GlcNAc-1,6-anhydro-MurNAc Moiety Affords Unusual Glycosyl Acceptor that Terminates Peptidoglycan Elongation.

Peptidoglycan (PG), an essential exoskeletal polymer in bacteria, is a well-known antibiotic target. PG polymerization requires the action of bacterial transglycosylases (TGases), which couple the incoming glycosyl acceptor to the donor. Interfering with the TGase activity can interrupt the PG assembly. Existing TGase inhibitors like moenomycin and Lipid II analogues always occupy the TGase active sites; other strategies to interfere with proper PG elongation have not been widely exploited. Inspired by the natural 1,6-anhydro-MurNAc termini that mark the ends of PG strands in bacteria, we hypothesized that the incorporation of an anhydromuramyl-containing glycosyl acceptor by TGase into the growing PG may effectively inhibit PG elongation. To explore this possibility, we synthesized 4-O-(N-acetyl-ß-d-glucosaminyl)-1,6-anhydro-N-acetyl-ß-d-muramyl-l-Ala-γ-d-Glu-l-Lys-d-Ala-d-Ala, 1, within 15 steps, and demonstrated that this anhydromuropeptide and its analogue lacking the peptide, 1-deAA, were both utilized by bacterial TGase as noncanonical anhydro glycosyl acceptors in vitro. The incorporation of an anhydromuramyl moiety into PG strands by TGases afforded efficient termination of glycan chain extension. Moreover, the preliminary in vitro studies of 1-deAA against Staphylococcus aureus showed that 1-deAA served as a reasonable antimicrobial adjunct of vancomycin. These insights imply the potential application of such anhydromuropeptides as novel classes of PG-terminating inhibitors, pointing toward novel strategies in antibacterial agent development.

A Strain-Promoted Divergent Chemical Steroidation Unveils Potent Anti-Inflammatory Pseudo-Steroidal Glycosides.

The development of novel agents with immunoregulatory effects is a keen way to combat the growing threat of inflammatory storms to global health. To synthesize pseudo-steroidal glycosides tethered by ether bonds with promising immunomodulatory potential, we develop herein a highly effective deoxygenative functionalization of a novel steroidal donor (steroidation) facilitated by strain-release, leveraging cost-effective and readily available Sc(OTf)3 catalysis. This transformation produces a transient steroid-3-yl carbocation which readily reacts with O-, C-, N-, S-, and P-nucleophiles to generate structurally diverse steroid derivatives. DFT calculations were performed to shed light on the mechanistic details of the regioselectivity, underlying an acceptor-dependent steroidation mode. This approach can be readily extended to the etherification of sugar alcohols to enable the achievement of a diversity-oriented, pipeline-like synthesis of pseudo-steroidal glycosides in good to excellent yields with complete stereo- and regiospecific control for anti-inflammatory agent discovery. Immunological studies have demonstrated that a meticulously designed cholesteryl disaccharide can significantly suppress interleukin-6 secretion in macrophages, exhibiting up to 99% inhibition rates compared to the negative control. These findings affirm the potential of pseudo-steroidal glycosides as a prospective category of lead agents for the development of novel anti-inflammatory drugs.

[Difference of effective component content and key enzyme gene expression of biosynthesis in Atractylodes chinensis with different leaf shapes].

