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1.
J Org Chem ; 2024 May 30.
Article in English | MEDLINE | ID: mdl-38814709

ABSTRACT

A gold-catalyzed oxidative rearrangement of propargyl alcohols, derived from commercially available cyclohex-2-en-1-ones and alkynes, was successfully developed for the efficient synthesis of seven-membered rings. Thorough investigations were conducted to optimize the reaction conditions and evaluate its compatibility with various functional groups. Additionally, this methodology was applied to the formal total synthesis of guanacastepene A, demonstrating its practical utility in complex natural product synthesis. This versatile and efficient approach opens up new possibilities for the construction of diverse seven-membered ring systems, providing valuable building blocks for further exploration in drug discovery and the synthesis of intricate molecules.

2.
Immunol Invest ; : 1-15, 2024 May 30.
Article in English | MEDLINE | ID: mdl-38814140

ABSTRACT

AIM: This study aimed to evaluate the miR-223-5p expression in patients with spinal cord injury (SCI) and to determine its role in the pathogenesis of SCI. METHODS: The serum miR-223-5p levels were analyzed using quantitative real-time polymerase chain reaction. The diagnostic accuracy of miR-223-5p was evaluated using the receiving operating characteristic curves. LPS-induced PC12 cells were established as an in vitro inflammatory cell model. Cell apoptosis, inflammation and oxidative stress were examined. The SCI rat model was constructed to evaluate the effects of miR-223-5p on inflammatory response and motor function in rats. RESULTS: MiR-223-5p expression was upregulated in SCI patients. MiR-223-5p expression in the complete SCI group was significantly higher than that in incomplete SCI group. ROC analysis showed that miR-223-5p can distinguish SCI patients from healthy volunteers. In vitro experiments demonstrated that LPS upregulated apoptosis and inflammation in PC12 cells. Treatment with miR-223-5p inhibitor alleviated the changes in LPS-induced PC12 cells . Inhibition of miR-223-5p can alleviate the activation of inflammatory response and the effects of SCI on the motor function in rats. CONCLUSIONS: MiR-223-5p is a potential diagnostic marker for SCI, and it can promote the SCI progression by regulating nerve cell survival, inflammation, and oxidative stress.

3.
Comput Struct Biotechnol J ; 23: 1594-1607, 2024 Dec.
Article in English | MEDLINE | ID: mdl-38680872

ABSTRACT

The high-osmolarity-sensitive protein Sho1 functions as a key membrane receptor in phytopathogenic fungi, which can sense and respond to external stimuli or stresses, and synergistically regulate diverse fungal biological processes through cellular signaling pathways. In this study, we investigated the biological functions of AaSho1 in Alternaria alternata, the causal agent of pear black spot. Targeted gene deletion revealed that AaSho1 is essential for infection structure differentiation, response to external stresses and synthesis of secondary metabolites. Compared to the wild-type (WT), the ∆AaSho1 mutant strain showed no significant difference in colony growth, morphology, conidial production and biomass accumulation. However, the mutant strain exhibited significantly reduced levels of melanin production, cellulase (CL) and ploygalacturonase (PG) activities, virulence, resistance to various exogenous stresses. Moreover, the appressorium and infection hyphae formation rates of the ∆AaSho1 mutant strain were significantly inhibited. RNA-Seq results showed that there were four branches including pheromone, cell wall stress, high osmolarity and starvation in the Mitogen-activated Protein Kinase (MAPK) cascade pathway. Furthermore, yeast two-hybrid experiments showed that AaSho1 activates the MAPK pathway via AaSte11-AaPbs2-AaHog1. These results suggest that AaSho1 of A. alternata is essential for fungal development, pathogenesis and osmotic stress response by activating the MAPK cascade pathway via Sho1-Ste11-Pbs2-Hog1.

4.
Cell Rep ; 43(4): 114094, 2024 Apr 23.
Article in English | MEDLINE | ID: mdl-38613784

ABSTRACT

The importance of trained immunity in antitumor immunity has been increasingly recognized, but the underlying metabolic regulation mechanisms remain incompletely understood. In this study, we find that squalene epoxidase (SQLE), a key enzyme in cholesterol synthesis, is required for ß-glucan-induced trained immunity in macrophages and ensuing antitumor activity. Unexpectedly, the shunt pathway, but not the classical cholesterol synthesis pathway, catalyzed by SQLE, is required for trained immunity induction. Specifically, 24(S),25-epoxycholesterol (24(S),25-EC), the shunt pathway metabolite, activates liver X receptor and increases chromatin accessibility to evoke innate immune memory. Meanwhile, SQLE-induced reactive oxygen species accumulation stabilizes hypoxia-inducible factor 1α protein for metabolic switching into glycolysis. Hence, our findings identify 24(S),25-EC as a key metabolite for trained immunity and provide important insights into how SQLE regulates trained-immunity-mediated antitumor activity.


Subject(s)
Mice, Inbred C57BL , Squalene Monooxygenase , Animals , Squalene Monooxygenase/metabolism , Mice , Cholesterol/metabolism , Cholesterol/biosynthesis , Cholesterol/analogs & derivatives , Liver X Receptors/metabolism , Macrophages/metabolism , Macrophages/immunology , Macrophages/drug effects , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Reactive Oxygen Species/metabolism , Immunity, Innate/drug effects , Humans , Cell Line, Tumor
5.
Zygote ; 32(2): 170-174, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38619002

ABSTRACT

Oocytes with excessively large first polar bodies (PB1) often occur in assisted reproductive procedures. Many times these oocytes are discarded without insemination and, as a result, the application of this portion of oocytes has scarcely been reported to date. Few studies have examined large PB1 oocytes in infertile women and have virtually entirely studied genetic variations for large PB1 oocyte abnormalities. Here, we describe an unusual case of a live birth from a remarkably large PB1 oocyte in a frozen embryo transfer (FET) cycle. This is the first instance of a successful live birth resulting from a PB1 oocyte with an extremely large polar body measuring 80 µM × 40 µM in size. The large PB1 oocyte was performed by an early rescue intracytoplasmic sperm injection (r-ICSI) and was formed into a blastocyst on day 5. Following FET, a healthy boy baby weighing 3100 g was finally delivered by caesarean section at 37 weeks and 5 days after conception. Additionally, there were no complications throughout the antenatal period or the perinatal phase of this following full-term delivery. In this study, it is revealed for the first time that a huge PB1 oocyte can be fertilized, resulting in the growth of a blastocyst, a subsequent pregnancy, and a live birth. This new information prompts us to reconsider the use of large PB1 oocytes. More insightful talks should be given attention to prevent the waste of embryos because not all oocytes with aberrant morphology are unavailable.


Subject(s)
Embryo Transfer , Live Birth , Oocytes , Polar Bodies , Sperm Injections, Intracytoplasmic , Humans , Female , Pregnancy , Sperm Injections, Intracytoplasmic/methods , Adult , Oocytes/physiology , Oocytes/cytology , Male , Embryo Transfer/methods , Infant, Newborn , Blastocyst/cytology , Blastocyst/physiology , Cryopreservation
6.
IEEE Trans Image Process ; 33: 2058-2073, 2024.
Article in English | MEDLINE | ID: mdl-38470576

ABSTRACT

Existing Cross-Domain Few-Shot Learning (CDFSL) methods require access to source domain data to train a model in the pre-training phase. However, due to increasing concerns about data privacy and the desire to reduce data transmission and training costs, it is necessary to develop a CDFSL solution without accessing source data. For this reason, this paper explores a Source-Free CDFSL (SF-CDFSL) problem, in which CDFSL is addressed through the use of existing pretrained models instead of training a model with source data, avoiding accessing source data. However, due to the lack of source data, we face two key challenges: effectively tackling CDFSL with limited labeled target samples, and the impossibility of addressing domain disparities by aligning source and target domain distributions. This paper proposes an Enhanced Information Maximization with Distance-Aware Contrastive Learning (IM-DCL) method to address these challenges. Firstly, we introduce the transductive mechanism for learning the query set. Secondly, information maximization (IM) is explored to map target samples into both individual certainty and global diversity predictions, helping the source model better fit the target data distribution. However, IM fails to learn the decision boundary of the target task. This motivates us to introduce a novel approach called Distance-Aware Contrastive Learning (DCL), in which we consider the entire feature set as both positive and negative sets, akin to Schrödinger's concept of a dual state. Instead of a rigid separation between positive and negative sets, we employ a weighted distance calculation among features to establish a soft classification of the positive and negative sets for the entire feature set. We explore three types of negative weights to enhance the performance of CDFSL. Furthermore, we address issues related to IM by incorporating contrastive constraints between object features and their corresponding positive and negative sets. Evaluations of the 4 datasets in the BSCD-FSL benchmark indicate that the proposed IM-DCL, without accessing the source domain, demonstrates superiority over existing methods, especially in the distant domain task. Additionally, the ablation study and performance analysis confirmed the ability of IM-DCL to handle SF-CDFSL. The code will be made public at https://github.com/xuhuali-mxj/IM-DCL.

7.
J Am Chem Soc ; 146(12): 8508-8519, 2024 Mar 27.
Article in English | MEDLINE | ID: mdl-38382542

ABSTRACT

Tricomponent cobalt(salen)-catalyzed carbofunctionalization of unsaturated substrates by radical-polar crossover has the potential to streamline access to broad classes of heteroatom-functionalized synthetic targets, yet the reaction platform has remained elusive, despite the well-developed analogous hydrofunctionalizations mediated by high-valent alkylcobalt intermediates. We report herein the development of a cobalt(salen) catalytic system that enables carbofunctionalization. The reaction entails a tricomponent decarboxylative 1,4-carboamination of dienes and provides a direct route to aromatic allylic amines by obviating preformed allylation reagents and protection of oxidation-sensitive aromatic amines. The catalytic system merges acridine photocatalysis with cobalt(salen)-catalyzed regioselective 1,4-carbofunctionalization that facilitates the crossover of the radical and polar phases of the tricomponent coupling process, revealing critical roles of the reactants, as well as ligand effects and the nature of the formal high-valent alkylcobalt species on the chemo- and regioselectivity.

8.
J Robot Surg ; 18(1): 88, 2024 Feb 22.
Article in English | MEDLINE | ID: mdl-38386236

ABSTRACT

Transoral vestibular robotic thyroidectomy can really make the patient's body surface free of scar. This study aimed to compare the surgical and patient-related outcomes between the transoral vestibular robotic thyroidectomy and traditional low-collar incision thyroidectomy. The clinical data of 120 patients underwent transoral vestibular robotic thyroidectomy (TOVRT) or traditional low-collar incision thyroidectomy (TLCIT) were collected from May 2020 to October 2021. Propensity score matching analysis was used to minimize selection bias. All these patients were diagnosed with papillary thyroid carcinoma (PTC) through ultrasound-guided fine-needle aspiration prior to surgical intervention and surgical plan was tailored for each patient. An intraoperative recurrent laryngeal nerve (RLN) detection system was used in all patients, whose RLNs were identified and protected. We performed transoral vestibular robotic thyroidectomy with three intraoral incisions. Additional right axillary fold incisions were adopted occasionally to enhance fine reverse traction of tissue for radical tumor dissection. Clinical data including gender, age, tumor size, BMI, operation time, postoperative drainage volume and time, pain score, postoperative length of stay (LOS),number of lymph nodes removed, complications, and medical expense were observed and analyzed. Propensity score matching was used for 1:1 matching between the TOVRT group and the TLCIT group. All these patients accepted total thyroidectomy(or lobectomy) plus central lymph node dissection and all suffered from PTC confirmed by postoperative pathology. No conversion to open surgery happened in TOVRT group. The operative time of TOVRT group was longer than that of TLCIT group (P < 0.05). The postoperative drainage volume of TOVRT group was more than that of TLCIT group (P < 0.05). The drainage tube placement time of TOVRT group were longer than that of TLCIT group (P < 0.05). Significant differences were also found in intraoperative bleeding volume, pain score and medical expense between the two groups (P < 0.05). The incidence of perioperative common complications such as hypoparathyroidism and vocal cord paralysis in the two groups was almost identical (P > 0.05). However, there were some specific complications such as surgical area infection (one case), skin burn (one case), oral tear (two cases), and paresthesia of the lower lip and the chin (two cases) were found in TOVRT group. Obviously, the postoperative cosmetic effect of the TOVRT group was better than TLCIT group (P < 0.05). TOVRT is safe and feasible for low to moderate-risk PTC patients and is a potential alternative for patients who require no scar on their neck. Patients accepted TOVRT can get more satisfaction and have less psychologic injury caused by surgery.


