A caprylate esterase-activated fluorescent probe for sensitive and selective detection of Salmonella enteritidis.

Salmonella enteritidis is one of the most common foodborne pathogens. Many methods have been developed to detect Salmonella, but most of them are expensive, time-consuming, and complex in experimental procedures. Developing a rapid, specific, cost-effective, and sensitive detection method is still demanded. In this work, a practical detection method is presented using salicylaldazine caprylate as the fluorescent probe, which could be hydrolyzed by caprylate esterase liberated from Salmonella lysed by phage, to form strong fluorescent salicylaldazine. The Salmonella could be detected accurately with a low limit of detection of 6 CFU/mL and a broad concentration range of 10-106 CFU/mL. Moreover, this method was successfully used for the rapid detection of Salmonella in milk within 2 h through pre-enrichment by ampicillin-conjugated magnetic beads. The novel combination of fluorescent turn-on probe salicylaldazine caprylate and phage ensures this method has excellent sensitivity and selectivity.

Chemical constituents, clinical efficacy and molecular mechanisms of the ethanol extract of Abelmoschus manihot flowers in treatment of kidney diseases.

Abelmoschus manihot, also called as "Huangkui" in Chinese, is an annual flowering herb plant in the family of Malvaceae. As a traditional Chinese medicine, the ethanol extract of the flower in Abelmoschus manihot is made as Huangkui capsule and has been used for medication of the patients with kidney diseases. Its efficacy in clinical symptoms is mainly improving renal function and reducing proteinuria among the patients with chronic kidney disease, diabetic kidney disease or IgA nephropathy. The possible mechanism of Huangkui capsule treatment in kidney diseases may include reducing inflammation and anti-oxidative stress, improving immune response, protecting renal tubular epithelial cells, ameliorating podocyte apoptosis, glomerulosclerosis and mesangial proliferation, as well as inhibiting renal fibrosis. In this review, we first described chemical constituents and pharmacokinetic characteristics in ethanol extract of the flower of Abelmoschus manihot. We then summarized the clinical and epidemiological relevancies of kidney diseases particularly in the mainland of China and discussed the possible molecular mechanisms of Huangkui capsule in the treatment of kidney diseases. Finally, we prospected further research on cellular and molecular mechanisms and application of this Chinese natural medicine in kidney diseases.

Colorless Silk/Copper Sulfide Hybrid Fiber and Fabric with Spontaneous Heating Property under Sunlight.

With the increasing demand for comfort, thinness, and warmth of fabrics, various functional fibers have emerged. However, natural silkworm silk, as one of the most widely used natural fibers in textile, faces the issue that it cannot be modified during the spinning process like synthetic fibers. Herein, copper sulfide nanoparticles (CuS NPs) with a near-infrared (NIR) absorption property were first prepared by using regenerated silk fibroin (RSF) as the biological template. Then, trace CuS NPs prepared in RSF solution (no more than 100 ppm) were added into the RSF spinning dope to prepare colorless RSF/CuS hybrid fibers via wet-spinning process. The tensile test of the RSF/CuS hybrid fibers showed that the toughness was improved with the addition of CuS NPs, which completely met the requirements of textile development. The temperature of RSF/CuS hybrid fiber bundles could increase 18.5 °C within 3 min under 1064 nm laser irradiation with power density of 1.0 W/cm2. Finally, these RSF/CuS hybrid fiber bundles were woven into silk fabric or embroidered on a cotton fabric. Under the simulated sunlight, the temperature of RSF/CuS fabric could increase to more than 40 °C from room temperature. Also, as per the infrared images, the pattern of embroidery displayed a significant difference in temperature increase as compared to cotton matrix. Based on these results, an almost colorless RSF/CuS hybrid fiber that can be mass produced by wet spinning may have great potential in the fabrication of dyeable, light, and comfortable silk functional fabric with spontaneous heating characteristics under sunlight.

Carbon dots as fluorescent nanoprobe for the determination of N-acetyl-ß-d-glucosaminidase activity.

