further structural improvements and additional research.

Decoding the Role of CYP450 Enzymes in Metabolism and Disease: A Comprehensive Review

Cytochrome P450 (CYP450) is a group of enzymes that play an essential role in Phase I metabolism, with 57 functional genes classified into 18 families in the human genome, of which the CYP1, CYP2, and CYP3 families are prominent. Beyond drug metabolism, CYP enzymes metabolize endogenous compounds such as lipids, proteins, and hormones to maintain physiological homeostasis. Thus, dysregulation of CYP450 enzymes can lead to different endocrine disorders. Moreover, CYP450 enzymes significantly contribute to fatty acid metabolism, cholesterol synthesis, and bile acid biosynthesis, impacting cellular physiology and disease pathogenesis. Their diverse functions emphasize their therapeutic potential in managing hypercholesterolemia and neurodegenerative diseases. Additionally, CYP450 enzymes are implicated in the onset and development of illnesses such as cancer, influencing chemotherapy outcomes. Assessment of CYP450 enzyme expression and activity aids in evaluating liver health state and differentiating between liver diseases, guiding therapeutic decisions, and optimizing drug efficacy. Understanding the roles of CYP450 enzymes and the clinical effect of their genetic polymorphisms is crucial for developing personalized therapeutic strategies and enhancing drug responses in diverse patient populations.

Silver(I) complexes with voriconazole as promising anti-Candida agents

Recognizing that metal ions play an important role in modifying the pharmacological properties of known organic-based drugs, the present manuscript addresses the complexation of the antifungal agent voriconazole (vcz) with the biologically relevant silver(I) ion as a strategy for the development of new antimycotics. The synthesized silver(I) complexes with vcz were characterized by mass spectrometry, IR, UV-Vis and NMR spectroscopy and single-crystal X-ray diffraction analysis. The crystallographic results showed that complexes {[Ag(vcz)(H2O)]CH3SO3}n (1), {[Ag(vcz)2]BF4}n (2) and {[Ag(vcz)2]PF6}n (3) have polymeric structures in the solid state, in which silver(I) ions have a distorted tetrahedral geometry. On the other hand, DFT calculations revealed that the investigated silver(I) complexes 1-3 in DMSO exist as linear [Ag(vcz-N2)(vcz-N19)]+ (1a), [Ag(vcz-N2)(vcz-N4)]+ (2a) and [Ag(vcz-N4)2]+ (3a) species, respectively. The evaluated complexes showed an enhanced anti-Candida activity compared to the parent drug with minimal inhibitory concentration (MIC) values in the range of 0.02-1.05 μM. In comparison with vcz, the corresponding silver(I) complexes showed better activity in prevention hyphae and biofilm formation of C. albicans, indicating that they could be considered as promising agents against Candida that significantly inhibit its virulence. Also, these complexes are much better inhibitors of ergosterol synthesis in the cell membrane of C. albicans at the concentration of 0.5 × MIC. This is also confirmed by a molecular docking, which revealed that complexes 1a - 3a showed better inhibitory activity than vcz against the sterol 14α-demethylase enzyme cytochrome P450 (CYP51B), which plays a crucial role in the formation of ergosterol.

Azole resistance in Aspergillus fumigatus- comprehensive review

Aspergillus fumigatus is a ubiquitous filamentous fungus commonly found in the environment. It is also an opportunistic human pathogen known to cause a range of respiratory infections, such as invasive aspergillosis, particularly in immunocompromised individuals. Azole antifungal agents are widely used for the treatment and prophylaxis of Aspergillus infections due to their efficacy and tolerability. However, the emergence of azole resistance in A. fumigatus has become a major concern in recent years due to their association with increased treatment failures and mortality rates. The development of azole resistance in A. fumigatus can occur through both acquired and intrinsic mechanisms. Acquired resistance typically arises from mutations in the target enzyme, lanosterol 14-α-demethylase (Cyp51A), reduces the affinity of azole antifungal agents for the enzyme, rendering them less effective, while intrinsic resistance refers to a natural resistance of certain A. fumigatus isolates to azole antifungals due to inherent genetic characteristics. The current review aims to provide a comprehensive overview of azole antifungal resistance in A. fumigatus, discusses underlying resistance mechanisms, including alterations in the target enzyme, Cyp51A, and the involvement of efflux pumps in drug efflux. Impact of azole fungicide uses in the environment and the spread of resistant strains is also explored.

Silver(I) complexes containing antifungal azoles: significant improvement of the anti-Candida potential of the azole drug after its coordination to the silver(I) ion

Inspired by the emergence of resistance to currently available antifungal therapy and by the great potential of metal complexes for the treatment of various diseases, we synthesized three new silver(I) complexes containing clinically used antifungal azoles as ligands, [Ag(ecz)2]SbF6 (1, ecz is econazole), {[Ag(vcz)2]SbF6}n (2, vcz is voriconazole), and [Ag(ctz)2]SbF6 (3, ctz is clotrimazole), and investigated their antimicrobial properties. The synthesized complexes were characterized by mass spectrometry, IR, UV-vis and 1H NMR spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction analysis. In the mononuclear complexes 1 and 3 with ecz and ctz, respectively, the silver(I) ion has the expected linear geometry, in which the azoles are monodentately coordinated to this metal center through the N3 imidazole nitrogen atom. In contrast, the vcz-containing complex 2 has a polymeric structure in the solid state in which the silver(I) ions are coordinated by four nitrogen atoms in a distorted tetrahedral geometry. DFT calculations were done to predict the most favorable structures of the studied complexes in DMSO solution. All the studied silver(I) complexes have shown excellent antifungal and good to moderate antibacterial activities with minimal inhibitory concentration (MIC) values in the ranges of 0.01-27.1 and 2.61-47.9 μM on the selected panel of fungi and bacteria, respectively. Importantly, the complexes 1-3 have exhibited a significantly improved antifungal activity compared to the free azoles, with the most pronounced effect observed in the case of complex 2 compared to the parent vcz against Candida glabrata with an increase of activity by five orders of magnitude. Moreover, the silver(I)-azole complexes 2 and 3 significantly inhibited the formation of C. albicans hyphae and biofilms at the subinhibitory concentration of 50% MIC. To investigate the impact of the complex 3 more thoroughly on Candida pathogenesis, its effect on the adherence of C. albicans to A549 cells (human adenocarcinoma alveolar basal epithelial cells), as an initial step of the invasion of host cells, was studied.

Pluronic F-127 Enhances the Antifungal Activity of Fluconazole against Resistant Candida Strains

Candida strains as the most frequent causes of infections, along with their increased drug resistance, pose significant clinical and financial challenges to the healthcare system. Some polymeric excipients were reported to interfere with the multidrug resistance mechanism. Bearing in mind that there are a limited number of marketed products with fluconazole (FLU) for the topical route of administration, Pluronic F-127 (PLX)/FLU formulations were investigated in this work. The aims of this study were to investigate (i) whether PLX-based formulations can increase the susceptibility of resistant Candida strains to FLU, (ii) whether there is a correlation between block polymer concentration and the antifungal efficacy of the FLU-loaded PLX formulations, and (iii) what the potential mode of action of PLX assisting FLU is. The yeast growth inhibition upon incubation with PLX formulations loaded with FLU was statistically significant. The highest efficacy of the azole agent was observed in the presence of 5.0 and 10.0% w/v of PLX. The upregulation of the CDR1/CDR2 genes was detected in the investigated Candida strains, indicating that the efflux of the drug from the fungal cell was the main mechanism of the resistance.

