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1.
Angew Chem Int Ed Engl ; : e202402028, 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38656658

RESUMO

A planar conjugated ligand functionalized with bithiophene and its Ru(II), Os(II), and Ir(III) complexes have been constructed as single-molecule platform for synergistic photodynamic, photothermal, and chemotherapy. The complexes have significant two-photon absorption at 808 nm and remarkable singlet oxygen and superoxide anion production in aqueous solution and cells when exposed to 808 nm infrared irradiation. The most potent Ru(II) complex Ru7 enters tumor cells via the rare macropinocytosis, locates in both nuclei and mitochondria, and regulates DNA-related chemotherapeutic mechanisms intranuclearly including DNA topoisomerase and RNA polymerase inhibition and their synergistic effects with photoactivated apoptosis, ferroptosis and DNA cleavage. Ru7 exhibits high efficacy in vivo for malignant melanoma and cisplatin-resistant non-small cell lung cancer tumors, with a 100% survival rate of mice, low toxicity to normal cells and low residual rate. Such an infrared two-photon activatable metal complex may contribute to a new generation of single-molecule-based integrated diagnosis and treatment platform to address drug resistance in clinical practice and phototherapy for large, deeply located solid tumors.

2.
Bioorg Chem ; 147: 107382, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38640720

RESUMO

Amino acid transferase is a family of enzymes used to catalyze and separate chiral amino acids. However, due to the low efficiency, by-products and reverse reactions occur in cascade reactions. Therefore, in the research, phenylglycine aminotransferase and aspartate aminotransferase were self-assembled in vitro by leucine zipper. The self-assembled enzyme system with d-phenylglycine and α-ketoglutarate as substrates were used for the chiral transformation reaction. By studying the enzyme combination, kinetic reaction stability and catalytic efficiency, it was found that the self-assembled enzyme showed improved stability and better affinity to the substrate than the control and achieved only ee value of 17.86% for the control at the substrate ratio was 1:2. In contrast, the self-assembled enzyme basically catalyzed the complete conversion of d-Phg to l-Phg, with the ee value as 99%. These results demonstrated the feasibility of the leucine zipper and the conversion of d-phenylglycine to the l-type by fusion enzyme.

4.
Plant Foods Hum Nutr ; 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38441843

RESUMO

The flowers of Edgeworthia gardneri are used as herbal tea and medicine to treat various metabolic diseases including hyperglycemia, hypertension, and hyperlipidemia. This paper investigate the chemical constituents and biological activities of ethanolic extract and its different fractions from E. gardneri flowers. Firstly, the E. gardneri flowers was extracted by ethanol-aqueous solution to obtain crude extract (CE), which was subsequently fractionated by different polar organic solution to yield precipitated crystal (PC), dichloromethane (DCF), ethyl acetate (EAF), n-butanol (n-BuF), and residue water (RWF) fractions. UHPLC-ESI-HRMS/MS analysis resulted in the identification of 25 compounds, and the main compounds were flavonoids and coumarins. The precipitated crystal fraction showed the highest phenolic and flavonoid contents with 344.4 ± 3.38 mg GAE/g extract and 305.86 ± 0.87 mg RE/g extract. The EAF had the strongest antioxidant capacity and inhibitory effect on α-glucosidase and pancreatic lipase with IC50 values of 126.459 ± 7.82 and 23.16 ± 0.79 µg/mL. Besides, both PC and EAF significantly regulated the glucose and lipid metabolism disorders by increasing glucose consumption and reducing TG levels in HepG2 cells. Molecular docking results suggested that kaempferol-3-O-glucoside and tiliroside had good binding ability with enzymes, indicating that they may be potential α-glucosidase and pancreatic lipase inhibitors. Therefore, the E. gardneri flowers could be served as a bioactive agent for the regulation of metabolic disorders.

