Synthesis, In Silico Study, and In Vitro Antifungal Activity of New 5-(1,3-Diphenyl-1H-Pyrazol-4-yl)-4-Tosyl-4,5-Dihydrooxazoles.

The increase in multi-drug resistant Candida strains has caused a sharp rise in life-threatening fungal infections in immunosuppressed patients, including those with SARS-CoV-2. Novel antifungal drugs are needed to combat multi-drug-resistant yeasts. This study aimed to synthesize a new series of 2-oxazolines and evaluate the ligands in vitro for the inhibition of six Candida species and in silico for affinity to the CYP51 enzymes (obtained with molecular modeling and protein homology) of the same species. The 5-(1,3-diphenyl-1H-pyrazol-4-yl)-4-tosyl-4,5-dihydrooxazoles 6a-j were synthesized using the Van Leusen reaction between 1,3-diphenyl-4-formylpyrazoles 4a-j and TosMIC 5 in the presence of K2CO3 or KOH without heating, resulting in short reaction times, high compound purity, and high yields. The docking studies revealed good affinity for the active site of the CYP51 enzymes of the Candida species in the following order: 6a-j > 4a-j > fluconazole (the reference drug). The in vitro testing of the compounds against the Candida species showed lower MIC values for 6a-j than 4a-j, and for 4a-j than fluconazole, thus correlating well with the in silico findings. According to growth rescue assays, 6a-j and 4a-j (like fluconazole) inhibit ergosterol synthesis. The in silico toxicity assessment evidenced the safety of compounds 6a-j, which merit further research as possible antifungal drugs.

Inhibitors of 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase Decrease the Growth, Ergosterol Synthesis and Generation of petite Mutants in Candida glabrata and Candida albicans.

Candida glabrata and Candida albicans, the most frequently isolated candidiasis species in the world, have developed mechanisms of resistance to treatment with azoles. Among the clinically used antifungal drugs are statins and other compounds that inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), resulting in decreased growth and ergosterol levels in yeasts. Ergosterol is a key element for the formation of the yeast cell membrane. However, statins often cause DNA damage to yeast cells, facilitating mutation and drug resistance. The aim of the current contribution was to synthesize seven series of compounds as inhibitors of the HMGR enzyme of Candida ssp., and to evaluate their effect on cellular growth, ergosterol synthesis and generation of petite mutants of C. glabrata and C. albicans. Compared to the reference drugs (fluconazole and simvastatin), some HMGR inhibitors caused lower growth and ergosterol synthesis in the yeast species and generated fewer petite mutants. Moreover, heterologous expression was achieved in Pichia pastoris, and compounds 1a, 1b, 6g and 7a inhibited the activity of recombinant CgHMGR and showed better binding energy values than for α-asarone and simvastatin. Thus, we believe these are good candidates for future antifungal drug development.

New Organotin (IV) Compounds Derived from Dehydroacetic Acid and Thiosemicarbazides: Synthesis, Rational Design, Cytotoxic Evaluation, and Molecular Docking Simulation.

