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1.
Chem Sci ; 13(8): 2418-2422, 2022 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-35310495

RESUMO

The use of hydrazine-catalyzed ring-closing carbonyl-olefin metathesis (RCCOM) to synthesize polycyclic heteroaromatic (PHA) compounds is described. In particular, substrates bearing Lewis basic functionalities such as pyridine rings and amines, which strongly inhibit acid catalyzed RCCOM reactions, are shown to be compatible with this reaction. Using 5 mol% catalyst loadings, a variety of PHA structures can be synthesized from biaryl alkenyl aldehydes, which themselves are readily prepared by cross-coupling.

2.
Org Lett ; 22(15): 6026-6030, 2020 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-32667809

RESUMO

The synthesis of 1,2-dihydroquinolines by the hydrazine-catalyzed ring-closing carbonyl-olefin metathesis (RCCOM) of N-prenylated 2-aminobenzaldehydes is reported. Substrates with a variety of substitution patterns are shown. With an acid-labile protecting group on the nitrogen atom, in situ deprotection and autoxidation furnish quinoline. In comparison with related oxygen-containing substrates, the cycloaddition step of the catalytic cycle is shown to be slower, but the cycloreversion is found to be more facile.


Assuntos
Alcenos/química , Hidrazinas/química , Quinolinas/síntese química , Catálise , Estrutura Molecular
3.
J Clin Med ; 9(7)2020 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-32664289

RESUMO

We investigated microbiota changes following surgical colon cancer resection and evaluate effects of probiotics on microbiota and surgical recovery. This randomized double-blind trial was performed at four medical centers in South Korea. Of 68 patients expected to undergo anterior sigmoid colon cancer resection, 60 were eligible, of whom 29 and 31 received probiotics and placebo, respectively, for four weeks, starting at one week preoperatively. Third- and/or fourth-week information on anterior resection syndrome (ARS), inflammatory markers, and quality of life was obtained. Stool sample analysis was conducted after randomization and bowel preparation and at three and four postoperative weeks. Bacteria were categorized into Set I (with probiotic effects) and II (colon cancer-associated). The probiotic group's ARS score showed an improving trend (p = 0.063), particularly for flatus control (p = 0.030). Serum zonulin levels significantly decreased with probiotics. Probiotic ingestion resulted in compositional changes in gut microbiota; greater increases and decreases in Set I and II bacteria, respectively, occurred with probiotics. Compositional increase in Set I bacteria was associated with reduced white blood cells, neutrophils, neutrophil-lymphocyte ratio, and zonulin. Bifidobacterium composition was negatively correlated with zonulin levels in the probiotic group. Probiotics improved postoperative flatus control and modified postoperative changes in microbiota and inflammatory markers.

4.
Prev Nutr Food Sci ; 25(2): 158-165, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32676467

RESUMO

Cudrania tricuspidata has been used as an East Asian folk remedy to treat various symptoms. Recently, scientific evidence of the efficacy of C. tricuspidata has emerged. The objective of this study was to elucidate protective role of C. tricuspidata in the gastric mucosa using pylorus-ligated Sprague-Dawley rats and primary parietal cells. C. tricuspidata ethanol extracts attenuated gastric mucosal damage, secretion, and juice acidity in pylorus-ligated rats; however, it did not affect expression of gastric acid-related genes [muscarinic acetylcholine receptor M3 receptor (M3R), histamine H2-receptors (H2R), and cholecystokinin-2/gastrin receptors (CCK2R)] or serum gastrin concentrations. Furthermore, extracts greatly reduced levels of gastric cyclic adenosine monophosphate (cAMP) and significantly increased mRNA levels of gastric-type mucins (MUC5AC and MUC6). To identify the mode of action of C. tricuspidata extract in regulating gastric acid secretion, intracellular cAMP and mRNA for H2R, M3R, and CCK2R were measured in primary parietal cells. mRNA levels of H2R, M3R, and CCK2R did not significantly differ following treatment with C. tricuspidata extract, whereas cAMP induced by the H2R-specific agonist was significantly decreased. C. tricuspidata may therefore reduce gastric acid secretion by inhibiting H2R activity rather than regulating mRNA expression. These finding suggest that ethanol extracts of C. tricuspidata inhibit H2R-related gastric acid secretion and increase gastric mucus to help prevent gastric mucosal damage. Therefore, C. tricuspidata extract has potential to be used in foods and medicines to prevent diseases related to gastric mucosal damage, such as gastritis and functional dyspepsia.

