A Functional Switch Between Asperfumene and Fusicoccadiene Synthase and Entrance to Asperfumene Biosynthesis through a Vicinal Deprotonation-Reprotonation Process.

The diterpene synthase AfAS was identified from Aspergillus fumigatiaffinis. Its amino acid sequence and - according to a structural model - active site architecture are highly similar to those of the fusicocca-2,10(14)-diene synthase PaFS, but AfAS produces a structurally much more complex diterpene with a novel 6-5-5-5 tetracyclic skeleton called asperfumene. The cyclisation mechanism of AfAS was elucidated through isotopic labelling experiments and DFT calculations. The reaction cascade proceeds in its initial steps through similar intermediates as for the PaFS cascade, but then diverges through an unusual vicinal deprotonation-reprotonation process that triggers a skeletal rearrangement at the entrance to the steps leading to the unique asperfumene skeleton. The structural model revealed only one major difference between the active sites: The PaFS residue F65 is substituted by I65 in AfAS. Intriguingly, site-directed mutagenesis experiments with both diterpene synthases revealed that position 65 serves as a bidirectional functional switch for the biosynthesis of tetracyclic asperfumene versus structurally less complex diterpenes.

[HADHA Inhibits the Migration and Invasion of HTR-8/SVneo Cells by Regulating PI3K/AKT Signaling Pathway].

Objective: To explore the effects of hydroxyacyl-CoA dehydrogenase alpha subunit (HADHA) on the migration and invasion of HTR-8/SVneo cells, a human trophoblast cell line, and its potential mechanism of action. Methods: Immunofluorescence staining was done to evaluate the expression levels of HADHA in samples of normal villi and recurrent spontaneous abortion (RSA) villi at 6-8 weeks. Lentiviral infection system was used to construct stable HTR-8/SVneo cell lines with HADHA overexpression and knockdown. Western blot, qRT-PCR, Wound-healing assay, and Transwell assay were used to determine the effect of HADHA on the migration and invasion of HTR-8/SVneo cells and the expression of relevant genes. Transcriptome sequencing and bioinformatics analysis were done to screen for the potential target genes and signaling pathways regulated by HADHA. The specific molecular mechanism of how HADHA regulates the migration and invasion of HTR-8/SVneo cells was examined by adding the inhibitor of protein kinase B (PKB/AKT). Results: HADHA was highly expressed in extravillous trophoblasts (EVT) of RSA villus samples as compared with samples from the normal control group. In HTR-8/SVneo cells overexpressing HADHA, the expression levels of migration and invasion-related genes, including HLA-G, MMP2, MMP9, and NCAD, were decreased (P<0.01,P<0.05), and the migration and invasion abilities of HTR-8/SVneo cells were weakened (P<0.05). HADHA knockdown increased the expression levels of HLA-G, MMP2, MMP9, and NCAD (P<0.01, P<0.05), and promoted the migration and invasion of HTR-8/SVneo cells (P<0.05). In addition, HADHA overexpression decreased the phosphorylation levels of PI3K and AKT (P<0.05) and inhibited the PI3K/AKT signaling pathway. HADHA knockdown activated the PI3K/AKT signaling pathway. When MK-2206, an AKT inhibitor, was added to stable HTR-8/SVneo cell lines with HADHA knockdown, the migration and invasion of the cells were significantly reduced. Conclusion: HADHA inhibits the migration and invasion of HTR-8/SVneo cells by inhibiting the PI3K/AKT signaling pathway.

Appropriate expression of P57kip2 drives trophoblast fusion via cell cycle arrest.

The syncytiotrophoblast, derived from cytotrophoblast fusion, is responsible for maternal-fetal exchanges, secretion of pregnancy-related hormones, and fetal defense against pathogens. Inadequate cytotrophoblast fusion can lead to pregnancy disorders, such as preeclampsia and fetal growth restriction. However, little is known about the mechanism of cytotrophoblast fusion in both physiological and pathological pregnancy conditions. In this study, P57kip2 (P57), a cell cycle-dependent kinase inhibitor that negatively regulates the cell cycle, was found to be up-regulated during the process of syncytialization in both primary trophoblast cells and BeWo cells. Co-immunofluorescence with proliferation markers Ki67 and Cyclin-CDK factors further showed that P57 specifically localizes in the post-mitotic cytotrophoblast subtype of the early pregnancy villi. Overexpression of P57 promoted trophoblast syncytialization by arresting the cell cycle at the G1/G0 phase and inhibiting proliferation. Blocking of the cell cycle through a serum starvation culture resulted in an enhancement of cytotrophoblast fusion and the up-regulation of P57. In both spontaneous cytotrophoblast fusion and forskolin-induced BeWo cell fusion models, an initial up-regulation of P57 was observed followed by a subsequent down-regulation. These findings indicate that proper expression of P57 at cytotrophoblast differentiation nodes plays an important role in trophoblast syncytialization.