Subject(s)
Neoplasms , Robotic Surgical Procedures , Humans , Thyroidectomy/adverse effects , Robotic Surgical Procedures/methods , Drainage , Cicatrix , Pain
9.
J Org Chem ; 89(5): 3331-3344, 2024 Mar 01.
Article in English | MEDLINE | ID: mdl-38363745

ABSTRACT

A gold(I)-catalyzed hydroamination/cycloisomerization cascade reaction was developed to yield indolizino[8,7-b]indole and indolo[2,3-a]-quinolizine derivatives from 2-ethynyltryptamides. The optimal conditions were determined by condition screening, and the functional group tolerances of these reactions were explored based on synthetic substrates. An insight into the explanation on the selectivity of the ring closure was obtained by density functional theory calculations. A plausible mechanism for the cascade reactions was proposed. Derivatization of the indolizino[8,7-b]indole and total synthesis of nauclefidine demonstrated the practicality of this strategy.

10.
Phytomedicine ; 126: 155426, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38367425

ABSTRACT

BACKGROUND: Hexokinase I (HK1) is highly expressed in a variety of malignancies, regulates glycolytic pathway in cancer cells, and thus considered to be one of the promising molecular targets for cancer therapy. Nonetheless, the development of a specific inhibitor against HK1 remains elusive. PURPOSE: This study aims to elucidate the mechanism by which oridonin inhibits the proliferation and immune evasion of bladder cancer cells, specifically through the suppression of HK1. METHODS: To examine the mechanisms by which oridonin directly binds to cysteines of HK1 and inhibits bladder cancer growth, this study utilized a variety of methods. These included the Human Proteome Microarray, Streptavidin-agarose affinity assay, Biolayer Interferometry (BLI) ainding analysis, Mass Spectrometry, Cellular Thermal Shift Assay, Extracellular Acidification Rate measurement, and Xenotransplant mouse models. RESULTS: As indicated by our current findings, oridonin forms a covalent bond with Cys-813, located adjacently to glucose-binding domain of HK1. This suppresses the enzymatic activity of HK1, leading to an effective reduction of glycolysis, which triggers cell death via apoptosis in cells derived from human bladder cancer. Significantly, oridonin also inhibits lactate-induced PD-L1 expression in bladder cancer. Furthermore, pairing oridonin with a PD-L1 inhibitor amplifies the cytotoxicity of CD8+ T cells against bladder cancer. CONCLUSION: This research strongly suggests that oridonin serves as a covalent inhibitor of HK1. Moreover, it indicates that functional cysteine residue of HK1 could operate as viable targets for selective inhibition. Consequently, oridonin exhibits substantial potential for the evolution of anti-cancer agents targeting the potential therapeutic target HK1 via metabolism immunomodulation.


