Site-selective and versatile aromatic C-H functionalization by thianthrenation.

Direct C-H functionalization can quickly increase useful structural and functional molecular complexity1-3. Site selectivity can sometimes be achieved through appropriate directing groups or substitution patterns1-4-in the absence of such functionality, most aromatic C-H functionalization reactions provide more than one product isomer for most substrates1,4,5. Development of a C-H functionalization reaction that proceeds with high positional selectivity and installs a functional group that can serve as a synthetic linchpin for further functionalization would provide access to a large variety of well-defined arene derivatives. Here we report a highly selective aromatic C-H functionalization reaction that does not require a particular directing group or substitution pattern to achieve selectivity, and provides functionalized arenes that can participate in various transformations. We introduce a persistent sulfur-based radical to functionalize complex arenes with high selectivity and obtain thianthrenium salts that are ready to engage in different transformations, via both transition-metal and photoredox catalysis. This transformation differs fundamentally from all previous aromatic C-H functionalization reactions in that it provides direct access to a large number of derivatives of complex small molecules, quickly generating functional diversity with selectivity that is not achievable by other methods.

A method comparison of three immunoassays for detection of neutralizing antibodies against SARS-CoV-2 receptor-binding domain in individuals with adenovirus type-5-vectored COVID-19 vaccination.

OBJECTIVE: Detecting neutralizing antibodies targeting receptor-binding domain (RBD) is important for the assessment of humoral protection and vaccine efficacy after vaccination. We compared the performance of three surrogate immunoassays for detection of neutralizing antibodies targeting RBD. METHODS: We analyzed 115 serum samples obtained from individuals with Ad5-vectored COVID-19 vaccination using two competitive enzyme-linked immunosorbent assays (Wantai BioPharm and Synthgene Medical Technology) and one competitive chemiluminescence assay (YHLO Biotech). Performance evaluation and methodology comparison were performed according to the Clinical and Laboratory Standards Institute related guidelines. RESULTS: The precision met the manufacturers' statements. The linear range of the WANTAI was 0.0625-0.545 U/ml and the YHLO was 0.260-242.4 U/ml. The WANTAI's limit of blank (LoB) and limit of detection (LoD) were 0.03 and 0.06 U/ml, respectively. The YHLO's LoB and LoD were 0.048 and 0.211 U/ml, respectively. The correlations of semi-quantitative results of Synthgene with quantitative results of YHLO (ρ = 0.566) and WANTAI (ρ = 0.512) were medium. For YHLO and WANTAI, there was a good agreement (0.62) and a strong correlation (ρ = 0.931). Passing-Bablok analysis and Bland-Altman plot showed a positive bias (112.3%) of the YHLO compared to the WANTAI. The exclusion of samples >50 U/ml did not decrease bias. CONCLUSION: These findings contribute to a deeper understanding of surrogate viral neutralization assays and provide useful data for future comparison studies.

A Catalytic Oxidative Quinone Heterofunctionalization Method: Synthesis of Strongylophorine-26.

The preparation of heteroatom-substituted p-quinones is ideally performed by direct addition of a nucleophile followed by in situ reoxidation. Albeit an appealing strategy, the reactivity of the p-quinone moiety is not easily tamed and no broadly applicable method for heteroatom functionalization exists. Shown herein is that Co(OAc)2 and Mn(OAc)3 ⋅2 H2 O act as powerful catalysts for oxidative p-quinone functionalization with a collection of O, N, and S nucleophiles, using oxygen as the terminal oxidant. Preliminary mechanistic observations and the first synthesis of the cytotoxic natural product strongylophorine-26 is presented.

A Concise Route to the Strongylophorines.

An efficient eight-step semisynthesis of strongylophorine-2 from the abundant building block isocupressic acid is reported. The route represents the first synthetic entry into this class of natural products and provides access to six additional family members. A novel iron(III)-mediated rearrangement-cyclization cascade and a directed photochemical sp(3) C-H δ-lactonization are the key transformations that enable concise assembly of these bioactive polycyclic meroterpenoids.

Total Synthesis and Biological Evaluation of Rakicidin†A and Discovery of a Simplified Bioactive Analogue.

We report a concise asymmetric synthesis of rakicidin A, a macrocyclic depsipeptide that selectively inhibits the growth of hypoxic cancer cells and stem-like leukemia cells. Key transformations include a diastereoselective organocatalytic cross-aldol reaction to build the polyketide portion of the molecule, a highly hindered ester fragment coupling reaction, an efficient Helquist-type Horner-Wadsworth-Emmons (HWE) macrocyclization, and a new DSC-mediated elimination reaction to construct the sensitive APD portion of rakicidin A. We further report the preparation of a simplified structural analogue (WY1) with dramatically enhanced hypoxia-selective activity.