4-Hydroxy Pyridones from Heterologous Expression and Cultivation of the Native Host.

4-Hydroxy pyridones are a class of fungi-derived polyketide-nonribosomal peptide products featuring a core of 4-hydroxy-2-pyridone which have a wide range of biological activities. Genome mining of in-house strains using polyketide synthase-nonribosomal peptide synthase as a query identified an endophyte Tolypocladium sp. 49Y, which possesses a potential 4-hydroxy pyridone biosynthetic gene cluster. Heterologous expression in Aspergillus oryzae NSAR1 revealed that this gene cluster is functional and able to produce a rare type of 4-hydroxy pyridones called tolypyridones (compounds 3 and 4). Tolypocladium sp. 49Y was grown in a variety of media which led to the isolation of six 4-hydroxy pyridones (5-10) and one pyrrolidone (11) from a rice culture, and compounds 3 and 9 showed antifungal activity. These latter compounds are different from those obtained by heterologous expression. This study shows that both heterologous expression and cultivation of the native host are complementary approaches to discover new natural products.

Metal-catalyzed alkyne oxidation/CH functionalization: Effects of oxidant, temperature, and metal catalyst on chemoselectivity.

Gold-catalyzed intermolecular alkyne oxidation has attracted much synthetic attention, but mostly suffering undesired over-oxidation. Recent experiments demonstrated that over-oxidation could be dramatically suppressed in zinc(II)-catalyzed intermolecular alkyne oxidation/CH functionalization. By means of first-principle density functional theory calculations, we explored the mechanism of the M-catalyzed intermolecular alkyne oxidations (M = Zn(OTf)2 and Au+ PR3 ) as well as the effects of oxidants, temperature, and metal catalysts on chemoselectivity, in an effort to disclose the origin of the extraordinary chemoselectivity pertaining to zinc catalysis. Our calculations indicate that the Zn-catalyzed intermolecular alkyne oxidation/CH functionalization proceeds by a Friedel-Crafts alkylation mechanism rather than metal carbene insertion mechanism. The chemoselectivity of CH functionalization against over-oxidation in Zn catalysis, in comparison with gold catalysis, can be jointly controlled by four factors: (1) the use of less nucleophilic N-oxide, (2) the enhanced electrophilicity and carbocationic nature of the carbenic site in the α-oxo metal carbenoid intermediate, (3) enhanced steric repulsion to incoming oxidant exerted by bulky ancillary ligand in the close nearby of the carbenic site to disfavor intermolecular over-oxidation and (4) the large negative value of activation entropy in the intermolecular over-oxidation pathway, that jointly give rise to lower activation free energy for the intramolecular cyclization/CH functionalization pathway than for the intermolecular over-oxidation pathway. © 2018 Wiley Periodicals, Inc.

Catalytic promiscuity of the non-native FPP substrate in the TEAS enzyme: non-negligible flexibility of the carbocation intermediate.

The TEAS, one of the sesquiterpene cyclases (FPPC), shows enzyme promiscuity that can effectively catalyze both the natural substrate (trans,trans)-FPP and the non-native (cis,trans)-FPP substrate to generate diverse products/byproducts. So far, the catalytic mechanism of the promiscuous substrate is still unclear. In this work, QM(DFT)/MM MD simulations were employed to illuminate the predominant 1,6-closure pathway reaction mechanism for the non-native substrate (cis,trans)-FPP, while the 1,10-closure pathway is the major reaction for the native substrate. It has been revealed that the catalytic promiscuity of TEAS is mostly attributable to the notable conformational dynamics of the branching intermediate bisabolyl cation. The comparative studies to FSTS (another widely studied FPPC) further indicate that the intrinsic intermediate flexibility in TEAS is highly correlated to the plasticity of the enzyme active site pocket contour. Finally, we propose a general picture for controlling the promiscuity and fidelity in FPPC catalysis, including substrate folding, intermediate flexibility and key residues.

