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1.
Chirality ; 36(1): e23620, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37727057

RESUMO

Chiral heterocyclic alcohols are important precursors for production of pharmaceutical medicines and natural products. (S)-1-(furan-2-yl)propan-1-ol ((S)-2) can be used production of pyranone, which can be used in the synthesis of sugar analogues, antibiotics, tirantamycines, and anticancer drugs. The synthetic approaches for (S)-2, however, have substantial difficulties in terms of inadequate enantiomeric excess (ee) and gram scale synthesis. Moreover, the biocatalytic synthesis of (S)-2 is unknown until now. In this study, the synthesis of (S)-2 was carried out by performing the asymmetric bioreduction of 1-(furan-2-yl)propan-1-one (1) using the Lactobacillus paracasei BD101 biocatalyst obtained from boza, a grain-based fermented beverage. (S)-2 was obtained with >99% conversion, >99% ee, and 96% yield under the optimized conditions. Furthermore, in 50 h, 8.37 g of 1 was entirely transformed into (S)-2 on gram scale (96% isolated yield, 8.11 g). This is the first report on the high-gram scale biocatalyzed synthesis of enantiopure (S)-2. These data suggest that L. paracasei BD101 can be used to bioreduction of 1 in gram scale and efficiently produce (S)-2. Furthermore, these findings laid the base for future study into the biocatalytic production of (S)-2. It was particularly notable as it was the highest known to date optical purity of (S)-2 generated by asymmetric reduction using a biocatalyst. This work offers a productive environmentally friendly method for producing (S)-2 using biocatalysts.


Assuntos
Lacticaseibacillus paracasei , Estereoisomerismo , Álcoois , Biocatálise , 1-Propanol , Fenilpropanolamina
2.
Prep Biochem Biotechnol ; 54(1): 12-18, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37083050

RESUMO

There has been an increasing interest in biocatalysts over the past few decades in order to obtain high efficiency, high yield, and environmentally benign procedures aiming at the manufacture of pharmacologically relevant chemicals. Lactic Acid Bacteria (LAB), a microbial group, can be employed as biocatalysts while performing asymmetric reduction of prochiral ketones. In this study, Leuconostoc mesenteroides N6 was used for the asymmetric bioreduction 1-indanone. And then, a novel and innovative face-centered design-based multi-objective optimization model was used to optimize experimental conditions. Also, the experimental design factors were defined as agitation speed, incubation period, pH, and temperature for optimization to acquire the maximum enantiomeric excess (ee) and conversion rate (cr) values. When using the face-centered design-based multi-objective optimization model, the optimum culture conditions corresponded to 96.34 and 99.42%, ee and cr responses, respectively, were pH = 5.87, incubation temperature = 35 °C, incubation period = 50.88 h, and agitation speed = 152.60 rpm. Notably, the validation experiment under the optimum model conditions confirmed the model results. This study demonstrated the importance of the optimization and the efficiency of the face-centered design-based multi-objective model.


Assuntos
Leuconostoc mesenteroides , Cetonas , Lactobacillales/química
3.
Prep Biochem Biotechnol ; 53(10): 1254-1262, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36876855

RESUMO

Prochiral ketones can be effectively bio-reduced to chiral secondary alcohols by whole-cell biocatalysts, which are possible useful precursors to synthesize physiologically active chemicals and natural products. When whole-cell biocatalysts strains are used, bioreduction process can be influenced by various cultural factors, and it is vital to optimize these factors that affect selectivity, conversion rate, and yield. In this study, Weissella cibaria N9 was used as whole-cell biocatalyst for bioreduction of 1-(thiophen-2-yl)ethanone, and cultural design factors were optimized using a desirability function-embedded face-centered optimization model. For this, effects of pH (4.5-5.5-6.5, x1), (2) temperature (25-30-35 °C, x2), (3) incubation period (24-48-72 h, x3), and (4) agitation speed (100-150-200 rpm, x4) on two response variables; (1) ee (%) and (2) cr (%) were tested. Next, desirability function-embedded face-centered optimization model revealed that a pH of 6.43, a temperature of 26.04 °C, an incubation period of 52.41 h, and an agitation speed of 150 rpm were the optimum levels and the estimated ee and cr responses were 99.31% and 98.16%, respectively. Importantly, the actual experimental ee and cr responses were similar to the estimated values indicating the capability of the offered desirability function-embedded face-centered optimization model when using the optimum cultural conditions.


