RESUMEN
A decoction of the roots (31.6-316 mg/kg) from Stevia serrata Cav. (Asteraceae) as well as the main component (5-150 mg/kg) showed hypoglycemic and antihyperglycemic effects in mice. The fractionation of the active extract led to the isolation of dammaradiene acetate (1), stevisalioside A (2), and three new chemical entities characterized by spectroscopic methods and named stevisaliosides B-D (3-5). Glycoside 2 (5 and 50 mg/kg) decreased blood glucose levels and the postprandial peak during oral glucose and insulin tolerance tests in STZ-hyperglycemic mice. Compounds 1-5 were tested also against PTP1B1-400 and showed IC50 values of 1180.9 ± 0.33, 526.8 ± 0.02, 532.1 ± 0.03, 928.2 ± 0.39, and 31.8 ± 1.09 µM, respectively. Compound 5 showed an IC50 value comparable to that of ursolic acid (IC50 = 30.7 ± 0.00 µM). Docking studies revealed that 2-5 and their aglycones bind to PTP1B1-400 in a pocket formed by the C-terminal region. The volatilome of S. serrata was characterized by a high content of (E)-longipinene, spathulenol, guaiadiene, seychellene, and aromandendrene. Finally, a UHPLC-UV method was developed and validated to quantify the content of 2 in the decoction of the plant.
Asunto(s)
Asteraceae , Stevia , Ratones , Animales , Hipoglucemiantes/farmacología , Hipoglucemiantes/química , Stevia/química , Extractos Vegetales/química , Glucosa , Asteraceae/química , Glucemia/análisisRESUMEN
Four new natural chemical entities, including 2-hydroxy-α-truxillic acid (2), (3R,4S)-2,2-dimethyl-3-hydroxy-4-(1-angeloyloxy)-6-acetyl-7-methoxychromane (3), N-tricosanoyltyramine (4), and grandifolamide (5), were isolated along with 11 known compounds (1, 6-15) from the aerial parts of Ageratina grandifolia. The chemical structures were elucidated using chemical derivatization and HR-MS, NMR, and DFT-calculated chemical shifts, combined with DP4+ statistical analysis. It was found that 2 decomposed into its biogenetic precursor, o-coumaric acid, upon standing at room temperature for a few weeks. 3,5-Diprenyl-4-hydroxyacetophenone (8), O-methylencecalinol (10), encecalin (11), and encecalinol (12) bound to calmodulin (CaM) with higher affinity than chlorpromazine, a well-known CaM inhibitor. Molecular dynamics studies revealed that the complexes of these compounds with CaM remained stable during the simulation. Altogether these results revealed the therapeutic and research tool potential of compounds 8, 10, 11, and 12.
Asunto(s)
Ageratina , Ageratina/química , Calmodulina/química , Calmodulina/metabolismo , Calmodulina/farmacología , Simulación de Dinámica Molecular , Espectroscopía de Resonancia Magnética , Estructura MolecularRESUMEN
In the present work, we studied the inhibitory and kinetic implications of classical PTP1B inhibitors (chlorogenic acid, ursolic acid, suramin) using three enzyme constructs (hPTP1B1-285, hPTP1B1-321, and hPTP1B1-400). The results indicate that the unstructured region of PTP1B (300-400 amino acids) is very important both to obtain optimal inhibitory results and propose classical inhibition mechanisms (competitive or non-competitive) through kinetic studies. The IC50 calculated for ursolic acid and suramin using hPTP1B1-400 are around four and three times lower to the short form of the enzyme, the complete form of PTP1B, the one found in the cytosol (in vivo). On the other hand, we highlight the studies of enzymatic kinetics using the hPTP1B1-400 to know the type of enzymatic inhibition and to be able to direct docking studies, where the unstructured region of the enzyme can be one more option for binding compounds with inhibitory activity.
