Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 58
Filtrar
1.
Int J Mol Sci ; 25(4)2024 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-38396842

RESUMO

Type 2 diabetes is characterized by hyperglycemia and a relative loss of ß-cell function. Our research investigated the antidiabetic potential of betulin, a pentacyclic triterpenoid found primarily in birch bark and, intriguingly, in a few marine organisms. Betulin has been shown to possess diverse biological activities, including antioxidant and antidiabetic activities; however, no studies have fully explored the effects of betulin on the pancreas and pancreatic islets. In this study, we investigated the effect of betulin on streptozotocin-nicotinamide (STZ)-induced diabetes in female Wistar rats. Betulin was prepared as an emulsion, and intragastric treatments were administered at doses of 20 and 50 mg/kg for 28 days. The effect of treatment was assessed by analyzing glucose parameters such as fasting blood glucose, hemoglobin A1C, and glucose tolerance; hepatic and renal biomarkers; lipid peroxidation; antioxidant enzymes; immunohistochemical analysis; and hematological indices. Administration of betulin improved the glycemic response and decreased α-amylase activity in diabetic rats, although insulin levels and homeostatic model assessment for insulin resistance (HOMA-IR) scores remained unchanged. Furthermore, betulin lowered the levels of hepatic biomarkers (aspartate aminotransferase, alanine aminotransferase, and alpha-amylase activities) and renal biomarkers (urea and creatine), in addition to improving glutathione levels and preventing the elevation of lipid peroxidation in diabetic animals. We also found that betulin promoted the regeneration of ß-cells in a dose-dependent manner but did not have toxic effects on the pancreas. In conclusion, betulin at a dose of 50 mg/kg exerts a pronounced protective effect against cytolysis, diabetic nephropathy, and damage to the acinar pancreas and may be a potential treatment option for diabetes.


Assuntos
Ácido Betulínico , Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Ratos , Feminino , Animais , Antioxidantes/uso terapêutico , Niacinamida/farmacologia , Niacinamida/uso terapêutico , Ratos Wistar , Estreptozocina/efeitos adversos , Diabetes Mellitus Experimental/induzido quimicamente , Glicemia , Extratos Vegetais/farmacologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/efeitos adversos , Glucose/efeitos adversos , Biomarcadores , alfa-Amilases
2.
Crit Rev Food Sci Nutr ; 63(2): 261-287, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-34251921

RESUMO

Isoflavones are secondary metabolites that represent the most abundant category of plant polyphenols. Dietary soy, kudzu, and red clover contain primarily genistein, daidzein, glycitein, puerarin, formononetin, and biochanin A. The structural similarity of these compounds to ß-estradiol has demonstrated protection against age-related and hormone-dependent diseases in both genders. Demonstrative shreds of evidence confirmed the fundamental health benefits of the consumption of these isoflavones. These relevant activities are complex and largely driven by the source, active ingredients, dose, and administration period of the bioactive compounds. However, the preclinical and clinical studies of these compounds are greatly variable, controversial, and still with no consensus due to the non-standardized research protocols. In addition, absorption, distribution, metabolism, and excretion studies, and the safety profile of isoflavones have been far limited. This highlights a major gap in understanding the potentially critical role of these isoflavones as prospective replacement therapy. Our general review exclusively focuses attention on the crucial role of isoflavones derived from these plant materials and critically highlights their bioavailability, possible anticancer, antiaging potentials, and microbiome modulation. Despite their fundamental health benefits, plant isoflavones reveal prospective therapeutic effects that worth further standardized analysis.


Assuntos
Feminino , Masculino , Humanos
3.
Mar Drugs ; 21(5)2023 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-37233457