In this study, four Atractylodes chinensis(A. chinensis) with different leaf shapes, such as the split leaf, long and narrow leaf, oval leaf, and large round leaf, were used as experimental materials to establish a method for simultaneously determining atractylodin, atractylenolide Ⅰ, ß-eudesmol, and atractylon in the rhizome of A. chinensis. The expression of key enzyme genes for biosynthesis of acetyl-CoA carboxylase(ACC), 3-hydroxy-3-methylglutaryl-CoA reductase(HMGR), and farnesyl pyrophosphate synthase(FPPS) was detected by real-time fluorescence quantitative polymerase chain reaction(qRT-PCR). High performance liquid chromatography(HPLC) was used to compare the difference in the content of four active components in A. chinensis with different leaf shapes, and the correlation between the content of active components and the expression of key enzyme genes in biosynthesis was discussed. The results show that there was good linearity among atractylodin, atractylenolide Ⅰ, ß-eudesmol, and atractylon in the range of 3.30-33.00 µg·mL~(-1)(r =0.999 7), 12.04-120.40 µg·mL~(-1)(r =0.999 5), 29.16-291.60 µg·mL~(-1)(r =0.999 5), and 14.20-142.00 µg·mL~(-1)(r =0.999 5), respectively. The average recoveries were 99.77%(RSD=2.1%), 98.56%(RSD=1.2%), 103.0%(RSD=1.2%), and 100.6%(RSD=1.5%), respectively. The method was accurate and had good reproducibility, which could be used to simultaneously detect atractylodin, atractylenolide Ⅰ, ß-eudesmol, and atractylon. The results showed that there were significant differences in the content of four active components in A. chinensis with different leaf shapes. The content of atractylodin, atractylenolide Ⅰ, and ß-eudesmol in A. chinensis with split leaves was the highest, which were 1.341 9, 5.237 2, and 12.084 3 mg·g~(-1), respectively. The content of atractylon in A. chinensis with long and narrow leaves was the highest(5.470 1 mg·g~(-1)). The content of atractylodin, atractylenolide Ⅰ, ß-eudesmol, and atractylon in A. chinensis with oval leaves was the lowest. The total content of the four effective components in descending order was A. chinensis with split leaves > A. chinensis with long and narrow leaves > A. chinensis with large round leaves > A. chinensis with oval leaves. The gene expression levels of key enzymes ACC, HMGR, and FPPS in A. chinensis with split leaves were the highest(P < 0.05), and the gene expression levels of key enzymes ACC and HMGR in A. chinensis with oval leaves were the lowest(P < 0.05). The gene expression level of key enzyme FPPS in A. chinensis with large round leaves was the lowest. In A. chinensis with different leaf shapes, the key enzyme gene ACC was significantly positively correlated with the polyacetylene component, namely atractylodin(P < 0.01), and the key enzyme genes HMGR and FPPS were positively correlated with the sesquiterpene components, namely atractylenolide Ⅰ, ß-eudesmol, and atractylon. In summary, the quality of A. chinensis with split leaves is the best, and the biosynthesis of atractylodin is significantly correlated with the gene expression of key enzyme ACC, which provides a theoretical basis for screening and optimizing the germplasm resources of A. chinensis and improving the quality of medicinal materials.

The complete mitochondrial genome of Ogmocotyle ailuri: gene content, composition and rearrangement and phylogenetic implications.

Trematodes of the genus Ogmocotyle are intestinal flukes that can infect a variety of definitive hosts, resulting in significant economic losses worldwide. However, there are few studies on molecular data of these trematodes. In this study, the mitochondrial (mt) genome of Ogmocotyle ailuri isolated from red panda (Ailurus fulgens) was determined and compared with those from Pronocephalata to investigate the mt genome content, genetic distance, gene rearrangements and phylogeny. The complete mt genome of O. ailuri is a typical closed circular molecule of 14 642 base pairs, comprising 12 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes and 2 non-coding regions. All genes are transcribed in the same direction. In addition, 23 intergenic spacers and 2 locations with gene overlaps were determined. Sequence identities and sliding window analysis indicated that cox1 is the most conserved gene among 12 PCGs in O. ailuri mt genome. The sequenced mt genomes of the 48 Plagiorchiida trematodes showed 5 types of gene arrangement based on all mt genome genes, with the gene arrangement of O. ailuri being type I. Phylogenetic analysis using concatenated amino acid sequences of 12 PCGs revealed that O. ailuri was closer to Ogmocotyle sikae than to Notocotylus intestinalis. These data enhance the Ogmocotyle mt genome database and provide molecular resources for further studies of Pronocephalata taxonomy, population genetics and systematics.

PGE1 and PGA1 bind to Nurr1 and activate its transcriptional function.