Asunto(s)
Inhibidores Enzimáticos , Hipoglucemiantes , Hipoglucemiantes/química , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/química , Cinética , Suramina , Simulación del Acoplamiento Molecular , Proteína Tirosina Fosfatasa no Receptora Tipo 1 , Ácido UrsólicoRESUMEN
Type 2 diabetes (T2D) is one of the most common diseases and the 8th leading cause of death worldwide. Individuals with T2D are at risk for several health complications that reduce their life expectancy and quality of life. Although several drugs for treating T2D are currently available, many of them have reported side effects ranging from mild to severe. In this work, we present the synthesis in a gram-scale as well as the in silico and in vitro activity of two semisynthetic glycyrrhetinic acid (GA) derivatives (namely FC-114 and FC-122) against Protein Tyrosine Phosphatase 1B (PTP1B) and α-glucosidase enzymes. Furthermore, the in vitro cytotoxicity assay on Human Foreskin fibroblast and the in vivo acute oral toxicity was also conducted. The anti-diabetic activity was determined in streptozotocin-induced diabetic rats after oral administration with FC-114 or FC-122. Results showed that both GA derivatives have potent PTP1B inhibitory activity being FC-122, a dual PTP1B/α-glucosidase inhibitor that could increase insulin sensitivity and reduce intestinal glucose absorption. Molecular docking, molecular dynamics, and enzymatic kinetics studies revealed the inhibition mechanism of FC-122 against α-glucosidase. Both GA derivatives were safe and showed better anti-diabetic activity in vivo than the reference drug acarbose. Moreover, FC-114 improves insulin levels while decreasing LDL and total cholesterol levels without decreasing HDL cholesterol.
Asunto(s)
Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Ácido Glicirretínico , Humanos , Animales , Ratas , Diabetes Mellitus Experimental/tratamiento farmacológico , Simulación del Acoplamiento Molecular , Calidad de Vida , alfa-Glucosidasas , Ácido Glicirretínico/farmacologíaRESUMEN
Eukarya pyruvate kinases possess glutamate at position 117 (numbering of rabbit muscle enzyme), whereas bacteria have either glutamate or lysine. Those with E117 are K+-dependent, whereas those with K117 are K+-independent. In a phylogenetic tree, 80% of the sequences with E117 are occupied by T113/K114/T120 and 77% of those with K117 possess L113/Q114/(L,I,V)120. This work aims to understand these residues' contribution to the K+-independent pyruvate kinases using the K+-dependent rabbit muscle enzyme. Residues 117 and 120 are crucial in the differences between the K+-dependent and -independent mutants. K+-independent activity increased with L113 and Q114 to K117, but L120 induced structural differences that inactivated the enzyme. T120 appears to be key in folding the protein and closure of the lid of the active site to acquire its active conformation in the K+-dependent enzymes. E117K mutant was K+-independent and the enzyme acquired the active conformation by a different mechanism. In the K+-independent apoenzyme of Mycobacterium tuberculosis, K72 (K117) flips out of the active site; in the holoenzyme, K72 faces toward the active site bridging the substrates through water molecules. The results provide evidence that two different mechanisms have evolved for the catalysis of this reaction.
Asunto(s)
Piruvato Quinasa/genética , Piruvato Quinasa/metabolismo , Piruvato Quinasa/ultraestructura , Secuencia de Aminoácidos/genética , Animales , Apoenzimas/metabolismo , Sitios de Unión , Catálisis , Dominio Catalítico , Ácido Glutámico/metabolismo , Lisina/metabolismo , Modelos Moleculares , Mycobacterium tuberculosis/enzimología , Mycobacterium tuberculosis/genética , Filogenia , Potasio/metabolismo , Conformación Proteica , ConejosRESUMEN
In the present study, we reported the interactions at the molecular level of a series of compounds called Bisindolylmaleimide, as potential inhibitors of the calmodulin protein. Bisindolylmaleimide compounds are drug prototypes derived from Staurosporine, an alkaloid with activity for cancer treatment. Bisindolylmaleimide compounds II, IV, VII, X, and XI, are proposed and reported as possible inhibitors of calmodulin protein for the first time. For the above, a biotechnological device was used (fluorescent biosensor hCaM M124C-mBBr) to directly determine binding parameters experimentally (Kd and stoichiometry) of these compounds, and molecular modeling tools (Docking, Molecular Dynamics, and Chemoinformatic Analysis) to carry out the theoretical studies and complement the experimental data. The results indicate that this compound binds to calmodulin with a Kd between 193-248 nM, an order of magnitude lower than most classic inhibitors. On the other hand, the theoretical studies support the experimental results, obtaining an acceptable correlation between the ΔGExperimental and ΔGTheoretical (r2 = 0.703) and providing us with complementary molecular details of the interaction between the calmodulin protein and the Bisindolylmaleimide series. Chemoinformatic analyzes bring certainty to Bisindolylmaleimide compounds to address clinical steps in drug development. Thus, these results make these compounds attractive to be considered as possible prototypes of new calmodulin protein inhibitors.