Assuntos
Álcoois , Weissella , Temperatura , Cetonas
4.
Chirality ; 34(8): 1120-1127, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35535726

RESUMO

Sulfur-containing chiral heterocyclic secondary alcohols are relevant intermediates in the preparation of enantiomerically pure compounds endowed with biological activity. In this report, we evaluated the reductive potential of different lactic acid bacteria as whole-cell biocatalysts of the enantioselective reduction of 1-(thiophen-2-yl)ethanone (1). Enterococcus faecium BY48, isolated from boza, a cereal-based fermented beverage, was found to be the best biocatalyst in our initial investigations. Using whole-cell preparations of E. faecium BY48, we then systematically analyzed the reaction parameters (pH, incubation period, agitation speed, and temperature) to optimize the yield, the enantiomeric excess (e. e.), and the conversion leading to (S)-1-(thiophen-2-yl)ethanol [(S)-2]. The target derivative, which is a precursor in the synthesis of biologically active chiral compounds, was obtained in enantiomerically pure form, gram-scale amounts, and high yield. This is also the first report that the manufacture of (S)-2 in excellent conversion, yield, enantiopure form, and gram scale used whole-cell biocatalyst. This whole-cell E. faecium BY48 biocatalyzed reaction is a clean, environmentally friendly, and cost-effective process, representing a valuable alternative to chemical catalysis or previously reported biocatalytic procedures in the preparation of (S)-2.


Assuntos
Enterococcus faecium , Etanol , Biocatálise , Estereoisomerismo , Tiofenos
5.
Chirality ; 34(5): 796-806, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35218076

RESUMO

Aromatic α-halohydrins, especially 2-haloethanols, which are a common pharmacological precursor, may be readily transformed to chiral ß-adrenergic receptor blockers. Studies including the synthesis of (S)-2-bromo-1-(naphthalen-2-yl)ethanol ((S)-2), an α-halohydrin, in high conversion, enantiomeric excess (ee), and yield by biocatalytic asymmetric reduction of 2-bromo-1-(naphthalen-2-yl)ethanone (1) are still insufficient. Moreover, asymmetric reduction of substrate 1 using a mathematical optimization method is not explored in the current literature. In this article, the four asymmetric bioreduction conditions, which are (1) pH, (2) temperature, (3) incubation period, and (4) agitation speed, of substrate 1 were optimized to obtain (S)-2 with A-optimal design-embedded model in the presence of Enterococcus faecium BY48. Optimum bioreduction conditions were determined by the A-optimal design-embedded model as follows: pH = 7, temperature = 25°C, incubation period = 24 h, and agitation speed = 200 rpm. And then, it was suggested that (S)-2 could be obtained with 98.88% ee and 100% conversion rate (cr) under these optimum conditions. As a result of the experimental reaction performed under the optimization conditions suggested by the model, (S)-2 was obtained with 99% ee and 100% cr. The study revealed that E. faecium BY48 could be used as a biocatalyst in asymmetric reduction reactions. Also, the A-optimal design-embedded model could have the great potential to obtain the optimum asymmetric bioreduction conditions.


Assuntos
Enterococcus faecium , Biocatálise , Etanol , Estereoisomerismo , Temperatura
6.
Prep Biochem Biotechnol ; 52(2): 218-225, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34028336