[Isoflavones and flavans from Millettia nitida var. hirsutissima].

The current study to separate and identify constituents from Millettia nitida var. hirsutissima. The compounds from Millettia nitida var. hirsutissima were isolated by means of various chromatographic techniques such as column chromatography over ODS and Sephadex LH-20, preparative HPLC, and the structures of these isolated compounds were identified through spectroscopic analyses. Nine isoflavonoids and two flavans were isolated and identified as 5-O-methy genistein (1), 7-hydroxy-3',4'-dimethoxyisoflavone (2), ononin (3), catechin (4), formononetin (5), genistein (6), calycosin (7), (-)-gallocatechin (8), sissotrin (9), wistin (10), daidzin (11). Compounds 1, 2, 9 are obtained from the genus Millettia for the first time,and compounds 4, 8 are isolated from this plant for the first time.

School climate and academic burnout in medical students: a moderated mediation model of collective self-esteem and psychological capital.

BACKGROUND: The study burnout of medical students is more and more serious, which directly affects the study style of university and the learning quality of students. This has aroused the high attention of researchers and universities. This study aimed to explore the mechanism of the influence of school climate on academic burnout among medical students in Chinese cultural context. METHODS: 2411 medical students (50.52% female; mean age = 19.55, SD = 1.41, rang = 17-24 years) were investigated with psychological environment questionnaire, collective self-esteem scale, psychological capital scale and academic burnout scale. The data were analyzed by using a moderated mediation model with SPSS and the Process 4.0 macro. RESULTS: The results revealed that: (1) school climate had a significant negative predictive effect on academic burnout among medical students controlling for gender, grade and age (B = -0.40, p < 0.001). (2) Collective self-esteem played a partial mediating role in school climate and academic burnout (indirect effect = -0.28, 95% CI = [-0.32,-0.25], accounting for 52.83%). (3) The first and second half of the indirect effect of school climate on medical students' academic burnout were moderated by psychological capital (B = 0.03, p < 0.01; B = -0.09, p < 0.001).High level of psychological capital can enhance the link between school climate and collective self-esteem as well as the link between self-esteem and academic burnout. CONCLUSION: Creating a good school atmosphere and improving the level of collective self-esteem and psychological capital are beneficial to improve the academic burnout of medical students.

School Psychological Environment and Learning Burnout in Medical Students: Mediating Roles of School Identity and Collective Self-Esteem.

Learning burnout is an important indicator that reflects an individual's learning state. Understanding the influencing factors and mechanism of learning burnout of medical students has practical significance for improving their mental health. This study aimed to explore the mediating roles of school identity and collective self-esteem between school psychological environment and learning burnout in medical students. A total of 2,031 medical students (942 men and 1,089 women, age range: 17-23 years) were surveyed using the School Psychological Environment Questionnaire (SPEQ), School Identity Questionnaire (SIQ), Collective Self-esteem Scale (CSES), and Learning Burnout Scale (LBS). The results showed the following: (1) school psychological environment had a negative effect on learning burnout among medical students (ß = -0.19, p < 0.001), and (2) school identity and collective self-esteem played significant mediating roles between school psychological environment and learning burnout [95% CI = (-0.43, -0.31)]. Specifically, there were three paths that school psychological environment and learning burnout: first, through the independent mediating role of school identity; second, through the independent mediating role of collective self-esteem; and third, through the chain mediating roles of school identity and collective self-esteem. The findings reveal that school psychological environment not only directly influences the learning burnout of medical students but also indirectly influences it through school identity and collective self-esteem. Thus, this study has some important implications for prevention and intervention of learning burnout among medical students.

Rapid Detection of SARS-CoV-2 Using Duplex Reverse Transcription-Multienzyme Isothermal Rapid Amplification in a Point-of-Care Testing.