The orphan nuclear receptor Nurr1 is critical for the development, maintenance and protection of midbrain dopaminergic (mDA) neurons. Here we show that prostaglandin E1 (PGE1) and its dehydrated metabolite, PGA1, directly interact with the ligand-binding domain (LBD) of Nurr1 and stimulate its transcriptional function. We also report the crystallographic structure of Nurr1-LBD bound to PGA1 at 2.05 Å resolution. PGA1 couples covalently to Nurr1-LBD by forming a Michael adduct with Cys566, and induces notable conformational changes, including a 21° shift of the activation function-2 helix (H12) away from the protein core. Furthermore, PGE1/PGA1 exhibit neuroprotective effects in a Nurr1-dependent manner, prominently enhance expression of Nurr1 target genes in mDA neurons and improve motor deficits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mouse models of Parkinson's disease. Based on these results, we propose that PGE1/PGA1 represent native ligands of Nurr1 and can exert neuroprotective effects on mDA neurons, via activation of Nurr1's transcriptional function.

[Research status on efficacy enhancement and toxicity reduction of Chinese medicine in treatment of malignant tumors: a review of projects supported by National Natural Science Foundation of China].

Through a retrospective analysis of the projects supported by the National Natural Science Foundation of China in the past ten years in the field of Chinese medicine for the treatment of malignant tumors, this article systematically summarized the main research contents and hotspots of Chinese medicine in efficacy enhancement and toxicity reduction. The efficacy enhancement of Chinese medicine mainly included the mitigation of molecule-targeted drug resistance, multidrug resistance, and chemotherapy resistance, synergistic efficacy enhancement, and radiotherapy sensitization. The toxicity reduction is mainly reflected in the alleviation of the side effects of radiotherapy and chemotherapy. In addition, Chinese medicine has advantages in reducing serious adverse reactions of malignant tumors, providing more options for the adjuvant treatment of tumors.

Zinc(II) Iodide-Directed ß-Mannosylation: Reaction Selectivity, Mode, and Application.

A direct, efficient, and versatile glycosylation methodology promises the systematic synthesis of oligosaccharides and glycoconjugates in a streamlined fashion like the synthesis of medium to long-chain nucleotides and peptides. The development of a generally applicable approach for the construction of 1,2-cis-glycosidic bond with controlled stereoselectivity remains a major challenge, especially for the synthesis of ß-mannosides. Here, we report a direct mannosylation strategy mediated by ZnI2, a mild Lewis acid, for the highly stereoselective construction of 1,2-cis-ß linkages employing easily accessible 4,6-O-tethered mannosyl trichloroacetimidate donors. The versatility and effectiveness of this strategy were demonstrated with successful ß-mannosylation of a wide variety of alcohol acceptors, including complex natural products, amino acids, and glycosides. Through iteratively performing ZnI2-mediated mannosylation with the chitobiosyl azide acceptor followed by site-selective deprotection of the mannosylation product, the novel methodology enables the modular synthesis of the key intermediate trisaccharide with Man-ß-(1 → 4)-GlcNAc-ß-(1 → 4)-GlcNAc linkage for N-glycan synthesis. Theoretical investigations with density functional theory calculations delved into the mechanistic details of this ß-selective mannosylation and elucidated two zinc cations' essential roles as the activating agent of the donor and the principal mediator of the cis-directing intermolecular interaction.

Antimicrobial Carbohydrate-Based Macromolecules: Their Structures and Activities.

Emerging drug resistance is creating an urgent demand for new antimicrobial therapeutics. Besides the development of conventional antibiotics, antimicrobial agents with novel mechanisms have attracted great attention, such as antimicrobial peptides and polymers. Interactions between carbohydrates and proteins on microbes are believed to be the first step of pathogenesis. Thus, considerable efforts have been made on the development of carbohydrate-containing molecules in antimicrobial research. Recent progress of glycosylated macromolecules for antimicrobial applications has been discussed with an emphasis on synthetic glycosylated materials.

Androgen deficit changes the response to antidepressant drugs in tail suspension test in mice.

Depressive symptoms are throughout our life, especially in the older population, the sex hormones reduction link to a high risk of depression. In this study, we investigated whether bilateral orchiectomy (ORX) modifies mice behaviors and antidepressant drugs effects through tail suspension test (TST). We evaluated behavioral changes at 1 week, 2 weeks, 1 month, and up to 2 months after ORX. The behavior responses to doxepin, fluoxetine, and venlafaxine at 1 week, 2 weeks, 1 month, and 2 months after ORX were evaluated. No apparent difference was detected among the durations of immobility of the control group, sham operation group, and ORX group in the TST at 1 week and 2 weeks after ORX. But the immobility time of ORX group was obvious longer than that of both control group and sham operation group at 1 month and 2 months after ORX. Only the antidepressant effect of venlafaxine was observed at 1 week and 2 weeks after ORX, while the antidepressant response to fluoxetine decreased 1 month and 2 months after ORX. The response to antidepressant drugs was strongly modified in ORX mice. Our results suggest that not all antidepressant drugs are suitable for depression with androgen deficiency.HighlightsMice with low androgen were more prone to depression-like behaviors.The response to antidepressants changed under the condition of low androgen in mice.Not all antidepressant drugs are appropriate for patients with low androgen.