Subject(s)
Antineoplastic Agents , Diterpenes, Kaurane , Urinary Bladder Neoplasms , Animals , Mice , Humans , Cell Line, Tumor , Urinary Bladder Neoplasms/drug therapy , Diterpenes, Kaurane/pharmacology , Diterpenes, Kaurane/chemistry , Antineoplastic Agents/pharmacology , Cell Proliferation , Apoptosis
11.
Cell Oncol (Dordr) ; 2024 Feb 05.
Article in English | MEDLINE | ID: mdl-38315285

ABSTRACT

PURPOSE: PIK3CA mutation or overexpression is associated with immunotherapy resistance in multiple cancer types, but is also paradoxically associated with benefit of COX-2 inhibition on patient survival of colorectal cancer (CRC) with mismatch repair deficiency (dMMR). This study examined whether and how PIK3CA status affected COX-2-mediated tumor inflammation and immunotherapy response of dMMR CRC. METHODS: Murine colon cancer cells MC38, CT26, and CT26-Mlh1-KO were used to construct PIK3CA knockdown and overexpression models to mimic dMMR CRC with PIK3CA dysregulation, and xenograft models were used to evaluate how PIK3CA regulate COX-2 expression, CD8+ T cells infiltration, tumor growth, and therapy response to anti-PD-L1 treatment using immunocompetent mice. Western blot was carried out to delineate the signaling pathways in human and mouse cancer cells, and immunohistochemical analysis together with bioinformatics analysis using human patient samples. RESULTS: PIK3CA upregulates COX-2 expression through MEK/ERK signaling pathway independent of AKT signaling to promote tumor inflammation and immunosuppression. PIK3CA knockdown profoundly reduced CT26 tumor growth in a CD8+ T cell-dependent manner, while PIK3CA overexpression significantly inhibited CD8+ T cells infiltration and promoted tumor growth. Furthermore, MEK or COX-2 inhibition augmented the anti-tumor activity of anti-PD-L1 immunotherapy on dMMR CRC mouse models, accompanied with increased CD8+ T cells infiltration and activated tumor microenvironment. CONCLUSION: Our results identified that the PIK3CA hyperactivation in dMMR CRC upregulated COX-2 through MEK signaling, which inhibited CD8+ T cells infiltration and promoted tumor growth, together led to immunotherapy resistance. COX-2 or MEK inhibition may relieve therapy resistance and promote therapy efficacy of anti-PD-1/PD-L1 immunotherapy for treating dMMR CRC with PIK3CA overexpression or activating mutation.

12.
Nat Commun ; 15(1): 1754, 2024 Feb 26.
Article in English | MEDLINE | ID: mdl-38409200

ABSTRACT

The response to programmed death-1 (PD-1) blockade varies in hepatocellular carcinoma (HCC). We utilize a panel of 16 serum factors to show that a circulating level of serum amyloid A (SAA) > 20.0 mg/L has the highest accuracy in predicting anti-PD-1 resistance in HCC. Further experiments show a correlation between peritumoral SAA expression and circulating SAA levels in patients with progressive disease after PD-1 inhibition. In vitro experiments demonstrate that SAA induces neutrophils to express PD-L1 through glycolytic activation via an LDHA/STAT3 pathway and to release oncostatin M, thereby attenuating cytotoxic T cell function. In vivo, genetic or pharmacological inhibition of STAT3 or SAA eliminates neutrophil-mediated immunosuppression and enhances antitumor efficacy of anti-PD-1 treatment. This study indicates that SAA may be a critical inflammatory cytokine implicated in anti-PD-1 resistance in HCC. Targeting SAA-induced PD-L1+ neutrophils through STAT3 or SAA inhibition may present a potential approach for overcoming anti-PD1 resistance.


Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , Humans , Carcinoma, Hepatocellular/genetics , Liver Neoplasms/genetics , B7-H1 Antigen/metabolism , Neutrophils/metabolism , Serum Amyloid A Protein/metabolism , Programmed Cell Death 1 Receptor , Glycolysis
13.
J Org Chem ; 88(16): 11377-11391, 2023 Aug 18.
Article in English | MEDLINE | ID: mdl-37540141

ABSTRACT

Over the past two decades, synthetic strategies for synthesizing the skeletons of various indole alkaloids based on tryptamine-ynamide have been continuously developed and applied to the total syntheses or formal total syntheses of related molecules. In this synopsis, we summarized the cyclization pathways of tryptamine-ynamide under different catalytic conditions, emphasizing the reaction mechanism and applications in the syntheses of indole alkaloids.

14.
J Org Chem ; 88(15): 10586-10598, 2023 Aug 04.
Article in English | MEDLINE | ID: mdl-37449800

ABSTRACT

Spiro[indoline-3,3'-pyrrolidine] and spiro[indoline-3,3'-piperidine] derivatives were synthesized in a substitution-controlled manner under the catalysis of cationic gold(I) species in the presence of Hantzsch ester (HEH). The optimal reaction condition was determined by screening, and the functional group tolerances of these two pathways were examined by readily synthetic substrates. The endo and exo selectivities of these cyclizations were elucidated by density functional theory calculations, and a plausible mechanism for these transformations was proposed.

15.
J Org Chem ; 88(11): 7179-7187, 2023 Jun 02.
Article in English | MEDLINE | ID: mdl-37172220

ABSTRACT

Six 8-oxoprotoberberines were synthesized collectively in four steps with acceptable yields (14-19%), of which the products 8-oxopalmatine, 8-oxopseudopalmatine, 8-oxoberberine, and 8-oxopseudoberberine come from nature. The synthetic route was featured with the In(OTf)3-catalyzed cyclization and Heck coupling. Moreover, the syntheses of the natural products berberine, canadine, and iambertine were achieved via various reductions from 8-oxoberberine, which provided a concise approach to the syntheses of this kind of alkaloids.

16.
Adv Sci (Weinh) ; 10(20): e2300418, 2023 07.
Article in English | MEDLINE | ID: mdl-37162249

ABSTRACT

Cancer vaccines have shown promise as effective means of antitumor immunotherapy by inducing tumor antigen-specific T cell immunity. In this study, a novel peptide-based tumor nanovaccine that boosts antigen presentation and elicits effective antitumor immunity is developed. The adjuvant characteristics of an antimicrobial peptide-derived core peptide, FK-13, are investigated and used it to generate a fusion peptide named FK-33 with tumor antigen epitopes. l-phenylalanine-based poly(ester amide) (Phe-PEA), 8p4, is also identified as a competent delivery vehicle for the fusion peptide FK-33. Notably, the vaccination of 8p4 + FK-33 nanoparticles (8FNs) in vivo induces dendritic cell activation in the lymph nodes and elicits robust tumor antigen-specific CD8+ T cell response. The nanovaccine 8FNs demonstrate significant therapeutic and prophylactic efficacy against in situ tumor growth, effectively inhibit tumor metastasis, and significantly prolong the survival of tumor-bearing mice. Moreover, 8FNs can incorporate different tumor antigens and exhibit a synergistic therapeutic effect with antiprogrammed cell death protein 1 (PD-1) therapy. In summary, 8FNs represent a promising platform for personalized cancer vaccines and may serve as a potential combinational modality to improve current immunotherapy.


Subject(s)
Cancer Vaccines , Neoplasms , Animals , Mice , Amides , Mice, Inbred C57BL , Neoplasms/therapy , Peptides , Adjuvants, Immunologic , CD8-Positive T-Lymphocytes , Antigens, Neoplasm
17.
J Org Chem ; 88(9): 5483-5496, 2023 May 05.
Article in English | MEDLINE | ID: mdl-37043684

ABSTRACT

Density functional theory calculations were applied to predict the pathways of gold(I)-catalyzed cycloisomerization of the indole substrates with 1,6-enynes, which were consistent with the ensuing experimental results. The substitution-controlled synthesis led to the formation of 1H-pyrido[4,3-b]indole and spiro[indoline-3,3'-pyridine] derivatives in a tunable way. The reactions had good functional group tolerances, and a possible mechanism was proposed based on the computational and experimental results.