5.
Biomolecules ; 10(5)2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32384794

RESUMO

Fermented vegetable juices have gained attention due to their various beneficial effects on human health. In this study, we employed gas chromatography-mass spectrometry, direct infusion-mass spectrometry, and liquid chromatography-mass spectrometry to identify useful metabolites, lipids, and carotenoids in vegetable juice (VJ) fermented with Lactobacillus plantarum HY7712, Lactobacillus plantarum HY7715, Lactobacillus helveticus HY7801, and Bifidobacterium animalis ssp. lactis HY8002. A total of 41 metabolites, 24 lipids, and 4 carotenoids were detected in the fermented and non-fermented VJ (control). The lycopene, α-carotene, and ß-carotene levels were higher in VJ fermented with L. plantarum strains (HY7712 and HY7715) than in the control. Proline content was also elevated in VJ fermented with HY7715. Uracil, succinic acid, and α-carotene concentration was increased in VJ fermented with HY7801, while glycine and lycopene levels were raised in VJ fermented with HY8002. This study confirmed that each probiotic strain has distinctive characteristics and produces unique changes to metabolic profiles of VJ during fermentation. Our results suggest that probiotic-fermented VJ is a promising functional beverage that contains more beneficial metabolites and carotenoids than commercial non-fermented VJ.


Assuntos
Fermentação , Sucos de Frutas e Vegetais/microbiologia , Probióticos/metabolismo , Carotenoides/metabolismo , Lactobacillus/metabolismo , Lipidômica , Metaboloma
6.
PLoS One ; 15(4): e0231268, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32275691

RESUMO

Despite increasing research on the gut-skin axis, there is a lack of comprehensive studies on the improvement of skin health through the regulation of the intestinal condition in humans. In this study, we investigated the benefits of Lactobacillus plantarum HY7714 (HY7714) consumption on skin health through its modulatory effects on the intestine and ensuing immune responses. HY7714 consumption led to differences in bacterial abundances from phylum to genus level, including increases in Actinobacteria followed by Bifidobacterium and a decrease in Proteobacteria. Additionally, HY7714 significantly ameliorated inflammation by reducing matrix metallopeptidases (MMP-2 and MMP-9), zonulin, and calprotectin in plasma, all of which are related to skin and intestinal permeability. Furthermore, RNA-seq analysis revealed its efficacy at restoring the integrity of the gut barrier by regulating gene expression associated with the extracellular matrix and immunity. This was evident by the upregulation of IGFBP5, SERPINE1, EFEMP1, COL6A3, and SEMA3B and downregulation of MT2A, MT1E, MT1X, MT1G, and MT1F between TNF- α and TNF- α plus HY7714 treated Caco-2 cells. These results propose the potential mechanistic role of HY7714 on skin health by the regulation of the gut condition.


Assuntos
Intestinos/microbiologia , Lactobacillus plantarum/fisiologia , Pele/microbiologia , Adulto , Idoso , Biodiversidade , Biomarcadores/sangue , Células CACO-2 , Feminino , Microbioma Gastrointestinal/efeitos dos fármacos , Ontologia Genética , Humanos , Inflamação/patologia , Lactobacillus plantarum/efeitos dos fármacos , Pessoa de Meia-Idade , Fator de Necrose Tumoral alfa/farmacologia , Adulto Jovem
7.
Biotechnol Lett ; 42(4): 519-528, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31970557

RESUMO

OBJECTIVES: To investigate the preventive effect of Lactobacillus casei HY2782 on toxicity induced by particulate matter (PM, inhalable particles less than 10 µm in diameter) in human intestinal CCD-18Co cells and a model animal Caenorhabditis elegans. RESULTS: L. casei HY2782 treatment prevented PM-induced intestinal cell death via cellular reactive oxygen species production and membrane disruption attenuation. PM significantly decreased the total number of eggs laid and the body bending activity of C. elegans, demonstrating PM toxicity. L. casei HY2782 treatment restored the reproductive toxicity and decline in locomotion activity induced by PM in C. elegans. Overall, L. casei HY2782 attenuated PM toxicity in vitro in cultured intestinal cells and in vivo in the model nematode. CONCLUSION: Our study provides a potential clue for developing L. casei HY2782 probiotics that attenuate PM-induced cellular and physiological toxicity; however, further in-depth preclinical trials using mammalian animal models and clinical trials are required.