Palladium(ii)-catalyzed stereoselective synthesis of C-glycosides from glycals with diaryliodonium salts.

An efficient palladium(ii) mediated C-glycosylation of glycals with diaryliodonium salts is described, providing a new strategy for the synthesis of 2,3-dideoxy C-aryl glycosides with excellent stereoselectivity. The C-glycosylation of a diverse range of glycals, including d-glucal, d-galactal, d-allal, l-rhamnal, l-fucal, l-arabinal, d-maltal, and d-lactal, occurred effectively and the corresponding C-glycosides were obtained in moderate to good yields. This protocol is commended as a significant addition to the field of carbohydrate chemistry due to the rich functional group compatibility, broad range of substrate scope and exceptional α-stereoselectivity.

Stereo- and regioselective glycosylation with protection-less sugar derivatives: an alluring strategy to access glycans and natural products.

In the pursuit of developing potent drug molecules, more efficient and straightforward procedures are in high demand. The evergrowing interest in carbohydrate-based therapeutics and vaccines particularly calls for such reliable and universal approaches that assemble oligosaccharides rapidly and stereoselectively. Hereby, we compiled remarkable efforts made in exploring the possibilities of protection-less glycosylation strategies. Pioneering works using organotin reagents or catalysts were introduced first, followed by the organoboron successors that were deemed less toxic and more versatile alternatives. In the meantime, more species such as copper or caesium were also included and supported by a mechanistic rationale. Lastly, we hope to bring further insights into the synthesis of intricate carbohydrate derivatives, achieved with the aid of glycosylation methods discussed herein.

Novel cucurbitane-type triterpene saponins from Hemsleya amabilis.

The rhizomes of the medicinal plant Hemsleya amabilis (Cucurbitaceae) yielded three new cucurbitane-type triterpene saponins xuedanosides K-M (1-3) by silica gel column, ODS column, and pre-HPLC techniques. The structure was determined by spectroscopic analysis and examined alongside existing data from prior studies. Compounds 1-3 were evaluated for cytotoxic activity against HeLa and HCT-8 human cancer cell lines and showed significant cytotoxicity with IC50 values of 2.01-14.56 and 8.94-27.48 µM, respectively.

[Analysis of projects funded by NSFC in field of efficacy material base of traditional Chinese medicine].

This paper introduces the application and financing of programs of efficacy material base of traditional Chinese medicine funded by the National Natural Science Foundation of China(NSFC), the Youth Science Fund and the Regional Science Fund from 2016 to 2019, and conducts analysis and summary in terms of research objects and analysis methods, with the aim to provide reference for applicants for programs of efficacy material base of traditional Chinese medicine.

[Analysis of projects funded by NSFC in field of pharmacology of traditional Chinese medicine in 2019].

The projects which supported by National Natural Science Foundation of China(NSFC) including General Program, Young Scientist Fund, and Fund for Less Developed Regions, in field of pharmacology of traditional Chinese medicine in 2019 were reviewed. Based on these research items, the main contents and characteristics, as well as the main problems from academic and non-academic point of view, were summarized for reference.

Venturing beyond Donor-Controlled Glycosylation: New Perspectives toward Anomeric Selectivity.

