Carbon-Carbon Bond Cleavage for Late-Stage Functionalization.

Late-stage functionalization (LSF) introduces functional group or structural modification at the final stage of the synthesis of natural products, drugs, and complex compounds. It is anticipated that late-stage functionalization would improve drug discovery's effectiveness and efficiency and hasten the creation of various chemical libraries. Consequently, late-stage functionalization of natural products is a productive technique to produce natural product derivatives, which significantly impacts chemical biology and drug development. Carbon-carbon bonds make up the fundamental framework of organic molecules. Compared with the carbon-carbon bond construction, the carbon-carbon bond activation can directly enable molecular editing (deletion, insertion, or modification of atoms or groups of atoms) and provide a more efficient and accurate synthetic strategy. However, the efficient and selective activation of unstrained carbon-carbon bonds is still one of the most challenging projects in organic synthesis. This review encompasses the strategies employed in recent years for carbon-carbon bond cleavage by explicitly focusing on their applicability in late-stage functionalization. This review expands the current discourse on carbon-carbon bond cleavage in late-stage functionalization reactions by providing a comprehensive overview of the selective cleavage of various types of carbon-carbon bonds. This includes C-C(sp), C-C(sp2), and C-C(sp3) single bonds; carbon-carbon double bonds; and carbon-carbon triple bonds, with a focus on catalysis by transition metals or organocatalysts. Additionally, specific topics, such as ring-opening processes involving carbon-carbon bond cleavage in three-, four-, five-, and six-membered rings, are discussed, and exemplar applications of these techniques are showcased in the context of complex bioactive molecules or drug discovery. This review aims to shed light on recent advancements in the field and propose potential avenues for future research in the realm of late-stage carbon-carbon bond functionalization.

N-Alkoxyphthalimides as Nitrogen Electrophiles to Construct C-N Bonds via Reductive Cross-Coupling.

N-Alkoxyphthalimides, one kind of phthalimide derivative, have great importance in synthesis, mainly used as free radical precursors. While the phthalimide unit, for a long time, was treated as part of the waste stream. Construction of C-N bonds has always been a hot spot, especially in reductive cross-coupling. Herein, a nickel-catalyzed reductive cross-coupling reaction of N-methoxyphthalimides with alkyl halides is described, where N-methoxyphthalimides serve as nitrogen electrophiles. This tactic provides a new approach to construct C-N bonds under mild neutral conditions. Alkyl chlorides, bromides, iodides, and sulfonates are all fit to this transformation. Moreover, the reaction could tolerate a broad substrate scope, especially base-sensitive functional groups (boron or silicon groups), as well as competitive nucleophilic groups (phenols and amides), which are incompatible with traditional Gabriel synthesis under basic conditions, demonstrating a complementary role of this work to Gabriel synthesis.

A longitudinal study of sexual activity and influencing factors in breast cancer patients during treatment in the Southwest of China: a trajectory analysis model.

PURPOSE: The aim of this study was to describe the longitudinal developmental trajectories and its influencing factors of sexual activity in patients with breast cancer during treatment. METHODS: A prospective longitudinal study was conducted, including 225 newly diagnosed breast cancer patients in A tumor specialty three-class hospital in Southwest China. We measured sexual activity at the time of admission and diagnosis (T0) and one month (T1), three months (T2), six months (T3), and nine months (T4) after diagnosis. A trajectory analysis model (GBTM) was used to explore the changes in sexual activity in breast cancer patients. Multivariate binary logistic regression analysis was used to analyse the factors that affected the classification of sexual activity trajectories. RESULTS: The ratio of sexual activity abruptly declined from 100% at baseline to 39.1% at T1. The percentage of sexual activity was improved, from 51.4% at T2 to 63.1% at T4. The optimal model was a 2-group trajectory of sexual activity in breast cancer patients,36.6% in the "low activity group" and 63.4% in the "high activity group." The multivariate binary logistic regression analysis revealed statistically significant and positive correlations between sexual activity and age (ß = 0.085, OR = 1.089, 95%CI 1.035 ∼ 1.145, P = 0.001),libido(ß = 0.774, OR = 2.168, 95%CI 1.337 ∼ 3.515, P = 0.002), vaginal lubrication(ß = 1.254, OR = 33.503, 95%CI 2.000 ∼ 6.137, P<0.001). CONCLUSIONS: Breast cancer patients exhibited varying levels of sexual activity during treatment; higher age was associated with increased sexual activity, which can contribute to the recovery of sexual function. Therefore, it is crucial to provide appropriate guidance on sexual health for younger patients.