RESUMO

Phlorotannins are secondary metabolites produced mainly by brown seaweeds (Phaeophyceae) and belong to the class of polyphenolic compounds with diverse bioactivities. The key factors in the extraction of polyphenols are the selection of a suitable solvent, method of extraction and selection of optimal conditions. Ultrasonic-assisted extraction (UAE) is one of the advanced energy-saving methods suitable for the extraction of labile compounds. Methanol, acetone, ethanol and ethyl acetate are the most commonly used solvents for polyphenol extraction. As alternatives to toxic organic solvents, a new class of green solvents, natural deep eutectic solvents (NADES), has been proposed for the efficient extraction of a wide range of natural compounds including polyphenols. Several NADES were screened previously for the extraction of phlorotannins; however, the extraction conditions were not optimized and chemical profiling of NADES extract was not performed. The purpose of this work was to study the effect of selected extraction parameters on the phlorotannin content in NADES extract from Fucus vesiculosus, optimization of extraction conditions and chemical profiling of phlorotannins in the NADES extract. A fast and green NADES-UAE procedure was developed for the extraction of phlorotannins. Optimization was performed through an experimental design and showed that NADES (lactic acid:choline chloride; 3:1) provides a high yield (137.3 mg phloroglucinol equivalents per g dry weight of algae) of phlorotannins under the following extraction conditions: extraction time 23 min, 30.0% water concentration and 1:12 sample to solvent ratio. The antioxidant activity of the optimized NADES extract was equal to that of EtOH extract. In total, 32 phlorotannins have been identified (one trimer, two tetramers, six pentamers, four hexamers, six heptamers, six octamers and seven nonamers) in NADES extracts from arctic F. vesiculosus using the HPLC-HRMS and MS/MS technique. It was noted that all the above-mentioned phlorotannins were identified in both EtOH and NADES extracts. Our results suggest that NADES could be considered as an alternative to the conventional techniques for the effective extraction of phlorotannins from F. vesiculosus with high antioxidant potential.


Assuntos
Fucus , Espectrometria de Massas em Tandem , Solventes Eutéticos Profundos , Fucus/química , Cromatografia Líquida de Alta Pressão/métodos , Extratos Vegetais/química , Solventes/química
4.
Int J Mol Sci ; 24(4)2023 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-36835513

RESUMO

Transplantation of mesenchymal stromal cells (MSCs) provides a powerful tool for the management of multiple tissue injuries. However, poor survival of exogenous cells at the site of injury is a major complication that impairs MSC therapeutic efficacy. It has been found that tissue-oxygen adaptation or hypoxic pre-conditioning of MSCs could improve the healing process. Here, we investigated the effect of low oxygen tension on the regenerative potential of bone-marrow MSCs. It turned out that incubation of MSCs under a 5% oxygen atmosphere resulted in increased proliferative activity and enhanced expression of multiple cytokines and growth factors. Conditioned growth medium from low-oxygen-adapted MSCs modulated the pro-inflammatory activity of LPS-activated macrophages and stimulated tube formation by endotheliocytes to a much higher extent than conditioned medium from MSCs cultured in a 21% oxygen atmosphere. Moreover, we examined the regenerative potential of tissue-oxygen-adapted and normoxic MSCs in an alkali-burn injury model on mice. It has been revealed that tissue-oxygen adaptation of MSCs accelerated wound re-epithelialization and improved the tissue histology of the healed wounds in comparison with normoxic MSC-treated and non-treated wounds. Overall, this study suggests that MSC adaptation to 'physiological hypoxia' could be a promising approach for facilitating skin injuries, including chemical burns.


Assuntos
Queimaduras Químicas , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Camundongos , Animais , Medula Óssea , Queimaduras Químicas/metabolismo , Oxigênio/metabolismo , Cicatrização , Hipóxia/metabolismo , Células-Tronco Mesenquimais/metabolismo
5.
Int J Mol Sci ; 24(11)2023 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-37298287

RESUMO

Glucocorticoids are metabolized by the CYP3A isoform of cytochrome P450 and by 11-ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD-1). Experimental data suggest that post-traumatic stress disorder (PTSD) is associated with an increase in hepatic 11ß-HSD-1 activity and a concomitant decrease in hepatic CYP3A activity. Trans-resveratrol, a natural polyphenol, has been extensively studied for its antipsychiatric properties. Recently, protective effects of trans-resveratrol were found in relation to PTSD. Treatment of PTSD rats with trans-resveratrol allowed the rats to be divided into two phenotypes. The first phenotype is treatment-sensitive rats (TSR), and the second phenotype is treatment-resistant rats (TRRs). In TSR rats, trans-resveratrol ameliorated anxiety-like behavior and reversed plasma corticosterone concentration abnormalities. In contrast, in TRR rats, trans-resveratrol aggravated anxiety-like behavior and decreased plasma corticosterone concentration. In TSR rats, hepatic 11ß-HSD-1 activity was suppressed, with a concomitant increase in CYP3A activity. In TRR rats, the activities of both enzymes were suppressed. Thus, the resistance of PTSD rats to trans-resveratrol treatment is associated with abnormalities in hepatic metabolism of glucocorticoids. The free energy of binding of resveratrol, cortisol, and corticosterone to the human CYP3A protein was determined using the molecular mechanics Poisson-Boltzmann surface area approach, indicating that resveratrol could affect CYP3A activity.