Impacts of prothioconazole and prothioconazole-desthio on bile acid and glucolipid metabolism: Upregulation of CYP7A1 expression in HepG2 cells

As an efficient triazole fungicide, prothioconazole (PTC) is widely used for the prevention and control of plant fungal pathogens. It was reported that the residues of PTC and prothioconazole-desthio (PTC-d) have been detected in the environment and crops, and the effects of PTC-d may be higher than that of PTC. Currently, PTC and PTC-d have been proven to induce hepatic metabolic disorders. However, their toxic effects on cellular bile acid (BA) and glucolipid metabolism remain unknown. In this study, HepG2 cells were exposed to 1-500 μM of PTC or PTC-d. High concentrations of PTC and PTC-d were found to induce cytotoxicity; thus, subsequent experimental exposure was conducted at concentrations of 10-50 μM. The expression levels of CYP7A1 and TG synthesis-related genes and levels of TG and total BA were observed to increase in HepG2 cells. Molecular docking analysis revealed direct interactions between PTC or PTC-d and CYP7A1 protein. To further investigate the underlying mechanisms, PTC and PTC-d were treated to HepG2 cells in which CYP7A1 expression was knocked down using siCYP7A1. It was observed that PTC and PTC-d affected the BA metabolism process and regulated the glycolipid metabolism process by promoting the expression of CYP7A1. In summary, we comprehensively analyzed the effects and mechanisms of PTC and PTC-d on cellular metabolism in HepG2 cells, providing theoretical data for evaluating the safety and potential risks associated with these substances.

Lipid-Centric Approaches in Combating Infectious Diseases: Antibacterials, Antifungals and Antivirals with Lipid-Associated Mechanisms of Action

One of the global challenges of the 21st century is the increase in mortality from infectious diseases against the backdrop of the spread of antibiotic-resistant pathogenic microorganisms. In this regard, it is worth targeting antibacterials towards the membranes of pathogens that are quite conservative and not amenable to elimination. This review is an attempt to critically analyze the possibilities of targeting antimicrobial agents towards enzymes involved in pathogen lipid biosynthesis or towards bacterial, fungal, and viral lipid membranes, to increase the permeability via pore formation and to modulate the membranes' properties in a manner that makes them incompatible with the pathogen's life cycle. This review discusses the advantages and disadvantages of each approach in the search for highly effective but nontoxic antimicrobial agents. Examples of compounds with a proven molecular mechanism of action are presented, and the types of the most promising pharmacophores for further research and the improvement of the characteristics of antibiotics are discussed. The strategies that pathogens use for survival in terms of modulating the lipid composition and physical properties of the membrane, achieving a balance between resistance to antibiotics and the ability to facilitate all necessary transport and signaling processes, are also considered.

The genomes of Scedosporium between environmental challenges and opportunism

Emerging fungal pathogens are a global challenge for humankind. Many efforts have been made to understand the mechanisms underlying pathogenicity in bacteria, and OMICs techniques are largely responsible for those advancements. By contrast, our limited understanding of opportunism and antifungal resistance is preventing us from identifying, limiting and interpreting the emergence of fungal pathogens. The genus Scedosporium (Microascaceae) includes fungi with high tolerance to environmental pollution, whilst some species can be considered major human pathogens, such as Scedosporium apiospermum and Scedosporium boydii. However, unlike other fungal pathogens, little is known about the genome evolution of these organisms. We sequenced two novel genomes of Scedosporium aurantiacum and Scedosporium minutisporum isolated from extreme, strongly anthropized environments. We compared all the available Scedosporium and Microascaceae genomes, that we systematically annotated and characterized ex novo in most cases. The genomes in this family were integrated in a Phylum-level comparison to infer the presence of putative, shared genomic traits in filamentous ascomycetes with pathogenic potential. The analysis included the genomes of 100 environmental and clinical fungi, revealing poor evolutionary convergence of putative pathogenicity traits. By contrast, several features in Microascaceae and Scedosporium were detected that might have a dual role in responding to environmental challenges and allowing colonization of the human body, including chitin, melanin and other cell wall related genes, proteases, glutaredoxins and magnesium transporters. We found these gene families to be impacted by expansions, orthologous transposon insertions, and point mutations. With RNA-seq, we demonstrated that most of these anciently impacted genomic features responded to the stress imposed by an antifungal compound (voriconazole) in the two environmental strains S. aurantiacum MUT6114 and S. minutisporum MUT6113. Therefore, the present genomics and transcriptomics investigation stands on the edge between stress resistance and pathogenic potential, to elucidate whether fungi were pre-adapted to infect humans. We highlight the strengths and limitations of genomics applied to opportunistic human pathogens, the multifactoriality of pathogenicity and resistance to drugs, and suggest a scenario where pressures other than anthropic contributed to forge filamentous human pathogens.

New pyrrole derivatives as DNA gyrase and 14α-demethylase inhibitors: Design, synthesis, antimicrobial evaluation, and molecular docking

An efficient one-pot reaction utilizing readily available chemical reagents was used to prepare novel 2-amino-1,5-diaryl-1H-pyrrole-3-carbonitrile derivatives and the structures of these compounds were validated by spectroscopic data and elemental analyses. All the synthetic compounds were evaluated for their antimicrobial activities (MZI assay). The tested compounds proved high activities on Staphylococcus aureus (Gram-positive bacteria) and Candida albicans (Pathogenic fungi). However, they did not show any activity on Escherichia coli (Gram-negative bacteria). The most effective compounds in MZI assay 7c, 9a, 9b, 11a, and 11b were selected to determine their MIC on S. aureus and C. albicans. Furthermore, DNA gyrase and 14-α demethylase inhibitory assays were performed to study the inhibitory activities of 7c, 9a, 9b, 11a, and 11b. The results illustrated that compound 9b was the most DNA gyrase inhibitor (IC50 of 0.0236 ± 0.45 µM, which was 1.3- fold higher than gentamicin reference IC50 values of 0.0323 ± 0.81 µM). In addition, compound 9b demonstrated the highest 14-α demethylase inhibitory effect with IC50 of 0.0013 ± 0.02 µM, compared to ketoconazole (IC50 of 0.0008 ± 0.03 µM) and fluconazole (IC50 of 0.00073 ± 0.01 µM), as antifungal reference drugs. Lastly, docking studies were performed to rationalize the dual inhibitory activities of the highly active compounds on both DNA gyrase and 14-α demethylase enzymes.