Iron metabolism and chronic inflammation in IgA nephropathy.

IgA nephropathy (IgAN), an immune-mediated chronic inflammatory kidney disease, is the most common primary glomerular disease in Asia, especially in China and Japan. The pathogenesis of IgAN is complex, and the main cause of IgAN is explained by the 'multiple hit' theory, which states that the deposition of immune complexes in renal mesangial cells induces chronic inflammation that leads to kidney damage. Chronic inflammation is associated with iron metabolism, which also plays an essential role in the pathogenesis, progression, diagnosis and prognosis of IgAN. Overall, this review aimed to explore the application of iron metabolism in IgAN by systematically elaborating the relationship between iron metabolism and chronic inflammation in IgAN to speculate on the possible diagnostic and therapeutic significance of iron metabolism indicators in IgAN.

Protein acetylation in mitochondria plays critical functions in the pathogenesis of fatty liver disease.

BACKGROUND: Fatty liver is a high incidence of perinatal disease in dairy cows caused by negative energy balance, which seriously threatens the postpartum health and milk production. It has been reported that lysine acetylation plays an important role in substance and energy metabolism. Predictably, most metabolic processes in the liver, as a vital metabolic organ, are subjected to acetylation. Comparative acetylome study were used to quantify the hepatic tissues from the severe fatty liver group and normal group. Combined with bioinformatics analysis, this study provides new insights for the role of acetylation modification in fatty liver disease of dairy cows. RESULTS: We identified 1841 differential acetylation sites on 665 proteins. Among of them, 1072 sites on 393 proteins were quantified. Functional enrichment analysis shows that higher acetylated proteins are significantly enriched in energy metabolic pathways, while lower acetylated proteins are significantly enriched in pathways related to immune response, such as drug metabolism and cancer. Among significantly acetylated proteins, many mitochondrial proteins were identified to be interacting with multiple proteins and involving in lipid metabolism. Furthermore, this study identified potential important proteins, such as HADHA, ACAT1, and EHHADH, which may be important regulatory factors through modification of acetylation in the development of fatty liver disease in dairy cows and possible therapeutic targets for NAFLD in human beings. CONCLUSION: This study provided a comprehensive acetylome profile of fatty liver of dairy cows, and revealed important biological pathways associated with protein acetylation occurred in mitochondria, which were involved in the regulation of the pathogenesis of fatty liver disease. Furthermore, potential important proteins, such as HADHA, ACAT1, EHHADH, were predicted to be essential regulators during the pathogenesis of fatty liver disease. The work would contribute to the understanding the pathogenesis of NAFLD, and inspire in the development of new therapeutic strategies for NAFLD.

Iron-Catalyzed Regiodivergent Alkyne Hydrosilylation.

Although tremendous effort has been devoted to the development of methods for iron catalysis, few of the catalysts reported to date exhibit clear superiority to other metal catalysts, and the mechanisms of most iron catalysis remain unclear. Herein, we report that iron complexes bearing 2,9-diaryl-1,10-phenanthroline ligands exhibit not only unprecedented catalytic activity but also unusual ligand-controlled divergent regioselectivity in hydrosilylation reactions of various alkynes. The hydrosilylation protocol described herein provides a highly efficient method for preparing useful di- and trisubstituted olefins on a relatively large scale under mild conditions, and its use markedly improved the synthetic efficiency of a number of bioactive compounds. Mechanistic studies based on control experiments and density functional theory calculations were performed to understand the catalytic pathway and the observed regioselectivity.