Assuntos
Glucocorticoides , Transtornos de Estresse Pós-Traumáticos , Ratos , Humanos , Animais , Glucocorticoides/farmacologia , Glucocorticoides/metabolismo , Corticosterona , Resveratrol/farmacologia , Transtornos de Estresse Pós-Traumáticos/tratamento farmacológico , Citocromo P-450 CYP3A , 11-beta-Hidroxiesteroide Desidrogenases , Hidroxiesteroide Desidrogenases/genética , Hidroxiesteroide Desidrogenases/metabolismo , 11-beta-Hidroxiesteroide Desidrogenase Tipo 1
6.
Int J Mol Sci ; 24(18)2023 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-37762647

RESUMO

Currently, the efficacy of drug therapy for post-traumatic stress disorder or PTSD leaves much to be desired, making nutraceutical support a promising avenue for treatment. Recent research has identified the protective effects of resveratrol in PTSD. Here, we tested the behavioral and neurobiological effects of combining cheese consumption with resveratrol supplements in an experimental PTSD model. Using the elevated plus maze test, we observed that cheese intake resulted in a shift from anxiety-like behavior to depressive behavior, evident in increased freezing acts. However, no significant changes in the anxiety index value were observed. Interestingly, supplementation with cheese and resveratrol only led to the elimination of freezing behavior in half of the PTSD rats. We further segregated the rats into two groups based on freezing behavior: Freezing+ and Freezing0 phenotypes. Resveratrol ameliorated the abnormalities in Monoamine Oxidize -A and Brain-Derived Neurotrophic Factor gene expression in the hippocampus, but only in the Freezing0 rats. Moreover, a negative correlation was found between the number of freezing acts and the levels of Monoamine Oxidize-A and Brain-Derived Neurotrophic Factor mRNAs in the hippocampus. The study results show promise for resveratrol supplementation in PTSD treatment. Further research is warranted to better understand the underlying mechanisms and optimize the potential benefits of resveratrol supplementation for PTSD.


Assuntos
Queijo , Transtornos de Estresse Pós-Traumáticos , Animais , Ratos , Transtornos de Estresse Pós-Traumáticos/tratamento farmacológico , Fator Neurotrófico Derivado do Encéfalo/genética , Resveratrol/farmacologia , Resveratrol/uso terapêutico , Aminas , Suplementos Nutricionais
7.
Crit Rev Food Sci Nutr ; 62(18): 5005-5028, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-33591215

RESUMO

Diabetes remains a major health emergency in our entire world, affecting hundreds of millions of people worldwide. In conjunction with its much-dreaded complications (e.g., nephropathy, neuropathy, retinopathy, cardiovascular diseases, etc.) it substantially reduces the quality of life, increases mortality as well as economic burden among patients. Over the years, oxidative stress and inflammation have been highlighted as key players in the development and progression of diabetes and its associated complications. Much research has been devoted, as such, to the role of antioxidants in diabetes. Astaxanthin is a powerful antioxidant found mostly in marine organisms. Over the past years, several studies have demonstrated that astaxanthin could be useful in the treatment and management of diabetes. It has been shown to protect ß-cells, neurons as well as several organs including the eyes, kidney, liver, etc. against oxidative injuries experienced during diabetes. Furthermore, it improves glucose and lipid metabolism along with cardiovascular health. Its beneficial effects are exerted through multiple actions on cellular functions. Considering these and the fact that foods and natural products with biological and pharmacological activities are of much interest in the 21st-century food and drug industry, astaxanthin has a bright prospect in the management of diabetes and its complications.


Assuntos
Antioxidantes , Diabetes Mellitus , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Diabetes Mellitus/tratamento farmacológico , Humanos , Estresse Oxidativo , Qualidade de Vida , Xantofilas/farmacologia , Xantofilas/uso terapêutico
8.
Appl Microbiol Biotechnol ; 106(9-10): 3531-3538, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35579685