Processive kinetics in the three-step lanosterol 14α-demethylation reaction catalyzed by human cytochrome P450 51A1

Cytochrome P450 (P450, CYP) family 51 enzymes catalyze the 14α-demethylation of sterols, leading to critical products used for membranes and the production of steroids, as well as signaling molecules. In mammals, P450 51 catalyzes the 3-step, 6-electron oxidation of lanosterol to form (4β,5α)-4,4-dimethyl-cholestra-8,14,24-trien-3-ol (FF-MAS). P450 51A1 can also use 24,25-dihydrolanosterol (a natural substrate in the Kandutsch-Russell cholesterol pathway). 24,25-Dihydrolanosterol and the corresponding P450 51A1 reaction intermediates, the 14α-alcohol and -aldehyde derivatives of dihydrolanosterol, were synthesized to study the kinetic processivity of the overall 14α-demethylation reaction of human P450 51A1. A combination of steady-state kinetic parameters, steady-state binding constants, dissociation rates of P450-sterol complexes, and kinetic modeling of the time course of oxidation of a P450-dihydrolanosterol complex showed that the overall reaction is highly processive, with koff rates of P450 51A1-dihydrolanosterol and the 14α-alcohol and 14α-aldehyde complexes being 1 to 2 orders of magnitude less than the forward rates of competing oxidations. epi-Dihydrolanosterol (the 3α-hydroxy analog) was as efficient as the common 3β-hydroxy isomer in the binding and formation of dihydro FF-MAS. The common lanosterol contaminant dihydroagnosterol was found to be a substrate of human P450 51A1, with roughly one-half the activity of dihydrolanosterol. Steady-state experiments with 14α-methyl deuterated dihydrolanosterol showed no kinetic isotope effect, indicating that C-14α C-H bond breaking is not rate-limiting in any of the individual steps. The high processivity of this reaction generates higher efficiency and also renders the reaction less sensitive to inhibitors.

Chronic exposure to tebuconazole alters thyroid hormones and plumage quality in house sparrows (Passer domesticus)

Triazoles belong to a family of fungicides that are ubiquitous in agroecosystems due to their widespread use in crops. Despite their efficiency in controlling fungal diseases, triazoles are also suspected to affect non-target vertebrate species through the disruption of key physiological mechanisms. Most studies so far have focused on aquatic animal models, and the potential impact of triazoles on terrestrial vertebrates has been overlooked despite their relevance as sentinel species of contaminated agroecosystems. Here, we examined the impact of tebuconazole on the thyroid endocrine axis, associated phenotypic traits (plumage quality and body condition) and sperm quality in wild-caught house sparrows (Passer domesticus). We experimentally exposed house sparrows to realistic concentrations of tebuconazole under controlled conditions and tested the impact of this exposure on the levels of thyroid hormones (T3 and T4), feather quality (size and density), body condition and sperm morphology. We found that exposure to tebuconazole caused a significant decrease in T4 levels, suggesting that this azole affects the thyroid endocrine axis, although T3 levels did not differ between control and exposed sparrows. Importantly, we also found that exposed females had an altered plumage structure (larger but less dense feathers) relative to control females. The impact of tebuconazole on body condition was dependent on the duration of exposure and the sex of individuals. Finally, we did not show any effect of exposure to tebuconazole on sperm morphology. Our study demonstrates for the first time that exposure to tebuconazole can alter the thyroid axis of wild birds, impact their plumage quality and potentially affect their body condition. Further endocrine and transcriptomic studies are now needed not only to understand the underlying mechanistic effects of tebuconazole on these variables, but also to further investigate their ultimate consequences on performance (i.e. reproduction and survival).

Revealing substrate-induced structural changes in active site of human CYP51 in the presence of its physiological substrates

The human sterol 14α-demethylases (CYP51, CYP is an abbreviation for cytochrome P450) catalyze three-step oxidative removal of 14α-methyl group of lanosterol by first forming an alcohol, then an aldehyde, and finally conducting a CC bond cleavage reaction. This present study utilizes a combination of Resonance Raman spectroscopy and Nanodisc technology to probe the active site structure of CYP51 in the presence of its hydroxylase and lyase substrates. Ligand-binding induced partial low-to-high-spin conversion is observed by applying electronic absorption spectroscopy and Resonance Raman (RR) spectroscopy. This low degree of spin conversion of CYP51 is contributed by the retention of the water ligand coordinated to the heme iron as well as direct interaction between the hydroxyl group of lyase substrate and the iron center. No significant changes in active site structure are found between detergent-stabilized CYP51 and nanodisc-incorporated CYP51, nevertheless, it is demonstrated that nanodisc-incorporated assemblies provide much more well-defined active site RR spectroscopic responses, which induces a larger conversion from low-to-high-spin state in presence of the substrates. Moreover, a positive polar environment around the exogenous diatomic ligand is detected, providing insight into the mechanism of this essential CC bond cleavage reaction.

Mechanism and Kinetics of Prothioconazole Photodegradation in Aqueous Solution

This study investigated the effects of light source, pH value, and NO₃^- concentration on the photodegradation of prothioconazole in aqueous solution. The half-life (t_1/2) of prothioconazole was 173.29, 21.66, and 11.18 min under xenon, ultraviolet, and high-pressure mercury lamps, respectively. At pH values of 4.0, 7.0, and 9.0 under a xenon lamp light source, the t_1/2 values were 693.15, 231.05, and 99.02 min, respectively. Inorganic substance NO₃^- clearly promoted the photodegradation of prothioconazole, with t_1/2 values of 115.53, 77.02, and 69.32 min at NO₃^- concentrations of 1.0, 2.0, and 5.0 mg L^-1, respectively. The photodegradation products were identified as C₁₄H₁₅Cl₂N₃O, C₁₄H₁₆ClN₃OS, C₁₄H₁₅Cl₂N₃O₂S, and C₁₄H₁₃Cl₂N₃ based on calculations and the Waters compound library. Furthermore, density functional theory (DFT) calculations showed that the C-S, C-Cl, C-N, and C-O bonds of prothioconazole were the reaction sites with high absolute charge values and greater bond lengths. Finally, the photodegradation pathway of prothioconazole was concluded, and the variation in energy of the photodegradation process was attributed to the decrease in activation energy caused by light excitation. This work provides new insight into the structural modification and photochemical stability improvement of prothioconazole, which plays an important role in decreasing safety risk during application that will reduce the exposure risk in field environment.

Impact of Laboratory-Adapted Intracellular Trypanosoma cruzi Strains on the Activity Profiles of Compounds with Anti-T. cruzi Activity

Chagas disease is caused by infection with the protozoan parasite, Trypanosoma cruzi. The disease causes ~12,000 deaths annually and is one of the world's 20 neglected tropical diseases, as defined by the World Health Organisation. The drug discovery pipeline for Chagas disease currently has few new clinical candidates, with high attrition rates an ongoing issue. To determine if the Trypanosoma cruzi strain utilised to assess in vitro compound activity impacts activity, a comparison of laboratory-adapted T. cruzi strains from differing geographical locations was undertaken for a selection of compounds with anti-T. cruzi activity. To minimise the possible effect of differences in experimental methodology, the same host cell and multiplicity of infection were utilised. To determine whether the compound exposure time influenced results, activity was determined following exposure for 48 and 72 h of incubation. To ascertain whether replication rates affected outcomes, comparative rates of replication of the T. cruzi strains were investigated, using the nucleoside analogue, 5-ethynyl-2'-deoxyuridine. Minimal differences in the in vitro activity of compounds between strains were observed following 48 h incubation, whereas significant differences were observed following 72 h incubation, in particular for the cytochrome P450 inhibitors tested and the cell cycle inhibitor, camptothecin. Thus, the use of panels of laboratory adapted strains in vitro may be dependent on the speed of action that is prioritised. For the identification of fast-acting compounds, an initial shorter duration assay using a single strain may be used. A longer incubation to identify compound activity may alternatively require profiling of compounds against multiple T. cruzi strains.