In December 2019, a severe acute respiratory syndrome caused by SARS-CoV-2 spread rapidly worldwide. Portable nucleic acid tests of SARS-CoV-2 are critically important for diagnostics. In this study, we used an isothermal amplification method-Multienzyme Isothermal Rapid Amplification (MIRA)-for rapid detection of SARS-CoV-2. We designed the primers and probes in ORF1ab and N gene of SARS-CoV-2. The amplicons could be monitored by lateral flow dipsticks (LFDs). The reaction temperature, time, concentrations of primers and probes, and working volume were optimized. Four commercial swab collection buffers were used to test the amplification efficacy of our assay without RNA extraction. Our assay was able to amplify duplex targets of SARS-CoV-2 in one single reaction using one-step RT-MIRA. The assay worked well in a low volume of 10 µl at 38°C for 20 min. Using three collection buffers without guanidinium, our assay was able to amplify efficaciously without RNA extraction. The 95% limit of detection (LoD) of the RT-MIRA assay was 49.5 (95% CI, 46.8-52.7) copies/ml for ORF1ab gene and 48.8 (95% CI, 46.5-52.6) copies/ml for N gene. There is no cross-reaction with other human respiratory pathogens, such as SARS-CoV, MERS-CoV, influenza A virus, influenza B virus, human adenovirus, respiratory syncytial virus, human parainfluenza virus, and coronavirus 229E in our assay. The precision evaluation revealed that the C50-20% to C50+20% range bounds the C5-C95 interval. This assay also showed high anti-interference ability. The extraction-free RT-MIRA and qPCR detection results of 243 nucleic acid specimens from suspected patients or national references showed a 100.0% (95% confidence interval, 94.2%-100.0%) positive predictive value and a 100.0% (95% confidence interval, 92.7%-100.0%) negative predictive value. Compared with qPCR, the kappa value of the two assays was 1.00 (P < 0.0001). In conclusion, we provide a portable and visualized method for detection of SARS-CoV-2 without RNA extraction, allowing its application in SARS-CoV-2 on-site detection.

Discovery of eudesmane-type sesquiterpenoids with neuroprotective effects from the roots of Chloranthus serratus.

Seven eudesmane-type sesquiterpenoids, including three pairs of racemic compounds (1a-3a and 1b-3b) and a sesquiterpenoid lactone (4), were obtained from the roots of Chloranthus serratus. The structures of these sesquiterpenoids were characterized based on spectroscopic analyses, ECD calculations, and X-ray diffraction experiment. Neuroprotection assays of the isolated eudesmane-type sesquiterpenoids were conducted on H2O2 damaged PC12 cells. At the concentration of 10 µM, compounds 1b and 4 increased cell viability from 54.8 ± 3.3% to 76.8 ± 2.3 and 72.7 ± 8.2%, respectively.

Sesquiterpenoids with neuroprotective activities from the Chloranthaceae plant Chloranthus henryi.

A rare sesquiterpenoid possessing a 6/6 bicyclic system fused with two clustered furan units and a pair of guaiane-type sesquiterpenoids were acquired from the roots of Chloranthus henryi. Their structures with absolute configurations were characterized with spectroscopic data, ECD, and X-ray diffraction analysis. All three sesquiterpenoids showed moderate neuroprotective activities on PC12 cells damaged with hydrogen peroxide.

miR-125a-5p increases cellular DNA damage of aging males and perturbs stage-specific embryo development via Rbm38-p53 signaling.

An increasing number of men are fathering children at an older age than in the past. While advanced maternal age has long been recognized as a risk factor for adverse reproductive outcomes, the influence of paternal age on reproduction is incompletely comprehended. Herein, we found that miR-125a-5p was upregulated in the sperm of aging males and was related to inferior sperm DNA integrity as an adverse predictor. Moreover, we demonstrated that miR-125a-5p suppressed mitochondrial function and increased cellular DNA damage in GC2 cells. We also found that miR-125a-5p perturbed embryo development at specific morula/blastocyst stages. Mechanistically, we confirmed that miR-125a-5p disturbed the mitochondrial function by targeting Rbm38 and activating the p53 damage response pathway, and induced a developmental delay in a p21-dependent manner. Our study revealed an important role of miR-125a-5p in sperm function and early embryo development of aging males, and provided a fresh view to comprehend the aging process in sperm.

Ethnomedicinal survey and in vitro anti-plasmodial activity of the palm Borassus aethiopum Mart.