5.
Carbohydr Polym ; 332: 121921, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38431398

RESUMO

Curdlan is a unique (1,3)-ß-D-glucan with bioactivity and exceptional gelling properties. By chemical functionalization such as carboxymethylation, the physicochemical properties of curdlan can be significantly tailored. However, how the carboxymethylation extent of curdlan affects its rheology and gelation characteristics has yet to be fully understood. Herein, we investigated the impact of the degree of substitution (DS, ranging from 0.04 to 0.97) on the rheological and gelation behavior of carboxymethylated curdlan (CMCD). It was found that CMCD with DS below 0.20, resembling native curdlan, still retained its gelling capability. As the DS increased beyond 0.36, there was a significant increase in its water solubility instead of gelation, resulting in transparent solutions with steady/complex viscosities adhering to the Cox-Merz rule. Moreover, CMCD with high DS demonstrated the ability to undergo in-situ gelation in the presence of metal ions, attributed to the nonspecific electrostatic binding. Additionally, in vitro cytocompatibility testing showed positive compatibility across varying DS in CMCD. This research offers a holistic understanding of the viscosifying and gelling behaviors of CMCD with varying DS, thereby fostering their practical application as thickeners and gelling agents in fields ranging from food and biomedicine to cosmetics and beyond.


Assuntos
beta-Glucanas , beta-Glucanas/química , Glucanos/química , Géis/química , Água , Reologia
6.
Nat Commun ; 15(1): 2540, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38528017

RESUMO

High-efficient heat dissipation plays critical role for high-power-density electronics. Experimental synthesis of ultrahigh thermal conductivity boron arsenide (BAs, 1300 W m-1K-1) cooling substrates into the wide-bandgap semiconductor of gallium nitride (GaN) devices has been realized. However, the lack of systematic analysis on the heat transfer across the GaN-BAs interface hampers the practical applications. In this study, by constructing the accurate and high-efficient machine learning interatomic potentials, we perform multiscale simulations of the GaN-BAs heterostructures. Ultrahigh interfacial thermal conductance of 260 MW m-2K-1 is achieved, which lies in the well-matched lattice vibrations of BAs and GaN. The strong temperature dependence of interfacial thermal conductance is found between 300 to 450 K. Moreover, the competition between grain size and boundary resistance is revealed with size increasing from 1 nm to 1000 µm. Such deep-potential equipped multiscale simulations not only promote the practical applications of BAs cooling substrates in electronics, but also offer approach for designing advanced thermal management systems.

7.
J Intern Med ; 295(5): 634-650, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38439117

RESUMO

BACKGROUND: The immune reconstitution after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is crucial for preventing infections and relapse and enhancing graft-versus-tumor effects. B cells play an important role in humoral immunity and immune regulation, but their reconstitution after allo-HSCT has not been well studied. METHODS: In this study, we analyzed the dynamics of B cells in 252 patients who underwent allo-HSCT for 2 years and assessed the impact of factors on B-cell reconstitution and their correlations with survival outcomes, as well as the development stages of B cells in the bone marrow and the subsets in the peripheral blood. RESULTS: We found that the B-cell reconstitution in the bone marrow was consistent with the peripheral blood (p = 0.232). B-cell reconstitution was delayed by the male gender, age >50, older donor age, the occurrence of chronic and acute graft-versus-host disease, and the infections of fungi and cytomegalovirus. The survival analysis revealed that patients with lower B cells had higher risks of death and relapse. More importantly, we used propensity score matching to obtain the conclusion that post-1-year B-cell reconstitution is better in females. Meanwhile, using mediation analysis, we proposed the age-B cells-survival axis and found that B-cell reconstitution at month 12 posttransplant mediated the effect of age on patient survival (p = 0.013). We also found that younger patients showed more immature B cells in the bone marrow after transplantation (p = 0.037). CONCLUSION: Our findings provide valuable insights for optimizing the management of B-cell reconstitution and improving the efficacy and safety of allo-HSCT.


Assuntos
Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas , Feminino , Humanos , Masculino , Transplante Homólogo , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Doença Enxerto-Hospedeiro/etiologia , Doença Enxerto-Hospedeiro/prevenção & controle , Doença Enxerto-Hospedeiro/epidemiologia , Linfócitos B , Recidiva
8.
Exp Ther Med ; 27(5): 196, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38544556