Carbon dots (CDs) were synthesized from p-aminophenol and ethylenediamine via one-step under mild condition and used as a sensitive fluorescent nanoprobe for the activity determination of N-acetyl-ß-d-glucosaminidase (NAG). In this assay, p-nitrophenol was in situ produced from p-nitrophenyl-ß-D-N-acetyl-glucosaminide, which was exclusively hydrolyzed by NAG. The UV absorption peak of p-nitrophenol (maximum at 400 nm) overlapped the excitation peak of CDs with maximum wavelength at 415 nm, which caused the fluorescence decline of CDs based on inner filter effect. The activity of NAG was determined by the fluorescence changes. The assay is highly sensitive to NAG with a low detection limit of 0.75 U L-1 (K = 3) and showed a good linear relationship in the range from 1 to 45 U L-1. This CDs nanoprobe was successfully applied for the determination of NAG activity in human serum and urine samples.

Qualitative and quantitative analysis of saponins in the flower bud of Panax ginseng (Ginseng Flos) by UFLC-Triple TOF-MS/MS and UFLC-QTRAP-MS/MS.

INTRODUCTION: Ginseng Flos (GF), the flower bud of Panax ginseng, is a worthy functional food with medicinal potential. A few studies have focused on the comprehensive and systematic analysis of its major bioactive constituents. OBJECTIVE: The aims are to develop the methods of ultra-fast liquid chromatography coupled with triple quadrupole-time of flight tandem mass spectrometry (UFLC-Triple TOF-MS/MS) and ultra-fast liquid chromatography coupled with triple quadrupole-linear ion trap tandem mass spectrometry (UFLC-QTRAP-MS/MS) for the qualitative and quantitative analysis of the saponins in GF. METHODOLOGY: UFLC-Triple TOF-MS/MS and UFLC-QTRAP-MS/MS were established for the qualitative and quantitative analysis of the saponins in GF, separately. RESULTS: Fifty-one saponins were identified in GF using UFLC-Triple TOF-MS/MS method; among them, 21 saponins were characterized by comparing with standards. Furthermore, 12 ginsenosides (ginsenoside Re, Rg1 , Rf, 20(S)-Rg2 , 20(R)-Rg2 , Rb1 , Rc, Ro, Rb2 , F1 , Rd, and F2 ) were synchronously determined by UFLC-QTRAP-MS/MS method after the extraction with 70% methanol. This UFLC-QTRAP-MS/MS method showed good linearity (r >0.9991), the interday and intraday precision, repeatability and stability were all satisfied, the average recoveries of standard addition for the compounds were between 94.01% and 105.16%, and the relative standard deviations were less than 5%. CONCLUSION: The results are available for the comprehensive quality control and assessment of GF and its relative products.

Organic polymer dot-based fluorometric determination of the activity of horseradish peroxidase and of the concentrations of glucose and the insecticidal protein toxin Cry1Ab/Ac.

Fluorescent polymer dots (PDs) with maximum excitation/emission wavelengths of 410/515 nm were prepared in water solution from 1,4-benzoquinone and ethylenediamine. The green fluorescence of these PDs is screened off by the red-colored oxidation product (PPDox, maximum absorption at 510 nm) formed by horseradish peroxidase (HRP)-catalyzed oxidation of p-phenylenediamine (PPD). It causes the reduction of the fluorescence intensity of the PDs due to spectral overlap and an inner filter effect (IFE). If glucose is enzymatically oxidized under the formation of H2O2, the formed H2O2 can be quantified by the above IFE. The assay for HRP activity and glucose have detection limits of 0.2 U·L-1 and 0.1 µM, respectively. The nanoprobe was further extended to an immunosorbent assay (ELISA) for the determination of insecticidal Cry1Ab/Ac protein with a detection limit of 0.25 ng·mL-1. The ELISA was applied to rice leaf analysis. Graphic abstract Schematic representation of fluorometrict enzyme-linked immunosorbent assay for Cry1Ab/Ac protein detection based on horseradish peroxidase (HRP)-triggered fluorescence quenching of polymer dots (PDs). Quenching is caused by an inner filter effect (IFE) caused by PPDox, the oxidation product of p-phenylenediamine (PPD).