Glycans are complex compounds consisting of sugars linked glycosidically, existing either as pure polysaccharides or as part of glycoconjugates. They are prevalent in nature and possess important functions in regulating biological pathways. However, their diversity coupled with physiochemical similarities makes it challenging to isolate them in large quantities for biochemical studies, hence hampering progress in glycobiology and glycomedicine. Glycochemistry presents an alternative strategy to obtain pure glycan compounds through artificial synthetic methods. Efforts in glycochemistry have been centered on glycosylation, the key reaction in glycochemistry, especially with regards to anomeric stereoselectivity in polysaccharides and glycoconjugates. In particular, the stereoelectronic and steric properties of glycosyl donors are commonly used to direct the stereoselectivity in glycosylation reactions. Classic glycosylation strategies typically involve saturated glycosyl donors, proceeding either directly using hydrogen bonds and conformational constraints or indirectly by installing moieties covalently through neighboring group participation and intramolecular aglycon delivery. Over the past years, new glycosylation strategies, tapping on the foundations of transition metal catalysis, have emerged. To leverage the power of coordination chemistry, unsaturated glycosyl donors were introduced. Not only are the number of protection/deprotection steps reduced, the resultant unsaturated glycoside provides opportunities for downstream functionalizations, allowing quick access to a variety of sugars, including rare sugars. Alongside the glycosyl donor, an equally important but neglected aspect for targeting stereoselective glycosylation is the glycosyl acceptor. In the case of dual-directing donors, glycosyl acceptors have proved themselves capable of becoming the dominating factor for stereocontrol. Interestingly, rational manipulation or selection of glycosyl acceptors with particular nucleophilicity and p Ka values can lead to different stereoselectivities, thereby proving the tunability of such acceptors to favor the formation of one anomer over the other stereoselectively. By further venturing beyond substrate controlled stereoselectivity, we are presented with the opportunity to effect stereoselective glycosylation through glycosylating reagents. Of the key reagents, stereoselective catalyst stands out as a greener and efficient alternative to direct stereoselective control with stoichiometric substrates. Recently, investigations into this approach of stereocontrol presented an intriguing range of stereoselectivities, achieved by merely varying the nature of catalysts used. Another crucial effort in glycochemistry is enhancing the efficiencies of glycosylations, by reducing the number of preparative steps before or during glycosylation. Through using transient masking groups or one-pot synthetic strategies, these streamlined approaches provide enormous convenience and practicability for oligosaccharide syntheses. This Account presents mainly our advancements beyond the conventional donor-controlled strategies over the past decade, with emphasis placed on mechanistic explanations of anomeric selectivities, thereby providing perspectives to inspire further progress toward a generalized unified strategy for preparing every type of glycan.

Synthesis of Antibacterial Glycosylated Polycaprolactones Bearing Imidazoliums with Reduced Hemolytic Activity.

Most synthetic antimicrobial polymers are not biodegradable, thus limiting their potential for large-scale applications in personal care disinfection and environmental contaminations. Poly(ε-caprolactone) (PCL) is known to be both biodegradable and biocompatible, thus representing an ideal candidate biopolymer for antimicrobial applications. Here we successfully grafted alkylimidazolium (Im) onto PCL to mimic the cationic properties of antimicrobial peptides. The poly(ε-caprolactone)- graft-butylimidazolium had only moderate MICs (32 µg/mL), reasonably good red blood cell selectivity (36) and relatively good fibroblast compatibility (81% cell viability at 100 µg/mL), indicating that combining the hydrophobic PCL backbone with the most hydrophilic butylimidazolium gives a good balance of MIC and cytotoxicity. On the other hand, the PCL- graft-hexylimidazolium and -octylimidazolium demonstrated better MICs (4-32 µg/mL), but considerably worse cytotoxicity. We postulated that the worse hydrophilicity of hexylimidazolium and octylimidazolium was responsible for their higher cytotoxicity and sought to moderate their cytotoxicity with different sugar compositions and lengths. Through our screening, we identified a candidate polymer, P(C6Im)0.35CL- co-P(Man)0.65CL, that demonstrated both superior MIC and very low cytotoxicity. We further demonstrated that our biopolymer hit had superior antimicrobial kinetics compared to the antibiotic vancomycin. This work paves the way forward for the use of biodegradable polyesters as the backbone scaffold for biocompatible antibacterial agents, by clicking with different types and ratios of alkylimidazolium and carbohydrate moieties.

[Identification of the Strain Which Highly Produces Protease and ß-D-glucosidase Isolated from Shuidouchi Produced in Sichuan and Evaluating Its Ability of Producing Protease].