RESUMO

Elastin expression in the conjoint facial sheath (CFS) of patients of different ages with severe ptosis has been extensively studied, but its expression in the CFS of pediatric patients with severe ptosis with different muscle strengths remains poorly understood. The aim of the present study was to investigate the expression of elastin in the CFS and levator palpebrae superioris muscle (LM) of children with severe congenital ptosis with different LM strengths. In total, 20 pediatric patients with unilateral severe congenital ptosis (20 eyes) were included, who underwent CFS + LM complex suspension surgery from June 2020 to February 2022. Among these patients, the LM strength was 0-1 mm in 10 patients and 2-3 mm in the other 10 patients. Excess CFS and LM tissue samples were obtained from the patients during surgery, before the protein expression levels of elastin in the specimens were measured by western blotting. During the 6-month postoperative follow-up period, the good correction rate, the degree of incomplete eyelid closure and the incidence of complications were observed. Western blotting results showed that, compared with that in the 0-1 mm group, elastin expression was not significantly different in the CFS, whereas it was significantly increased (P=0.021) in the LM of the 2-3 mm group. In addition, elastin expression in the CFS was markedly higher compared with that in the LM in both groups (in the 0-1 mm group, P=0.005; in the 2-3 mm group, P=0.009). Additionally, the curative effect evaluation revealed that the good correction rates in the 0-1 and 2-3 mm groups were 90 and 100%, respectively. In total, 3 patients experienced conjunctival prolapse during the follow-up period, including 2 patients in the 0-1 mm group and 1 patient in the 2-3 mm group, but there were no other complications. To conclude, elastin expression in the CFS was found to be higher compared with that in the LM of children with severe congenital ptosis. Although elastin expression in the LM was positively associated with LM strength, its expression in the CFS displayed no clear association with LM function. Therefore, these observations suggested that CFS + LM complex suspension surgery is viable to correct severe congenital ptosis in pediatric patients.

9.
Nat Commun ; 15(1): 2541, 2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38514672

RESUMO

Two-dimensional (2D) van der Waals (vdW) materials offer rich tuning opportunities generated by different stacking configurations or by introducing intercalants into the vdW gaps. Current knowledge of the interplay between stacking polytypes and intercalation often relies on macroscopically averaged probes, which fail to pinpoint the exact atomic position and chemical state of the intercalants in real space. Here, by using atomic-resolution electron energy-loss spectroscopy in a scanning transmission electron microscope, we visualize a stacking-selective self-intercalation phenomenon in thin films of the transition-metal dichalcogenide (TMDC) Nb1+xSe2. We observe robust contrasts between 180°-stacked layers with large amounts of Nb intercalants inside their vdW gaps and 0°-stacked layers with little detectable intercalants inside their vdW gaps, coexisting on the atomic scale. First-principles calculations suggest that the films lie at the boundary of a phase transition from 0° to 180° stacking when the intercalant concentration x exceeds ~0.25, which we could attain in our films due to specific kinetic pathways. Our results offer not only renewed mechanistic insights into stacking and intercalation, but also open up prospects for engineering the functionality of TMDCs via stacking-selective self-intercalation.

10.
J Am Chem Soc ; 146(12): 8520-8527, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38491937

RESUMO

Two-dimensional (2D) zeolite, with a high aspect ratio, has more open skeletons and accessible active sites than its three-dimensional (3D) counterpart. However, traditional methods of obtaining 2D zeolites often cause structural damage and widespread skeleton defects, hindering efficient selectivity in molecular separation. In this study, we present, for the first time, a direct epitaxial synthesis of 2D zeolite (Epi-MWW) guided by hexagonal boron nitride (h-BN) with a coincidence matching of site lattices to MWW zeolite. The as-grown Epi-MWW zeolite possesses a high crystallinity and intact hexagonal 2D morphology, with an average thickness of 10 nm and an aspect ratio of over 50. Thanks to its excellent molecular accessibility, the diffusion time constants of o-xylene (OX) and p-xylene (PX) are as 12 and 133 times higher than those of conventional MCM-22, respectively; the PX/OX selectivity of Epi-MWW is 7.4 times better than MCM-22 as calculated by the ideal adsorbed solution theory.

11.
J Org Chem ; 89(7): 4467-4473, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38502932

RESUMO

A trifluoroacetic anhydride-mediated cascade process for the synthesis of thiadiazole derivatives is described. 1,2,5-Thiadiazoles and 1,2,4-thiadiazolones could be obtained by variation of the reaction conditions. A group of functionalized thiadiazole derivatives were synthesized in moderate to good yields from nitro-group-containing N-tert-butanesulfinamides. The reactions involved in this tandem process are a Pummerer-like rearrangement of the tert-butanesulfinamide unit, a nitrile oxide formation via nitro group rearrangement, addition of oxygenated nucleophiles, and an N-S bond forming cyclization followed by concomitant elimination.