Alternating Sequence Control for Poly(ester amide)s by Organocatalyzed Ring-Opening Polymerization.

Sequence-controlled polymerization is the forefront of polymer chemistry. Herein, the feasibility of sequence regulation by using organocatalyzed ring-opening polymerization (ROP) is demonstrated. In particular, ring expansion strategy is employed to synthesize pre-organized monomers 1 and 2. ROP is conducted by using 1,5,7-triazabicyclo[4.4.0]dec-5-ene and benzyl alcohol as the catalyst and initiator, respectively. Poly(ester amide)s (PEAs) P1-P3 comprising glycolic acid, lactic acid, and 7-aminoheptanoic acid units are obtained in high molecular weights and good yields. NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry results verify the microstructural integrity of P1 and P2. Differential scanning calorimetry results show that PEA without methyl branches is crystalline. Moreover, thermal stability, surface wettability, and degradation profiles of P1-P3 are also investigated.

The determination of α-glucosidase activity through a nano fluorescent sensor of F-PDA-CoOOH.

A sensitive nanocomplex probe prepared from fluorescent polydopamine nanoparticles (F-PDA) and cobalt oxyhydroxide (CoOOH) nanosheets was established for the determination of α-glucosidase activity. In this detection system, the fluorescence of F-PDA was firstly quenched by CoOOH nanosheets based on fluorescence resonance energy transfer (FRET). Subsequently, ascorbic acid was produced from 2-O-α-d-glucopyranosyl-l-ascorbic acid which was selectively hydrolyzed by α-glucosidase. CoOOH was reduced to Co2+ by the released ascorbic acid, which resulted in the recovery of F-PDA nanoparticles fluorescence. In consequence, α-glucosidase activity was determined by the fluorescence recovery degree of the F-PDA nanoparticle. This fluorescent method showed a good linear relationship with the activity of α-glucosidase from 2 to 80 U L-1 and low detection limit of 1.65 U L-1 (S/N = 3). This fluorescence probe with high selectivity and sensitivity demonstrated a remarkable applicability in human serum samples and provided an alternative for α-glucosidase inhibitors screening in the discovery of anti-diabetes drugs.

Quality Evaluation of Wild and Cultivated Schisandrae Chinensis Fructus Based on Simultaneous Determination of Multiple Bioactive Constituents Combined with Multivariate Statistical Analysis.

Schisandrae Chinensis Fructus, also called wuweizi in China, was a widely used folk medicine in China, Korea, and Russia. Due to the limited natural resources and huge demand of wuweizi, people tend to cultivate wuweizi to protect this species. However, the quality of wild and cultivated herbs of the same species may change. Little attention has been paid to comparing wild and cultivated wuweizi based on simultaneous determination of its active components, such as lignans and organic acids. An analytical method based on UFLC-QTRAP-MS/MS was used for the simultaneous determination of 15 components, including 11 lignans (schisandrin, gomisin D, gomisin J, schisandrol B, angeloylgomisin H, schizantherin B, schisanhenol, deoxyschizandrin, γ-schisandrin, schizandrin C, and schisantherin) and 4 organic acids (quinic acid, d(-)-tartaric acid, l-(-)-malic acid, and protocatechuic acid) in wuweizi under different ecological environments. Principal components analysis (PCA), partial least squares discrimination analysis (PLS-DA), independent sample t-test, and gray relational analysis (GRA) have been applied to classify and evaluate samples from different ecological environments according to the content of 15 components. The results showed that the differential compounds (i.e., quinic acid, l-(-)-malic acid, protocatechuic acid, schisandrol B) were significantly related to the classification of wild and cultivated wuweizi. GRA results demonstrated that the quality of cultivated wuweizi was not as good as wild wuweizi. The protocol not just provided a new method for the comprehensive evaluation and quality control of wild and cultivated wuweizi, but paved the way to differentiate them at the chemistry level.