Electrocatalytic Generation of Amidyl Radicals for Olefin Hydroamidation: Use of Solvent Effects to Enable Anilide Oxidation.

Oxidative generation of synthetically important amidyl radicals from N-H amides is an appealing and yet challenging task. Previous methods require a stoichiometric amount of a strong oxidant and/or a costly noble-metal catalyst. We report herein the first electrocatalytic method that employs ferrocene (Fc), a cheap organometallic reagent, as the redox catalyst to produce amidyl radicals from N-aryl amides. Based on this radical-generating method, an efficient intramolecular olefin hydroamidation reaction has been developed.

Generation of α-Imino Gold Carbenes through Gold-Catalyzed Intermolecular Reaction of Azides with Ynamides.

The generation of α-imino gold carbenes via gold-catalyzed intermolecular reaction of azides and ynamides is disclosed. This new methodology allows for highly regioselective access to valuable 2-aminoindoles and 3-amino-ß-carbolines in generally good to excellent yields. A mechanistic rationale for this tandem reaction, especially for the observed high regioselectivity, is supported by DFT calculations.

Zinc-Catalyzed Alkyne Oxidation/C-H Functionalization: Highly Site-Selective Synthesis of Versatile Isoquinolones and ß-Carbolines.

An efficient zinc(II)-catalyzed alkyne oxidation/C-H functionalization sequence was developed, thus leading to highly site-selective synthesis of a variety of isoquinolones and ß-carbolines. Importantly, in contrast to the well-established gold-catalyzed intermolecular alkyne oxidation, over-oxidation can be completely suppressed in this system and the reaction most likely proceeds by a Friedel-Crafts-type pathway. Mechanistic studies and theoretical calculations are described.

Gestational diabetes mellitus aggravates adverse perinatal outcomes in women with intrahepatic cholestasis of pregnancy.

PURPOSE: To evaluate the effect of intrahepatic cholestasis of pregnancy (ICP) with gestational diabetes mellitus (GDM) on perinatal outcomes and establish a prediction model of adverse perinatal outcomes in women with ICP. METHODS: This multicenter retrospective cohort study included the clinical data of 2,178 pregnant women with ICP, including 1,788 women with ICP and 390 co-occurrence ICP and GDM. The data of all subjects were collected from hospital electronic medical records. Univariate and multivariate logistic regression analysis were used to compare the incidence of perinatal outcomes between ICP with GDM group and ICP alone group. RESULTS: Baseline characteristics of the population revealed that maternal age (p < 0.001), pregestational weight (p = 0.01), pre-pregnancy BMI (p < 0.001), gestational weight gain (p < 0.001), assisted reproductive technology (ART) (p < 0.001), and total bile acid concentration (p = 0.024) may be risk factors for ICP with GDM. Furthermore, ICP with GDM demonstrated a higher association with both polyhydramnios (OR 2.66) and preterm labor (OR 1.67) compared to ICP alone. Further subgroup analysis based on the severity of ICP showed that elevated total bile acid concentrations were closely associated with an increased risk of preterm labour, meconium-stained amniotic fluid, and low birth weight in both ICP alone and ICP with GDM groups. ICP with GDM further worsened these outcomes, especially in women with severe ICP. The nomogram prediction model effectively predicted the occurrence of preterm labour in the ICP population. CONCLUSIONS: ICP with GDM may result in more adverse pregnancy outcomes, which are associated with bile acid concentrations.

Functional and structural dissection of glycosyltransferases underlying the glycodiversity of wolfberry-derived bioactive ingredients lycibarbarspermidines.