12.
Gene ; 906: 148256, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38341003

RESUMO

Nucleotide-binding sites and leucine-rich repeat proteins (NLRs) act as critical intracellular immune receptors. Previous studies reported an Arabidopsis-resistant gene L3 (AT1G15890), which encoded a coiled-coil (CC) NLR that conferred cell death in bacteria; however, its function in planta remains unclear. This study describes a comprehensive structure-function analysis of L3 in Nicotiana benthamiana. The results of the transient assay showed that the L3 CC domain is sufficient for cell-death induction. The first 140 amino acid segment constituted the minimal function region that could cause cell death. The YFP-labeled L3 CC domain was localized to the plasma membrane, which was considered crucial for the function and self-interaction of the L3 CC domain. The results of point mutations analysis showed that L3 CC domain function is affected by mutations in some specific residues, and loss-of-function mutations in the CC domain affected the function of full-length L3. These study results offered considerable evidence to understand the activation mechanism of L3.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Tabaco/genética , Sequência de Aminoácidos , Expressão Ectópica do Gene , Proteínas de Transporte/genética , Proteínas de Arabidopsis/metabolismo , Morte Celular/genética , Doenças das Plantas/genética , Proteínas de Plantas/metabolismo
13.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 32(1): 146-154, 2024 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-38387913

RESUMO

OBJECTIVE: To explore the effects of pre-transplant controlling nutritional status (CONUT) and post-transplant minimal residual disease (MRD) on prognosis of patients with multiple myeloma (MM) after autologous hematopoietic stem cell transplantation (auto-HSCT). METHODS: The clinical data of 79 patients who received auto-HSCT from 2011 to 2020 in The First Affiliated Hospital of Chongqing Medical University were retrospectively analyzed. The patients were divided into Low-CONUT group (n=62) and High-CONUT group (n=17) according to whether the CONUT score was less than 5. The differences in clinical features, hematopoietic reconstruction, adverse reactions, efficacy and survival between the two groups were compared. In addition, the prognostic risk factors were analyzed and verified by time-dependent ROC curve. RESULTS: The proportions of male patients and bone marrow plasma cells>30% at initial diagnosis in High-CONUT group were both higher than those in Low-CONUT group (both P <0.05). While, there were no significant differences in hematopoietic reconstruction and adverse reactions (>grade 2) between the two groups. The complete response (CR) rate and CR+very good partial response (VGPR) rate before transplantation in Low-CONUT group were both significantly higher than those in High-CONUT group (both P <0.05). After 3 months of transplantation, the CR+VGPR rate still remained an advantage in Low-CONUT group compared with High-CONUT group (P <0.01), but CR rate did not(P >0.05). The overall survival (OS) and progression-free survival (PFS) in Low-CONUT group were both superior to those in High-CONUT group (both P <0.05). Low CONUT score (0-4) before transplantation and negative MRD at 6 months after transplantation were favorable factors affecting OS and PFS (both P <0.05), while the International Myeloma Working Group (IMWG) high-risk at initial diagnosis and lactate dehydrogenase (LDH) level>250 U/L before transplantation were only risk factors for PFS (both P <0.05). Time-dependent ROC curve analysis showed that pre-transplant CONUT score and MRD status at 6 months after transplantation could independently or jointly predict 1- and 2-year OS and PFS, and the combined prediction was more effective. CONCLUSION: The combination of pre-transplant CONUT and post-transplant MRD can better predict the prognosis of MM patients.


Assuntos
Transplante de Células-Tronco Hematopoéticas , Mieloma Múltiplo , Humanos , Masculino , Mieloma Múltiplo/diagnóstico , Resultado do Tratamento , Neoplasia Residual , Estudos Retrospectivos , Prognóstico , Transplante Autólogo
14.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 32(1): 250-256, 2024 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-38387930