Assuntos
Caenorhabditis elegans/fisiologia , Intestinos/citologia , Lacticaseibacillus casei/fisiologia , Material Particulado/toxicidade , Animais , Caenorhabditis elegans/efeitos dos fármacos , Linhagem Celular , Proliferação de Células , Sobrevivência Celular , Humanos , Intestinos/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo
8.
Org Lett ; 21(17): 6715-6719, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31419145

RESUMO

Water enables the highly challenging enantioselective Michael addition of sterically congested ß-trifluoromethyl-ß-aryl- or -alkyl-substituted nitroolefins with dithiomalonates. Under on-water conditions, the reaction rates were remarkably accelerated as a result of enforced hydrophobic interactions between catalysts and reactants. Takemoto-type thiourea catalysts are very effective for this transformation, affording highly enantioenriched Michael adducts that provide simple access to chiral γ-aminobutyric acid (GABA) analogues with a ß-trifluoromethylated quaternary stereocenter.

9.
Prev Nutr Food Sci ; 24(2): 136-143, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31328117

RESUMO

Obesity is a major health issue worldwide, and is associated with many diseases including type 2 diabetes. In this study, we evaluated the anti-obesity effects of combinations of two lactic acid bacteria (LAB), Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032, and Cinnamomi Ramulus (CR) extract, and explored the mechanism through which they modulate gut microbiota using diet-induced obese mice. Male C57BL/6J mice were randomly divided into five groups that received a high-fat diet (HFD), HFD and LAB (HFD+LAB), HFD and CR extract (HFD+CR), HFD with LAB and CR extract (HFD+LAB+CR), or normal diet for 10 weeks. The mice in the HFD+LAB+CR group showed significant reductions in body weight gain, in particular epididymal fat and liver, blood leptin levels, and an increase in the levels of blood adiponectin. In addition, the LAB and CR extract altered the gut microbiota, mainly increasing the alpha diversity. These results demonstrate that a mixture of two LAB (Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032) and CR extracts alleviate HFD-induced obesity, and has potential of being used as a strategy for the treatment of obesity.

10.
Prev Nutr Food Sci ; 24(2): 159-164, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31328120

RESUMO

Cudrania tricuspidata has been used in East Asia as a folk medicine for symptoms such as inflammation, allergy, and gastritis. Administration of C. tricuspidata extract to pylori-ligated rat stomachs reduces gastric acid secretion and alleviates esophagus damage caused by gastric reflux. Therefore, in this study we aimed to investigate whether C. tricuspidata extracts inhibit reflux esophagitis by blocking H2 histamine receptor (H2R). Dimaprit, a H2R specific agonist, induced intracellular cyclic adenosine monophosphate (cAMP) production in U937 cells. Pretreatment with C. tricuspidata extracts significantly blocked dimaprit-induced cAMP production in a concentration-dependent manner. To extracted C. tricuspidata with different ethanol concentrations to determine the optimum method. We found that the 70% ethanol extract showed the most potent H2R antagonistic effect against dimaprit-induced cAMP production. However, water extract did not show any H2R blocking effect. These findings suggest that C. tricuspidata extracted using ethanol specifically inhibits gastric acid secretion and reduces esophageal injury by blocking H2R in a competitive manner. Therefore, C. tricuspidata extracts may be used in food or medicine to prevent H2R-related diseases, such as gastric hyperacidity and reflux esophagitis.