Potential anti-acanthamoebic effects through inhibition of CYP51 by novel quinazolinones

Acanthamoeba spp. are free living amoebae which can give rise to Acanthamoeba keratitis and granulomatous amoebic encephalitis. The surface of Acanthamoeba contains ergosterol which is an important target for drug development against eukaryotic microorganisms. A library of ten functionally diverse quinazolinone derivatives (Q1-Q10) were synthesised to assess their activity against Acanthamoeba castellanii T4. The in-vitro effectiveness of these quinazolinones were investigated against Acanthamoeba castellanii by amoebicidal, excystation, host cell cytopathogenicity, and NADPH-cytochrome c reductase assays. Furthermore, wound healing capability was assessed at different time durations. Maximum inhibition at 50 μg/mL was recorded for compounds Q5, Q6 and Q8, while the compound Q3 did not exhibit amoebicidal effects at tested concentrations. Moreover, LDH assay was conducted to assess the cytotoxicity of quinazolinones against HaCaT cell line. The results of wound healing assay revealed that all compounds are not cytotoxic and are likely to promote wound healing at 10 μg/mL. The excystation assays revealed that these compounds significantly inhibit the morphological transformation of A. castellanii. Compound Q3, Q7 and Q8 elevated the level of NADPH-cytochrome c reductase up to five folds. Sterol 14alpha-demethylase (CYP51) a reference enzyme in ergosterol pathway was used as a potential target for anti-amoebic drugs. In this study using i-Tasser, the protein structure of Acanthamoeba castellanii (AcCYP51) was developed in comparison with Naegleria fowleri protein (NfCYP51) structure. The sequence alignment of both proteins has shown 42.72% identity. Compounds Q1-Q10 were then molecularly docked with the predicted AcCYP51. Out of ten quinazolinones, three compounds (Q3, Q7 and Q8) showed good binding activity within 3 Å of TYR 114. The in-silico study confirmed that these compounds are the inhibitor of CYP51 target site. This report presents several potential lead compounds belonging to quinazolinone derivatives for drug discovery against Acanthamoeba infections.

A New Variant of Mutational and Polymorphic Signatures in the ERG11 Gene of Fluconazole-Resistant Candida albicans

Background

Resistance to antifungal drugs for treating Candida infections remains a major concern globally despite the range of medications available. Most of these drugs target key proteins essential to the life cycle of the organism. An enzyme essential for fungal cell membrane integrity, lanosterol 14–α demethylase (CYP51), is encoded by the ERG11 gene in Candida species. This enzyme is the target of azole–based drugs. The organism has, however, devised molecular adaptations to evade the activity of these drugs.

Materials and Methods

Classical methods were employed to characterize clinical isolates sampled from women and dogs of reproductive age. For fluconazole efficacy studies, CLSI guidelines on drug susceptibility testing were used. To understand the susceptibility pattern, various molecular and structural analytic approaches, including sequencing, in silico site-directed mutagenesis, and protein-ligand profiling, were applied to the ERG11 gene and CYP51 protein sequences. Several platforms, comprising Clustal Omega, Pymol plugin manager, Pymol molecular visualizer, Chimera–curated Dynameomics rotamer library, protein–ligand interaction profiler, Charmm36 force field, GROMACS, Geneious, and Mega7, were employed for this analysis.

Results

The following Candida species distribution was obtained: 37.84% C. albicans, 8.12% C. glabrata, 10.81% C. krusei, 5.41% C. tropicalis, and 37.84% of other unidentified Candida species. Two codons in the nucleotide sequence of the wild-type (CTC and CCA) coding for LEU–370 and PRO–375, respectively, were mutated to L370S and P375H in the resistant strain. The mutation stabilized the protein at the expense of the heme moiety. We found that the susceptible isolate from dogs (Can–iso–029/dog) is closely related to the most resistant isolate from humans.

Conclusion

Taken together, our results showed new mutations in the heme-binding pocket of caCYP51 that explain the resistance to fluconazole exhibited by the Candida isolates. So far, the L370S and P375H resistance-linked mutations have not been previously reported.

Clinically used antifungal azoles as ligands for gold(III) complexes: the influence of the Au(III) ion on the antimicrobial activity of the complex

In a search for novel antimicrobial metal-based therapeutic agents, mononuclear gold(III) complexes 1-7 of the general formula [AuCl₃(azole)], where azole stands for imidazole (im, 1), 1-isopropylimidazole (ipim, 2), 1-phenylimidazole (phim, 3), clotrimazole (ctz, 4), econazole (ecz, 5), tioconazole (tcz, 6) and voriconazole (vcz, 7) were synthesized, characterized and biologically evaluated. In all complexes, the corresponding azole ligand is monodentately coordinated to the Au(III) via the imidazole or triazole nitrogen atom, while the remaining coordination sites are occupied by chloride anions leading to the square-planar arrangement. In vitro antimicrobial assays showed that the complexation of inactive azoles, imidazole, 1-isopropylimidazole and 1-phenylimidazole, to the Au(III) ion led to complexes 1-3, respectively, with moderate activity against the investigated strains and low cytotoxicity on the human normal lung fibroblast cell line (MRC-5). Moreover, gold(III) complexes 4-7 with clinically used antifungal agents clotrimazole, econazole, tioconazole and voriconazole, respectively, have, in most cases, enhanced antimicrobial effectiveness relative to the corresponding azoles, with the best improvement achieved after complexation of tioconazole (6) and voriconazole (7). The complexes 4-7 and the corresponding antifungal azoles inhibited the growth of dermatophyte Microsporum canis at 50 and 25 μg mL^-1. Gold(III) complexes 1-3 significantly reduced the amount of ergosterol in the cell membrane of Candida albicans at the subinhibitory concentration of 0.5 × MIC (minimal inhibitory concentration), while the corresponding imidazole ligands did not significantly affect the ergosterol content, indicating that the mechanism of action of the gold(III)-azole complexes is associated with inhibition of ergosterol biosynthesis. Finally, complexes 5 and 6 significantly reduced the production of pyocyanin, a virulence factor in Pseudomonas aeruginosa controlled by quorum sensing, and increased cell survival after exposure to this bacterium. These findings could be of importance for the development of novel gold(III)-based antivirulence therapeutic agents that attenuate virulence without pronounced effect on the growth of the pathogens, offering a lower risk for resistance development.

Cytochrome P450 168A1 from Pseudomonas aeruginosa is involved in the hydroxylation of biologically relevant fatty acids

The cytochrome P450 CYP168A1 from Pseudomonas aeruginosa was cloned and expressed in Escherichia coli followed by purification and characterization of function. CYP168A1 is a fatty acid hydroxylase that hydroxylates saturated fatty acids, including myristic (0.30 min-1), palmitic (1.61 min-1) and stearic acids (1.24 min-1), at both the ω-1- and ω-2-positions. However, CYP168A1 only hydroxylates unsaturated fatty acids, including palmitoleic (0.38 min-1), oleic (1.28 min-1) and linoleic acids (0.35 min-1), at the ω-1-position. CYP168A1 exhibited a catalytic preference for palmitic, oleic and stearic acids as substrates in keeping with the phosphatidylcholine-rich environment deep in the lung that is colonized by P. aeruginosa.

Repurposing Antifungals for Host-Directed Antiviral Therapy?