Organotin complexes were prepared through a one-pot reaction with three components by reacting thiosemicarbazide or 4-methyl-3-thiosemicarbazide or 4-phenylthiosemicarbazide, dehydroacetic acid (DHA) and dibutyl, diphenyl, dicyclohexyl, and bis[(trimethylsilyl)methyl]tin(IV) oxides; all complexes were characterized by infrared (IR), ultraviolet-visible (UV-vis), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. The 119Sn NMR revealed chemical shifts corresponding to a pentacoordinated environment in solution. The X-ray crystallography of the two complexes evidenced the formation of monomeric complexes with a pentacoordinated geometry around tin via three donor atoms from the ligand, the sulfur of the thiol, the nitrogen of the imine group, and the oxygen of the pyran ring. The geometries of the five-coordinated complexes 3a (Bu2SnL3), 3c (Ph2SnL3), and 3d (Cy2SnL3) acid were intermediate between square pyramidal and trigonal bipyramidal, and complex 1a (Bu2SnL1) adopted a bipyramidal trigonal geometry (BPT). The sulforhodamine B assay assessed the cytotoxicity of organotin(IV) complexes against the MDA-MB-231 and MCF-7 (human mammary adenocarcinoma) cell lines and one normal COS-7 (African green monkey kidney fibroblast). The IC50 values evidenced a significant antiproliferative effect on cancer cells; the complexes were more potent than the positive cisplatin control and the corresponding ligands, dehydroacetic acid thiosemicarbazone (L1), dehydroacetic acid-N(4)-methylthiosemicarbazone (L2), and dehydroacetic acid-N(4)-phenylthiosemicarbazone (L3). The IC50 values also indicated that the organotin(IV) complexes were more cytotoxic against the triple-negative breast cell line MDA-MB-231 than MCF-7, inducing significant morphological alterations. The interactions of organotin(IV) 1c (Ph2SnL1), 1d (Cy2SnL1), and 1e (((CH3)3SiCH2)2SnL1) were evaluated with ss-DNA by fluorescence; intensity changes of the fluorescence were indicative of the displacement of ethidium bromide (EB), confirming the interaction of the organotin(IV) complexes with ss-DNA; the results showed a DNA binding affinity. The thermodynamic parameters obtained through isothermal titration calorimetry showed that the interaction of 1c (Ph2SnL1), with ss-ADN, was exothermic. Molecular docking studies also demonstrated that the organotin(IV) complexes were intercalated in DNA by conventional hydrogen bonds, carbon-hydrogen bonds, and π-alkyl interactions. These complexes furthermore showed a greater affinity towards DNA than cisplatin.

Pyrrole-Based Enaminones as Building Blocks for the Synthesis of Indolizines and Pyrrolo[1,2-a]pyrazines Showing Potent Antifungal Activity.

As a new approach, pyrrolo[1,2-a]pyrazines were synthesized through the cyclization of 2-formylpyrrole-based enaminones in the presence of ammonium acetate. The enaminones were prepared with a straightforward method, reacting the corresponding alkyl 2-(2-formyl-1H-pyrrol-1-yl)acetates, 2-(2-formyl-1H-pyrrol-1-yl)acetonitrile, and 2-(2-formyl-1H-pyrrol-1-yl)acetophenones with DMFDMA. Analogous enaminones elaborated from alkyl (E)-3-(1H-pyrrol-2-yl)acrylates were treated with a Lewis acid to afford indolizines. The antifungal activity of the series of substituted pyrroles, pyrrole-based enaminones, pyrrolo[1,2-a]pyrazines, and indolizines was evaluated on six Candida spp., including two multidrug-resistant ones. Compared to the reference drugs, most test compounds produced a more robust antifungal effect. Docking analysis suggests that the inhibition of yeast growth was probably mediated by the interaction of the compounds with the catalytic site of HMGR of the Candida species.

Synthesis and Molecular Docking Studies of Alkoxy- and Imidazole-Substituted Xanthones as α-Amylase and α-Glucosidase Inhibitors.

Current antidiabetic drugs have severe side effects, which may be minimized by new selective molecules that strongly inhibit α-glucosidase and weakly inhibit α-amylase. We have synthesized novel alkoxy-substituted xanthones and imidazole-substituted xanthones and have evaluated them for their in silico and in vitro α-glucosidase and α-amylase inhibition activity. Compounds 6c, 6e, and 9b promoted higher α-glucosidase inhibition (IC50 = 16.0, 12.8, and 4.0 µM, respectively) and lower α-amylase inhibition (IC50 = 76.7, 68.1, and >200 µM, respectively) compared to acarbose (IC50 = 306.7 µM for α-glucosidase and 20.0 µM for α-amylase). Contrarily, derivatives 10c and 10f showed higher α-amylase inhibition (IC50 = 5.4 and 8.7 µM, respectively) and lower α-glucosidase inhibition (IC50 = 232.7 and 145.2 µM, respectively). According to the structure-activity relationship, attaching 4-bromobutoxy or 4'-chlorophenylacetophenone moieties to the 2-hydroxy group of xanthone provides higher α-glucosidase inhibition and lower α-amylase inhibition. In silico studies suggest that these scaffolds are key in the activity and interaction of xanthone derivatives. Enzymatic kinetics studies showed that 6c, 9b, and 10c are mainly mixed inhibitors on α-glucosidase and α-amylase. In addition, drug prediction and ADMET studies support that compounds 6c, 9b, and 10c are candidates with antidiabetic potential.