Asunto(s)
Biopelículas , Calmodulina , Calmodulina/química , Ligandos , Reactores Biológicos , Simulación de Dinámica Molecular , Unión ProteicaRESUMEN
Regulating insulin and leptin levels using a protein tyrosine phosphatase 1B (PTP1B) inhibitor is an attractive strategy to treat diabetes and obesity. Glycyrrhetinic acid (GA), a triterpenoid, may weakly inhibit this enzyme. Nonetheless, semisynthetic derivatives of GA have not been developed as PTP1B inhibitors to date. Herein we describe the synthesis and evaluation of two series of indole- and N-phenylpyrazole-GA derivatives (4a-f and 5a-f). We measured their inhibitory activity and enzyme kinetics against PTP1B using p-nitrophenylphosphate (pNPP) assay. GA derivatives bearing substituted indoles or N-phenylpyrazoles fused to their A-ring showed a 50% inhibitory concentration for PTP1B in a range from 2.5 to 10.1 µM. The trifluoromethyl derivative of indole-GA (4f) exhibited non-competitive inhibition of PTP1B as well as higher potency (IC50 = 2.5 µM) than that of positive controls ursolic acid (IC50 = 5.6 µM), claramine (IC50 = 13.7 µM) and suramin (IC50 = 4.1 µM). Finally, docking and molecular dynamics simulations provided the theoretical basis for the favorable activity of the designed compounds.
Asunto(s)
Inhibidores Enzimáticos , Ácido Glicirretínico , Indoles , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Proteína Tirosina Fosfatasa no Receptora Tipo 1 , Pirazoles , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Ácido Glicirretínico/análogos & derivados , Ácido Glicirretínico/síntesis química , Ácido Glicirretínico/química , Humanos , Indoles/síntesis química , Indoles/química , Proteína Tirosina Fosfatasa no Receptora Tipo 1/antagonistas & inhibidores , Proteína Tirosina Fosfatasa no Receptora Tipo 1/química , Pirazoles/síntesis química , Pirazoles/química , Relación Estructura-ActividadRESUMEN
During a search for new α-glucosidase and protein tyrosine phosphatase 1B inhibitors from fungal sources, eight new secondary metabolites, including two anthranilic acid-derived peptides (1 and 2), four glycosylated anthraquinones (3-6), 4-isoprenylravenelin (7), and a dimer of 5,8-dihydroxy-4-methoxy-α-tetralone (8), along with four known compounds (9-12), were isolated from solid rice-based cultures of Malbranchea circinata. The structural elucidation of these metabolites was performed using 1D and 2D NMR techniques and DFT-calculated chemical shifts. Compounds 1-3, 9, and 10 showed inhibitory activity to yeast α-glucosidase (αGHY), with IC50 values ranging from 57.4 to 261.3 µM (IC50 acarbose = 585.8 µM). The effect of 10 (10.0 mg/kg) was corroborated in vivo using a sucrose tolerance test in normoglucemic mice. The most active compounds against PTP-1B were 8-10, with IC50 values from 10.9 to 15.3 µM (IC50 ursolic acid = 27.8 µM). Docking analysis of the active compounds into the crystal structures of αGHY and PTP-1B predicted that all compounds bind to the catalytic domains of the enzymes. Together, these results showed that M. circinata is a potential source of antidiabetic drug leads.