RESUMO

Astaxanthin is an important ketocarotenoid with remarkable biological activities and high economic value. In recent times, natural astaxanthin production by microorganisms has attracted much attention particularly in pharmaceuticals, nutraceuticals, cosmetics, and food and feed industries. Though, currently, productivity is still low and has restricted scale-up application in the commercial market, microbial production of astaxanthin has enormous prospects as it is a greener alternative to the predominating chemical synthesis. Over the years, Phaffia rhodozyma has attracted immense interest particularly in the field of biovalorization and sustainable production of natural nutraceuticals as a promising source of natural astaxanthin since it is able to use agro-food waste as inexpensive nutrient source. Many research works have, thus, been devoted to improving the astaxanthin yield from this yeast. Considering that the yeast was first isolated from tree exudates, the use of phytohormones and plant growth stimulators as prospective stimulants of astaxanthin production in the yeast is promising. Besides, it has been shown in several studies that phytohormones could improve cell growth and astaxanthin production of algae. Nevertheless, this option is less explored for P. rhodozyma. The few studies that have examined the effect of phytohormones on the yeast and its astaxanthin productivity reported positive results, with phytohormones such as 6-benzylaminopurin and gibberellic acid resulting in increased expression of carotenogenesis genes. Although the evidence available is scanty, the results are promising. KEY POINTS: • Phaffia rhodozyma is a promising source of natural astaxanthin • For industrialization, astaxanthin productivity of P. rhodozyma still needs optimization • Phytohormones could potentially augment astaxanthin yield of P. rhodozyma.


Assuntos
Basidiomycota , Eliminação de Resíduos , Basidiomycota/metabolismo , Alimentos , Reguladores de Crescimento de Plantas/metabolismo , Estudos Prospectivos , Saccharomyces cerevisiae , Xantofilas
9.
Int J Mol Sci ; 23(4)2022 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-35216511

RESUMO

The modification of chitosan represents a challenging task in obtaining biopolymeric materials with enhanced removal capacity for heavy metals. In the present work, the adsorption characteristics of chitosan modified with carboxyl groups (CTS-CAA) towards copper (II) and zinc (II) ions have been tested. The efficacy of the synthesis of CTS-CAA has been evaluated by studying various properties of the modified chitosan. Specifically, the functionalized chitosan has been characterized by using several techniques, including thermal analyses (differential scanning calorimetry and thermogravimetry), spectroscopies (FT-IR, XRD), elemental analysis, and scanning electron microscopy. The kinetics and the adsorption isotherms of CTS-CAA towards both Cu (II) and Zn (II) have been determined in the aqueous solvent under variable pH. The obtained results have been analyzed by using different adsorption models. In addition, the experiments have been conducted at variable temperatures to explore the thermodynamics of the adsorption process. The regeneration of CTS-CAA has been investigated by studying the desorption process using different eluents. This paper reports an efficient protocol to synthesize chitosan-based material perspective as regenerative adsorbents for heavy metals.


Assuntos
Materiais Biocompatíveis/química , Quitosana/química , Cobre/química , Íons/química , Água/química , Zinco/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Termodinâmica , Poluentes Químicos da Água/química , Purificação da Água/métodos
10.
Phytother Res ; 33(8): 1966-1980, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31209936

RESUMO

The use of mushrooms as functional foods and in the treatment of diseases has a long history. Inonotus obliquus is a mushroom belonging to the Hymenochaetaceae family and has possible anticancer, antiviral, and hypoglycemic properties. Chemical analysis of this mushroom has allowed the identification of various constituents such as melanins, phenolic compounds, and lanostane-type triterpenoids. A plethora of findings have highlighted the potential molecular mechanisms of actions of this mushroom such as its ability to scavenge reactive oxygen species, inhibit the growth of tumors, decrease inflammation and insulin resistance in type 2 diabetes, and stimulate the immune system. This review summarizes the relevant findings with reference to the therapeutic potential of this mushroom in countering the progression of cancers, diabetes mellitus, and antiviral activities, while highlighting its possible molecular mechanisms of action. The possible role of this mushroom as a therapeutic agent in addressing the pathogenesis of diabetes and cancer has also been suggested.


Assuntos
Agaricales/química , Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/uso terapêutico , Neoplasias/tratamento farmacológico , Animais , Humanos , Hipoglicemiantes/farmacologia , Camundongos , Ratos
11.
Proc Natl Acad Sci U S A ; 111(48): 17122-7, 2014 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-25362050

RESUMO

The emerging method of femtosecond crystallography (FX) may extend the diffraction resolution accessible from small radiation-sensitive crystals and provides a means to determine catalytically accurate structures of acutely radiation-sensitive metalloenzymes. Automated goniometer-based instrumentation developed for use at the Linac Coherent Light Source enabled efficient and flexible FX experiments to be performed on a variety of sample types. In the case of rod-shaped Cpl hydrogenase crystals, only five crystals and about 30 min of beam time were used to obtain the 125 still diffraction patterns used to produce a 1.6-Å resolution electron density map. For smaller crystals, high-density grids were used to increase sample throughput; 930 myoglobin crystals mounted at random orientation inside 32 grids were exposed, demonstrating the utility of this approach. Screening results from cryocooled crystals of ß2-adrenoreceptor and an RNA polymerase II complex indicate the potential to extend the diffraction resolution obtainable from very radiation-sensitive samples beyond that possible with undulator-based synchrotron sources.