Molecular Recognition of Citroflavonoids Naringin and Naringenin at the Active Site of the HMG-CoA Reductase and DNA Topoisomerase Type II Enzymes of Candida spp. and Ustilago maydis.

Two agents from natural sources, citroflavonoids naringin and naringenin, can target enzymes in pathogenic yeasts responsible for hospital infections and crop failure. The aim of this study was to examine the molecular recognition site for naringin and naringenin on the HMGR and TOPOII enzymes of eleven Candida species and one phytopathogen, U. maydis, and evaluate yeast susceptibility to these flavonoids. The HMGR and TOPOII enzymes were analyzed in silico. The alignment of the two enzymes in the twelve pathogenic organisms with the corresponding enzyme of Homo sapiens revealed highly conserved amino acid sequences. Modeling studies of the enzymes indicated highly conserved structures. According to molecular docking simulations, both citroflavonoids recognized the amino acid residues of the active site of the enzymes. Binding energy values were higher for naringin (-10.75 and -9.38 kcal/mol, respectively) than simvastatin on HMGR (-9.9) and curcumin on TOPOII (-8.37). The appraisal of twenty-nine virtual mutations provided evidence of probable mechanisms of resistance (high binding energy) or susceptibility (low energy) to the drugs and emphasized the role of key residues. An in vitro susceptibility evaluation of the twelve yeasts demonstrated that the two flavonoids have similar or better MIC values than those reported for the reference compounds, obtaining the lowest with Candida dubliniensis (2.5 µg/ml) and U. maydis (5 µg/ml). Based on the present findings, naringin and naringenin could possibly be effective for treating diseases caused by pathogenic yeasts of the Candida species and U. maydis, presumably by inhibition of their HMGR and TOPOII enzymes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12088-021-00980-0.

Vacuolar proteases and autophagy in phytopathogenic fungi: A review.

Autophagy (macroautophagy) is a survival and virulence mechanism of different eukaryotic pathogens. Autophagosomes sequester cytosolic material and organelles, then fuse with or enter into the vacuole or lysosome (the lytic compartment of most fungal/plant cells and many animal cells, respectively). Subsequent degradation of cargoes delivered to the vacuole via autophagy and endocytosis maintains cellular homeostasis and survival in conditions of stress, cellular differentiation, and development. PrA and PrB are vacuolar aspartyl and serine endoproteases, respectively, that participate in the autophagy of fungi and contribute to the pathogenicity of phytopathogens. Whereas the levels of vacuolar proteases are regulated by the expression of the genes encoding them (e.g., PEP4 for PrA and PRB1 for PrB), their activity is governed by endogenous inhibitors. The aim of the current contribution is to review the main characteristics, regulation, and role of vacuolar soluble endoproteases and Atg proteins in the process of autophagy and the pathogenesis of three fungal phytopathogens: Ustilago maydis, Magnaporthe oryzae, and Alternaria alternata. Aspartyl and serine proteases are known to participate in autophagy in these fungi by degrading autophagic bodies. However, the gene responsible for encoding the vacuolar serine protease of U. maydis has yet to be identified. Based on in silico analysis, this U. maydis gene is proposed to be orthologous to the Saccharomyces cerevisiae genes PRB1 and PBI2, known to encode the principal protease involved in the degradation of autophagic bodies and its inhibitor, respectively. In fungi that interact with plants, whether phytopathogenic or mycorrhizal, autophagy is a conserved cellular degradation process regulated through the TOR, PKA, and SNF1 pathways by ATG proteins and vacuolar proteases. Autophagy plays a preponderant role in the recycling of cell components as well as in the fungus-plant interaction.