RESUMO

To analyze the risk factors for late-onset hemorrhagic cystitis (LOHC) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), the risk factors for the progression of LOHC to severe LOHC, and the effect of LOHC on survival. METHODS: The clinical data of 300 patients who underwent allo-HSCT at the First Affiliated Hospital of Chongqing Medical University from January 2015 to December 2021 were retrospectively analyzed. The relevant clinical parameters that may affect the occurance of LOHC after allo-HSCT were selected for univariate and multivariate analysis. Then, the differences in overall survival (OS) and progression-free survival (PFS) between different groups were analyzed. RESULTS: The results of multivariate analysis showed that the independent risk factors for LOHC after allo-HSCT were as follows: age≤45 years old (P =0.039), intensified conditioning regimen with fludarabine/cladribine and cytarabine (P =0.002), albumin≤30 g/L on d30 after transplantation (P =0.007), CMV-DNA positive (P =0.028), fungal infection before transplantation (P =0.026), and the occurrence of grade Ⅱ - Ⅳ aGVHD (P =0.006). In the transplant patients who have already developed LOHC, the occurance of LOHC within 32 days after transplantation (P =0.008) and albumin≤30 g/L on d30 after transplantation (P =0.032) were independent risk factors for the progression to severe LOHC. The OS rate of patients with severe LOHC was significantly lower than that of patients without LOHC (P =0.041). CONCLUSION: For the patients aged≤45 years old and with intensified conditioning regimen, it is necessary to be vigilant about the occurrence of LOHC; For the patients with earlier occurrence of LOHC, it is necessary to be vigilant that it develops into severe LOHC. Early prevention and treatment of LOHC are essential. Regular monitoring of CMV-DNA and albumin levels, highly effective antiviral and antifungal therapies, and prevention of aGVHD are effective measures to prevent the occurrence and development of LOHC.


Assuntos
60507 , Cistite , Infecções por Citomegalovirus , Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas , Humanos , Pessoa de Meia-Idade , Estudos Retrospectivos , Cistite/etiologia , Cistite/tratamento farmacológico , Cistite/epidemiologia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Fatores de Risco , Infecções por Citomegalovirus/complicações , Albuminas/uso terapêutico , DNA/uso terapêutico , Doença Enxerto-Hospedeiro/complicações
15.
J Biotechnol ; 381: 57-66, 2024 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-38185430

RESUMO

Dextranases are hydrolases that exclusively catalyze the disruption of α-1,6 glycosidic bonds. A series of variant enzymes were obtained by comparing the sequences of dextranases from different sources and introducing sequence substitutions. A correlation was found between the number of amino acids in the 397-401 region and the hydrolytic process. When there were no more than 5 amino acids in the 397-401 region, the enzyme first hydrolyzed the dextran T70 to a low molecular weight dextran with a molecular weight of about 5000, then IMOs1 appeared in the system if the degradation continued, showing a clear sequential relationship. And when there are more than 5 amino acids in the 397-401 region, IMOs were produced at the beginning of hydrolysis and continue to increase throughout the hydrolytic process. At the same time, we investigated the enzymatic properties of the variants and found that the hydrolytic rate of A-Ca was 11 times higher than that of the original enzyme. The proportion of IMOs produced by A-Ca was 80.68%, which was nearly10% higher than the original enzyme, providing a new enzyme for the industrial preparation of IMOs.


Assuntos
Dextranase , Dextranos , Hidrólise , Dextranase/genética , Dextranase/química , Dextranos/química , Peso Molecular , Aminoácidos
16.
J Helminthol ; 98: e13, 2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38263743

RESUMO

To investigate the effects of co-infection with Clonorchis sinensis (C. sinensis) on T cell exhaustion levels in patients with chronic hepatitis B, we enrolled clinical cases in this study, including the patients with concomitant C. sinensis and HBV infection. In this study, we detected inhibitory receptors and cytokine expression in circulating CD4+ and CD8+ T cells by flow cytometry. PD-1 and TIM-3 expression levels were significantly higher on CD4+ T and CD8+ T cells from co-infected patients than on those from the HBV patients. In addition, CD4+ T cells and CD8+ T cells function were significantly inhibited by C. sinensis and HBV co-infection compared with HBV single infection, secreting lower levels of Interferon gamma (IFN-γ), Interleukin-2 (IL-2), and TNF-α. Our current results suggested that C. sinensis co-infection could exacerbate T cell exhaustion in patients with chronic hepatitis B. PD-1 and TIM-3 could be novel biomarkers for T cell exhaustion in patients with Clonorchis sinensis and chronic hepatitis B co-infection. Furthermore, it may be one possible reason for the weaker response to antiviral therapies and the chronicity of HBV infection in co-infected patients. We must realize the importance of C. sinensis treatment for HBV-infected patients. It might provide useful information for clinical doctors to choose the right treatment plans.