Assuntos
Físico-Química/instrumentação , Cristalografia por Raios X/métodos , Conformação Proteica , Proteínas/química , Cristalização , Elétrons , Lasers , Modelos Moleculares , Mioglobina/química , RNA Polimerase II/química , Receptores Adrenérgicos beta 2/química , Reprodutibilidade dos Testes , Síncrotrons , Difração de Raios X/métodos , Raios X
12.
J Biol Inorg Chem ; 21(5-6): 589-603, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27229511

RESUMO

The diiron cluster-containing oxygenase CmlI catalyzes the conversion of the aromatic amine precursor of chloramphenicol to the nitroaromatic moiety of the active antibiotic. The X-ray crystal structures of the fully active, N-terminally truncated CmlIΔ33 in the chemically reduced Fe(2+)/Fe(2+) state and a cis µ-1,2(η (1):η (1))-peroxo complex are presented. These structures allow comparison with the homologous arylamine oxygenase AurF as well as other types of diiron cluster-containing oxygenases. The structural model of CmlIΔ33 crystallized at pH 6.8 lacks the oxo-bridge apparent from the enzyme optical spectrum in solution at higher pH. In its place, residue E236 forms a µ-1,3(η (1):η (2)) bridge between the irons in both models. This orientation of E236 stabilizes a helical region near the cluster which closes the active site to substrate binding in contrast to the open site found for AurF. A very similar closed structure was observed for the inactive dimanganese form of AurF. The observation of this same structure in different arylamine oxygenases may indicate that there are two structural states that are involved in regulation of the catalytic cycle. Both the structural studies and single crystal optical spectra indicate that the observed cis µ-1,2(η (1):η (1))-peroxo complex differs from the µ-η (1):η (2)-peroxo proposed from spectroscopic studies of a reactive intermediate formed in solution by addition of O2 to diferrous CmlI. It is proposed that the structural changes required to open the active site also drive conversion of the µ-1,2-peroxo species to the reactive form.


Assuntos
Cloranfenicol/biossíntese , Oxigenases/metabolismo , Cloranfenicol/química , Cristalografia por Raios X , Modelos Moleculares , Conformação Molecular , Oxigenases/química , Oxigenases/genética
13.
Arch Biochem Biophys ; 602: 61-68, 2016 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-26944553

RESUMO

Serial femtosecond crystallography (SFX) employing high-intensity X-ray free-electron laser (XFEL) sources has enabled structural studies on microcrystalline protein samples at non-cryogenic temperatures. However, the identification and optimization of conditions that produce well diffracting microcrystals remains an experimental challenge. Here, we report parallel SFX and transmission electron microscopy (TEM) experiments using fragmented microcrystals of wild type (WT) homoprotocatechuate 2,3-dioxygenase (HPCD) and an active site variant (H200Q). Despite identical crystallization conditions and morphology, as well as similar crystal size and density, the indexing efficiency of the diffraction data collected using the H200Q variant sample was over 7-fold higher compared to the diffraction results obtained using the WT sample. TEM analysis revealed an abundance of protein aggregates, crystal conglomerates and a smaller population of highly ordered lattices in the WT sample as compared to the H200Q variant sample. While not reported herein, the 1.75 Å resolution structure of the H200Q variant was determined from ∼16 min of beam time, demonstrating the utility of TEM analysis in evaluating sample monodispersity and lattice quality, parameters critical to the efficiency of SFX experiments.


Assuntos
Cristalização/métodos , Cristalografia/métodos , Teste de Materiais/métodos , Microscopia Eletrônica de Transmissão/métodos , Proteínas/química , Proteínas/ultraestrutura , Cristalografia/tendências
14.
Inorg Chem ; 55(12): 5862-70, 2016 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-27275865