Three-Component Synthesis of 2-Amino-3-cyano-4H-chromenes, In Silico Analysis of Their Pharmacological Profile, and In Vitro Anticancer and Antifungal Testing.

Chromenes are compounds that may be useful for inhibiting topoisomerase and cytochrome, enzymes involved in the growth of cancer and fungal cells, respectively. The aim of this study was to synthesize a series of some novel 2-amino-3-cyano-4-aryl-6,7-methylendioxy-4H-chromenes 4a-o and 2-amino-3-cyano-5,7-dimethoxy-4-aryl-4H-chromenes 6a-h by a three-component reaction, and test these derivatives for anticancer and antifungal activity. Compounds 4a and 4b were more active than cisplatin (9) and topotecan (7) in SK-LU-1 cells, and more active than 9 in PC-3 cells. An evaluation was also made of the series of compounds 4 and 6 as potential antifungal agents against six Candida strains, finding their MIC50 to be less than or equal to that of fluconazole (8). Molecular docking studies are herein reported, for the interaction of 4 and 6 with topoisomerase IB and the active site of CYP51 of Candida spp. Compounds 4a-o and 6a-h interacted in a similar way as 7 with key amino acids of the active site of topoisomerase IB and showed better binding energy than 8 at the active site of CYP51. Hence, 4a-o and 6a-h are good candidates for further research, having demonstrated their dual inhibition of enzymes that participate in the growth of cancer and fungal cells.

Point mutations in Candida glabrata 3-hydroxy-3-methylglutaryl-coenzyme A reductase (CgHMGR) decrease enzymatic activity and substrate/inhibitor affinity.

3-Hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) is a crucial enzyme in the ergosterol biosynthesis pathway. The aim of this study was to obtain, purify, characterize, and overexpress five point mutations in highly conserved regions of the catalytic domain of Candida glabrata HMGR (CgHMGR) to explore the function of key amino acid residues in enzymatic activity. Glutamic acid (Glu) was substituted by glutamine in the E680Q mutant (at the dimerization site), Glu by glutamine in E711Q (at the substrate binding site), aspartic acid by alanine in D805A, and methionine by arginine in M807R (the latter two at the cofactor binding site). A double mutation, E680Q-M807R, was included. Regarding recombinant and wild-type CgHMGR, in vitro enzymatic activity was significantly lower for the former, as was the in silico binding energy of simvastatin, alpha-asarone and the HMG-CoA substrate. E711Q displayed the lowest enzymatic activity and binding energy, suggesting the importance of Glu711 (in the substrate binding site). The double mutant CgHMGR E680Q-M807R exhibited the second lowest enzymatic activity. Based on the values of the kinetic parameters KM and Vmax, the mutated amino acids appear to participate in binding. The current findings provide insights into the role of residues in the catalytic site of CgHMGR.

Etoposide and Camptothecin Reduce Growth, Viability, the Generation of Petite Mutants, and Recognize the Active Site of DNA Topoisomerase I and II Enzymes in Candida glabrata.

Candidemia, one of the most common invasive fungal infections in hospitalized patients, can lead to death and huge financial losses. Candida albicans is the main causative agent of this disorder and Candida glabrata occupies the second or third place, for which new therapeutic alternatives must be found. The objective of the present study was to evaluate the inhibitory effect of etoposide and camptothecin (inhibitors of deoxyribonucleic acid (DNA) topoisomerase) on the C. glabrata CBS138 strain. Etoposide and camptothecin showed better or similar MIC (minimum inhibitory concentration) (5 and 2.5 µg/mL, respectively), with respect to fluconazole (8 µg/mL) and itraconazole (4 µg/mL). They also suppressed colony formation during the 12-h test. On the other hand, petite colonies were less formed by exposing C. glabrata to etoposide or camptothecin (indicating low toxicity), with respect fluconazole and itraconazole. Such colonies are phenotypically observed as limited growth in medium containing a non-fermentable carbon source, and are genotypically characterized by a partial or total loss of mitochondrial DNA (mtDNA) fragments. Using PCR techniques and cell staining with 4',6-diamidino-2-phenylindole (DAPI), loss of mtDNA was detected only in yeast cells treated with fluconazole. Additionally, molecular docking studies with etoposide and camptothecin showed recognition in the active site of the Topo I and II enzymes from C. glabrata. Since etoposide and camptothecin showed good inhibitory activity and low toxicity on C. glabrata; they should certainly be of interest for the treatment of C. glabrata infections and the design and development of new antifungal compounds derived from these drugs. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12088-021-00942-6.