Asunto(s)
Inhibidores de Glicósido Hidrolasas/farmacología , Onygenales/química , Proteína Tirosina Fosfatasa no Receptora Tipo 1/antagonistas & inhibidores , Animales , Productos Biológicos/aislamiento & purificación , Productos Biológicos/farmacología , Inhibidores de Glicósido Hidrolasas/aislamiento & purificación , Hipoglucemiantes , Masculino , Ratones , Ratones Endogámicos ICR , Simulación del Acoplamiento Molecular , Estructura Molecular , alfa-GlucosidasasRESUMEN
A critical biological event that contributes to the appearance and progress of cancer and diabetes is the reversible phosphorylation of proteins, a process controlled by protein tyrosine-kinases (PTKs) and protein tyrosine-phosphatases (PTPs). Within the PTPs, PTP1B has gained significant interest since it is a validated target in drug discovery. Indeed, several PTP1B inhibitors have been developed, from both, synthesis and natural products. However, none have been approved by the FDA, due to their poor selectivity and/or pharmacokinetic properties. One of the most significant challenges to the discovery of PTP1B inhibitors (in vitro or in silico) is the use of truncated structures (PTP1B1-300), missing valuable information about the mechanisms of inhibition, and selectivity of ligands. The present study describes the biochemical characterization of a full-length PTP1B (hPTP1B1-400), as well as the description of phenalenones 1-4 and ursolic acid (5) as allosteric modulators. Compounds 1-5 showed inhibitory potential on hPTP1B1-400, with IC50 values ranging from 12.7 to 82.1 µM. Kinetic studies showed that 1 and 5 behave as mixed and non-competitive inhibitors, respectively. Circular dichroism experiments confirmed that 1 and 5 induced conformational changes to hPTP1B1-400. Further insights into the structure of hPTP1B1-400 were obtained from a homology model, which pointed out that the C-terminus (residues 301-400) is highly disordered. Molecular docking with the homologated model suggested that compounds 1 and 3-5 bind to the C-terminal domain, likely inducing conformational changes on the protein. Docking positions of compounds 1, 4, and 5 were refined with molecular dynamics simulations. Importantly, these simulations confirmed the high flexibility of the C-terminus of hPTP1B1-400, as well as the changes to its rigidity when bound to 1, 4, and 5.
Asunto(s)
Fenalenos/farmacología , Proteína Tirosina Fosfatasa no Receptora Tipo 1/antagonistas & inhibidores , Talaromyces/química , Simulación por Computador , Dimerización , Humanos , Técnicas In Vitro , Cinética , Simulación del Acoplamiento Molecular , Fenalenos/químicaRESUMEN
An infusion prepared from the aerial parts of Salvia amarissima Ortega inhibited the enzyme protein tyrosine phosphatase 1B (PTP-1B) (IC50~88 and 33 µg/mL, respectively). Phytochemical analysis of the infusion yielded amarisolide (1), 5,6,4'-trihydroxy-7,3'-dimethoxyflavone (2), 6-hydroxyluteolin (3), rutin (4), rosmarinic acid (5), isoquercitrin (6), pedalitin (7) and a new neo-clerodane type diterpenoid glucoside, named amarisolide G (8a,b). Compound 8a,b is a new natural product, and 2-6 are reported for the first time for the species. All compounds were tested for their inhibitory activity against PTP-1B; their IC50 values ranged from 62.0 to 514.2 µM. The activity was compared to that of ursolic acid (IC50 = 29.14 µM). The most active compound was pedalitin (7). Docking analysis predicted that compound 7 has higher affinity for the allosteric site of the enzyme. Gas chromatography coupled to mass spectrometry analyses of the essential oils prepared from dried and fresh materials revealed that germacrene D (15) and ß-selinene (16), followed by ß-caryophyllene (13) and spathulenol (17) were their major components. An ultra-high performance liquid chromatography coupled to mass spectrometry method was developed and validated to quantify amarisolide (1) in the ethyl acetate soluble fraction of the infusion of S. amarissima.