RESUMO

The extradiol, aromatic ring-cleaving enzyme homoprotocatechuate 2,3-dioxygenase (HPCD) catalyzes a complex chain of reactions that involve second sphere residues of the active site. The importance of the second-sphere residue His200 was demonstrated in studies of HPCD variants, such as His200Cys (H200C), which revealed significant retardations of certain steps in the catalytic process as a result of the substitution, allowing novel reaction cycle intermediates to be trapped for spectroscopic characterization. As the H200C variant largely retains the wild-type active site structure and produces the correct ring-cleaved product, this variant presents a valuable target for mechanistic HPCD studies. Here, the high-spin Fe(II) states of resting H200C and the H200C-homoprotocatechuate enzyme-substrate (ES) complex have been characterized with Mössbauer spectroscopy to assess the electronic structures of the active site in these states. The analysis reveals a high-spin Fe(II) center in a low symmetry environment that is reflected in the values of the zero-field splitting (ZFS) (D ≈ - 8 cm(-1), E/D ≈ 1/3 in ES), as well as the relative orientations of the principal axes of the (57)Fe magnetic hyperfine (A) and electric field gradient (EFG) tensors relative to the ZFS tensor axes. A spin Hamiltonian analysis of the spectra for the ES complex indicates that the magnetization axis of the integer-spin S = 2 Fe(II) system is nearly parallel to the symmetry axis, z, of the doubly occupied dxy ground orbital deduced from the EFG and A-values, an observation, which cannot be rationalized by DFT assisted crystal-field theory. In contrast, ORCA/CASSCF calculations for the ZFS tensor in combination with DFT calculations for the EFG- and A-tensors describe the experimental data remarkably well.


Assuntos
Dioxigenases/metabolismo , Dioxigenases/química , Espectroscopia de Ressonância de Spin Eletrônica , Espectroscopia de Mossbauer/métodos , Especificidade por Substrato
15.
Biochemistry ; 54(34): 5329-39, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26267790

RESUMO

Kinetic and spectroscopic studies have shown that the conserved active site residue His200 of the extradiol ring-cleaving homoprotocatechuate 2,3-dioxygenase (FeHPCD) from Brevibacterium fuscum is critical for efficient catalysis. The roles played by this residue are probed here by analysis of the steady-state kinetics, pH dependence, and X-ray crystal structures of the FeHPCD position 200 variants His200Asn, His200Gln, and His200Glu alone and in complex with three catecholic substrates (homoprotocatechuate, 4-sulfonylcatechol, and 4-nitrocatechol) possessing substituents with different inductive capacity. Structures determined at 1.35-1.75 Å resolution show that there is essentially no change in overall active site architecture or substrate binding mode for these variants when compared to the structures of the wild-type enzyme and its analogous complexes. This shows that the maximal 50-fold decrease in kcat for ring cleavage, the dramatic changes in pH dependence, and the switch from ring cleavage to ring oxidation of 4-nitrocatechol by the FeHPCD variants can be attributed specifically to the properties of the altered second-sphere residue and the substrate. The results suggest that proton transfer is necessary for catalysis, and that it occurs most efficiently when the substrate provides the proton and His200 serves as a catalyst. However, in the absence of an available substrate proton, a defined proton-transfer pathway in the protein can be utilized. Changes in the steric bulk and charge of the residue at position 200 appear to be capable of altering the rate-limiting step in catalysis and, perhaps, the nature of the reactive species.


Assuntos
Proteínas de Bactérias/química , Dioxigenases/química , Substituição de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Brevibacterium/enzimologia , Brevibacterium/genética , Domínio Catalítico/genética , Sequência Conservada , Cristalografia por Raios X , Dioxigenases/genética , Dioxigenases/metabolismo , Histidina/química , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Oxigênio/metabolismo , Prótons , Especificidade por Substrato
16.
Inorg Chem ; 54(21): 10269-80, 2015 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-26485328

RESUMO

The extradiol-cleaving dioxygenase homoprotocatechuate 2,3-dioxygenase (HPCD) binds substrate homoprotocatechuate (HPCA) and O2 sequentially in adjacent ligand sites of the active site Fe(II). Kinetic and spectroscopic studies of HPCD have elucidated catalytic roles of several active site residues, including the crucial acid-base chemistry of His200. In the present study, reaction of the His200Cys (H200C) variant with native substrate HPCA resulted in a decrease in both kcat and the rate constants for the activation steps following O2 binding by >400 fold. The reaction proceeds to form the correct extradiol product. This slow reaction allowed a long-lived (t1/2 = 1.5 min) intermediate, H200C-HPCAInt1 (Int1), to be trapped. Mössbauer and parallel mode electron paramagnetic resonance (EPR) studies show that Int1 contains an S1 = 5/2 Fe(III) center coupled to an SR = 1/2 radical to give a ground state with total spin S = 2 (J > 40 cm(-1)) in Hexch = JS1·SR. Density functional theory (DFT) property calculations for structural models suggest that Int1 is a (HPCA semiquinone(•))Fe(III)(OOH) complex, in which OOH is protonated at the distal O and the substrate hydroxyls are deprotonated. By combining Mössbauer and EPR data of Int1 with DFT calculations, the orientations of the principal axes of the (57)Fe electric field gradient and the zero-field splitting tensors (D = 1.6 cm(-1), E/D = 0.05) were determined. This information was used to predict hyperfine splittings from bound (17)OOH. DFT reactivity analysis suggests that Int1 can evolve from a ferromagnetically coupled Fe(III)-superoxo precursor by an inner-sphere proton-coupled-electron-transfer process. Our spectroscopic and DFT results suggest that a ferric hydroperoxo species is capable of extradiol catalysis.