18.
Opt Express ; 31(5): 8820-8843, 2023 Feb 27.
Article in English | MEDLINE | ID: mdl-36859989

ABSTRACT

In allusion to the privacy and security problems in 3D point cloud classification, a novel privacy protection method for 3D point cloud classification based on optical chaotic encryption scheme is proposed and implemented in this paper for the first time. The mutually coupled spin-polarized vertical-cavity surface-emitting lasers (MC-SPVCSELs) subject to double optical feedback (DOF) are studied to generate optical chaos for permutation and diffusion encryption process of 3D point cloud. The nonlinear dynamics and complexity results demonstrate that the MC-SPVCSELs with DOF have high chaotic complexity and can provide tremendously large key space. All the test-sets of ModelNet40 dataset containing 40 object categories are encrypted and decrypted by the proposed scheme, and then the classification results of 40 object categories for original, encrypted, and decrypted 3D point cloud are entirely enumerated through the PointNet++. Intriguingly, the class accuracies of the encrypted point cloud are nearly all equal to 0.0000% except for the plant class with 100.0000%, indicating the encrypted point cloud cannot be classified and identified. The decryption class accuracies are very close to the original class accuracies. Therefore, the classification results verify that the proposed privacy protection scheme is practically feasible and remarkably effective. Additionally, the encryption and decryption results show that the encrypted point cloud images are ambiguous and unrecognizable, while the decrypted point cloud images are identical to original images. Moreover, this paper improves the security analysis via analyzing 3D point cloud geometric features. Eventually, various security analysis results validate that the proposed privacy protection scheme has high security level and good privacy protection effect for 3D point cloud classification.

19.
Org Biomol Chem ; 21(12): 2610-2619, 2023 Mar 22.
Article in English | MEDLINE | ID: mdl-36896738

ABSTRACT

The regioselectivity for gold(I)-catalyzed intramolecular cycloisomerizations of tryptamine-ynamides has long been elusive despite various synthetic examples of similar substrates being available. Computational studies were carried out to provide insight into the mechanisms and the origin of the substrate-dependent regioselectivity of these transformations. Based on the analyses of non-covalent interactions, distortion/interaction, and energy decomposition on the interactions between the terminal substituent of alkynes and the gold(I) catalytic ligand, the electrostatic effect was determined to be the key factor for α-position selectivity while the dispersion effect was determined to be the key factor for ß-position selectivity. Our computational results were consistent with the experimental observations. This study provides useful guidance for understanding other similar gold(I)-catalyzed asymmetric alkyne cyclization reactions.

20.
Int J Biol Macromol ; 236: 124036, 2023 May 01.
Article in English | MEDLINE | ID: mdl-36921818

ABSTRACT

Starch degradation occurs rapidly in stressed plants, but it is unclear how starch degradation occurs in potato tubers after they incur mechanical wounding. In this study, we found that wounding significantly upregulated the expression levels of StGWD, StAMY, StBAM, and StISA, and decreased the starch content of potato tubers. Meanwhile, wounding markedly upregulated the expression levels of StSUS, StBG, and StINV genes, and increased the content of sucrose, glucose, and fructose. Furthermore, wounding reduced the proportion of small starch granules and increase that of large as well as medium starch granules, in this way enhancing the average size distribution of starch. Initially, the hard surface layer of starch granules was removed by wounding, but the internal channels and other structures were only slightly affected. Taken together, the results show that wounding can accelerate starch degradation by promoting the accumulation of sucrose, glucose, and fructose, and the hydrolysis of starch granules in potato tubers.


Subject(s)
Solanum tuberosum , Solanum tuberosum/genetics , Solanum tuberosum/metabolism , Plants, Genetically Modified/metabolism , Starch/metabolism , Glucose/metabolism , Sucrose/metabolism , Fructose/metabolism , Plant Tubers/metabolism
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