Asunto(s)
Flavonoides/aislamiento & purificación , Flavonoides/farmacología , Proteína Tirosina Fosfatasa no Receptora Tipo 1/antagonistas & inhibidores , Salvia/química , Terpenos/aislamiento & purificación , Terpenos/farmacología , Sitio Alostérico , Inhibidores Enzimáticos/aislamiento & purificación , Inhibidores Enzimáticos/farmacología , Humanos , Hipoglucemiantes/aislamiento & purificación , Hipoglucemiantes/farmacología , Técnicas In Vitro , México , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Estructura Molecular , Fitoterapia , Extractos Vegetales/química , Extractos Vegetales/farmacología , Plantas Medicinales/química , Proteína Tirosina Fosfatasa no Receptora Tipo 1/químicaRESUMEN
BACKGROUND: The amino acid taurine (2-Aminoethanesulfonic acid) modulates inhibitory neurotransmitter receptors. This study aimed to determine if the dual action of taurine on GABAC-ρ1R relates to its structure. To address this, we tested the ability of the structurally related compounds homotaurine, hypotaurine, and isethionic acid to modulate GABAC-ρ1R. RESULTS: In Xenopus laevis oocytes, hypotaurine and homotaurine partially activate heterologously expressed GABAC-ρ1R, showing an increment in its deactivation time with no changes in channel permeability, whereas isethionic acid showed no effect. Competitive assays suggest that hypotaurine and homotaurine compete for the GABA-binding site. In addition, their effects were blocked by the ion-channel blockers picrotixin and Methyl(1,2,5,6-tetrahydropyridine-4-yl) phosphinic acid. In contrast to taurine, co-application of GABA with hypotaurine or homotaurine revealed that the dual effect is present separately for each compound: hypotaurine modulates positively the GABA current, while homotaurine shows a negative modulation, both in a dose-dependent manner. Interestingly, homotaurine diminished hypotaurine-induced currents. Thus, these results strongly suggest a competitive interaction between GABA and homotaurine or hypotaurine for the same binding site. "In silico" modeling confirms these observations, but it also shows a second binding site for homotaurine, which could explain the negative effect of this compound on the current generated by GABA or hypotaurine, during co-application protocols. CONCLUSIONS: The sulfur-containing compounds structurally related to taurine are partial agonists of GABAC-ρ1R that occupy the agonist binding site. The dual effect is unique to taurine, whereas in the case of hypotaurine and homotaurine it presents separately; hypotaurine increases and homotaurine decreases the GABA current.
Asunto(s)
Receptores de GABA/efectos de los fármacos , Compuestos de Azufre/farmacología , Taurina/análogos & derivados , Taurina/efectos de los fármacos , Animales , Técnicas de Placa-Clamp/métodos , Taurina/metabolismo , Xenopus laevis , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Mimotopes, or epitope mimics, can be applied to competitive immunoassays, for the detection of low molecular weight natural toxicants, as an alternative to toxin-conjugates. In this work, we report the development of a microarray-based immunoassay for the detection of fumonisin B1 using a novel mimotope selected by phage display technology. Fumonisin-specific antibody was used to isolate mimotopes from a 12-mer peptide library in successive selection rounds. Enrichment of antibody binding phages was observed after three panning rounds, and sequence analysis of randomly selected monoclonal phages revealed two conserved peptide sequences. Clone A2, with peptide sequence VTPNDDTFDPFR, showed the best response in enzyme-linked immunosorbent assay (ELISA) in terms of sensitivity and reproducibility and was selected for microarray development. A biotinylated synthetic derivative of this mimotope was immobilized onto epoxy-glass slides, and fumonisin B1 was detected in a competitive binding inhibition assay using the antifumonisin antibody and a labeled secondary antibody. The array showed an IC50 value of 37.1 ± 2.4 ng mL-1 (n = 9), a detection limit of 11.1 ng mL-1, and a dynamic range from 17.3 to 79.6 ng mL-1. Good specificity toward fumonisin B1 and its structural analog, fumonisin B2, was observed, together with negligible cross-reactivity for other mycotoxins produced by the same fungi species. The mimotope microarray was applied to the analysis of fumonisin B1 in spiked maize and wheat samples. The method enabled quantification of the mycotoxin at the levels set by European legislation and holds promise for future adaptation to include other mycotoxins for multiplex detection.