RESUMO

The biocatalytic asymmetric reduction of prochiral ketones is a significant transformation in organic chemistry as chiral carbinols are biologically active molecules and may be used as precursors of many drugs. In this study, the bioreduction of 1-(benzo [d] [1,3] dioxol-5-yl) ethanone for the production of enantiomerically pure (S)-1-(1,3-benzodioxal-5-yl) ethanol was investigated using freeze-dried whole-cell of Lactobacillus fermentum P1 and the reduction conditions was optimized with a D-optimal experimental design-based optimization methodology. This is the first study using this optimization methodology in a biocatalytic asymmetric reduction. Using D-optimal experimental design-based optimization, optimum reaction conditions were predicted as pH 6.20, temperature 30 °C, incubation time 30 h, and agitation speed 193 rpm. For these operating conditions, it was estimated that the product could be obtained with 94% enantiomeric excess (ee) and 95% conversion rate (cr). Besides, the actual ee and cr were found to be 99% tested under optimized reaction conditions. These findings demonstrated that L. fermentum P1 as an effective biocatalyst to obtain (S)-1-(1,3-benzodioxal-5-yl) ethanol and with the D-optimal experimental design-based optimization, this product could be obtained with the 99% ee and 99% cr. Finally, the proposed mathematical optimization technique showed the applicability of the obtained results for asymmetric reduction reactions.


Assuntos
Derivados de Benzeno/química , Limosilactobacillus fermentum/metabolismo , Biocatálise , Concentração de Íons de Hidrogênio , Oxirredução , Estereoisomerismo , Temperatura
7.
Chirality ; 33(9): 535-542, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34240754

RESUMO

There is a considerable interest in the asymmetric production of chiral allylic alcohols, the main building blocks of many functional molecules. The asymmetric reduction of α,ß-unsaturated ketones is difficult with traditional chemical protocols in a regioselective and stereoselective manner. In this study, the reductive capacity of whole cell of Leuconostoc mesenteroides N6, Weissella paramesenteroides N7, Weissella cibaria N9, and Leuconostoc pseudomesenteroides N13 was investigated as whole-cell biocatalysts in the enantioselective reduction of (E)-4-phenylbut-3-en-2-one (1). The biocatalytic reduction of 1 to (S,E)-4-phenylbut-3-en-2-ol ((S,E)-2) using the whole cell of W. cibaria N9 isolated from Turkish sourdough was developed in a regioselective fashion, occurring with excellent conversion and recovering the product in good yield. In biocatalytic reduction reactions, the conversion of the substrate and the enantiomeric excess (ee) of the product are significantly affected by optimization parameters such as temperature, agitation rate, pH, and incubation time. Effects of these parameters on ee and conversion were investigated comprehensively. In addition, to our knowledge, this is the first report on production of (S,E)-2 using whole-cell biocatalyst in excellent yield, conversion with enantiopure form and at gram scale. These findings pave the way for the use of whole cell of W. cibaria N9 for challenging higher substrate concentrations of different α,ß-unsaturated ketones for regioselective reduction at industrial scale.


Assuntos
Butanonas/metabolismo , Weissella/metabolismo , Biocatálise , Butanonas/química , Cromatografia Líquida de Alta Pressão/métodos , Oxirredução , Análise Espectral/métodos , Estereoisomerismo , Temperatura
8.
Chirality ; 33(8): 447-453, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33970507

RESUMO

Asymmetric bioreduction of ketones is a fundamental process in the production of organic molecules. Compounds containing tetralone rings are found in the structure of many biologically active and pharmaceutical molecules. Biocatalytic reduction of ketones is one of the most promising and significant routes to prepare optically active alcohols. In this study, the reductive capacity of Lactobacillus paracasei BD101 was investigated as whole-cell biocatalyst in the enantioselective reduction of 1-tetralone (1). In biocatalytic reduction reactions, the conversion of the substrate and the enantiomeric excess (ee) of the product are significantly affected by optimization parameters such as temperature, agitation rate, pH, and incubation time. Effects of these parameters on ee and conversion were investigated comprehensively. (R)-1-tetralol ((R)-2), which can be used to treat disorder such as obsessive compulsive, post-traumatic stress, premenstrual dysphoric, and social anxiety, was manufactured in enantiopure form, high yield and gram-scale, using whole-cell biocatalysts of L. paracasei BD101. The 7.04 g of (R)-2 was obtained in optically pure form with 95% yield. Also, to our knowledge, this is the first report on production of (R)-2 using whole-cell biocatalyst in excellent yield, conversion, enantiopure form and gram scale. This is a clean, eco-friendly and cheap method for the synthesis of (R)-2 compared with chemical catalyst.