Because of their epidemic and pandemic potential, emerging viruses are a major threat to global healthcare systems. While vaccination is in general a straightforward approach to prevent viral infections, immunization can also cause escape mutants that hide from immune cell and antibody detection. Thus, other approaches than immunization are critical for the management and control of viral infections. Viruses are prone to mutations leading to the rapid emergence of resistant strains upon treatment with direct antivirals. In contrast to the direct interference with pathogen components, host-directed therapies aim to target host factors that are essential for the pathogenic replication cycle or to improve the host defense mechanisms, thus circumventing resistance. These relatively new approaches are often based on the repurposing of drugs which are already licensed for the treatment of other unrelated diseases. Here, we summarize what is known about the mechanisms and modes of action for a potential use of antifungals as repurposed host-directed anti-infectives for the therapeutic intervention to control viral infections.

Azole-resistant alleles of ERG11 in Candida glabrata trigger activation of the Pdr1 and Upc2A transcription factors

Azoles, the most commonly used antifungal drugs, specifically inhibit the fungal lanosterol α-14 demethylase enzyme, which is referred to as Erg11. Inhibition of Erg11 ultimately leads to a reduction in ergosterol production, an essential fungal membrane sterol. Many Candida species, such as Candida albicans , develop mutations in this enzyme which reduces the azole binding affinity and results in increased resistance. Candida glabrata is also a pathogenic yeast that has low intrinsic susceptibility to azole drugs and easily develops elevated resistance. In C. glabrata , these azole resistant mutations typically cause hyperactivity of the Pdr1 transcription factor and rarely lie within the ERG11 gene. Here, we generated C. glabrata ERG11 mutations that were analogous to azole resistance alleles from C. albicans ERG11 . Three different Erg11 forms (Y141H, S410F, and the corresponding double mutant (DM)) conferred azole resistance in C. glabrata with the DM Erg11 form causing the strongest phenotype. The DM Erg11 also induced cross-resistance to amphotericin B and caspofungin. Resistance caused by the DM allele of ERG11 imposed a fitness cost that was not observed with hyperactive PDR1 alleles. Crucially, the presence of the DM ERG11 allele was sufficient to activate the Pdr1 transcription factor in the absence of azole drugs. Our data indicate that azole resistance linked to changes in ERG11 activity can involve cellular effects beyond an alteration in this key azole target enzyme. Understanding the physiology linking ergosterol biosynthesis with Pdr1-mediated regulation of azole resistance is crucial for ensuring the continued efficacy of azole drugs against C. glabrata .

A world-wide analysis of reduced sensitivity to DMI fungicides in the banana pathogen Pseudocercospora fijiensis

BACKGROUND

Pseudocercospora fijiensis is the causal agent of the black leaf streak disease (BLSD) of banana. Bananas are important global export commodities and a major staple food. Their susceptibility to BLSD pushes disease management towards excessive fungicide use, largely relying on multisite inhibitors and sterol demethylation inhibitors (DMIs). These fungicides are ubiquitous in plant disease control, targeting the CYP51 enzyme. We examined sensitivity to DMIs in P. fijiensis field isolates collected from various major banana production zones in Colombia, Costa Rica, Dominican Republic, Ecuador, the Philippines, Guadalupe, Martinique and Cameroon and determined the underlying genetic reasons for the observed phenotypes.

RESULTS

We observed a continuous range of sensitivity towards the DMI fungicides difenoconazole, epoxiconazole and propiconazole with clear cross-sensitivity. Sequence analyses of PfCYP51 in 266 isolates showed 28 independent amino acid substitutions, nine of which correlated with reduced sensitivity to DMIs. In addition to the mutations, we observed up to six insertions in the Pfcyp51 promoter. Such promoter insertions contain repeated elements with a palindromic core and correlate with the enhanced expression of Pfcyp51 and hence with reduced DMI sensitivity. Wild-type isolates from unsprayed bananas fields did not contain any promoter insertions.

CONCLUSION

The presented data significantly contribute to understanding of the evolution and global distribution of DMI resistance mechanisms in P. fijiensis field populations and facilitate the prediction of different DMI efficacy. The overall reduced DMI sensitivity calls for the deployment of a wider range of solutions for sustainable control of this major banana disease. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Dissecting cholesterol and phytosterol biosynthesis via mutants and inhibitors

Plants stand out among eukaryotes due to the large variety of sterols and sterol derivatives that they can produce. These metabolites not only serve as critical determinants of membrane structures, but also act as signaling molecules, as growth-regulating hormones, or as modulators of enzyme activities. Therefore, it is critical to understand the wiring of the biosynthetic pathways by which plants generate these distinct sterols, to allow their manipulation and to dissect their precise physiological roles. Here, we review the complexity and variation of the biosynthetic routes of the most abundant phytosterols and cholesterol in the green lineage and how different enzymes in these pathways are conserved and diverged from humans, yeast, and even bacteria. Many enzymatic steps show a deep evolutionary conservation, while others are executed by completely different enzymes. This has important implications for the use and specificity of available human and yeast sterol biosynthesis inhibitors in plants, and argues for the development of plant-tailored inhibitors of sterol biosynthesis.

An Integrated Approach to Identify New Anti-Filarial Leads to Treat River Blindness, a Neglected Tropical Disease

Filarial worms cause multiple debilitating diseases in millions of people worldwide, including river blindness. Currently available drugs reduce transmission by killing larvae (microfilariae), but there are no effective cures targeting the adult parasites (macrofilaricides) which survive and reproduce in the host for very long periods. To identify effective macrofilaricides, we carried out phenotypic screening of a library of 2121 approved drugs for clinical use against adult Brugia pahangi and prioritized the hits for further studies by integrating those results with a computational prioritization of drugs and associated targets. This resulted in the identification of 18 hits with anti-macrofilaricidal activity, of which two classes, azoles and aspartic protease inhibitors, were further expanded upon. Follow up screening against Onchocerca spp. (adult Onchocerca ochengi and pre-adult O. volvulus) confirmed activity for 13 drugs (the majority having IC50 < 10 μM), and a counter screen of a subset against L. loa microfilariae showed the potential to identify selective drugs that prevent adverse events when co-infected individuals are treated. Stage specific activity was also observed. Many of these drugs are amenable to structural optimization, and also have known canonical targets, making them promising candidates for further optimization that can lead to identifying and characterizing novel anti-macrofilarial drugs.

[Screening of potential non-azole inhibitors of lanosterol14-alpha demethylase (CYP51) of Candida fungi]

Currently, opportunistic fungi of the genus Candida are the main causative agents of mycoses, which are especially severe upon condition of acquired immunodeficiency. The main target for the development of new antimycotics is the cytochrome P450 51 (CYP51) of the pathogenic fungus. Due to the widespread distribution of Candida strains resistancy to inhibitors of the azole class, the screening for CYP51 inhibitors both among non-azole compounds and among clinically used drugs repurposing as antimycotics is becoming urgent. To identify potential inhibitors from the non-azole group, an integrated approach was applied, including bioinformatics analysis, computer molecular modeling, and a surface plasmon resonance (SPR) technology. Using in silico modeling, the binding sites for acetylsalicylic acid, ibuprofen, chlorpromazine and haloperidol (this compounds, according to the literature, showed antimycotic activity) were predicted in the active site of CYP51 of Candida albicans and Candida glabrata. The Kd values of molecular complexes of acetylsalicylic acid, ibuprofen and haloperidol with CYP51, determined by SPR analysis, ranged from 18 μM to 126 μM. It was also shown that structural derivatives of haloperidol, containing various substituents, could be positioned in the active site of CYP51 of Candida albicans with the possible formation of coordination bonds between the hydroxyl groups of the derivatives and the iron atom in the heme of CYP51. Thus, the potential basic structures of non-azole compounds have been proposed, which can be used for the design of new CYP51 inhibitors of Candida fungi.