ETHNOPHARMACOLOGICAL RELEVANCE: Malaria remains a major global health threat, with the heaviest burden of disease in sub-Saharan Africa. Effective treatment is not available in many affected areas, and the Plasmodium falciparum parasite is becoming resistant to existing drugs. Alternative therapies are necessary to overcome these challenges. Borassus aethiopum is the third most used palm species in traditional medicines in Africa. Yet, there is only limited information substantiating medicinal properties of the palm. The objective of this study was to document medicinal uses of B. aethiopum and investigate anti-plasmodial activity of the palm extracts used in traditional medicine to treat malaria. MATERIALS AND METHODS: The fieldwork and collection of samples was done in Ghana in the Greater Accra, Brong Ahafo, and Volta regions. Our ethnomedicinal survey did not specifically focus on medicinal uses against malaria; any medicinal application of B. aethiopum was of interest. Data collection employed a structured questionnaire, open-ended questions, and group discussion. The experimental extraction of samples was carried out using three common solvents: distilled water, absolute ethanol, and dichloromethane (CH2Cl2). Anti-plasmodial activity of compounds was determined against erythrocytic stages of the FCR3 strain of P. falciparum by a [3H]-hypoxanthine incorporation assay. RESULTS: A total of 37 use records were documented regarding the medicinal uses of B. aethiopum for the management of 24 different disorders. The highest medicinal use value was recorded for the use of B. aethiopum against malaria, and a subsequent laboratory investigation focused on evaluating anti-plasmodial activity of the palm. Several root and leaf extracts displayed anti-plasmodial activity, with the highest (78% at 50 µg/mL) elicited by one of the dichloromethane root extracts. CONCLUSION: Our results demonstrate the value of integrating ethnobotanical and pharmacological research in the study of beneficial effects of palm products on human health. While the high inhibitory activity found in dichloromethane extracts cannot validate the ethnomedicinal use, the anti-plasmodial effect observed cannot be nullified. We brought preliminary evidence that this palm is a promising source of alternative medicines that could contribute to improving health conditions in malaria endemic areas of sub-Saharan Africa.

Generation of insulin-producing cells from rat mesenchymal stem cells using an aminopyrrole derivative XW4.4.

Type 1 diabetes mellitus (T1DM), a multisystem disease with both biochemical and anatomical/structural consequences, is a major health concern worldwide. Pancreatic islet transplantation provides a promising treatment for T1DM. However, the limited availability of islet tissue or new sources of insulin producing cells (IPCs) that are responsive to glucose hinder this promising approach. Though slow, the development of pancreatic beta-cell lines from rodent or human origin has been steadily progressing. Bone marrow-derived mesenchymal stem cells (MSCs) are multipotent, culture-expanded, non-hematopoietic cells that are currently being investigated as a novel cellular therapy. The in vitro differentiation potential of IPCs has raised hopes for a treatment of clinical diseases associated with autoimmunity. We screened for small molecules that induce pancreatic differentiation of IPCs. There are some compounds which showed positive effects on the DTZ staining. The aminopyrrole derivative compound XW4.4 which shows the best activity among them was found to induce pancreatic differentiation of rat MSCs (rMSCs). The in vitro studies indicated that treatment of rMSCs with compound XW4.4 resulted in differentiated cells with characteristics of IPCs including islet-like clusters, spherical, grape-like morphology, insulin secretion, positive for dithizone, glucose stimulation and expression of pancreatic endocrine cell marker genes. The data has also suggested that hepatocyte nuclear factor 3ß (HNF 3ß) may be involved in pancreatic differentiation of rMSCs when treated with XW4.4. Results indicate that XW4.4 induced rMSCs support the efforts to derive functional IPCs and serve as a means to alleviate limitations surrounding islet cell transplantation in the treatment of T1DM.

Design, Synthesis, and Biological Evaluation of Novel Conformationally Constrained Inhibitors Targeting EGFR.

This letter describes the construction of conformationally constrained quinazoline analogues. Structure-activity relationship studies led to the identification of the lead compound 9n . Compound 9n exhibits effective in vitro activity against A431(WT,overexpression) and H1975([L858R/T790M]) cancer cell lines but is significantly less effective against EGFR negative cancer cell lines (SW620, A549, and K562). Compound 9n was also assessed for potency in enzymatic assays and in vivo antitumor studies. The results indicated that 9n is a potent kinase inhibitor against both wild-type and T790M mutant EGFR kinase. Meanwhile, an oral administration of 9n at a dose of 200 mg/kg produced a considerable antitumor effect in a A431 xenograft model, as compared to gefitinib. A preliminary pharmacokinetic study of 9n also indicates it has good pharmacokinetic properties, and therefore, it is a good starting point for further development.

A "one-pot" multicomponent approach to polysubstituted 4-aminopyridines.

A novel and facile domino reaction has been developed to synthesize a variety of polysubstituted 4-aminopyridines from α-azidovinylketones, aldehydes and methylamine derivatives in reasonably good yields under mild conditions. Additionally, a possible mechanism is proposed.