Asunto(s)
Ensayo de Inmunoadsorción Enzimática , Fumonisinas/análisis , Análisis por Matrices de Proteínas , Triticum/química , Zea mays/químicaRESUMEN
A dried infusion prepared from the aerial parts of Salvia circinata did not provoke acute toxicity in mice (LD50 > 5 g/kg). This infusion showed poor hypoglycemic and antihyperglycemic effects (100-570 mg/kg) when tested in normal and hyperglycemic mice using acute and oral glucose tolerance tests, respectively. However, this infusion possessed antihyperglycemic action in vivo during an oral sucrose tolerance test (31.6-316 mg/kg), suggesting the presence of α-glucosidase inhibitors in S. circinata. Fractionation of a nonpolar extract of the aerial parts of the plant yielded a new biflavone (1) and four new neoclerodane diterpenoid glucosides (2-5) along with the known compounds amarisolide (6), pedalitin (7), apigenin-7-O-ß-d-glucoside (8), and the flavone 2-(3,4-dimethoxyphenyl)-5,6-dihydroxy-7-methoxy-4H-chromen-4-one (9). Compounds 1 and 6-9 were active against mammalian α-glucosidases; 6 and 7 were also active against a recombinant α-glucosidase from Ruminococcus obeum and reduced significantly the postprandial peak during an oral sucrose tolerance test in healthy mice, consistent with their α-glucosidase inhibitory activity. Molecular docking and dynamic studies revealed that compounds 6 and 7 might bind to α-glucosidases at the catalytic center of the enzyme.
Asunto(s)
Inhibidores de Glicósido Hidrolasas/aislamiento & purificación , Inhibidores de Glicósido Hidrolasas/farmacología , Hipoglucemiantes/aislamiento & purificación , Salvia/química , alfa-Glucosidasas/efectos de los fármacos , Animales , Inhibidores de Glicósido Hidrolasas/química , Hipoglucemiantes/química , Hipoglucemiantes/farmacología , Ratones , Simulación del Acoplamiento Molecular , Estructura Molecular , alfa-Glucosidasas/químicaRESUMEN
BACKGROUND: N-benzylpiperazine (BZP) belongs to a class of piperazine derivatives (PZDs) that have emerged as recreational drugs. These compounds increase the release of dopamine and serotonin. BZP mimics the psychoactive effects of 3,4-methylenedioxymethylamphetamine. BZP is metabolized to N-benzylethylenediamine (BEDA) and benzylamine. The compound N,N'-dibenzylpiperazine (DBZP) is obtained as a byproduct during the synthesis of BZP. Some PZDs have shown effects on memory; however, there are no previous reports on the activity of BZP, BEDA, and DBZP on memory or on a description of their neuropharmacological profile. We evaluated the effects of these compounds on acquisition, formation, and consolidation memory and explored their neuropharmacological profile in mice. METHODS: We used the passive avoidance test to evaluate the nootropic effect and for memory experiments. We also evaluated the sedative, myo-relaxant, motor coordination, anxiogenic, and locomotor activity of these compounds. RESULTS: We showed that BZP, its metabolite BEDA, and the disubstituted analogue DBZP enhance the memory and show anxiogenic effects. BZP, as well as DBZP but not BEDA, showed a strong myo-relaxant effect without impairing motor coordination. CONCLUSIONS: BZP and BEDA enhanced the acquisition and consolidation of memory, whereas DBZP only enhances the acquisition of the memory. BEDA and DBZP have an anxiogenic profile similar to that of BZP. BEDA and DBZP represent new psychoactive compounds with the potential to be new BZP-like recreational entities.