Inhibitors of DNA topoisomerases I and II applied to Candida dubliniensis reduce growth, viability, the generation of petite mutants and toxicity, while acting synergistically with fluconazole.

The increasing resistance of Candida species to azoles emphasizes the urgent need for new antifungal agents with novel mechanisms of action. The aim of this study was to examine the effect of three DNA topoisomerase inhibitors of plant origin (camptothecin, etoposide and curcumin) on the growth of Candida dubliniensis. The phylogenetic analysis showed a close relationship between the topoisomerase enzymes of C. dubliniensis and Candida albicans. The alignment of the amino acid sequences of topoisomerase I and II of yeasts and humans evidenced conserved domains. The docking study revealed affinity of the test compounds for the active site of topoisomerase I and II in C. dubliniensis. Curcumin and camptothecin demonstrated a stronger in vitro antifungal effect than the reference drugs (fluconazole and itraconazole). Significant synergistic activity between the topoisomerase inhibitors and fluconazole at the highest concentration (750 µM) was observed. Fluconazole induced the petite phenotype to a greater degree than the topoisomerase inhibitors, indicating a tendency to generate resistance. Lower toxicity was found for such inhibitors versus reference drugs on Galleria mellonella larva. The topoisomerase inhibitors exhibited promising antifungal activity, and the DNA topoisomerase enzymes of C. dubliniensis proved to be an excellent model for evaluating new antifungal compounds.

Inhibition of recombinant enzyme 3-hydroxy-3-methylglutaryl-CoA reductase from Candida glabrata by α-asarone-based synthetic compounds as antifungal agents.

Due to increasing resistance of Candida species to antifungal drugs, especially azoles, new drugs are needed. The proposed compounds 3 and 4 are analogous to α-asarone (2), a naturally occurring potent inhibitor of HMGR with hypolipidemic and antifungal activity. We used the recombinant enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase of Candida glabrata (CgHMGR) as a model to test the effectiveness of the test compounds. Compounds 3 and 4 demonstrated inhibitory kinetics, having lower IC50 values (42.65 µM and 28.77 µM, respectively) than compound 2 (>100 µM). The docking studies showed better binding energies for compounds 3 and 4 (-5.35 and -6.1 kcal/mol, respectively) than for compound 2 (-4.53 kcal/mol). These findings suggest that the tested compounds are better than their natural analogue. Plaque assays were performed on the C. glabrata strain CBS138 by applying ergosterol or cholesterol to evaluate the possible reversal of the inhibition induced by compounds 2, 3 and 4. Inhibition was easily suppressed in all three cases, recovering the viability of C. glabrata. These results reveal that the CgHMGR model is excellent for testing antifungals. Compound 4 produced the best effect and is herein proposed as a new potent antifungal agent.

Dibutyltin(IV) Complexes Derived from L-DOPA: Synthesis, Molecular Docking, Cytotoxic and Antifungal Activity.

A series of organotin(IV) complexes was herein prepared and characterized. A one-pot synthetic strategy afforded reasonable to high yields, depending on the nature of the ligand. All new complexes were fully characterized by spectroscopic techniques, consisting of IR, MS and NMR (1H, 13C and 119Sn). The in vitro cytotoxicity tests demonstrated that the organotin complexes produced a greater inhibition, versus cisplatin (the positive control), of the growth of six human cancer cell lines: U-251 (glioblastoma), K-562 (chronic myelogenous leukemia), HCT-15 (colorectal), MCF-7 (breast), MDA-MB-231 (breast) and SKLU-1 (non-small cell lung). The potency of this cytotoxic activity depended on the nature of the substituent bonded to the aromatic ring. All complexes exhibited excellent IC50 values. The test compounds were also screened in vitro for their antifungal effect against Candida glabrata and Candida albicans, showing minimum inhibitory concentration (MIC) values lower than those obtained for fluconazole. A brine shrimp bioassay was performed to examine the toxic properties. Molecular docking studies demonstrated that the organotin(IV) complexes bind at the active site of topoisomerase I in a similar manner to topotecan, sharing affinity for certain amino acid side chains (Ile535, Arg364 and Asp533), as well as for similar DNA regions (DA113, DC112 and DT10).

Synthesis, Molecular Docking, and Antimycotic Evaluation of Some 3-Acyl Imidazo[1,2-a]pyrimidines.

A series of 3-benzoyl imidazo[1,2-a]pyrimidines, obtained from N-heteroarylformamidines in good yields, was tested in silico and in vitro for binding and inhibition of seven Candida species (Candida albicans (ATCC 10231), Candida dubliniensis (CD36), Candida glabrata (CBS138), Candida guilliermondii (ATCC 6260), Candida kefyr, Candida krusei (ATCC 6358) and Candida tropicalis (MYA-3404)). To predict binding mode and energy, each compound was docked in the active site of the lanosterol 14α-demethylase enzyme (CYP51), essential for fungal growth of Candida species. Antimycotic activity was evaluated as the 50% minimum inhibitory concentration (MIC50) for the test compounds and two reference drugs, ketoconazole and fluconazole. All test compounds had a better binding energy (range: -6.11 to -9.43 kcal/mol) than that found for the reference drugs (range: 48.93 to -6.16 kcal/mol). In general, the test compounds showed greater inhibitory activity of yeast growth than the reference drugs. Compounds 4j and 4f were the most active, indicating an important role in biological activity for the benzene ring with electron-withdrawing substituents. These compounds show the best MIC50 against C. guilliermondii and C. glabrata, respectively. The current findings suggest that the 3-benzoyl imidazo[1,2-a]pyrimidine derivatives, herein synthesized by an accessible methodology, are potential antifungal drugs.

Recombinant 3-Hydroxy 3-Methyl Glutaryl-CoA Reductase from Candida glabrata (Rec-CgHMGR) Obtained by Heterologous Expression, as a Novel Therapeutic Target Model for Testing Synthetic Drugs.

The enzyme 3-hydroxy-3-methyl-glutaryl CoA reductase (HMGR) is a glycoprotein of the endoplasmic reticulum that participates in the mevalonate pathway, the precursor of cholesterol in human and ergosterol in fungi. This enzyme has three domains: transmembrane, binding, and soluble. In this study, we expressed and purified the soluble fraction of the HMGR enzyme from Candida glabrata (CgHMGR) in an Escherichia coli heterologous system and used it as a model for studying its inhibitory activity. The soluble fraction of CgHMGR was fused to the maltose binding protein (MBP), purified, and characterized. Optimal pH was 8.0, and its optimal temperature activity was 37 °C. The k m and V max for the HMG-CoA were 6.5 µM and 2.26 × 10-3 µM min-1, respectively. Recombinant CgHMGR was inhibited by simvastatin presenting an IC50 at 14.5 µM. In conclusion, our findings suggest that the recombinant HMGR version from C. glabrata may be used as a study model system for HMGR inhibitors such as statins and newly synthesized inhibitor compounds that might be used in the treatment of hypercholesterolemia or mycosis.

The 3-hydroxy-3-methylglutaryl coenzyme-A reductases from fungi: a proposal as a therapeutic target and as a study model / La enzima 3-hidroxi-3-metilglutaril coenzima A reductasa de hongos: propuesta como diana terapéutica y como modelo de estudio

The enzyme 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR) catalyzes the conversion of HMG-Co-A into mevalonate. This step is the limiting point for the synthesis of cholesterol in mammals and ergosterol in fungi. We describe in this article the genome organization of HMGR coding genes and those deduced from different fungi, recount the evidence showing statins as HMGR inhibitors for ergosterol synthesis and its effect in yeast viability, and propose fungal HMGR (HMGRf) as a model to study the use of pharmaceutical compounds to inhibit cholesterol and ergosterol synthesis. Bibliographical search and bioinformatic analyses were performed and discussed. HMGRfs belong to the class I with a high homology in the catalytic region. The sterol biosynthetic pathway in humans and fungi share many enzymes in the initial steps (such as the HMGR enzyme), but in the last steps enzymes are different rendering the two final products: cholesterol in mammals and ergosterol in fungi. With regards to inhibitors such as statins and other compounds, these affect also fungal viability. Since HMGR from Schizosaccharomyces pombe and Ustilago maydis are very similar to the human HMGR in the catalytic regions, we propose that fungal enzymes can be used to test inhibitors for a potential use in humans. We consider that HMGRf is a good therapeutic target to design and test new antifungal compounds. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012) (AU)

La enzima 3-hidroxi-3-metilglutaril coenzima A reductasa (HMGR) cataliza la conversión de HMG-Co-A a mevalonato, paso limitante en la síntesis de colesterol en mamíferos y de ergosterol en hongos. El presente artículo describe la organización de genes codificantes y proteínas de las diferentes HMGR de hongos (HMGRf), expone las evidencias disponibles en la inhibición de HMGR en la síntesis de ergosterol y su efecto en la viabilidad de los hongos, y propone las HMGRf como modelo de estudio para la aplicación de fármacos inhibidores de las síntesis de colesterol y ergosterol. Para ello se realizó una búsqueda bibliográfica y análisis bioinformáticos, con descripción de los datos. Las HMGRf son de clase i y presentan una alta homología en la región catalítica. La vía biosintética de esteroles en el ser humano y en los hongos comparte algunas enzimas iniciales (como la HMGR) pero, en los últimos pasos, las enzimas son diferentes, lo que genera productos finales distintos: colesterol y ergosterol, respectivamente. La inhibición de HMGRf por estatinas afecta a la síntesis de ergosterol y la viabilidad. Dado que el sitio catalítico de las HMGR de Schizosaccharomyces pombe y Ustilago maydis es muy similar al de la enzima humana, podrían servir como modelos para el estudio de fármacos inhibidores de la síntesis de colesterol. La HMGRf es una diana terapéutica adecuada para el diseño de nuevos antimicóticos.Este artículo forma parte de una serie de estudios presentados en el «V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi» (Oaxaca, México, 2012)(AU)

The 3-hydroxy-3-methylglutaryl coenzyme-A reductases from fungi: a proposal as a therapeutic target and as a study model.

The enzyme 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR) catalyzes the conversion of HMG-Co-A into mevalonate. This step is the limiting point for the synthesis of cholesterol in mammals and ergosterol in fungi. We describe in this article the genome organization of HMGR coding genes and those deduced from different fungi, recount the evidence showing statins as HMGR inhibitors for ergosterol synthesis and its effect in yeast viability, and propose fungal HMGR (HMGRf) as a model to study the use of pharmaceutical compounds to inhibit cholesterol and ergosterol synthesis. Bibliographical search and bioinformatic analyses were performed and discussed. HMGRfs belong to the class I with a high homology in the catalytic region. The sterol biosynthetic pathway in humans and fungi share many enzymes in the initial steps (such as the HMGR enzyme), but in the last steps enzymes are different rendering the two final products: cholesterol in mammals and ergosterol in fungi. With regards to inhibitors such as statins and other compounds, these affect also fungal viability. Since HMGR from Schizosaccharomyces pombe and Ustilago maydis are very similar to the human HMGR in the catalytic regions, we propose that fungal enzymes can be used to test inhibitors for a potential use in humans. We consider that HMGRf is a good therapeutic target to design and test new antifungal compounds. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012).