Lycibarbarspermidines are unusual phenolamide glycosides characterized by a dicaffeoylspermidine core with multiple glycosyl substitutions, and serve as a major class of bioactive ingredients in the wolfberry. So far, little is known about the enzymatic basis of the glycosylation of phenolamides including dicaffeoylspermidine. Here, we identify five lycibarbarspermidine glycosyltransferases, LbUGT1-5, which are the first phenolamide-type glycosyltransferases and catalyze regioselective glycosylation of dicaffeoylspermidines to form structurally diverse lycibarbarspermidines in wolfberry. Notably, LbUGT3 acts as a distinctive enzyme that catalyzes a tandem sugar transfer to the ortho-dihydroxy group on the caffeoyl moiety to form the unusual ortho-diglucosylated product, while LbUGT1 accurately discriminates caffeoyl and dihydrocaffeoyl groups to catalyze a site-selective sugar transfer. Crystal structure analysis of the complexes of LbUGT1 and LbUGT3 with UDP, combined with molecular dynamics simulations, revealed the structural basis of the difference in glycosylation selectivity between LbUGT1 and LbUGT3. Site-directed mutagenesis illuminates a conserved tyrosine residue (Y389 in LbUGT1 and Y390 in LbUGT3) in PSPG box that plays a crucial role in regulating the regioselectivity of LbUGT1 and LbUGT3. Our study thus sheds light on the enzymatic underpinnings of the chemical diversity of lycibarbarspermidines in wolfberry, and expands the repertoire of glycosyltransferases in nature.

Discovery of a Potent Antiosteoporotic Drug Molecular Scaffold Derived from Angelica sinensis and Its Bioinspired Total Synthesis.

Angelica sinensis, commonly known as Dong Quai in Europe and America and as Dang-gui in China, is a medicinal plant widely utilized for the prevention and treatment of osteoporosis. In this study, we report the discovery of a new category of phthalide from Angelica sinensis, namely falcarinphthalides A and B (1 and 2), which contains two fragments, (3R,8S)-falcarindiol (3) and (Z)-ligustilide (4). Falcarinphthalides A and B (1 and 2) represent two unprecedented carbon skeletons of phthalide in natural products, and their antiosteoporotic activities were evaluated. The structures of 1 and 2, including their absolute configurations, were established using extensive analysis of NMR spectra, chemical derivatization, and ECD/VCD calculations. Based on LC-HR-ESI-MS analysis and DFT calculations, a production mechanism for 1 and 2 involving enzyme-catalyzed Diels-Alder/retro-Diels-Alder reactions was proposed. Falcarinphthalide A (1), the most promising lead compound, exhibits potent in vitro antiosteoporotic activity by inhibiting NF-κB and c-Fos signaling-mediated osteoclastogenesis. Moreover, the bioinspired gram-scale total synthesis of 1, guided by intensive DFT study, has paved the way for further biological investigation. The discovery and gram-scale total synthesis of falcarinphthalide A (1) provide a compelling lead compound and a novel molecular scaffold for treating osteoporosis and other metabolic bone diseases.

Identification of highly reliable risk genes for Alzheimer's disease through joint-tissue integrative analysis.

Numerous genetic variants associated with Alzheimer's disease (AD) have been identified through genome-wide association studies (GWAS), but their interpretation is hindered by the strong linkage disequilibrium (LD) among the variants, making it difficult to identify the causal variants directly. To address this issue, the transcriptome-wide association study (TWAS) was employed to infer the association between gene expression and a trait at the genetic level using expression quantitative trait locus (eQTL) cohorts. In this study, we applied the TWAS theory and utilized the improved Joint-Tissue Imputation (JTI) approach and Mendelian Randomization (MR) framework (MR-JTI) to identify potential AD-associated genes. By integrating LD score, GTEx eQTL data, and GWAS summary statistic data from a large cohort using MR-JTI, a total of 415 AD-associated genes were identified. Then, 2873 differentially expressed genes from 11 AD-related datasets were used for the Fisher test of these AD-associated genes. We finally obtained 36 highly reliable AD-associated genes, including APOC1, CR1, ERBB2, and RIN3. Moreover, the GO and KEGG enrichment analysis revealed that these genes are primarily involved in antigen processing and presentation, amyloid-beta formation, tau protein binding, and response to oxidative stress. The identification of these potential AD-associated genes not only provides insights into the pathogenesis of AD but also offers biomarkers for early diagnosis of the disease.

Enantioselective synthesis of α,α-diarylketones by sequential visible light photoactivation and phosphoric acid catalysis.