Assuntos
Lacticaseibacillus paracasei , Tetralonas , Biocatálise , Concentração de Íons de Hidrogênio , Estereoisomerismo , Temperatura
9.
Tuberk Toraks ; 69(1): 21-29, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33853302

RESUMO

INTRODUCTION: Our study aimed to evaluate the relationship between pneumonia, air pollution (sulfur dioxide [SO2] and particulate matter [PM10]) and meteorological data (atmospheric pressure, amount of rainfall, temperature, rate of humidity, sunshine duration and wind velocity). MATERIALS AND METHODS: Our study included 822 of the 826 patients who were admitted to the emergency service of our hospital between August 2016 and July 2017 and who were diagnosed with pneumonia. Four patients whose information was not available were excluded from the study. The data for the patients were obtained retrospectively from the hospital information system and patient emergency files. The meteorological data were obtained from the website of the Ministry of the Environment and Urbanization and from the Directorate General of Meteorology of our city. Daily meteorological data (SO2, PM10, air pressure, temperature, humidity, wind speed and sunshine duration) were compared with the number of daily patients admitted to the emergency department and diagnosed with pneumonia. Statistical analysis was performed using Pearson correlation analysis. RESULT: Three hundred and twenty-nine of the patients were female, and 493 were male. A total of 605 inpatients, of whom 106 were in the intensive care unit, were treated in the hospital, while 217 were outpatients. A statistically significant relationship was found between the number of patients with pneumonia and the intensity of SO2 (r= 0.740; p<0.001), atmospheric pressure (r= -0.691; p<0.01), wind velocity (r= 0.777; p<0.001), average humidity rate (r= -0.454; p<005) and sunshine duration (r= 0.475; p<0.05). CONCLUSIONS: We determined that meteorological changes are important risk factors in the development of pneumonia and that reducing air pollution and taking protective measures may decrease the frequency of pneumonia and the mortality rates related to pneumonia.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Exposição Ambiental/efeitos adversos , Admissão do Paciente/estatística & dados numéricos , Pneumonia/etiologia , Poluição do Ar/efeitos adversos , Feminino , Humanos , Umidade , Masculino , Meteorologia , Material Particulado/efeitos adversos , Pneumonia/epidemiologia , Estudos Retrospectivos , Fatores de Risco , Estações do Ano , Temperatura , Turquia
10.
Chirality ; 32(3): 400-406, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31970848

RESUMO

Chromane, which has a fused cyclic structure, is a significant molecule that can be found in the structure of many important compounds. Lactobacillus paracasei BD101 was demonstrated as whole-cell biocatalyst for the synthesis of (S)-6-chlorochroman-4-ol with immense enantioselectivity. The conditions of asymmetric reduction were optimized one factor by one factor using L paracasei BD101 to achieve enantiomerically pure product and complete conversion. Using these obtained optimization conditions, asymmetric reduction of 6-chlorochroman-4-one was performed under environmentally friendly conditions; 6-chlorochroman-4-one, having a fused cyclic structure as previously noted to be difficult to asymmetric reduction with biocatalysts, was enantiomerically reduced to (S)-6-chlorochroman-4-ol with an enantiomeric excess >99% on a high gram scale. This study is the first example in the literature for the enantiopure synthesis of (S)-6-chlorochroman-4-ol using a biocatalyst. Also notably, the optical purity of (S)-6-chlorochroman-4-ol obtained in this study through asymmetric bioreduction using whole-cell biocatalyst is the highest value in the literature. In this study, (S)-6-chlorochroman-4-ol was produced on a gram scale by an easy, inexpensive, and environmentally friendly method, which has shown the production of valuable chiral precursors for drug synthesis and other industrial applications. This study provides a convenient method for the production of (S)-6-chlorochroman-4-ol, which can meet the industrial green production demand of this chiral secondary alcohol.