Assuntos
Clonorquíase , Clonorchis sinensis , Coinfecção , Hepatite B Crônica , Animais , Humanos , Receptor Celular 2 do Vírus da Hepatite A , Receptor de Morte Celular Programada 1 , Exaustão das Células T
17.
J Clin Ultrasound ; 2024 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-38288546

RESUMO

A rare case of unicornuate uterus with interstitial ectopic pregnancy was diagnosed using three-dimensional transvaginal ultrasound (3D-TVUS). The ultrasound revealed a "lancet-shaped" endometrial corona, a gestational sac near the uterus base extending toward the uterine serosa, and visible interstitial lines. The patient underwent laparoscopic surgery for a lesion in the right fallopian tube. 3D-TVUS was crucial in precisely locating the gestational sac, aiding in effective treatment. Interstitial ectopic pregnancies risk severe hemorrhaging upon rupture. Rapid, accurate diagnosis is vital for lifesaving treatment and preventing critical complications.

18.
Int J Biol Macromol ; 254(Pt 2): 127847, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37924910

RESUMO

The physicochemical properties and applications of polysaccharides are highly dependent on their chemical structures, including the monosaccharide composition, degree of substitution, and position of substituent groups in the backbone. The occurrence of side groups or side chains in the chain backbone of polysaccharides is often an essential factor influencing their conformational and physicochemical properties. Welan gum produced by the fermentation of Sphingomonas sp. ATCC 31555 microorganisms has been widely used in food, construction, and oil drilling fields. While understanding the physicochemical properties of welan gum solution has been highly developed, there is still little information about the determination strategy of the glycosyl side groups in welan gum. In this study, the NMR method was established to quantitatively determine the substituent groups in the chain backbone of welan gum. The delicate chemical structures of welan gum obtained at different fermentation conditions were clarified. The composition and content of side substituents were also identified by high-performance liquid chromatography to confirm the accuracy of NMR analysis. The quantitative determination of substituent groups in gellan gum based on NMR analysis was also elaborated for comparison. This work provides insights for profoundly understanding the structure-function relationship of welan gum.


Assuntos
Polissacarídeos Bacterianos , Sphingomonas , Polissacarídeos Bacterianos/química , Monossacarídeos , Fermentação
19.
Angew Chem Int Ed Engl ; 63(2): e202315481, 2024 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-38009457

RESUMO

Herein we report a structure-unit-based asymmetric total synthesis of sinulochmodin C, a norcembranoid diterpenoid bearing a transannular strained ether bridge ß-keto tetrahydrofuran moiety. Our synthetic route features an intramolecular double Michael addition to construct stereospecifically the [7,6,5,5] tetracyclic skeleton, a vinylogous hydroxylation/oxidation procedure or a stereospecific epoxide opening/oxidation sequence to establish the γ-keto enone intermediate, a Lewis acid/Brønsted acid mediated transannular oxa-Michael addition to fuse the ß-keto tetrahydrofuran moiety, a Mukaiyama hydration/Pd-C hydrogenation to reverse the C1-configuration of the isopropenyl unit, and a bioinspired transformation of sinulochmodin C into scabrolide A.

20.
Int J Biol Macromol ; 254(Pt 3): 128002, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37949280

RESUMO

Blue algae, a type of harmful microalgae, are responsible for causing harmful algal blooms that result in severe environmental issues. To address this problem, a biopolysaccharide-based flocculant was developed for treating blue algae blooms. This flocculant was created by modifying high molecular weight dextran using the natural cationic monomer betaine (Dex-Bet), making it environmentally friendly. Various techniques were used to characterize the prepared Dex-Bet flocculant, including infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The effectiveness of the Dex-Bet flocculant was evaluated using kaolin-simulated wastewater. The results showed that the treated supernatant had a transmittance of up to 98.25 %. Zeta potential analysis revealed that the main mechanisms of flocculation were charge neutralization, charge patching, and adsorption bridging. The application of Dex-Bet in treating blue-green algae resulted in a maximum removal rate of 98.2 %. This study provides a potential flocculant for blue algae bloom treatment.


Assuntos
Dextranos , Caulim , Caulim/química , Águas Residuárias , Espectroscopia de Ressonância Magnética , Eutrofização , Floculação
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