Chiral ketones and their derivatives are useful synthetic intermediates for the synthesis of biologically active natural products and medicinally relevant molecules. Nevertheless, general and broadly applicable methods for enantioenriched acyclic α,α-disubstituted ketones, especially α,α-diarylketones, remain largely underdeveloped, owing to the easy racemization. Here, we report a visible light photoactivation and phosphoric acid-catalyzed alkyne-carbonyl metathesis/transfer hydrogenation one-pot reaction using arylalkyne, benzoquinone, and Hantzsch ester for the expeditious synthesis of α,α-diarylketones with excellent yields and enantioselectivities. In the reaction, three chemical bonds, including C═O, C─C, and C─H, are formed, providing a de novo synthesis reaction for chiral α,α-diarylketones. Moreover, this protocol provides a convenient and practical method to synthesize or modify complex bioactive molecules, including efficient routes to florylpicoxamid and BRL-15572 analogs. Computational mechanistic studies revealed that C-H/π interactions, π-π interaction, and the substituents of Hantzsch ester all play crucial roles in the stereocontrol of the reaction.

Oxidative aromatization mechanism of ligustilide.

The aromatization mechanisms of ligustilide (1), a versatile monomeric phthalide, were investigated. DFT calculations combined with control experiments prove that the aromatization could result from direct oxidation by triplet oxygen in mild conditions with no catalyst, which is generally thought to be difficult. Moreover, it is predicted that the aromatization could rapidly clear away the harmful-to-organism singlet oxygen, which may be relevant to the general antioxidation activity of phthalides, providing a new point of view to understand the bioactivity from chemical reaction.

Home Quarantine: A Double-Edged Sword During COVID-19 Pandemic for Hypertensive Disorders of Pregnancy and the Related Complications.

Object: COVID-19 pandemic and worldwide quarantine seriously affected the physical and mental health of the general public. Our study aimed to investigate the effects of the COVID-19 quarantine on pregnancy outcomes among pregnant women with hypertensive disorders of pregnancy (HDP). Methods: This single-center retrospective cohort study collected complete clinical data of HDP patients with a history of home quarantine in The First Affiliated Hospital of Chongqing Medical University (Chongqing, China) in 2020 as well as the patients without home quarantine in 2018 and 2019. Then, the maternal and neonatal outcomes of two subtypes of HDP, gestational hypertension (GH) and preeclampsia/eclampsia (PE/E), were analyzed over the three years. Results: The incidence of HDP increased from 0.84% in 2018 and 0.51% in 2019 to 2.30% in 2020. The data suggested that home quarantine was associated with higher gestational weight gain, obesity rates, blood pressure, and uric acid among the patients with HDP in 2020. Furthermore, HDP patients with a history of home quarantine may have worse neonatal outcomes, including lower newborn weight, shorter body length, lower Apgar score, and higher risk of fetal growth restriction. Conclusion: Our results suggested that COVID-19 quarantine may be a risk factor for poor pregnancy outcomes in HDP patients. Lifestyle guidance and antenatal care may be necessary for HDP patients with home quarantine in an epidemic outbreak.

Biotransformation of α-asarone by Alternaria longipes CGMCC 3.2875.

Biotransformation of α-asarone by Alternaria longipes CGMCC 3.2875 yielded two pairs of new neolignans, (+) (7S, 8S, 7'S, 8'R) iso-magnosalicin (1a)/(-) (7R, 8R, 7'R, 8'S) iso-magnosalicin (1b) and (+) (7R, 8R, 7'S, 8'R) magnosalicin (2a)/(-) (7S, 8S, 7'R, 8'S) magnosalicin (2b), and four known metabolites, (±) acoraminol A (3), (±) acoraminol B (4), asaraldehyde (5), and 2, 4, 5-trimethoxybenzoic acid (6). Their structures, including absolute configurations, were determined by extensive analysis of NMR spectra, X-ray crystallography, and quantum chemical ECD calculations. The cytotoxic activity and Aß42 aggregation inhibitory activity of all the compounds were evaluated. Compound 2 displayed significant anti-Aß42 aggregation activity with an inhibitory rate of 60.81% (the positive control EGCG: 69.17%). In addition, the biotransformation pathway of α-asarone by Alternaria longipes CGMCC 3.2875 was proposed.

The Oxidation Cascade of a Rare Multifunctional P450 Enzyme Involved in Asperterpenoid A Biosynthesis.