Pyridylethanol(phenylethyl)amines are non-azole, highly selective Candida albicans sterol 14α-demethylase inhibitors

Sterol 14α-demethylase (CYP51) is the main drug target for the treatment of fungal infections. The worldwide increase in the incidence of opportunistic fungal infections and the emerging resistance to available azole-based antifungal drugs, raise the need to develop structurally distinct and selective fungal CYP51 inhibitors. In this work we have, for the first time, investigated the binding of pyridylethanol(phenylethyl)amines to any fungal CYP51. The comparison of the binding to Candida albicans and human CYP51 studied by spectroscopic and modeling methods revealed moieties decisive for selectivity and potency and resulted in the development of highly selective derivatives with significantly increased inhibitory potency. The structure-based insight into the selectivity requirements of this new chemical class of fungal CYP51 inhibitors, their unique binding properties and the low molecular weight of lead derivatives offer novel directions for the targeted development of antifungal clinical candidates.

Clade-Specific Sterol Metabolites in Dinoflagellate Endosymbionts Are Associated with Coral Bleaching in Response to Environmental Cues

Cnidarians cannot synthesize sterols (which play essential roles in growth and development) de novo but often use sterols acquired from endosymbiotic dinoflagellates. While sterol availability can impact the mutualistic interaction between coral host and algal symbiont, the biosynthetic pathways (in the dinoflagellate endosymbionts) and functional roles of sterols in these symbioses are poorly understood. In this study, we found that itraconazole, which perturbs sterol metabolism by inhibiting the sterol 14-demethylase CYP51 in dinoflagellates, induces bleaching of the anemone Heteractis crispa and that bleaching perturbs sterol metabolism of the dinoflagellate. While Symbiodiniaceae have clade-specific sterol metabolites, they share features of the common sterol biosynthetic pathway but with distinct architecture and substrate specificity features of participating enzymes. Tracking sterol profiles and transcripts of enzymes involved in sterol biosynthesis across time in response to different environmental cues revealed similarities and idiosyncratic features of sterol synthesis in the endosymbiont Breviolum minutum Exposure of algal cultures to high levels of light, heat, and acidification led to alterations in sterol synthesis, including blocks through downregulation of squalene synthase transcript levels accompanied by marked growth reductions.IMPORTANCE These results indicate that sterol metabolites in Symbiodiniaceae are clade specific, that their biosynthetic pathways share architectural and substrate specificity features with those of animals and plants, and that environmental stress-specific perturbation of sterol biosynthesis in dinoflagellates can impair a key mutualistic partnership for healthy reefs.

Sterol 14-α-demethylase is vital for mitochondrial functions and stress tolerance in Leishmania major

Sterol 14-α-demethylase (C14DM) is a key enzyme in the biosynthesis of sterols and the primary target of azoles. In Leishmania major, genetic or chemical inactivation of C14DM leads to accumulation of 14-methylated sterol intermediates and profound plasma membrane abnormalities including increased fluidity and failure to maintain ordered membrane microdomains. These defects likely contribute to the hypersensitivity to heat and severely reduced virulence displayed by the C14DM-null mutants (c14dm‾). In addition to plasma membrane, sterols are present in intracellular organelles. In this study, we investigated the impact of C14DM ablation on mitochondria. Our results demonstrate that c14dm‾ mutants have significantly higher mitochondrial membrane potential than wild type parasites. Such high potential leads to the buildup of reactive oxygen species in the mitochondria, especially under nutrient-limiting conditions. Consistent with these mitochondrial alterations, c14dm‾ mutants show impairment in respiration and are heavily dependent on glucose uptake and glycolysis to generate energy. Consequently, these mutants are extremely sensitive to glucose deprivation and such vulnerability can be rescued through the supplementation of glucose or glycerol. In addition, the accumulation of oxidants may also contribute to the heat sensitivity exhibited by c14dm‾. Finally, genetic or chemical ablation of C14DM causes increased susceptibility to pentamidine, an antimicrobial agent with activity against trypanosomatids. In summary, our investigation reveals that alteration of sterol synthesis can negatively affect multiple cellular processes in Leishmania parasites and make them vulnerable to clinically relevant stress conditions.

Small-Molecule Inhibitors Targeting Sterol 14α-Demethylase (CYP51): Synthesis, Molecular Modelling and Evaluation Against Candida albicans

Fungal infections are a global issue affecting over 150 million people worldwide annually, with 750 000 of these caused by invasive Candida infections. Azole drugs are the frontline treatment against fungal infections; however, resistance to current azole antifungals in C. albicans poses a threat to public health. Two series of novel azole derivatives, short and extended derivatives, have been designed, synthesised and investigated for CYP51 inhibitory activity, binding affinity and minimum inhibitory concentration (MIC) against C. albicans strains. The short derivatives were more potent against the C. albicans strains (e. g., MIC 2-(4-chlorophenyl)-N-(2,4-dichlorobenzyl)-3-(1H-imidazol-1-yl)propanamide (5 f) <0.03 μg/mL, N-(4-((4-chlorophenyl)sulfonamido)benzyl)-2-phenyl-3-(1H-1,2,4-triazol-1-yl)propanamide (12 c), 1 μg/mL, fluconazole 0.125 μg/mL) but both displayed comparable enzyme binding and inhibition (5 f Kd 62±17 nM, IC50 0.46 μM; 12 c Kd 43±18 nM, IC50 0.33 μM, fluconazole Kd 41±13 nM, IC50 0.31 μM, posaconazole Kd 43±11 nM, IC50 0.2 μM). The short series had poor selectivity for CaCYP51 over the human homologue, whereas the selectivity of the extended series, for example, compound 12 c, was higher (21.5-fold) than posaconazole (4.7-fold) based on Kd values, although posaconazole was more selective (615-fold) than 12 c (461-fold) based on IC50 values. Based on inhibitory activity and selectivity profile, the extended series are the better of the two series for further development.

A binding mode hypothesis for prothioconazole binding to CYP51 derived from first principles quantum chemistry

In order to assess safety and efficacy of small molecule drugs as well as agrochemicals, it is key to understanding the nature of protein-ligand interaction on an atomistic level. Prothioconazole (PTZ), although commonly considered to be an azole-like inhibitor of sterol 14-α demethylase (CYP51), differs from classical azoles with respect to how it binds its target. The available evidence is only indirect, as crystallographic elucidation of CYP51 complexed with PTZ have not yet been successful. We derive a binding mode hypothesis for PTZ binding its target, compare to DPZ, a triazole-type metabolite of PTZ, and set our findings into context of its biochemistry and spectroscopy. Quantum Theory of Atoms in Molecules (QTAIM) analysis of computed DFT electron densities is used to qualitatively understand the topology of binding, revealing significant differences of how R- and S-enantiomers are binding and, in particular, how the thiozolinthione head of PTZ binds to heme compared to DPZ's triazole head. The difference of binding enthalpy is calculated at coupled cluster (DLPNO-CCSD(T)) level of theory, and we find that DPZ binds stronger to CYP51 than PTZ by more than ΔH ~ 11 kcal/mol.