[Quality evaluation of Gastrodiae Rhizoma standard decoction based on UPLC fingerprint and quantitative analysis multi-components method].

To establish the quantitative analysis multi-components with a single-marker(QAMS) method for six components and fingerprint of standard decoction of Gastrodiae Rhizoma, verify the accuracy and feasibility of the method, and evaluate the quality of standard decoction. Based on UPLC with gastrodin as the internal standard, relative correction factors of p-hydroxybenzyl alcohol, parishin E, parishin B, parishin C, parishin A and gastrodin were determined by investigating the column temperature, flow rate, chromatographic columns and multi-point concentration correction. The total contents in 18 batches of standard decoction of Gastrodiae Rhizoma and the similarity were determined to calculate the similarity. The results of standard curve method, external standard one-point method and quantitative analysis multi-components with a single-marker(QAMS) were compared, and the results showed that there was no significant difference among these three methods. By analyzing the results of standard decoctions from different origins, it can be seen that the quality of Gastrodia standard decoctions derived from Anhui and Yunnan was better, followed by Shaanxi and Hubei, and relatively poor in Gansu, with similarities all above 0.90 in the fingerprints. Therefore, the QAMS method that can measure the contents of gastrodin, p-hydroxybenzyl alcohol, parishin E, parishin B, parishin C and parishin A in standard decoction of Gastrodiae Rhizoma combined with fingerprint is accurate, feasible and fast, which can be used to evaluate the quality of standard decoction of Gastrodiae Rhizoma, and also provide a reference for the research on the quality standards of raw materials for Gastrodiae Rhizoma prepared slices and alike.

Iron-Catalyzed Dihydrosilylation of Alkynes: Efficient Access to Geminal Bis(silanes).

Geminal bis(silanes) are versatile synthetic building blocks owing to their stability and propensity to undergo a variety of transformations. However, the scarcity of catalytic methods for their synthesis limits their structural diversity and thus their utility for further applications. Herein we report a new method for synthesis of geminal bis(silanes) by means of iron-catalyzed dihydrosilylation of alkynes. Iron catalysts were distinctly superior to the other tested catalysts, which clearly demonstrates that novel reactivity can be found by using iron catalysts. This method features 100% atom economy, regiospecificity, mild reaction conditions, and readily available starting materials. Using this method, we prepared a new type of geminal bis(silane) with secondary silane moieties, the Si-H bonds of which can easily undergo various transformations, facilitating the synthetic applications of these compounds. Preliminary mechanistic studies demonstrated that the reaction proceeds via two iron-catalyzed hydrosilylation reactions, the first generating ß-( E)-vinylsilanes and the second producing geminal bis(silanes).

Northern pig-tailed macaques (Macaca leonina) maintain superior CD4+ T-cell homeostasis during SIVmac239 infection.

Gradual depletion of CD4+ T cells is a typical characteristic of pathogenic SIV infection. Intriguingly, we find a spontaneous CD4+ T-cell homeostasis in northern pig-tailed macaques (Macaca leonina) during SIVmac239 infection.

High-performance millimeter-wave synergetic optoelectronic oscillator with regenerative frequency-dividing oscillation technique.

A novel millimeter-wave synergetic optoelectronic oscillator based on regenerative frequency-dividing oscillation and phase-locking techniques is proposed and experimentally demonstrated. The regenerative frequency-dividing oscillator is embedded for millimeter-wave frequency division, and then synergistically oscillates with the optoelectronic oscillator (OEO) due to injection-locking effect. The phase-locking stabilization technique is skillfully utilized in millimeter-wave OEO via commercial analog phase shifter. As a result, a 40-GHz signal is generated featuring low phase noise, high stability and low spurs. The single-sideband phase noise is about -117 dBc/Hz at 10-kHz offset frequency and the spurious suppression ratio reaches more than 80 dBc. The measured overlapping Allan deviation of the proposed synergetic OEO reaches lower than 10-13 at 1024-s averaging time, which is five orders of magnitude lower than free-running millimeter-wave OEO.