OBJECTIVE: To select and identify the bacterium which highly produces protease and ß-D-glucosidase from 72 strains of Shuidouchi from Sichuan, and to provide evidence for further research on its nutritional value and fermentation strain exploiting. METHODS: Casein degradation test and pNPG chemical test were applied respectively to detect the capacity to produce protease and ß-D-glucosidase of each strain. Characteristics of morphology, biochemistry, 16S rRNA and MALDI-TOF-MS were used to identify the fermentation strain, which genetic stability, curves of growth and enzyme producing were also obtained. RESULTS: The strain with the highest enzyme activity of ß-D-glucosidase (0.084 U/L) among the top 10 strains for producing protease was selected as the fermentation strain and was identified as Bacillus subtilis, which curves of growth and enzyme producing conformed as well. The result of genetic stability showed that capacity of enzyme producing was stable until the 10th generation. CONCLUSIONS: The fermentation strain which highly produced protease and ß-D-glucosidase was selected from 72 strains of shuidouchi from Sichuan and was identified as Bacillus subtilis.

[Analysis on projects of ethnomedicine and ethnopharmacology funded by National Natural Science Foundation of China from 1986-2018].

Through summarizing the applications and funding for research related to ethnomedicine and ethnopharmacology in the department of Health Sciences of the National Natural Science Foundation of China( NSFC) from 1986 to 2018,and analyzing the categories,numbers,funds and research contents of all funded projects including Mongolian,Uygur,Tibetan,Zhuang,Miao,the study is aimed to provide certain reference for the declaration of ethnic medicine project. The results showed that the national medicine project application numbers and the amount of funding growth after 2011 have increased significantly,but the overall level of research remained to be further promoted,and the lack of suitable for the study of ethnic medicine features and ways,has yet to mainland medical universities and research institutions to give more attention and jointly promote the development of basic research in the field of ethnic medicine.

A similar effect of P16 hydroxymethylation and true-methylation on the prediction of malignant transformation of oral epithelial dysplasia: observation from a prospective study.

BACKGROUND: Total P16 methylation (P16M), including P16 hydroxymethylation (P16H) and true-P16M, correlates with malignant transformation of oral epithelial dysplasia (OED). Both true-P16M and P16H are early events in carcinogenesis. The aim of this study is to prospectively determine if discrimination of true-P16M from P16H is necessary for prediction of cancer development from OEDs. METHODS: Patients (n = 265) with mild or moderate OED were recruited into the double blind two-center cohort. Total-P16M and P16H were analyzed using the 115-bp MethyLight, TET-assisted bisulfite (TAB) methylation-specific PCR (MSP), and TAB-sequencing. Total-P16M-positive and P16H-negative samples were defined as true-P16M-positive. Progression of OEDs was monitored for a minimum 24 months follow-up period. RESULTS: P16H was detected in 23 of 73 (31.5%) total-P16M-positive OEDs. Follow-up information was obtained from 247 patients with an ultimate compliance rate of 93.2%. OED-derived squamous cell carcinomas were observed in 13.0% (32/247) patients during follow-up (median, 41.0 months). The cancer progression rate for total-P16M-positive patients was significantly increased when compared to total-P16M-negative patients [23.3% vs 8.6%; adjusted odds ratio = 2.67 (95% CI: 1.19-5.99)]. However, the cancer progression rates were similar between P16H- and true-P16M-positive OEDs [26.1% (6/23) vs 22.0% (11/50); odds ratio = 0.80 (95% CI: 0.22-2.92)]. The cancer-free survival was also similar for these patients. CONCLUSION: P16H and true-P16M are similar biomarkers for determining malignant potential of OEDs. Discrimination of P16H from true-P16M, at least in OED, may be not necessary in clinical applications. TRIAL REGISTRATION: This study is registered prospectively in the U.S. National Institutes of Health Clinical Trials Protocol Registration System (trial number NCT02967120, available at https://ClinicalTrials.gov/ct2/show/NCT02967120 ).

Recent progress of C-glycosylation methods in the total synthesis of natural products and pharmaceuticals.

Chemical C-glycosylation has been well developed to improve stereoselectivity in recent years. Due to its high efficiency to build C-glycosides or O-cyclic compounds, C-glycosylation has found widespread use in the synthesis of biologically active molecules. This review highlights the C-glycosylation methods that have been practised in the total synthesis of natural products and pharmaceuticals in the past decade.