Assuntos
Dioxigenases/química , Espectroscopia de Ressonância de Spin Eletrônica , Espectroscopia de Mossbauer
17.
Metabolites ; 14(1)2024 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-38248857

RESUMO

Blood metabolomics profiling using mass spectrometry has emerged as a powerful approach for investigating non-cancer diseases and understanding their underlying metabolic alterations. Blood, as a readily accessible physiological fluid, contains a diverse repertoire of metabolites derived from various physiological systems. Mass spectrometry offers a universal and precise analytical platform for the comprehensive analysis of blood metabolites, encompassing proteins, lipids, peptides, glycans, and immunoglobulins. In this comprehensive review, we present an overview of the research landscape in mass spectrometry-based blood metabolomics profiling. While the field of metabolomics research is primarily focused on cancer, this review specifically highlights studies related to non-cancer diseases, aiming to bring attention to valuable research that often remains overshadowed. Employing natural language processing methods, we processed 507 articles to provide insights into the application of metabolomic studies for specific diseases and physiological systems. The review encompasses a wide range of non-cancer diseases, with emphasis on cardiovascular disease, reproductive disease, diabetes, inflammation, and immunodeficiency states. By analyzing blood samples, researchers gain valuable insights into the metabolic perturbations associated with these diseases, potentially leading to the identification of novel biomarkers and the development of personalized therapeutic approaches. Furthermore, we provide a comprehensive overview of various mass spectrometry approaches utilized in blood metabolomics research, including GC-MS, LC-MS, and others discussing their advantages and limitations. To enhance the scope, we propose including recent review articles supporting the applicability of GC×GC-MS for metabolomics-based studies. This addition will contribute to a more exhaustive understanding of the available analytical techniques. The Integration of mass spectrometry-based blood profiling into clinical practice holds promise for improving disease diagnosis, treatment monitoring, and patient outcomes. By unraveling the complex metabolic alterations associated with non-cancer diseases, researchers and healthcare professionals can pave the way for precision medicine and personalized therapeutic interventions. Continuous advancements in mass spectrometry technology and data analysis methods will further enhance the potential of blood metabolomics profiling in non-cancer diseases, facilitating its translation from the laboratory to routine clinical application.

18.
Nutrients ; 16(2)2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38257139

RESUMO

Circadian rhythm disruption is increasingly considered an environmental risk factor for the development and exacerbation of inflammatory bowel disease. We have reported in a previous study that nychthemeral dysregulation is associated with an increase in intestinal barrier permeability and inflammation in mice with dextran sulfate sodium (DSS)-induced colitis. To investigate the effect of circadian rhythm disruption on the composition and diversity of the gut microbiota (GM), sixty male C57BL/6J mice were initially divided to two groups, with the shifted group (n = 30) exposed to circadian shifts for three months and the non-shifted group (n = 30) kept under a normal light-dark cycle. The mice of the shifted group were cyclically housed for five days under the normal 12:12 h light-dark cycle, followed by another five days under a reversed light-dark cycle. At the end of the three months, a colitis was induced by 2% DSS given in the drinking water of 30 mice. Animals were then divided into four groups (n = 15 per group): sham group non-shifted (Sham-NS), sham group shifted (Sham-S), DSS non-shifted (DSS-NS) and DSS shifted (DSS-S). Fecal samples were collected from rectal content to investigate changes in GM composition via DNA extraction, followed by high-throughput sequencing of the bacterial 16S rRNA gene. The mouse GM was dominated by three phyla: Firmicutes, Bacteroidetes and Actinobacteria. The Firmicutes/Bacteroidetes ratio decreased in mice with induced colitis. The richness and diversity of the GM were reduced in the colitis group, especially in the group with inverted circadian rhythm. Moreover, the GM composition was modified in the inverted circadian rhythm group, with an increase in Alloprevotella, Turicibacter, Bacteroides and Streptococcus genera. Circadian rhythm inversion exacerbates GM dysbiosis to a less rich and diversified extent in a DSS-induced colitis model. These findings show possible interplay between circadian rhythm disruption, GM dynamics and colitis pathogenesis.