Successful implementation of intestinal endoscopy in non-human primates prompts the possibility of achieving AIDS longitudinal intestinal research.

HIV infection induces pathological changes in the intestinal mucosa. Here, a successful endoscopy was performed on the colon of a Chinese rhesus macaque by using Olympus CV170 gastroscope. The stability on postoperative recovery and the integrity of biopsy tissue implied a possibility of achieving AIDS longitudinal intestinal research on macaques.

Predict disease progression from T-cell phenotypes in northern pig-tailed macaques (Macaca leonina) during SIVmac239 infection.

Macaca leonina (northern pig-tailed macaques, NPMs) have variable disease progression during SIVmac239 infection. In the present study, we analysed, for the first time, the correlations between T-cell phenotypes and disease progression in NPMs during SIVmac239 infection. In comparison to normal progressors (NPs), slow progressors (SPs) had lower chronic T-cell activation and exhaustion levels. In addition, SPs showed higher peripheral CD4+ T-cell count and CD4 : CD8 ratio, and lower plasma viral load than NPs. CD4+ T-cell count and CD4 : CD8 ratio decreased more sharply in NPs than in SPs. Furthermore, T cells in NPs were more highly differentiated, at least in acute infection, than in SPs. These results indicated that T-cell phenotypes were correlated with disease progression in SIVmac239-infected NPMs and these correlations may provide valuable guidance for the improvement of therapeutic strategies tested in NPMs.

Effects of simvastatin on the expression of inducible nitric oxide synthase and brain-derived neurotrophic factor in a lipopolysaccharide-induced rat model of Parkinson disease.

OBJECTIVE: To investigate the effects of simvastatin on the expression of inducible nitric oxide synthase (iNOS) and brain-derived neurotrophic factor (BDNF) in the substantia nigra in a lipopolysaccharide (LPS)-induced rat model of Parkinson disease (PD), and to study the mechanisms underlying the neuroprotective effects of simvastatin in PD. METHODS: The LPS-PD model was established by injection of LPS (5 mg/mL, 2.0 µL) into the right substantia nigra compacta (SNC). Rats in the sham-operated group received saline. The simvastatin treatment group was intraperitoneally administered simvastatin (5 mg/kg, 2.0 µL) at 1 h before, and daily for 14 days after surgery, while the sham-operated and LPS-model groups received saline. Iba-1-positive cells and tyrosine hydroxylase (TH), as well as iNOS and BDNF in the SNC were detected by immunohistochemistry and Western blotting, respectively. The effect of simvastatin in the PD model was also examined in behavioral tests. RESULTS: The LPS-model group exhibited typical animal PD behaviors. Compared with the control group, the LPS-model group exhibited a decreased number of DA neurons (p < 0.01) in the SNC, as well as increases in the Iba-1-positive cell number and iNOS expression (p < 0.05), while BDNF expression was downregulated (p < 0.01). These effects were inhibited by simvastatin treatment (p < 0.05). CONCLUSION: Simvastatin mediates a protective effect on dopaminergic neurons in the SNC in the LPS-PD model, possibly by promoting neuronal repair and regeneration, and by inhibiting oxidative stress, thus improving substantia nigra function.

Immunobiology of COVID-19: Mechanistic and therapeutic insights from animal models.

The distribution of the immune system throughout the body complicates in vitro assessments of coronavirus disease 2019 (COVID-19) immunobiology, often resulting in a lack of reproducibility when extrapolated to the whole organism. Consequently, developing animal models is imperative for a comprehensive understanding of the pathology and immunology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This review summarizes current progress related to COVID-19 animal models, including non-human primates (NHPs), mice, and hamsters, with a focus on their roles in exploring the mechanisms of immunopathology, immune protection, and long-term effects of SARS-CoV-2 infection, as well as their application in immunoprevention and immunotherapy of SARS-CoV-2 infection. Differences among these animal models and their specific applications are also highlighted, as no single model can fully encapsulate all aspects of COVID-19. To effectively address the challenges posed by COVID-19, it is essential to select appropriate animal models that can accurately replicate both fatal and non-fatal infections with varying courses and severities. Optimizing animal model libraries and associated research tools is key to resolving the global COVID-19 pandemic, serving as a robust resource for future emerging infectious diseases.