Prediction and Characterization of CYP3A4-mediated Metabolisms of Azole Fungicides: an Application of the Fused-grid Template* system

Human CYP3A4 is involved in metabolisms of diverse hydrophobic chemicals. Using the data of therapeutic azole fungicides known to interact with CYP3A4, applicability of CYP3A4 Template system was first confirmed to reconstitute faithfully the interaction on Template. More than twenty numbers of pesticide azoles were then applied to the Template system. All the azole stereo-isomers applied, except for talarozole, interacted through nitrogen atoms of triazole or imidazole parts and sat stably for inhibitions through fulfilling three-essential interactions. For their CYP3A4-mediated oxidations, clear distinctions were suggested among the enantiomers and diastereomers of azole pesticides on Templates. Thus, the stereoisomers would have their-own regio- and stereo-selective profiles of the metabolisms. A combined metabolic profile of each azole obtained with CYP3A4 Template system, however, resembled with the reported profile of the in vivo metabolism in rats. These results suggest the major roles of CYP3A forms on the metabolisms of most of azole pesticides in both rats and humans. Free triazole is a metabolite of azole fungicides having a methylene-spacer between triazole and the rest of the main structures in experimental animals and humans. During the simulation experiments, a placement for the oxidation of a methylene spacer between the triazole and main carbon-skeleton was found to be available throughout the azole fungicides tested on Template. The occurrence of this reaction to lead to triazole-release is thus discussed in relation to the possible involvement of CYP3A forms.

Design, synthesis, mechanistic studies and in silico ADME predictions of benzimidazole derivatives as novel antifungal agents

Herein, novel three series of benzimidazole scaffold bearing hydrazone, 1,2,4-triazole and 1,3,4-oxadiazole moieties 1-3, 4a-j, 6a-c and 7 derivatives were designed, synthesized and evaluated for their antimicrobial activity. The structures of the prepared compounds were assigned using different spectroscopic techniques such as IR, ¹H NMR, ¹³C NMR and elemental analyses. Compounds 3, 4a, 4e and 4f exhibited remarkable antifungal activity against C. albicans and C. neoformans var. grubii with MIC values ranging from 4 to 16 μg/mL. Furthermore, they were not cytotoxic against red blood cells and human embryonic kidney cells at concentration up to 32 μg/mL. The study was expanded to forecast the mechanism of action of the prepared compounds and determine sterol quantitation method (SQM) by spectrophotometric assay. On the other hand, compound 4e showed the highest inhibitory activity against lanosterol 14α-demethylase (CYP51) with IC₅₀ value = 0.19 μg/mL compared to fluconazole as reference IC₅₀ value = 0.62 μg/mL. Also, compounds 4d and 4f exhibited mild to moderate antibacterial activity. Moreover, molecular docking of the active target compound 4e in active site of lanosterol 14α-demethylase (CYP51) revealed that docking scores and binding mode are comparable to that of co-crystallized ligand confirming their antifungal activity. In silico ADME prediction investigations also forecasting the drug-like characters of these compounds.

Combined Machine Learning and Molecular Modelling Workflow for the Recognition of Potentially Novel Fungicides

Novel machine learning and molecular modelling filtering procedures for drug repurposing have been carried out for the recognition of the novel fungicide targets of Cyp51 and Erg2. Classification and regression approaches on molecular descriptors have been performed using stepwise multilinear regression (FS-MLR), uninformative-variable elimination partial-least square regression, and a non-linear method called Forward Stepwise Limited Correlation Random Forest (FS-LM-RF). Altogether, 112 prediction models from two different approaches have been built for the descriptor recognition of fungicide hit compounds. Aiming at the fungal targets of sterol biosynthesis in membranes, antifungal hit compounds have been selected for docking experiments from the Drugbank database using the Autodock4 molecular docking program. The results were verified by Gold Protein-Ligand Docking Software. The best-docked conformation, for each high-scored ligand considered, was submitted to quantum mechanics/molecular mechanics (QM/MM) gradient optimization with final single point calculations taking into account both the basis set superposition error and thermal corrections (with frequency calculations). Finally, seven Drugbank lead compounds were selected based on their high QM/MM scores for the Cyp51 target, and three were selected for the Erg2 target. These lead compounds could be recommended for further in vitro studies.

Screening ToxCast™ for Chemicals That Affect Cholesterol Biosynthesis: Studies in Cell Culture and Human Induced Pluripotent Stem Cell-Derived Neuroprogenitors

BACKGROUND

Changes in cholesterol metabolism are common hallmarks of neurodevelopmental pathologies. A diverse array of genetic disorders of cholesterol metabolism support this claim as do multiple lines of research that demonstrate chemical inhibition of cholesterol biosynthesis compromises neurodevelopment. Recent work has revealed that a number of commonly used pharmaceuticals induce changes in cholesterol metabolism that are similar to changes induced by genetic disorders with devastating neurodevelopmental deficiencies.

OBJECTIVES

We tested the hypothesis that common environmental toxicants may also impair cholesterol metabolism and thereby possibly contribute to neurodevelopmental toxicity.

METHODS

Using high-throughput screening with a targeted lipidomic analysis and the mouse neuroblastoma cell line, Neuro-2a, the ToxCast™ chemical library was screened for compounds that impact sterol metabolism. Validation of chemical effects was conducted by assessing cholesterol biosynthesis in human induced pluripotent stem cell (hiPSC)-derived neuroprogenitors using an isotopically labeled cholesterol precursor and by monitoring product formation with UPLC-MS/MS.

RESULTS

Twenty-nine compounds were identified as validated lead-hits, and four were prioritized for further study (endosulfan sulfate, tributyltin chloride, fenpropimorph, and spiroxamine). All four compounds were validated to cause hypocholesterolemia in Neuro-2a cells. The morpholine-like fungicides, fenpropimorph and spiroxamine, mirrored their Neuro-2a activity in four immortalized human cell lines and in a human neuroprogenitor model derived from hiPSCs, but endosulfan sulfate and tributyltin chloride did not.

CONCLUSIONS

These data reveal the existence of environmental compounds that interrupt cholesterol biosynthesis and that methodologically hiPSC neuroprogenitor cells provide a particularly sensitive system to monitor the effect of small molecules on de novo cholesterol formation. https://doi.org/10.1289/EHP5053.

Indole-Containing Phytoalexin-Based Bioisosteres as Antifungals: In Vitro and In Silico Evaluation against Fusarium oxysporum

There is a continuous search for more reliable and effective alternatives to control phytopathogens through different strategies. In this context, indole-containing phytoalexins are stimuli-induced compounds implicated in plant defense against plant pathogens. However, phytoalexins' efficacy have been limited by fungal detoxifying mechanisms, thus, the research on bioisosteres-based analogs can be a friendly alternative regarding the control of Fusarium phytopathogens, but there are currently few studies on it. Thus, as part of our research on antifungal agents, a set of 21 synthetic indole-containing phytoalexin analogs were evaluated as inhibitors against the phyopathogen Fusarium oxysporum. Results indicated that analogs of the N,N-dialkylthiourea, N,S-dialkyldithiocarbamate and substituted-1,3-thiazolidin-5-one groups exhibited the best docking scores and interaction profiles within the active site of Fusarium spp. enzymes. Vina scores exhibited correlation with experimental mycelial growth inhibition using supervised statistics, and this antifungal dataset correlated with molecular interaction fields after CoMFA. Compound 24 (tert-butyl (((3-oxo-1,3-diphenylpropyl)thio)carbonothioyl)-l-tryptophanate), a very active analog against F. oxysporum, exhibited the best interaction with lanosterol 14α-demethylase according to molecular docking, molecular dynamics and molecular mechanic/poisson-boltzmann surface area (MM/PBSA) binding energy performance. After data analyses, information on mycelial growth inhibitors, structural requirements and putative enzyme targets may be used in further antifungal development based on phytoalexin analogs for controlling phytopathogens.