11.
Org Lett ; 21(12): 4567-4570, 2019 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-31184184

RESUMO

A broadly applicable biomimetic enantioselective decarboxylative catalytic aldol reaction of trifluoromethyl ketones with malonic acid half-thioesters (MAHTs) is described. Utilizing cinchona-based thioureas as highly efficient polyketide synthase-mimic catalysts, chiral tertiary aldols, ß-trifluoromethyl-ß-hydroxy thioesters, were obtained in up to 99% yield and 95% ee. Facile transformation of the thioester moiety of the aldol adducts showcases the synthetic utility of this biomimetic aldol protocol to deliver a range of chiral trifluoromethylated tertiary aldol pharmacophores.


Assuntos
Materiais Biomiméticos/química , Hidrocarbonetos Fluorados/síntese química , Cetonas/química , Catálise , Hidrocarbonetos Fluorados/química , Estrutura Molecular , Estereoisomerismo
12.
Prev Nutr Food Sci ; 24(1): 64-69, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31008098

RESUMO

In addition to intestinal balance, probiotics are known to have beneficial effects on skin inflammation, metabolic diseases, and emotions. Previously, we have reported the skin anti-aging effects of Lactobacillus plantarum HY7714 (HY7714) in a clinical trial. To prove the protective skin effects of HY7714 through the intestinal tight junction (TJ), we investigated the effects of HY7714 on the intestines through tumor necrosis factor (TNF)-α induced TJ defects in Caco-2 cells. Specifically, 24 h treatment with HY7714 restored the decreased expression of zonula occludens-1, occludin, and claudin-1 compared to the TNF-α-treated groups (P<0.05). It also attenuated the level of pro-inflammatory cytokines interleukin-6, 8, and 1ß. Further, increases in the mRNA levels of Elk-1, nuclear factor-κB, and myosin light chain kinase expression induced by TNF-α were recovered by HY7714. These findings imply that HY7714 improves intestinal barrier integrity and is a potential therapeutic agent for dysfunctions derived from TJ defects.

13.
J Med Food ; 21(9): 876-886, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30148699

RESUMO

Some lactic acid bacteria (LAB) and their cellular components have antiobesity effects. In this study, we evaluated the antiadipogenic effects of a mixture of two LAB-Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032-using 3T3-L1 preadipocytes and HepG2 hepatocarcinoma cells. 3T3-L1 cells treated with a 1:1 ratio of HY7601 and KY1032 during differentiation showed reduced lipid accumulation by Oil Red O staining, as well as decreased leptin secretion and mRNA expression of peroxisome proliferator-activated receptor-γ and CCAAT/enhancer binding protein-α. HY7601 and KY1032 treatment also suppressed mitochondrial biogenesis and inhibited the expression of genes encoding mitochondrial transcription factors, as well as those related to fatty acid synthesis in HepG2 cells. The antiadipogenic effects of LAB were associated with the cell membrane fraction. These results demonstrate that a mixture of two LAB (HY7601 and KY1032) inhibits adipogenesis in preadipocytes and liver cells and is a potential therapeutic strategy for the treatment of obesity.


Assuntos
Adipócitos/citologia , Adipogenia , Lactobacillus plantarum/química , Lactobacillus/química , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Brassica/microbiologia , Proteína alfa Estimuladora de Ligação a CCAAT/genética , Proteína alfa Estimuladora de Ligação a CCAAT/metabolismo , Células Hep G2 , Humanos , Lactobacillus plantarum/genética , Lactobacillus plantarum/isolamento & purificação , Metabolismo dos Lipídeos/efeitos dos fármacos , Camundongos , PPAR gama/genética , PPAR gama/metabolismo , Triglicerídeos/metabolismo , Verduras/microbiologia
14.
J Med Food ; 21(11): 1086-1095, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30004273

RESUMO

The intestinal microflora plays important roles in the health of the host, such as nutrient processing and the modulation of intestinal immune responses. The constituents of the diet greatly affect the composition of the microbiota and its metabolites. The human intestinal microbiota is made up of around 100 trillion microbial cells encompassing at least 300 species. Consuming probiotics may lead to changes in the intestinal microflora that influence host health. Metabolomics is a powerful tool for revealing metabolic changes in biofluids, tissues, and organs of hosts induced by the consumption of probiotics, and lipidomics in particular is a technical approach that focuses on the analysis of lipids in various cells and biofluids. Metabolomics and lipidomics have been used to investigate intracellular and extracellular metabolites as well as for the nontargeted profiling and fingerprinting of metabolites. Based on metabolomics and lipidomics investigations, we reviewed the effects of consuming probiotics on metabolic profiles in controlled intestinal environments. We also discuss the associations between metabolic changes and human diseases after consuming probiotics in uncontrolled intestinal environments. In addition, we review the metabolic changes that take place within the food matrix during probiotic fermentation.