Ligand Relay for Nickel-Catalyzed Decarbonylative Alkylation of Aroyl Chlorides.

Transition metal-catalyzed direct decarboxylative transformations of aromatic carboxylic acids usually require high temperatures, which limit the substrate's scope, especially for late-stage applications. The development of the selective decarbonylative of carboxylic acid derivatives, especially the most fundamental aroyl chlorides, with stable and cheap electrophiles under mild conditions is highly desirable and meaningful, but remains challenging. Herein, a strategy of nickel-catalyzed decarbonylative alkylation of aroyl chlorides via phosphine/nitrogen ligand relay is reported. The simple phosphine ligand is found essential for the decarbonylation step, while the nitrogen ligand promotes the cross-electrophile coupling. Such a ligand relay system can effectively and orderly carry out the catalytic process at room temperature, utilizing easily available aroyl chlorides as an aryl electrophile for reductive alkylation. This discovery provides a new strategy for direct decarbonylative coupling, features operationally simple, mild conditions, and excellent functional group tolerance. The mild approach is applied to the late-stage methylation of various pharmaceuticals. Extensive experiments are carried out to provide insights into the reaction pathway and support the ligand relay process.

Nonnegligible Contribution of Nonlymphoid Tissue to Viral Reservoir During the Short-Term Early cART in SIVmac239-Infected Chinese Rhesus Macaques.

HIV/AIDS cannot be cured because of the persistence of the viral reservoir. Because of the complexity of the cellular composition and structure of the human organs, HIV reservoirs of anatomical site are also complex. Recently, although a variety of molecules have been reported to be involved in the establishment and maintenance of the viral reservoirs, or as marker of latent cells, the research mainly focuses on blood and lymph nodes. Now, the characteristics of the viral reservoir in tissue are not yet fully understood. In this study, various tissues were collected from SIVmac239-infected monkeys, and the level of total SIV DNA, SIV 2-LTR DNA, and cell-associated virus RNA in them were compared with character of the anatomical viral reservoir under early treatment. The results showed that short-term combination antiretroviral therapy (cART) starting from 3 days after infection could significantly inhibit viremia and reduce the size of the anatomical viral reservoir, but it could not eradicate de novo infections and ongoing replication of virus. Moreover, the effects of early cART on the level of total SIV DNA, SIV 2-LTR DNA, and cell-associated virus RNA in different tissues were different, which changed the size distribution of viral reservoir in anatomical site. Finally, the contribution of nonlymphoid tissues, especially liver and lung, to the viral reservoir increased after treatment, while the contribution of intestinal lymphoid to the viral reservoir significantly reduced. These results suggested that early treatment effectively decreased the size of viral reservoir, and that the effects of cART on the tissue viral reservoir varied greatly by tissue type. The results implied that persistent existence of virus in nonlymphoid tissues after short-term treatment suggested that the role of nonlymphoid tissues cannot be ignored in development strategies for AIDS therapy.

Magnesium-promoted nickel-catalysed chlorination of aryl halides and triflates under mild conditions.

In this study, we present a ligand-free nickel(II)-catalyzed halogen exchange of aromatic halides with magnesium chloride. This method effectively facilitates the retro-Finkelstein reaction for a wide range of aryl bromides, iodides and triflates, demonstrating excellent functional group tolerance. Mechanistic studies reveal that magnesium plays a crucial role in the challenging reductive elimination from Ni(II) intermediates.

Comparison of remimazolam and propofol combined with low dose esketamine for pediatric same-day painless bidirectional endoscopy: a randomized, controlled clinical trial.