Synthesis of nitrogen-doped graphene quantum dots (N-GQDs) from marigold for detection of Fe3+ ion and bioimaging.

Graphene quantum dots (GQDs) are synthesized by the method of high-temperature pyrolysis from marigold granules and subsequently nitrogen-doped graphene quantum dots (N-GQDs) are synthesized from ethylenediamine by hydrothermal treatment, which shows a strong blue emission with 7.84% quantum yield (QY). This will be used in detection of Fe3+ in water environments and the field of bioimaging.

[Comparative analysis of multiple index constituents in Ophiopogonis Radix and Liriopes Radix].

An analytical method based on UFLC-QTRAP-MS/MS was established for simultaneous determination of thirty-three components including steroidal saponins, homoisoflavonoids, amino acids and nucleosides in Ophiopogonis Radix. Thirty-three target components of commercial medicinal materials of Maidong were comparative analysis. Synergi™ Hydro-RP 100 column (2.0 mm × 100 mm, 2.5 µm) was used with 0.1% formic acid solution-0.1% formic acid acetonitrile for gradient elution at a flow rate of 0.4 mL·min⁻¹. In addition, multiple reaction monitoring (MRM) mode was employed. The data were comprehensively processed and analyzed with hierarchical clustering analysis(HCA), principal component analysis(PCA) and partial least squares discriminant analysis(PLS-DA) methods. All components showed good linearity(r>0.999 0) within the tested ranges. The average recoveries were between 96.23%-102.0%, and the relative standard deviation(RSD) were less than 5%. The results showed that there were significant differences in components between Ophiopogonis Radix and Liriopes Radix, with seven components obviously different. This method was useful for providing basis for the comprehensive evaluation and intrinsic quality control of Ophiopogonis Radix and Liriopes Radix , and may provide a new method reference for the identification of Ophiopogonis Radix and Liriopes Radix.

[Simultaneous determination of lignans and organic acids in Schisandrae Chinensis Fructus by UFLC-Q-TRAP-MS/MS].

An analytical method based on UFLC-QTRAP-MS/MS was developed for simultaneous determination of fifteen components including eleven lignans (schizantherin B, schisandrol B, schizandrin C, γ-schisandrin, deoxyschizandrin, schisantherin, schisandrin, schisanhenol, gomisin D, gomisin J, and angeloylgomisin H) and organic acids (S)-malic acid, D(-)-tartaric acid, protocatechuic acid, and quinic acid) in Schisandrae Chinensis Fructus. Samples from different product specifications were evaluated and analyzed. The chromatographic separation was performed on a Synergi™ Hydro-RP 100Å column (2.0 mm×100 mm, 2.5 µm) at 40 °C with a gradient elution by employing 0.1% aqueous formic acid (A)-acetonitrile (B) as the mobile phase, and the flow rate was 0.4 mL·min⁻¹, using an electrospray ionization (ESI) source and multiple reaction monitoring (MRM) mode. Fifteen components were evaluated synthetically by TOPSIS and gray related degree. The results showed that fifteen components had good linearity (r>0.999 90), and the limits of detection were all satisfactory. The average recoveries of standard addition for the compounds were between 95.42 % and 98.86 %, and the relative standard deviations were less than 5%. The greatest difference of ri in grey related degree was 58.1%, whilst the greatest difference of Ci value in TOPSIS method was 94.8%. The results of these two methods showed that the holistic quality of No. 14 sample was the best. The developed method was accurate and reliable, which was suitable for the simultaneous determination of multiple functional substances and able to provide a new basis for the comprehensive assessment and overall control of the quality of Schisandrae Chinensis Fructus.

SWOT analysis and revelation in traditional Chinese medicine internationalization.