Assuntos
Microbioma Gastrointestinal , Mucosa Intestinal/metabolismo , Lipídeos/química , Probióticos/metabolismo , Animais , Bactérias/química , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Humanos , Intestinos/química , Intestinos/microbiologia , Metabolismo dos Lipídeos , Metabolômica
15.
Lab Anim Res ; 34(4): 216-222, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30671108

RESUMO

The efficacy of standard therapeutic strategies for Helicobacter pylori (H. pylori) infection is decreasing over time due to the emergence of drug-resistant strains. As an alternative, the present study investigated the capacity of Lactobacilllus paracasei (L. paracasei) HP7, isolated from kimchi, to inhibit H. pylori growth. The effects of L. paracasei HP7 on H. pylori adhesion and H. pylori-induced inflammation were examined in AGS human gastric adenocarcinoma epithelial cells and a mouse model of H. pylori SS1 infection. L. paracasei HP7 reduced H. pylori adhesion to AGS cells and suppressed the inflammatory response in infected cells by downregulating interleukin-8. H. pylori colonization in the stomach of C57BL/6 mice was demonstrated by rapid urease test, and results showed significant decrease in mice post-treated with L. paracasei HP7. Additionally, L. paracasei HP7 decreased gastric inflammation and epithelial lesions in the stomach of H. pylori-infected mice. These results demonstrate that L. paracasei HP7 treatment can inhibit H. pylori growth and is thus a promising treatment for patients with gastric symptoms such as gastritis that are caused by H. pylori infection.

16.
J Microbiol Biotechnol ; 27(12): 2237-2240, 2017 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-29032654

RESUMO

In the present study, we investigated the effect of tyndallized HY7712 (tHY7712) on the expression of Th cell specific transcription factors and cytokines in whole-body γ-irradiated mice. Oral administration of tHY7712 strongly recovered the γ-irradiation-suppressed expression of helper T (Th) cell- and regulatory T cell-related transcription factors and cytokines, such as T-bet, Foxp3, IFN-γ, TNF-α, and IL-10, and suppressed Th2 cell-associated transcription factor and cytokine GATA3 and IL-5, respectively. Furthermore, compared with the control, tHY7712 treatment also restored γ-irradiation-impaired natural killer and cytotoxic T cell activities against YAC-1 tumor cells to 97.8% and 98.6%, respectively.


Assuntos
Diferenciação Celular/efeitos da radiação , Raios gama/efeitos adversos , Lactobacillus plantarum/fisiologia , Linfócitos T Auxiliares-Indutores/efeitos da radiação , Irradiação Corporal Total , Animais , Citocinas/metabolismo , Camundongos , Probióticos/administração & dosagem , Linfócitos T Auxiliares-Indutores/citologia , Linfócitos T Reguladores/citologia , Linfócitos T Reguladores/efeitos da radiação , Fatores de Transcrição/metabolismo
17.
Angew Chem Int Ed Engl ; 56(7): 1835-1839, 2017 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-28097766

RESUMO

Water enables new catalytic reactions for otherwise unreactive substrate systems. Under the "on water" reaction conditions, extremely unreactive ß,ß-disubstituted nitroalkenes smoothly underwent enantioselective Michael addition reactions with dithiomalonates using a chiral squaramide catalyst, affording both enantiomers of highly enantioenriched Michael adducts with all-carbon-substituted quaternary centers. The developed "on water" protocol was successfully applied for the scalable one-pot syntheses of chiral GABA analogs with all-carbon quaternary stereogenic centers at the ß-position, which might show highly interesting pharmaceutical properties.