Background: Remimazolam has shown similar or even superior properties to propofol in procedural sedation in adults, but few studies have been conducted in pediatric populations. Thus, we aimed to compare the effect and safety of remimazolam and propofol combined with low dose esketamine for pediatric same-day bidirectional endoscopy (BDE). Methods: Pediatrics <18 years scheduled for elective BDE under sedation were included and randomly assigned to remimazolam group (R group) or propofol group (P group). The primary outcome was the success rate of sedation. Secondary outcomes include sedation-related information and adverse events. Mean arterial pressure (MAP), heart rate (HR), and perfusion index (PI) were recorded during sedation. Results: A total of 106 patients were enrolled and analyzed. The success rate of sedation was 100% in both groups. Compared with the P group, the induction time of the R group was significantly prolonged (p < 0.001), and the incidence of injection pain, intraoperative respiratory depression, hypotension and bradycardia was significantly lower (p < 0.001). The changes in MAP, HR and PI were relatively stable in the R group compared with the P group. Additionally, awake time significantly decreased with age by approximately 1.12 index points for each increase in age in the P group (p = 0.002) but not in the R group (p > 0.05). Furthermore, the decline in PI and PI ratio during BDE was related to body movement in the P group. Conclusion: Remimazolam combined with low dose esketamine has a non-inferior sedative effect than propofol for pediatric BDE, with no injection pain, less respiratory depression, more stable hemodynamics. Moreover, early detection of the decline in PI may avoid harmful stimulation under light anesthesia. Clinical trial registration: https://www.clinicaltrials.gov/study/NCT05686863?id=NCT05686863&rank=1, NCT05686863.

Spin effect on redox acceleration and regioselectivity in Fe-catalyzed alkyne hydrosilylation.

Iron catalysts are ideal transition metal catalysts because of the Earths abundant, cheap, biocompatible features of iron salts. Iron catalysts often have unique open-shell structures that easily undergo spin crossover in chemical transformations, a feature rarely found in noble metal catalysts. Unfortunately, little is known currently about how the open-shell structure and spin crossover affect the reactivity and selectivity of iron catalysts, which makes the development of iron catalysts a low efficient trial-and-error program. In this paper, a combination of experiments and theoretical calculations revealed that the iron-catalyzed hydrosilylation of alkynes is typical spin-crossover catalysis. Deep insight into the electronic structures of a set of well-defined open-shell active formal Fe(0) catalysts revealed that the spin-delocalization between the iron center and the 1,10-phenanthroline ligand effectively regulates the iron center's spin and oxidation state to meet the opposite electrostatic requirements of oxidative addition and reductive elimination, respectively, and the spin crossover is essential for this electron transfer process. The triplet transition state was essential for achieving high regioselectivity through tuning the nonbonding interactions. These findings provide an important reference for understanding the effect of catalyst spin state on reaction. It is inspiring for the development of iron catalysts and other Earth-abundant metal catalysts, especially from the point of view of ligand development.

Large expansion of plasma commensal viruses is associated with SIV pathogenesis in Macaca leonina.

Human immunodeficiency virus-1 (HIV-1) infection disrupts the homeostatic equilibrium between the host and commensal microbes. However, the dynamic changes of plasma commensal viruses and their role in HIV/simian immunodeficiency virus (SIV) pathogenesis are rarely reported. Here, we investigated the longitudinal changes of plasma virome, inflammation levels, and disease markers using an SIV-infected Macaca leonina model. Large expansions of plasma Anelloviridae, Parvoviridae, Circoviridae and other commensal viruses, and elevated levels of inflammation and D-dimer were observed since the chronic phase of SIV infection. Anelloviridae abundance appears to correlate positively with the CD4+ T cell count but negatively with SIV load especially at the acute phase, whereas other commensal viruses' abundances show opposite correlations with the two disease markers. Antiretroviral therapy slightly reduces but does not substantially reverse the expansion of commensal viruses. Furthermore, 1387 primate anellovirus open reading frame 1 sequences of more than 1500 nucleotides were annotated. The data reveal different roles of commensal viruses in SIV pathogenesis.