Assuntos
Cromanos/síntese química , Lacticaseibacillus paracasei/metabolismo , Álcool Desidrogenase/metabolismo , Biocatálise , Cromanos/química , Concentração de Íons de Hidrogênio , Estereoisomerismo , Temperatura
11.
Chirality ; 31(10): 892-897, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31423658

RESUMO

Optically active aromatic alcohols are valuable chiral building blocks of many natural products and chiral drugs. Lactobacillus paracasei BD87E6, which was isolated from a cereal-based fermented beverage, was shown as a biocatalyst for the bioreduction of 1-(benzofuran-2-yl) ethanone to (S)-1-(benzofuran-2-yl) ethanol with highly stereoselectivity. The bioreduction conditions were optimized using L. paracasei BD87E6 to obtain high enantiomeric excess (ee) and conversion. After optimization of the bioreduction conditions, it was shown that the bioreduction of 1-(benzofuran-2-yl)ethanone was performed in mild reaction conditions. The asymmetric bioreduction of the 1-(benzofuran-2-yl)ethanone had reached 92% yield with ee of higher than 99.9% at 6.73 g of substrate. Our study gave the first example for enantiopure production of (S)-1-(benzofuran-2-yl)ethanol by a biological green method. This process is also scalable and has potential in application. In this study, a basic and novel whole-cell mediated biocatalytic method was performed for the enantiopure production of (S)-1-(benzofuran-2-yl)ethanol in the aqueous medium, which empowered the synthesis of a precious chiral intermediary process to be converted into a sophisticated molecule for drug production.


Assuntos
Benzofuranos/síntese química , Etanol/análogos & derivados , Etanol/síntese química , Química Verde/métodos , Lacticaseibacillus paracasei/metabolismo , Biocatálise , Concentração de Íons de Hidrogênio , Lacticaseibacillus paracasei/isolamento & purificação , Estereoisomerismo , Temperatura
12.
Chirality ; 31(3): 211-218, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30633374

RESUMO

In this study, a total of 10 bacterial strains were screened for their ability to reduce cyclohexyl(phenyl)methanone 1 to its corresponding alcohol. Among these strains, Lactobacillus paracasei BD101 was found to be the most successful biocatalyst to reduce the ketones to the corresponding alcohols. The reaction conditions were systematically optimized for the reducing agent L paracasei BD101, which showed high enantioselectivity and conversion for the bioreduction. The preparative scale asymmetric reduction of cyclohexyl(phenyl)methanone (1) by L paracasei BD101 gave (S)-cyclohexyl(phenyl)methanol (2) with 92% yield and >99% enantiomeric excess. The preparative scale study was carried out, and a total of 5.602 g of (S)-cyclohexyl(phenyl)methanol in high enantiomerically pure form (>99% enantiomeric excess) was produced. L paracasei BD101 has been shown to be an important biocatalyst in asymmetric reduction of bulky substrates. This study demonstrates the first example of the effective synthesis of (S)-cyclohexyl(phenyl)methanol by the L paracasei BD101 as a biocatalyst in preparative scale.

13.
Prep Biochem Biotechnol ; 49(9): 884-890, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31259668

RESUMO

Whole cell applications are one of the main methodologies for the bioreduction of prochiral ketones to obtain enantiomerically rich chiral secondary alcohols which are mainly affected by the culture parameters of the whole cell. In this study, whole cell of Lactobacillus senmaizukei as a safe Lactic Acid Bacteria (LAB) was used for the reduction of acetophenone and Response Surface Methodology (RSM) application was used to optimize the culture parameters in terms of temperature, pH, incubation time, and agitation level to obtain the highest enantiomeric excess (ee) and conversion rate. The predicted optimum conditions for the bioreduction with whole cell Lactobacillus senmaizukei were found to be pH of 5.25, temperature of 25 °C, incubation time of 72 hr, and agitation level of 100 rpm. Importantly, the efficiency of the reduction of the acetophenone was significantly affected by the linear and quadratic effects of culture parameters. These findings are important to show the role of culture parameters for the bioreduction reactions and also the efficiency of the RSM technique to optimize these parameters.