18.
Food Funct ; 8(1): 250-261, 2017 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-28001147

RESUMO

Our previous study showed that supplementation with a combination of Lactobacillus curvatus (L. curvatus) HY7601 and Lactobacillus plantarum (L. plantarum) KY1032 reduced the body weight, body fat percentage, body fat mass and L1 subcutaneous fat area in overweight subjects. We aimed to evaluate whether the changes in adiposity after supplementation with Lactobacillus strains were associated with metabolic intermediates. A randomized, double-blind, placebo-controlled study was conducted on 66 non-diabetic and overweight individuals. Over a 12-week period, the probiotic group consumed 2 g of probiotic powder, whereas the placebo group consumed the same product without the probiotics. To investigate metabolic alterations, we performed plasma metabolomics using ultra-performance liquid chromatography and mass spectrometry (UPLC-LTQ/Orbitrap MS). Probiotic supplementation significantly increased the levels of octenoylcarnitine (C8:1), tetradecenoylcarnitine (C14:1), decanoylcarnitine (C10) and dodecenoylcarnitine (C12:1) compared with the levels from placebo supplementation. In the probiotic group, the changes in the body weight, body fat percentage, body fat mass and L1 subcutaneous fat area were negatively associated with changes in the levels of C8:1, C14:1, C10 and C12:1 acylcarnitines. In overweight individuals, probiotic-induced weight loss and adiposity reduction from the probiotic supplementation were associated with an increase in medium-chain acylcarnitines.


Assuntos
Tecido Adiposo/metabolismo , Carnitina/análogos & derivados , Lactobacillus/fisiologia , Sobrepeso/tratamento farmacológico , Probióticos/administração & dosagem , Carnitina/administração & dosagem , Carnitina/química , Suplementos Nutricionais/análise , Método Duplo-Cego , Humanos , Lactobacillus plantarum/fisiologia , Sobrepeso/metabolismo , Sobrepeso/fisiopatologia , Triglicerídeos/metabolismo , Redução de Peso
19.
Artigo em Inglês | MEDLINE | ID: mdl-27516803

RESUMO

To evaluate the pharmacokinetics of compound K after oral administration of HYFRG and RG in humans, an open-label, randomized, single-dose, fasting, and one-period pharmacokinetic study was conducted. After oral administration of a single 3 g dose of HYFRG and RG to 24 healthy Korean males, the mean (±SD) of AUC0-t and C max of compound K from HYFRG were 1466.83 ± 295.89 ng·h/mL and 254.45 ± 51.20 ng/mL, being 115.2- and 80-fold higher than those for RG (12.73 ± 7.83 ng·h/mL and 3.18 ± 1.70 ng/mL), respectively; in case of Sprague Dawley rats the mean (±SD) of AUC0-t and C max of compound K from HYFRG was 58.03 ± 32.53 ng·h/mL and 15.19 ± 10.69 ng/mL, being 6.3- and 6.0-fold higher than those from RG (9.21 ± 7.52 ng·h/mL and 2.55 ± 0.99 ng/mL), respectively. T max of compound K in humans and rats was 2.54 ± 0.92 and 3.33 ± 0.50 h for HYFRG and 9.11 ± 1.45 and 6.75 ± 3.97 hours for RG, respectively. In conclusion, the administration of HYFRG resulted in a higher and faster absorption of compound K in both humans and rats compared to RG.

20.
Angew Chem Int Ed Engl ; 55(36): 10825-9, 2016 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-27486059

RESUMO

In this study, dithiomalonates (DTMs) were demonstrated to be exceptionally efficient Mannich donors in terms of reactivity and stereoselectivity in cinchona-based-squaramide-catalyzed enantioselective Mannich reactions of diverse imines or α-amidosulfones as imine surrogates. Owing to the superior reactivity of DTMs as compared to conventional malonates, the catalyst loading could be reduced to 0.1 mol % without the erosion of enantioselectivity (up to 99 % ee). Furthermore, by the use of a DTM, even some highly challenging primary alkyl α-amidosulfones were smoothly converted into the desired adducts with excellent enantioselectivity (up to 97 % ee), whereas the use of a malonate or monothiomalonate resulted in no reaction under identical conditions. The synthetic utility of the chiral Mannich adducts obtained from primary alkyl substrates was highlighted by the organocatalytic, coupling-reagent-free synthesis of the antidiabetic drug (-)-(R)-sitagliptin.

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