Asunto(s)
Bencilaminas/farmacología , Etilenodiaminas/farmacología , Memoria/efectos de los fármacos , Piperazinas/farmacología , Animales , Reacción de Prevención/efectos de los fármacos , Conducta Animal/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Masculino , RatonesRESUMEN
TRK transporters, a class of proteins which generally carry out the bulk of K(+) accumulation in plants, fungi, and bacteria, mediate ion currents driven by the large membrane voltages (-150 to -250 mV) common to non-animal cells. Bacterial TRK proteins resemble K(+) channels in their primary sequence, crystallize as membrane dimers having intramolecular K(+)-channel-like folding, and complex with a cytoplasmic collar formed of four RCK domains (Nature 471:336, 2011; Ibid 496:324, 2013). Fungal TRK proteins appear simpler in form than the bacterial members, but do possess two special features: a large built-in regulatory domain, and a highly conserved pair of transmembrane helices (TM7 and TM8, ahead of the C-terminus), which were postulated to facilitate intramembranal oligomerization (Biophys. J. 77:789, 1999; FEMS Yeast Res. 9:278, 2009). A surprising associated functional process in the fungal proteins which have been explored (Saccharomyces, Candida, and Neurospora) is facilitation of channel-like chloride efflux. That process is suppressed by osmoprotective agents, appears to involve hydrophobic gating, and strongly resembles conduction by Cys-loop ligand-gated anion channels. And it leads to a rather general hypothesis: that the thermodynamic tendency for hydrophobic or amphipathic transmembrane helices to self-organize into oligomers can create novel ionic pathways through biological membranes: fundamental hydrophobic nanopores, pathways of low selectivity governed by the chaotropic behavior of individual ionic species and under the strong influence of membrane voltage.
Asunto(s)
Cloruros/metabolismo , Canales de Potasio/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Secuencia de Aminoácidos , Datos de Secuencia Molecular , Potasio/metabolismo , Canales de Potasio/química , Estructura Terciaria de Proteína , Proteínas de Saccharomyces cerevisiae/química , Levaduras/genética , Levaduras/metabolismoRESUMEN
Calmodulin (CaM) plays a central role in regulating a myriad of cellular functions in physiological and pathophysiological processes, thus representing an important drug target. In previous reviews, our group has reported relevant information regarding natural anti-CaM compounds up to 2009. Natural sources continue to provide a diverse and unique reservoir of CaM inhibitors for drug and research tool discovery. This review provides an update of natural products with reported CaM inhibitory properties, which includes around 70 natural products and some synthetic analogues, belonging to different structural classes. Most of these natural inhibitors were isolated from fungi and plants and belong to the stilbenoid, polyketide, alkaloid, and peptide structural classes. These products were discovered mainly using a fluorescence-based method on rationally designed biosensors, which are highly specific, low-cost, and selective and have short reaction times. The effect of several antimitotic drugs on Ca(2+)-hCaM is also described.
Asunto(s)
Productos Biológicos , Calmodulina/antagonistas & inhibidores , Calcio/metabolismo , Flavonoides/química , Flavonoides/aislamiento & purificación , Flavonoides/farmacología , Estructura Molecular , Terpenos/química , Terpenos/aislamiento & purificación , Terpenos/farmacologíaRESUMEN
It has been suggested that the N-terminal strand of the light chain variable domain (V(L)) protects the molecule from aggregation by hindering spurious intermolecular contacts. We evaluated the impact of mutations in the N-terminal strand on the thermodynamic stability and kinetic of fibrillogenesis of the V(L) protein 6aJL2. Mutations in this strand destabilized the protein in a position-dependent manner, accelerating the fibrillogenesis by shortening the lag time; an effect that correlated with the extent of destabilization. In contrast, the effect on the kinetics of fibril elongation, as assessed in seeding experiments was of different nature, as it was not directly dependant on the degree of destabilization. This finding suggests different factors drive the nucleation-dependent and elongation phases of light chain fibrillogenesis. Finally, taking advantage of the dependence of the Trp fluorescence upon environment, four single Trp substitutions were made in the N-terminal strand, and changes in solvent exposure during aggregation were evaluated by acrylamide-quenching. The results suggest that the N-terminal strand is buried in the fibrillar state of 6aJL2 protein. This finding suggest a possible explanation for the modulating effect exerted by the mutations in this strand on the aggregation behavior of 6aJL2 protein.