The cytochrome P450 enzymes (P450s or CYPs) are heme-containing enzymes which catalyze a wide range of oxidation reactions in nature. In our previous study, a rare multifunctional P450 AstB was found, which can dually oxidize two methyl groups (C-19 and C-21) of preasperterpenoid A to asperterpenoid A with 3-carboxyl and 11-hydroxymethyl groups. However, the oxidation order of C-19 and C-21 catalyzed by AstB is unclear. In order to reveal this oxidation order, probable pathways catalyzed by AstB were proposed, and the oxidation order of C-19 and C-21 was obtained by quantum chemistry calculations. The potential intermediates (three new asperterpenoids D-F, 1-3) were obtained through the chemical investigation on the extract of the transformant strain and chemical conversions, which were used as the standards to detect their existences in the extract of the transformant strain with HPLC-MS. Combined with the quantum chemistry calculation and the HPLC-MS analysis, the catalyzed order of AstB in asperterpenoid A biosynthesis was revealed. Furthermore, the mPTPB inhibition of obtained asperterpenoids was evaluated, and the results showed that 3-carboxyl and the oxidation station of C-21 would be the key factors for mPTPB inhibition of asperterpenoids.

THBS1 regulates trophoblast fusion through a CD36-dependent inhibition of cAMP, and its upregulation participates in preeclampsia.

Preeclampsia is a pregnancy complication which threatens the survival of mothers and fetuses. It originates from abnormal placentation, especially insufficient fusion of the cytotrophoblast cells to form the syncytiotrophoblast. In this study, we found that THBS1, a matricellular protein that mediates cell-to-cell and cell-to-matrix interactions, is downregulated during the fusion of primary cytotrophoblast and BeWo cells, but upregulated in the placenta of pregnancies complicated by preeclampsia. Also, THBS1 was observed to interact with CD36, a membrane signal receptor and activator of the cAMP signaling pathway, to regulate the fusion of cytotrophoblast cells. Overexpression of THBS1 inhibited the cAMP signaling pathway and reduced the BeWo cells fusion ratio, while the effects of THBS1 were abolished by a CD36-blocking antibody. Our results suggest that THBS1 signals through a CD36-mediated cAMP pathway to regulate syncytialization of the cytotrophoblast cells, and that its upregulation impairs placental formation to cause preeclampsia. Thus, THBS1 can serve as a therapeutic target regarding the mitigation of abnormal syncytialization and preeclampsia.

[Relationship between gene polymorphism of fibronectin and pneumoconiosis].

OBJECTIVE: To explore the relationship between the genetic polymorphism of fibronectin (FN) (4 genetic locus) and pneumoconiosis. METHODS: 128 male I-period pneumoconiosis were selected as cases who were examined with radiography and diagnosed by the Pneumoconiosis Diagnosis Expert Panel, based on the Chinese National Diagnosis Criteria of Pneumoconiosis (GBZ 70 - 2002). According to 1:1 paired matching method, 128 dust exposure workers were selected as control who were exposed to same dust as cases. The difference of age and cumulative length of service between case and control was not over five years and two years, respectively. 5 ml peripheral venous blood was drawn and anticoagulated with 2% EDTA. The polymorphisms of FN (MspI, TaqIb, HindIII, HaeIIIb) were detected, using the method of polymerase chain restriction fragment length polymorphism (PCR-RFLP) techniques and PCR. RESULTS: The frequencies of FN Msp I (CC) in cases and control groups were 10.9% and 3.9%, respectively. The difference was significant (P < 0.05). The frequencies of FN (MspI) C allele were 41.8% and 31.2% in case and control, and the difference between cases and controls was significant (P < 0.05). The frequencies of FN HaeIIIb (AA) genotype in cases (24.2%) was higher than that in control groups (17.9%), OR = 5.0 (95% CI: 4.840 approximately 24.210). The frequencies of FN (HaeIIIb) A allele were 51.9% and 42.2% in case and control, and the difference was significant (P < 0.05). The difference of TaqIb and HindIII genotype between cases and controls were not significant (P > 0.05). CONCLUSION: The risk of suffering from pneumoconiosis increases in workers carrying FN (MspICC or HaeIIIb AA) genotype after exposure to dust. Workers both carrying FN (HaeIIIb AA) and (MspICC) genotypes are more susceptible to pneumoconiosis. The relationship between genetic polymorphism of FN (TaqIIb, HindIII) and pneumoconiosis has not been found.