Assuntos
Colite , Microbioma Gastrointestinal , Masculino , Animais , Camundongos , Camundongos Endogâmicos C57BL , Sulfato de Dextrana/toxicidade , Disbiose , RNA Ribossômico 16S/genética , Colite/induzido quimicamente , Ritmo Circadiano , Bacteroidetes , Firmicutes
19.
Arch Insect Biochem Physiol ; 84(4): 175-93, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24186432

RESUMO

Termites and their gut microbial symbionts efficiently degrade lignocellulose into fermentable monosaccharides. This study examined three glycosyl hydrolase family 7 (GHF7) cellulases from protist symbionts of the termite Reticulitermes flavipes. We tested the hypotheses that three GHF7 cellulases (GHF7-3, GHF7-5, and GHF7-6) can function synergistically with three host digestive enzymes and a fungal cellulase preparation. Full-length cDNA sequences of the three GHF7s were assembled and their protist origins confirmed through a combination of quantitative PCR and cellobiohydrolase (CBH) activity assays. Recombinant versions of the three GHF7s were generated using a baculovirus-insect expression system and their activity toward several model substrates compared with and without metallic cofactors. GHF7-3 was the most active of the three cellulases; it exhibited a combination of CBH, endoglucanase (EGase), and ß-glucosidase activities that were optimal around pH 7 and 30°C, and enhanced by calcium chloride and zinc sulfate. Lignocellulose saccharification assays were then done using various combinations of the three GHF7s along with a host EGase (Cell-1), beta-glucosidase (ß-glu), and laccase (LacA). GHF7-3 was the only GHF7 to enhance glucose release by Cell-1 and ß-glu. Finally, GHF7-3, Cell-1, and ß-glu were individually tested with a commercial fungal cellulase preparation in lignocellulose saccharification assays, but only ß-glu appreciably enhanced glucose release. Our hypothesis that protist GHF7 cellulases are capable of synergistic interactions with host termite digestive enzymes is supported only in the case of GHF7-3. These findings suggest that not all protist cellulases will enhance saccharification by cocktails of other termite or fungal lignocellulases.


Assuntos
Celulases/metabolismo , Eucariotos/enzimologia , Isópteros/enzimologia , Isópteros/parasitologia , Lignina/metabolismo , Sequência de Aminoácidos , Animais , Celulases/química , Celulases/genética , Eucariotos/genética , Proteínas Fúngicas/metabolismo , Trato Gastrointestinal/enzimologia , Trato Gastrointestinal/parasitologia , Regulação Enzimológica da Expressão Gênica , Dados de Sequência Molecular , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Transcriptoma
20.
Biomolecules ; 13(7)2023 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-37509141

RESUMO

Betulin is a natural triterpene, usually from birch bark, known for its potential wound-healing properties. Despite having a wide range of pharmacological targets, no studies have proposed betulin as a multitarget compound. Betulin has protective effects against cardiovascular and liver diseases, cancer, diabetes, oxidative stress, and inflammation. It reduces postprandial hyperglycemia by inhibiting α-amylase and α-glucosidase activity, combats tumor cells by inducing apoptosis and inhibiting metastatic proteins, and modulates chronic inflammation by blocking the expression of proinflammatory cytokines via modulation of the NFκB and MAPKs pathways. Given its potential to influence diverse biological networks with high target specificity, it can be hypothesized that betulin may eventually become a new lead for drug development because it can modify a variety of pharmacological targets. The summarized research revealed that the diverse beneficial effects of betulin in various diseases can be attributed, at least in part, to its multitarget anti-inflammatory activity. This review focuses on the natural sources, pharmacokinetics, pharmacological activity of betulin, and the multi-target effects of betulin on signaling pathways such as MAPK, NF-κB, and Nrf2, which are important regulators of the response to oxidative stress and inflammation in the body.


Assuntos
Triterpenos , Humanos , Triterpenos/farmacologia , Ácido Betulínico , Citocinas/metabolismo , Inflamação/tratamento farmacológico , NF-kappa B/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA