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1.
J Am Chem Soc ; 146(28): 18892-18898, 2024 Jul 17.
Article in English | MEDLINE | ID: mdl-38968086

ABSTRACT

Herein, we designed a reaction for the desymmetrization-addition of cyclopropenes to imines by leveraging the synergy between photoredox and asymmetric cobalt catalysis. This protocol facilitated the synthesis of a series of chiral functionalized cyclopropanes with high yield, enantioselectivity, and diastereoselectivity (44 examples, up to 93% yield and >99% ee). A possible reaction mechanism involving cyclopropene desymmetrization by Co-H species and imine addition by Co-alkyl species was proposed. This study provides a novel route to important chiral cyclopropanes and extends the frontier of asymmetric metallaphotoredox catalysis.

2.
Ultrason Sonochem ; 107: 106935, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38850642

ABSTRACT

Myofibrillar proteins (MPs) have a notable impact on the firmness and flexibility of gel-based products. Therefore, enhancing the gelation and emulsification properties of scallop MPs is of paramount significance for producing high-quality scallop surimi products. In this study, we investigated the effects of high-intensity ultrasound on the physicochemical and gelation properties of MPs from bay scallops (Argopecten irradians). The carbonyl content of MPs significantly increased with an increase in ultrasound power (150, 350, and 550 W), indicating ultrasound-induced MP oxidation. Meanwhile, high-intensity ultrasound treatment (550 W) enhanced the emulsifying capacity and the short-term stability of MPs (up to 72.05 m2/g and 153.05 min, respectively). As the ultrasound power increased, the disulfide bond content and surface hydrophobicity of MPs exhibited a notable increase, indicating conformational changes in MPs. Moreover, in the secondary structure of MPs, the α-helix content significantly decreased, whereas the ß-sheet content increased, thereby suggesting the ultrasound-induced stretching and flexibility of MP molecules. Sodium-dodecyl sulfate-polyacrylamide gel electrophoresis and scanning electron microscopy analysis further elucidated that high-intensity ultrasound induced MP oxidation, leading to modification of amino acid side chains, intra- and intermolecular cross-linking, and MP aggregation. Consequently, high-intensity ultrasound treatment was found to augment the viscoelasticity, gel strength, and water-holding capacity of MP gels, because ultrasound treatment facilitated the formation of a stable network structure in protein gels. Thus, this study offers theoretical insights into the functional modification of bay scallop MPs and the processing of its surimi products.


Subject(s)
Gels , Muscle Proteins , Pectinidae , Pectinidae/chemistry , Animals , Gels/chemistry , Muscle Proteins/chemistry , Ultrasonic Waves , Chemical Phenomena , Hydrophobic and Hydrophilic Interactions , Emulsions/chemistry
3.
Cell Biosci ; 14(1): 66, 2024 May 23.
Article in English | MEDLINE | ID: mdl-38783336

ABSTRACT

BACKGROUND: Human patients often experience an episode of serious seizure activity, such as status epilepticus (SE), prior to the onset of temporal lobe epilepsy (TLE), suggesting that SE can trigger the development of epilepsy. Yet, the underlying mechanisms are not fully understood. The low-density lipoprotein receptor related protein (Lrp4), a receptor for proteoglycan-agrin, has been indicated to modulate seizure susceptibility. However, whether agrin-Lrp4 pathway also plays a role in the development of SE-induced TLE is not clear. METHODS: Lrp4f/f mice were crossed with hGFAP-Cre and Nex-Cre mice to generate brain conditional Lrp4 knockout mice (hGFAP-Lrp4-/-) and pyramidal neuron specific knockout mice (Nex-Lrp4-/-). Lrp4 was specifically knocked down in hippocampal astrocytes by injecting AAV virus carrying hGFAP-Cre into the hippocampus. The effects of agrin-Lrp4 pathway on the development of SE-induced TLE were evaluated on the chronic seizure model generated by injecting kainic acid (KA) into the amygdala. The spontaneous recurrent seizures (SRS) in mice were video monitored. RESULTS: We found that Lrp4 deletion from the brain but not from the pyramidal neurons elevated the seizure threshold and reduced SRS numbers, with no change in the stage or duration of SRS. More importantly, knockdown of Lrp4 in the hippocampal astrocytes after SE induction decreased SRS numbers. In accord, direct injection of agrin into the lateral ventricle of control mice but not mice with Lrp4 deletion in hippocampal astrocytes also increased the SRS numbers. These results indicate a promoting effect of agrin-Lrp4 signaling in hippocampal astrocytes on the development of SE-induced TLE. Last, we observed that knockdown of Lrp4 in hippocampal astrocytes increased the extracellular adenosine levels in the hippocampus 2 weeks after SE induction. Blockade of adenosine A1 receptor in the hippocampus by DPCPX after SE induction diminished the effects of Lrp4 on the development of SE-induced TLE. CONCLUSION: These results demonstrate a promoting role of agrin-Lrp4 signaling in hippocampal astrocytes in the development of SE-induced development of epilepsy through elevating adenosine levels. Targeting agrin-Lrp4 signaling may serve as a potential therapeutic intervention strategy to treat TLE.

4.
Mol Cell Endocrinol ; 588: 112213, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38556162

ABSTRACT

OBJECTIVE: Difficult-to-heal wound is a prevalent and significant complication of diabetes, characterized by impaired functionality of epithelial cells such as fibroblasts. This study aims to investigate the potential mechanism of ADSC-Exos promoting diabetic wound healing by regulating fibroblast function. MATERIALS AND METHODS: ADSC-Exos were confirmed through TEM, NTA, and Western Blot techniques. The study conducted on rat skin fibroblasts (RSFs) exposed to 33 mmol/L glucose in vitro. We used cck-8, EDU, transwell, and scratch assays to verify the proliferation and migration of RSFs. Furthermore, levels of TGF-ß1 and α-SMA proteins were determined by immunofluorescence and Western Blot. RSFs were transfected with miR-128-1-5p mimics and inhibitors, followed by quantification of TGF-ß1, α-SMA, Col I and Smad2/3 protein levels using Western Blot. In vivo, the effects of ADSC-Exos on diabetic wounds were assessed using digital imaging, histological staining, as well as Western Blot analysis. RESULTS: In vitro, ADSC-Exos significantly enhanced proliferation and migration of RSFs while reducing the expression of TGF-ß1 and α-SMA. In vivo, ADSC-Exos effectively promoted diabetic wound healing and mitigated scar fibrosis. Additionally, ADSC-Exos exhibited elevated levels of miR-128-1-5p, which targets TGF-ß1, resulting in a notable reduction in TGF-ß1, α-SMA, Col I and smad2/3 phosphorylation in RSFs. CONCLUSION: In conclusion, our results demonstrated that ADSC-Exos promoted diabetic wound healing, and inhibited skin fibrosis by regulating miR-128-1-5p/TGF-ß1/Smad signaling pathway, which provides a promising innovative treatment for diabetic wound healing.


Subject(s)
Diabetes Mellitus, Experimental , Exosomes , Fibroblasts , Fibrosis , Mesenchymal Stem Cells , MicroRNAs , Rats, Sprague-Dawley , Signal Transduction , Transforming Growth Factor beta1 , Wound Healing , MicroRNAs/genetics , MicroRNAs/metabolism , Animals , Transforming Growth Factor beta1/metabolism , Mesenchymal Stem Cells/metabolism , Exosomes/metabolism , Rats , Diabetes Mellitus, Experimental/metabolism , Diabetes Mellitus, Experimental/complications , Diabetes Mellitus, Experimental/pathology , Diabetes Mellitus, Experimental/genetics , Fibroblasts/metabolism , Male , Cell Proliferation , Cell Movement , Smad2 Protein/metabolism , Adipose Tissue/metabolism , Adipose Tissue/cytology , Smad3 Protein/metabolism , Smad3 Protein/genetics , Smad Proteins/metabolism
5.
Free Radic Biol Med ; 215: 37-47, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38408545

ABSTRACT

Increasing evidence has revealed the emerging role of ferroptosis in the pathophysiology of type 2 diabetes mellitus (T2DM) and its complications. Platelet-rich plasma (PRP) has been demonstrated to facilitate the healing of T2DM ulcers. However, the mechanism by which PRP repairs T2DM ulcers remains unclear. Here, we sought to investigate the interaction between PRP and ferroptosis in repairing T2DM ulcers. The results showed that the cellular activity, proliferation, and migration of fibroblasts were down-regulated, and the cellular activity and normal function of vascular endothelial cells were impaired in the high glucose environment or under RSL3 conditions (a GSH peroxidase 4 inhibitor and ferroptosis inducer). Additionally, both cells experienced over-activation of multiple forms of reactive oxygen species (ROS) and lipid peroxidation. In the T2DM rat model, we observed a decreased rate of ulcer wound healing, impaired proliferative capacity, diminished vascular regeneration, and marked inflammation and hyperfibrosis. More importantly, there was typical damage to mitochondria, increased levels of iron ions, and consistent alterations in protein expression of ferroptosis-related factors. These factors include cyclooxygenase-2 (COX2), glutathione peroxidase 4 (GPX4), transferrin receptor (TFRC), and Solute Carrier Family 7 Member 11 (SLC7A11), among others. Due to the strong association between ferroptosis and T2DM ulcers, the use of allogeneic platelet-rich plasma (Al-PRP) exhibited physiological effects similar to those of the ferroptosis inhibitor Ferrostatin-1 (Fer-1). In vivo experiments, both drugs inhibited a range of impediments to wound healing caused by T2DM and ameliorated the adverse effects associated with ferroptosis. Moreover, Al-PRP attenuated the impairment of normal cellular function, activation of ROS and lipid peroxidation induced by high glucose or RSL3. These results suggested that ferroptosis was involved in the development of T2DM ulcers, which could be treated with Al-PRP by inhibiting ferroptosis, and inhibition of ferroptosis may be a suitable treatment strategy for T2DM ulcers.


Subject(s)
Diabetes Complications , Diabetes Mellitus, Type 2 , Ferroptosis , Hematopoietic Stem Cell Transplantation , Animals , Rats , Ulcer , Diabetes Mellitus, Type 2/genetics , Diabetes Mellitus, Type 2/therapy , Endothelial Cells , Ferroptosis/genetics , Reactive Oxygen Species , Glucose
6.
Angew Chem Int Ed Engl ; 63(13): e202319728, 2024 Mar 22.
Article in English | MEDLINE | ID: mdl-38285535

ABSTRACT

Organic molecules bearing chiral sulfur stereocenters exert a great impact on asymmetric catalysis and synthesis, chiral drugs, and chiral materials. Compared with acyclic ones, the catalytic asymmetric synthesis of thio-heterocycles has largely lagged behind due to the lack of efficient synthetic strategies. Here we establish the first modular platform to access chiral thio-oxazolidinones via Pd-catalyzed asymmetric [3+2] annulations of vinylethylene carbonates with sulfinylanilines. This protocol is featured by readily available starting materials, and high enantio- and diastereoselectivity. In particular, an unusual effect of a non-chiral supporting ligand on the diastereoselectivity was observed. Possible reaction mechanisms and stereocontrol models were proposed.

7.
Chemistry ; 30(10): e202303476, 2024 Feb 16.
Article in English | MEDLINE | ID: mdl-38065837

ABSTRACT

The construction of an all-in-one catalyst, in which the photosensitizer and the transition metal site are close to each other, is important for improving the efficiency of metallaphotoredox catalysis. However, the development of convenient synthetic strategies for the precise construction of an all-in-one catalyst remains a challenging task due to the requirement of precise installation of the catalytic sites. Herein, we have successfully established a facile bottom-up strategy for the direct synthesis of Ni(II)-incorporated covalent organic framework (COF), named LZU-713@Ni, as a versatile all-in-one metallaphotoredox catalyst. LZU-713@Ni showed excellent activity and recyclability in the photoredox/nickel-catalyzed C-O, C-S, and C-P cross-coupling reactions. Notably, this catalyst displayed a better catalytic activity than its homogeneous analogues, physically mixed dual catalyst system, and, especially, LZU-713/Ni which was prepared through post-synthetic modification. The improved catalytic efficiency of LZU-713@Ni should be attributed to the implementation of bottom-up strategy, which incorporated the fixed, ordered, and abundant catalytic sites into its framework. This work sheds new light on the exploration of concise and effective strategies for the construction of multifunctional COF-based photocatalysts.

8.
Angew Chem Int Ed Engl ; 62(51): e202312102, 2023 Dec 18.
Article in English | MEDLINE | ID: mdl-37936319

ABSTRACT

The exploration of value-added conversions of naturally abundant amino acids has received considerable attention from the synthetic community. Compared with the well-established asymmetric decarboxylative transformation, the asymmetric deaminative transformation of amino acids still remains a formidable challenge, mainly due to the lack of effective strategies for the C-N bond activation and the potential incompatibility with chiral catalysts. Here, we disclose a photoinduced Cu-catalyzed asymmetric deaminative coupling reaction of amino acids with arylboronic acids. This new protocol provides a series of significant chiral phenylacetamides in generally good yields and excellent stereoselectivity under mild and green conditions (42-85 % yields, up to 97 % ee). Experimental investigations and theoretical calculations were performed to reveal the crucial role of additional phenols in improving catalytic efficiency and enantiocontrol.

9.
J Trace Elem Med Biol ; 80: 127288, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37659123

ABSTRACT

This investigation was designed to examine the potential involvement of RAGE/NADPH oxidase signaling in the damage to the brain caused by chronic fluorosis. Sprague-Dawley rats were divided randomly into 9 groups each containing 20 animals, Controls (C); rats receiving low (i.e., 10 ppm) (LF) or high does ( i.e., 50 ppm) (HF) of fluoride in their drinking water; and these same groups injected with FPS-ZM1, an inhibitor of RAGE, (CF, LFF and HFF, respectively) or administered EGb761, an active ingredient of Ginkgo biloba extract, intragastrically (CE, LFE, and HFE). Following 3 and 6 months of such treatment, the spatial learning and memory of the animals were assessed with the Morris water maze test; the levels of malondialdehyde (MDA), hydrogen peroxide (H2O2) and superoxide dismutase (SOD) assayed by biochemical methods; and the levels of proteins related to the RAGE/NADPH pathway determined by Western blot and of the corresponding mRNAs by qPCR. After 6 months, the spatial learning and memory of the LF and HF groups had declined; their brain contents of MDA and H2O2 increased and SOD activity decreased; and the levels of the RAGE, gp91, P47, phospho-P47phox and P22 proteins and corresponding mRNAs in their brains were all elevated. Interestingly, all of these pathological changes caused by fluorosis could be attenuated by both FPS-ZM1 and EGb761. These findings indicate that the brain damage induced by fluorosis may be caused, at least in part, by enhanced RAGE/NADPH oxidase signaling and that FPS-ZM1 or EGb761 might be of clinical value in connection with the treatment of this condition.


Subject(s)
Brain , Hydrogen Peroxide , Rats , Animals , Rats, Sprague-Dawley , Hydrogen Peroxide/metabolism , Brain/metabolism , Oxidative Stress , NADPH Oxidases , Signal Transduction , Superoxide Dismutase/metabolism
10.
J Evid Based Med ; 16(3): 376-393, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37743650

ABSTRACT

BACKGROUND: Knee osteoarthritis (KOA) is the most common degenerative joint disease in China, causing a huge economic burden on patients, families, and society. Standardized KOA rehabilitation treatment is an important means to prevent and treat the disease and promote the development of high-quality medical services. This guideline is updated on the basis of the 2016 and 2019 editions. METHODS: Clinical questions regarding rehabilitation assessment and treatment were selected through clinical questions screening and deconstruction, and multiple rounds of Delphi questionnaire consultation. The International Classification of Functioning, Disability and Health (ICF) was used as the theoretical framework, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method was used to grade the quality of evidence and recommendations. RESULTS: The reporting of this guideline followed the standard of Reporting Items for Practice Guidelines in Healthcare (RIGHT). Taking into account patients' preferences and values and the needs of Chinese clinical practice, a total of 11 clinical questions and 28 recommendations were established. The clinical questions were grouped into two categories: KOA assessment (body function, body structure, activity and participation, quality of life, and environmental factors and clinical outcomes assessment, resulting in 9 recommendations) and KOA treatment (health education, therapeutic exercise, therapeutic modalities, occupational therapy, assistive devices, and regenerative rehabilitation approaches, resulting in 19 recommendations). CONCLUSION: This is the first evidence-based guideline for KOA rehabilitation in China utilizing the ICF framework. This guideline provides key guidance for developing systematic, standardized, and precise rehabilitation protocols for KOA across various healthcare settings.


Subject(s)
Osteoarthritis, Knee , Humans , Osteoarthritis, Knee/therapy , Osteoarthritis, Knee/diagnosis , Quality of Life , Evidence-Based Practice , Evidence-Based Medicine/methods , China
11.
BMC Med ; 21(1): 322, 2023 08 25.
Article in English | MEDLINE | ID: mdl-37626339

ABSTRACT

BACKGROUND: There is limited evidence to support the use of vestibular rehabilitation therapy (VRT) on improving balance and gait in patients after stroke. This systematic review aimed to evaluate the effects of VRT in addition to usual rehabilitation compared with usual rehabilitation on improving balance and gait for patients after stroke. METHODS: This review followed the Preferred Reporting Items for Systematic reviews and Meta-Analysis statement guidelines. Ten electronic databases were searched up to 1 June 2023 without restrictions in language and publication status. The PEDro scale and the Grading of Recommendations Assessment Development, and Evaluation were used to evaluate the risk of bias and the certainty of evidence. The meta-analysis was conducted with Review Manager 5.3. RESULTS: Fifteen randomised controlled trials with 769 participants were included. PEDro scale was used to assess the risk of bias with a mean score of 5.9 (0.7). VRT was effective in improving balance for patients after stroke (SMD = 0.59, 95% CI (0.40, 0.78), p < 0.00001), particularly for patients after stroke that occurred within 6 months (SMD = 0.56, 95% CI (0.33, 0.79), p < 0.00001) with moderate certainty of evidence. Subgroup analysis showed that VRT provided as gaze stability exercises combined with swivel chair training (SMD = 0.85, 95% CI (0.48, 1.22), p < 0.00001) and head movements (SMD = 0.75, 95% CI (0.43, 1.07), p < 0.00001) could significantly improve balance. Four-week VRT had better effect on balance improvement (SMD = 0.64, 95% CI (0.40, 0.89), p < 0.00001) than the less than 4-week VRT. The pooled mean difference of values of Timed Up-and-Go test showed that VRT could significantly improve gait function for patients after stroke (MD = -4.32, 95% CI (-6.65, -1.99), p = 0.0003), particularly for patients after stroke that occurred within 6 months (MD = -3.92, 95% CI (-6.83, -1.00), p = 0.008) with moderate certainty of evidence. CONCLUSIONS: There is moderate certainty of evidence supporting the positive effect of VRT in improving balance and gait of patients after stroke. TRIAL REGISTRATION: PROSPERO CRD42023434304.


Subject(s)
Medicine , Stroke , Humans , Patients , Exercise Therapy , Gait , Randomized Controlled Trials as Topic
12.
J Craniofac Surg ; 34(5): e474-e477, 2023.
Article in English | MEDLINE | ID: mdl-37185316

ABSTRACT

OBJECTIVE: This study aimed to investigate the survival quality of peroneal artery perforator flap in the reconstruction of oral and maxillofacial malignant tumors. METHODS: Thirty-two cases with a diagnosis of oral and maxillofacial malignant tumors admitted to our hospital from January 2019 to December 2019 were randomly divided into 2 groups. The observation group was reconstructed with free open artery perforator flaps, and the control group was repaired with free forearm flaps. RESULTS: The observation group had significantly lower scores in terms of postoperative pain, appearance, and anxiety, compared with the control group ( P <0.05). Both groups had high scores on taste, saliva, and shoulder function although there was no significant difference ( P >0.05). The scores of the observation group were significantly higher than those in the control group in terms of chewing, swallowing, speech, activity, mood, and entertainment ( P <0.05). There was 1 case accompanied by postoperative wound dehiscence and 2 cases with wound infection in the observation group while there were 3 cases with wound dehiscence and 2 cases with wound infection in the control group ( P >0.05). CONCLUSION: Compared with the forearm flap, the peroneal artery perforator flap can improve the survival quality of patients, especially in postoperative function with the fibula joint to repair the oral and maxillofacial defects. It has a wide application prospect as one of the ideal flaps in oral and maxillofacial postoperative repair and reconstruction.


Subject(s)
Neoplasms , Perforator Flap , Plastic Surgery Procedures , Soft Tissue Injuries , Humans , Neoplasms/surgery , Perforator Flap/surgery , Skin Transplantation , Soft Tissue Injuries/surgery , Tibial Arteries , Treatment Outcome
13.
Sheng Li Xue Bao ; 75(2): 303-315, 2023 Apr 25.
Article in Chinese | MEDLINE | ID: mdl-37089104

ABSTRACT

Interleukin 27 (IL-27) is a pleiotropic cytokine that is involved in the regulation of the body's innate and adaptive immunity. Previous studies have shown that IL-27 mediates a variety of inflammatory responses in vivo. With the development of animal models and technical tools, several studies have shown that it is also closely associated with autoimmune diseases and other immune related diseases, and is considered as an important candidate for the treatment of viral disease, autoimmune diseases, tumors and obesity. Therefore, this paper reviews recent progress on the role of IL-27 in acquired immunodeficiency syndrome (AIDS), rheumatoid arthritis, tumors and obesity, with the aim of providing new ideas for the treatment of immune related diseases.


Subject(s)
Arthritis, Rheumatoid , Autoimmune Diseases , Interleukin-27 , Neoplasms , Animals , Cytokines
14.
Angew Chem Int Ed Engl ; 62(21): e202301592, 2023 May 15.
Article in English | MEDLINE | ID: mdl-36932035

ABSTRACT

Metal-polarized aza-ortho-quinone methides (aza-o-QMs) are a unique and efficient handle for azaheterocycle synthesis. Despite great achievements, the potential of these reactive intermediates has not yet been fully exploited, especially the new reaction modes. Herein, we disclosed an unprecedented dearomatization process of metal-polarized aza-o-QMs, affording transient dearomatized spiroaziridine intermediates. Based on this serendipity, we accomplished three sequential dearomatization-rearomatization reactions of benzimidazolines with aza-sulfur ylides, enabling the divergent synthesis of bis-nitrogen heterocycles with high efficiency and flexibility. Moreover, experimental and theoretical studies were performed to explain the proposed mechanisms and observed selectivity. Further cellular evaluation of the dibenzodiazepine products identified a hit compound for new antitumor drugs.

15.
Angew Chem Int Ed Engl ; 62(21): e202300233, 2023 May 15.
Article in English | MEDLINE | ID: mdl-36896733

ABSTRACT

Visible-light copper photocatalysis has recently emerged as a viable technology for building sustainable synthetic processes. To broaden the applications of phosphine-ligated copper(I) complexes, we describe herein an effective metal-organic framework (MOF)-supported copper(I) photocatalyst for multiple iminyl radical-mediated reactions. Due to site isolation, the heterogenized copper photosensitizer has a significantly higher catalytic activity than its homogeneous counterpart. Using a hydroxamic acid linker to immobilize copper species on MOF supports affords the heterogeneous catalysts with high recyclability. The post-synthetic modification sequence on MOF surfaces allows for the preparation of previously unavailable monomeric copper species. Our findings highlight the potential of using MOF-based heterogeneous catalytic systems to address fundamental challenges in the development of synthetic methodologies and mechanistic investigations of transition-metal photoredox catalysis.

16.
J Am Chem Soc ; 145(12): 6944-6952, 2023 Mar 29.
Article in English | MEDLINE | ID: mdl-36920031

ABSTRACT

Enantioselective metallaphotoredox catalysis, which combines photoredox catalysis and asymmetric transition-metal catalysis, has become an effective approach to achieve stereoconvergence under mild conditions. Although many impressive synthetic approaches have been developed to access central chirality, the construction of axial chirality by metallaphotoredox catalysis still remains underexplored. Herein, we report two visible light-induced cobalt-catalyzed asymmetric reductive couplings of biaryl dialdehydes to synthesize axially chiral aldehydes (60 examples, up to 98% yield, >19:1 dr, and >99% ee). This protocol shows good functional group tolerance, broad substrate scope, and excellent diastereo- and enantioselectivity.

17.
J Am Chem Soc ; 145(14): 7983-7991, 2023 Apr 12.
Article in English | MEDLINE | ID: mdl-36974976

ABSTRACT

Conjugate addition is among the most important synthetic protocols for constructing carbon skeletons and is widely used to synthesize natural products and drugs. However, asymmetric catalysis studies have mainly focused on constructing stereogenic centers arising from conjugate alkenes. Here, we report the first photoinduced cobalt-catalyzed dynamic kinetic reductive conjugate addition reaction that enables the formation of heterobiaryls with axial chirality (45 examples, up to 91% yield and 97% ee). This method features mild reaction conditions, good functional-group tolerance, and excellent enantiomeric control. Significantly, large amounts of metal waste and precious metal catalysts can be avoided under these conditions. Migration of the chiral arylcobalt species into the alkene might be the rate-determining step based on kinetic studies.

18.
J Sci Food Agric ; 103(4): 1964-1973, 2023 Mar 15.
Article in English | MEDLINE | ID: mdl-36533998

ABSTRACT

BACKGROUND: In this study, a new crosslinking agent (CA) containing whey protein, papin, glycerin, and epigallocatechin gallate (EGCG), was prepared. The effects of CA content (0, 10, 20, 30, and 40%, v/v) on food packaging properties, crystallinity, microstructure, and antioxidant properties of pectin-CA and chitosan-CA composite films were analyzed. The results of this research offer a theoretical basis for engineering improved films for food packing. RESULTS: Pectin-CA (30%) and chitosan-CA (40%) composite films showed the best light transmission, water retention, breathability, plasticity, and antioxidant activity. Scanning electron microscopy revealed that these composite films exhibited a uniform and homogeneous structure without obvious pores. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) indicated that the amino acids and EGCG in CA were bonded to the film substrate (pectin/chitosan) via electrostatic interactions, hydrogen bonding, and covalent bonding, which led to an improvement in the film's properties. CONCLUSION: The CA has broad application prospects in food packaging as a cross-linking agent and antioxidant. © 2022 Society of Chemical Industry.


Subject(s)
Chitosan , Chitosan/chemistry , Antioxidants/chemistry , Pectins/chemistry , X-Ray Diffraction , Food Packaging/methods , Spectroscopy, Fourier Transform Infrared
19.
Angew Chem Int Ed Engl ; 62(3): e202212444, 2023 01 16.
Article in English | MEDLINE | ID: mdl-36377924

ABSTRACT

Ring-opening transformations of donor-acceptor (D-A) cyclopropanes enable the rapid assembly of complex molecules. However, the enantioselective formation of chiral quaternary stereocenters using substrates bearing two different acceptors remains a challenge. Herein, we describe the first palladium-catalyzed highly diastereo- and enantioselective (3+2) cycloaddition of vinyl cyclopropanes bearing two different electron-withdrawing groups, a subset of D-A cyclopropanes. The key to the success of this reaction is the remote stereoinduction through hydrogen bond from chiral ligands, which thereby addressed the aforementioned challenge. A variety of chiral five-membered heterocycles were produced in good yields and with high stereoselectivity (up to 99 % yields, 99 : 1 er and >19 : 1 dr). In-depth mechanistic investigations, including control experiments and theoretical calculations, revealed the origin of the stereoselectivity and the importance of H-bonding in stereocontrol.


Subject(s)
Cyclopropanes , Palladium , Palladium/chemistry , Cycloaddition Reaction , Catalysis , Stereoisomerism , Cyclopropanes/chemistry
20.
BMJ Open ; 12(11): e064328, 2022 11 07.
Article in English | MEDLINE | ID: mdl-36344002

ABSTRACT

INTRODUCTION: Premenopausal and postmenopausal osteoporosis and associated fragility fractures are major public health problems. Exercise, especially moderate-to-high-intensity impact exercise, has been recommended as an effective, low-cost non-pharmacological strategy for bone strength improvement; however, evidence on fracture risk is limited. In addition, maintaining regular training is currently a problem. Therefore, this study aims to conduct a randomised controlled trial of moderate-to-high-intensity tele-exercise intervention using a tele-rehabilitation app and quantify its effects on vertical fracture and fall prevention in women at high risk of osteoporotic fractures. METHODS AND ANALYSIS: In this multicentre, randomised controlled trial, 794 women at high risk of osteoporotic fractures will be recruited and randomised into either the tele-exercise rehabilitation or control group. Participants in the control group will receive routine remote rehabilitation, while those in the intervention group will be provided with a 6-month tele-exercise rehabilitation. The primary outcomes are the percentage of participants with one or more new vertebral fractures and incidence of falls. Intention-to-treat, full analysis set and per-protocol approaches will be used for outcome analyses. ETHICS AND DISSEMINATION: The study was approved by the biomedical research ethics committee of the West China Hospital of Sichuan University (2021-579). Written informed consent will be obtained from each participant after agreeing to participate in the study. The study findings will be presented at national and international scientific conferences and published in peer-reviewed journals. Results are propagated regardless of the magnitude or direction of the impact. Authorship is assigned according to authorship guidelines as defined by the International Board of Medical Journal Editors, and each author's role is based on journal requirements for publication. TRIAL REGISTRATION NUMBER: The study was registered with the Chinese Clinical Trial Registry (ChiCTR2200058780) prior to recruitment (May 2022).


Subject(s)
Osteoporotic Fractures , Telerehabilitation , Humans , Female , Osteoporotic Fractures/prevention & control , Exercise Therapy/methods , Exercise , Accidental Falls/prevention & control , Quality of Life , Randomized Controlled Trials as Topic , Multicenter Studies as Topic
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