Assuntos
Acetofenonas/metabolismo , Lactobacillus/metabolismo , Álcoois/metabolismo , Biocatálise , Concentração de Íons de Hidrogênio , Microbiologia Industrial , Lactobacillus/citologia , Oxirredução , Temperatura
14.
Chirality ; 30(2): 189-194, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29110342

RESUMO

Piperonyl ring is found in a number of naturally occurring compounds and possesses enormous biological activities. There are many studies in the literature with compounds containing a piperonyl ring, but there are very few studies on the synthesis of chiral piperonyl carbinol. The objective of this study was to determine the microbial reduction ability of bacterial strains and to reveal the effects of different physicochemical parameters on this reduction ability. A total of 15 bacterial isolates were screened for their ability to reduce 1-(benzo[d][1,3]dioxol-5-yl) ethanone 1 to its corresponding alcohol. Among these isolates Lactobacillus paracasei BD101 was found to be the most successful biocatalyst to reduce the ketone containing piperonyl ring to the corresponding alcohol. The reaction conditions were systematically optimized for the reducing agent L paracasei BD101, which showed high enantioselectivity and conversion for the bioreduction. The preparative scale study was performed, and a total of 3.72 g of (R)-1-(1,3-benzodioxol-5-yl) ethanol in high enantiomeric form (>99% enantiomeric excess) was produced in a mild, cheap, and environment-friendly process. This study demonstrates that L paracasei BD101 can be used as a biocatalyst to obtain chiral carbinol with excellent yield and selectivity.


Assuntos
Benzoxazóis/química , Benzoxazóis/metabolismo , Etanol/química , Etanol/metabolismo , Lacticaseibacillus paracasei/metabolismo , Concentração de Íons de Hidrogênio , Estereoisomerismo , Temperatura
15.
Chem Biodivers ; 15(6): e1800028, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29667758

RESUMO

Global sales of single enantiomeric drug products are growing at an alarming rate every year. A total of 7 bacterial strains were screened for their ability to reduce acetophenones to its corresponding alcohol. Among these strains Lactobacillus paracasei BD87E6 was found to be the most successful biocatalyst to reduce the ketones to the corresponding alcohols. The reaction conditions were systematically optimized for the reducing agent Lactobacillus paracasei BD87E6, which showed high enantioselectivity and conversion for the bioreduction. The preparative scale asymmetric reduction of 3-methoxyacetophenone (1h) by Lactobacillus paracasei BD87E6 gave (R)-1-(3-methoxyphenyl)ethanol (2h) with 92% yield and 99% enantiomeric excess. Compound 2h could be used for the synthesis of (S)-rivastigmine which has a great potential for the treatment of Alzheimer's disease. This study demonstrates that Lactobacillus paracasei BD87E6 can be used as a biocatalyst to obtain chiral carbinol with excellent yield and selectivity. The whole cell catalyzed the reductions of ketone substrates on the preparative scale, demonstrating that Lactobacillus paracasei BD87E6 would be a valuable biocatalyst for the preparation of chiral aromatic alcohols of pharmaceutical interest.


Assuntos
Lacticaseibacillus paracasei/química , Metanol/metabolismo , Rivastigmina/metabolismo , Biocatálise , Lacticaseibacillus paracasei/citologia , Lacticaseibacillus paracasei/metabolismo , Metanol/química , Estrutura Molecular , Oxirredução , Rivastigmina/química , Estereoisomerismo
16.
Chem Biodivers ; 14(9)2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28746771

RESUMO

The increasing demand for biocatalysts in synthesizing enantiomerically pure chiral alcohols results from the outstanding characteristics of biocatalysts in reaction, economic, and ecological issues. Herein, fifteen yeast strains belonging to three food originated yeast species Candida zeylanoides, Pichia fermentans, and Saccharomyces uvarum were tested for their capability for asymmetric reduction of acetophenone to 1-phenylethanol as biocatalysts. Of these strains, C. zeylanoides P1 showed an effective asymmetric reduction ability. Under optimized conditions, substituted acetophenones were converted to corresponding optically active secondary alcohols in up to 99% enantiomeric excess and at high yields. The preparative scale asymmetric bioreduction of 4-nitroacetophenone (1m) by C. zeylanoides P1 gave (S)-1-(4-nitrophenyl)ethanol (2m) with 89% yield and > 99% enantiomeric excess. Compound 2m has been obtained in an enantiomerically pure and inexpensive form. Additionally, these results indicate that C. zeylanoides P1 is a promising biocatalyst for the synthesis of chiral alcohols in industry.