UV increases skin-derived 1α,25-dihydroxyvitamin D3 production, leading to MMP-1 expression by altering the balance of vitamin D and cholesterol synthesis from 7-dehydrocholesterol

The skin is a unique site in the human body that has the capacity to synthesize the active form of vitamin D, 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃), from 7-dehydrocholesterol (7DHC) upon UV irradiation. Keratinocytes express both 25-hydroxylase (CYP27A1 and CYP2R1) and 1α-hydroxylase (CYP27B1), critical enzymes involved in active vitamin D synthesis. Here, we investigated the effect of skin-derived 1α,25(OH)₂D₃, synthesized purely within the keratinocytes, on MMP-1 expression. Treatment of human epidermal keratinocytes with 1α,25(OH)₂D_3, but not 7DHC or 25OHD₃, significantly increased MMP-1 expression. UV irradiation increases 1α,25(OH)₂D₃ levels, and ketoconazole inhibits UV-induced production of 1α,25(OH)₂D₃. Upregulation of MMP-1 by UV was reversed by inhibition of 1α,25(OH)₂D₃ synthesis using ketoconazole or CYP27B1 siRNA. In keratinocytes, 7DHC is a substrate for both cholesterol and 1α,25(OH)₂D₃ synthesis. We demonstrated that UV irradiation leads to decreased expression of DHCR7 (7-dehydrocholesterol reductase), the enzyme that converts 7DHC to cholesterol. Inhibition of DHCR7 with its inhibitor BM15766 decreased cholesterol synthesis and increased UV-induced MMP-1 expression, which was attenuated by ketoconazole. These findings suggest that UV-induced reduction of DHCR7 leads to a decrease in cholesterol synthesis, thereby increasing 7DHC availability for 1α,25(OH)₂D₃ production, which enhances MMP-1 expression. Finally, UV irradiation in human skin in vivo significantly increased CYP27B1 mRNA and decreased DHCR7 mRNA expression. Taken together, we demonstrate here that skin-derived 1α,25(OH)₂D₃ significantly increases MMP-1 expression in human keratinocytes, a previously unappreciated function of 1α,25(OH)₂D_3. Moreover, UV irradiation upregulates the enzyme CYP27B1, which leads to 1α,25(OH)₂D₃ synthesis, but downregulates the cholesterol-producing enzyme DHCR7, both of which collectively lead to increased MMP-1 expression in human keratinocytes. This pathway may be exploited to develop a novel cutaneous anti-aging agent that blocks local cutaneous 1α,25(OH)₂D₃ synthesis.

Gonadal disruption after single dose exposure of prothioconazole and prothioconazole-desthio in male lizards (Eremias argus)

Prothioconazole (PTC) is a widely used triazole fungicide with low toxicity, and its desulfurization metabolite, prothioconazole-desthio (PTC-d), is reported to have higher reproductive toxicity to mammals. However, little is known about the reproductive toxicity, much less endocrine disrupting effect, of these two chemicals on reptiles. In this study, we investigated the effects of single dose of PTC/PTC-d (100 mg kg^-1 body weight) exposure on the pathomorphism of testes and epididymides, serum sex steroid hormones (testosterone and 17β-estradiol) and transcription of steroidogenic-related genes (STARD, cyp11A, cyp17, cyp19A, 17β-HSD, 3β-HSD, AR and ER-α) in gonads of male lizards (Eremias argus). Although structural disorder existed in PTC-d exposure group, severe gonadal disruption, especially suppression of spermatogenesis was only observed in testis after PTC treatment, which consequently led to the lack of spermatozoa in epididymal ducts. Consistent with this result, T/E₂ value in PTC exposure was elevated to a significant higher level compared with control and continually increased over time, while T/E₂ value in the PTC-d exposure group slightly increased only at 12 h. These results demonstrated a more serious disruption of PTC on male lizard gonads than PTC-d. In addition, the expression of cyp17 gene was inhibited at 6 h, however, was induced at 12 h, and exhibited negative correlations with STARD, cyp11A and 3β-HSD after PTC exposure at each timepoint. In PTC-d group, the expression of STARD and 3β-HSD were significantly down-regulated, in contrast, cyp11A and cyp17 were up-regulated, and each gene showed consistent changes over time. For 17β-HSD, no significance was observed in both treated groups. This study was the first to compare the gonadal disruption of PTC and PTC-d in male lizards and elucidated that these two chemicals influenced the physiological function of male gonads through differential transcriptional modulation.

Identification of novel antifungal agents: antimicrobial evaluation, SAR, ADME-Tox and molecular docking studies of a series of imidazole derivatives

Thirty-four imidazole-based compounds synthesized by one-pot catalytic method were evaluated for their antifungal and antibacterial activities against several fungal and bacterial strains. None of the compounds had antibacterial activity. Interestingly, compounds 1, 2, 3, 10 and 15 displayed a strong antifungal activity against all the tested fungal species, while compounds 5, 7, 9, 11, 21 and 27 showed a moderate antifungal activity. To better understand the biological activity of the most active compounds ADME-Tox and molecular docking studies were carried out. Interestingly, compounds 1, 2, 3, 7, 10 and 15 showed excellent bioavailability. In addition, compounds 1, 2 and 3, exhibited good toxicity profiles. Docking studies of the two most active compounds 2 (IC50 of 95 ± 7.07 μM) and 10 (IC50 of 235 ± 7.07 μM) suggested that they might act by inhibiting the fungal lanosterol 14α-demethylase. Therefore, these novel antifungal agents merit further characterization for the development of new antifungal therapeutics.

Inhibitors of Brassinosteroid Biosynthesis and Signal Transduction

Chemical inhibitors are invaluable tools for investigating protein function in reverse genetic approaches. Their application bears many advantages over mutant generation and characterization. Inhibitors can overcome functional redundancy, their application is not limited to species for which tools of molecular genetics are available and they can be applied to specific tissues or developmental stages, making them highly convenient for addressing biological questions. The use of inhibitors has helped to elucidate hormone biosynthesis and signaling pathways and here we review compounds that were developed for the plant hormones brassinosteroids (BRs). BRs are steroids that have strong growth-promoting capacities, are crucial for all stages of plant development and participate in adaptive growth processes and stress response reactions. In the last two decades, impressive progress has been made in BR inhibitor development and application, which has been instrumental for studying BR modes of activity and identifying and characterizing key players. Both, inhibitors that target biosynthesis, such as brassinazole, and inhibitors that target signaling, such as bikinin, exist and in a comprehensive overview we summarize knowledge and methodology that enabled their design and key findings of their use. In addition, the potential of BR inhibitors for commercial application in plant production is discussed.