Asunto(s)
Amiloide/química , Cadenas Ligeras de Inmunoglobulina/química , Cadenas lambda de Inmunoglobulina/química , Amiloide/genética , Sitios de Unión , Cadenas Ligeras de Inmunoglobulina/genética , Cadenas lambda de Inmunoglobulina/genética , Mutagénesis Sitio-Dirigida , Mutación , Unión Proteica , Estructura Terciaria de Proteína , Relación Estructura-ActividadRESUMEN
Protein tyrosine phosphatase 1B (PTP1B) is a promising drug target for treating type 2 diabetes (T2DM) and obesity. As a result, developing new therapies that target PTP1B is an attractive strategy for treating these diseases. Herein, we detail the synthesis of 15 lithocholic acid (LA) derivatives, each containing different benzylaminomethyl groups attached to the C3 position of the steroid skeleton. The derivatives were assessed against two forms of PTP1B enzyme (hPTP1B1-400 and hPTP1B1-285), and the most potent compounds were then tested against T-cell protein tyrosine phosphatase (TCPTP) to determine their selectivity. The results showed that compounds 6m and 6n were more potent than the reference compounds (ursolic acid, chlorogenic acid, suramin, and TCS401). Additionally, both compounds exhibited greater potency over hPTP1B1-400. Furthermore, enzyme kinetic studies on hPTP1B1-400 revealed that these two lithocholic acid derivatives have an uncompetitive inhibition against hPTP1B1-400 with K i values of 2.5 and 3.4 µM, respectively. Interestingly, these compounds were around 75-fold more selective for PTP1B over TCPTP. Finally, docking studies and molecular dynamics simulations (MDS) were conducted to determine how these compounds interact with PTP1B. The docking studies revealed hydrophobic and H-bond interactions with amino acid residues in the unstructured region. MDS showed that these interactions persisted throughout the 200 ns simulation, indicating the crucial role of the unstructured zone in the biological activity and inhibition of PTP1B.
RESUMEN
Current treatments for type 2 diabetes (T2D) mainly rely on exercise, dietary control, and anti-diabetic drugs to enhance insulin secretion and improve insulin sensitivity. However, there is a need for more therapeutic options. A potential target that has attracted attention is the protein tyrosine phosphatase 1B (PTP1B), which negatively regulates the insulin signaling pathway. In this work, a comprehensive computational screening was carried out using cheminformatics and molecular docking on PTP1B, employing a rigorous repurposing approach. The screening involved approved drugs and compounds under research as anti-diabetics that bind to targets such as peroxisome proliferator-activated receptor gamma (PPAR-gamma) and alpha-glucosidase. Some computational hits were then meticulously tested in vitro against PTP1B; particularly the 13-cis-retinoic acid ( 3a) showed an IC 50 of 0.044 mM and competitive inhibition. Molecular dynamics studies agrees that 3a can bind to the catalytic binding site of PTP1B. It is worth mentioning that 3a has been reported by the first time as an inhibitor of PTP1B in this work, making it a potentially valuable candidate for further studies in D2T treatment.
RESUMEN
Tyrosine protein phosphatase non-receptor type 1 (PTP1B; also known as protein tyrosine phosphatase 1B) is a member of the protein tyrosine phosphatase (PTP) family and is a soluble enzyme that plays an essential role in different physiological processes, including the regulation of metabolism, specifically in insulin and leptin sensitivity. PTP1B is crucial in the pathogenesis of type 2 diabetes mellitus and obesity. These biological functions have made PTP1B validated as an antidiabetic and anti-obesity, and potentially anticancer, molecular target. Four main approaches aim to inhibit PTP1B: orthosteric, allosteric, bidentate inhibition, and PTPN1 gene silencing. Developing a potent and selective PTP1B inhibitor is still challenging due to the enzyme's ubiquitous expression, subcellular location, and structural properties. This article reviews the main advances in the study of PTP1B since it was first isolated in 1988, as well as recent contextual information related to the PTP family to which this protein belongs. Furthermore, we offer an overview of the role of PTP1B in diabetes and obesity, and the challenges to developing selective, effective, potent, bioavailable, and cell-permeable compounds that can inhibit the enzyme.