Assuntos
Acetofenonas/metabolismo , Álcoois Benzílicos/metabolismo , Candida/metabolismo , Acetofenonas/química , Álcoois Benzílicos/química , Biocatálise , Candida/química , Candida/classificação , Microbiologia de Alimentos , Microbiologia Industrial , Oxirredução , Estereoisomerismo
17.
Chem Biodivers ; 14(11)2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28792667

RESUMO

Chiral secondary alcohols are valuable intermediates for many important enantiopure pharmaceuticals and biologically active molecules. In this work, we studied asymmetric reduction of aromatic ketones to produce the corresponding chiral secondary alcohols using lactic acid bacteria (LAB) as new biocatalysts. Seven LAB strains were screened for their ability to reduce acetophenones to their corresponding alcohols. Among these strains, Lactobacillus paracasei BD101 was found to be the most successful at reducing the ketones to the corresponding alcohols. The reaction conditions were further systematically optimized for this strain and high enantioselectivity (99%) and very good yields were obtained. These secondary alcohols were further tested for their antimicrobial activities against important pathogens and significant levels of antimicrobial activities were observed although these activities were altered depending on the secondary alcohols as well as their enantiomeric properties. The current methodology demonstrates a promising and alternative green approach for the synthesis of chiral secondary alcohols of biological importance in a cheap, mild, and environmentally useful process.


Assuntos
Álcoois/metabolismo , Anti-Infecciosos/metabolismo , Lacticaseibacillus paracasei/metabolismo , Acetofenonas/química , Acetofenonas/metabolismo , Álcoois/química , Álcoois/farmacologia , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Biocatálise , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Oxirredução , Estereoisomerismo , Especificidade por Substrato , Temperatura , Fatores de Tempo
19.
Neural Comput Appl ; 33(24): 17589-17609, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34345118

RESUMO

COVID-19 has caused a pandemic crisis that threatens the world in many areas, especially in public health. For the diagnosis of COVID-19, computed tomography has a prognostic role in the early diagnosis of COVID-19 as it provides both rapid and accurate results. This is crucial to assist clinicians in making decisions for rapid isolation and appropriate patient treatment. Therefore, many researchers have shown that the accuracy of COVID-19 patient detection from chest CT images using various deep learning systems is extremely optimistic. Deep learning networks such as convolutional neural networks (CNNs) require substantial training data. One of the biggest problems for researchers is accessing a significant amount of training data. In this work, we combine methods such as segmentation, data augmentation and generative adversarial network (GAN) to increase the effectiveness of deep learning models. We propose a method that generates synthetic chest CT images using the GAN method from a limited number of CT images. We test the performance of experiments (with and without GAN) on internal and external dataset. When the CNN is trained on real images and synthetic images, a slight increase in accuracy and other results are observed in the internal dataset, but between 3 % and 9 % in the external dataset. It is promising according to the performance results that the proposed method will accelerate the detection of COVID-19 and lead to more robust systems.

20.
Carbohydr Res ; 486: 107837, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31655418

RESUMO

Gentiobiose-derived oligosaccharides were synthesized by the acceptor reaction of glucansucrase E81 obtained from Lactobacillus reuteri E81 with sucrose and gentiobiose as donor-acceptor sugars, respectively. The reaction products were monitored by TLC analysis and gentiobiose-derived oligosaccharides up to DP 8 were formed during the acceptor reaction as determined by ESI-MS/MS analysis. The glycosylation of the gentiobiose with α-(1 → 6) linkages and α-(1 → 3) linkages was shown by 1H and 13C NMR analysis confirming the structure of these gentiobiose-derived oligosaccharides. The in vitro prebiotic function of the oligosaccharides was determined in which probiotic strains were stimulated whereas no growth was observed in pathogen strains. Gentiobiose-derived oligosaccharides showed immune-modulatory functions in vitro and triggered the production of IL-4, IL12 and TNF-α cytokines in HT29 cells in a dose dependent manner. This study showed the production and functional characterisation of gentiobiose-derived oligosaccharides establishing a promising avenue for future applications.


Assuntos
Dissacarídeos/química , Dissacarídeos/farmacologia , Glicosiltransferases/metabolismo , Fatores Imunológicos/química , Fatores Imunológicos/farmacologia , Prebióticos , Células HT29 , Humanos
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