Traditional Chinese medicine (TCM) is currently the best-preserved and most influential traditional medical system with the largest number of users worldwide. In recent years, the trend of TCM adoption has increased greatly, but the process of TCM internationalization has suffered from a series of setbacks for both internal and external reasons. Thus, the process of TCM internationalization faces formidable challenges, although it also has favourable opportunities. Using SWOT analysis, this paper investigates the strengths, weaknesses, opportunities and threats for TCM. These findings can serve as references for TCM enterprises with global ambitions.

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.

Hyperbranched Aliphatic Polyester via Cross-Metathesis Polymerization: Synthesis and Postpolymerization Modification.

A novel postpolymerization modification methodology is demonstrated to achieve selective functionalization of hyperbranched polymer (HBP). Terminal and internal acrylates of HBP derived from cross-metathesis polymerization (CMP) are functionalized in a chemoselective fashion using the thiol-Michael chemistries. Model reactions between different thiols (benzyl mercaptan and methyl thioglycolate) and acrylates (n-hexyl acrylate and ethyl trans-2-decenoate) by using dimethylphenylphosphine or amylamine as the catalyst are investigated to optimize the modification protocol for HBP. High-molecular-weight HBP P0 is generated through CMP of AB2 monomer 2, a compound containing one α-olefin and two acrylate metathetically polymerizable groups. CMP kinetics is monitored by NMR and gel permeation chromatography (GPC). Accordingly, microstructural analysis is conducted in detail, and CMP procedure is optimized. Postpolymerization modification of HBP P0 is performed via two distinguished strategies, namely one-step complete modification and sequential modification, to generate terminally and/or internally functionalized HBPs P1-P3 in a chemoselective fashion by using phosphine-initiated and/or base-catalyzed thiol-Michael chemistries. Finally, thermal stability and glass transition behaviors of HBPs P0-P3 are studied by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively.

Precision Aliphatic Polyesters with Alternating Microstructures via Cross-Metathesis Polymerization: An Event of Sequence Control.

Sequence-regulated polymerization is realized upon sequential cross-metathesis polymerization (CMP) and exhaustive hydrogenation to afford precision aliphatic polyesters with alternating sequences. This strategy is particularly suitable for the arrangement of well-known monomer units including glycolic acid, lactic acid, and caprolactic acid on polymer chain in a predetermined sequence. First of all, structurally asymmetric monomers bearing acrylate and α-olefin terminuses are generated in an efficient and straightforward fashion. Subsequently, cross-metathesis (co)polymerization of M1 and M2 using the Hoveyda-Grubbs second-generation catalyst (HG-II) furnishes P1-P3, respectively. Finally, hydrogenation yields the desired saturated polyesters HP1-HP3. It is noteworthy that the ε-caprolactone-derived unit is generated in situ rather than introduced to tailor-made monomers prior to CMP. NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) results verify the microstructural periodicity of these precision polyesters. Differential scanning calorimetry (DSC) results reflect that polyesters without methyl side groups exhibit crystallinity, and unsaturated polyester samples show higher glass transition temperatures than their hydrogenated counterparts owing to structural rigidity.

Synthesis of Oxylipin Mimics and Their Antifungal Activity against the Citrus Postharvest Pathogens.

Nine oxylipin mimics were designed and synthesized starting from d-mannose. Their antifungal activity against three citrus postharvest pathogens was evaluated by spore germination assay. The results indicated that all the compounds significantly inhibited the growth of Penicillium digitatum, Penicillium italicum and Aspergillus niger. The compound (3Z,6Z,8S,9R,10R)-octadeca-3,6-diene-8,9,10-triol (3) exhibited excellent inhibitory effect on both Penicillium digitatum (IC50 = 34 ppm) and Penicillium italicum (IC50 = 94 ppm). Their in vivo antifungal activities against citrus postharvest blue mold were tested with fruit inoculated with the pathogen Penicillium italicum. The compound (3R,4S)-methyl 3,4-dihydroxy-5-octyltetrahydrofuran-2-carboxylate (9) demonstrated significant efficacy by reducing the disease severity to 60%. The antifungal mechanism of these oxylipin mimics was postulated in which both inhibition of pathogenic mycelium and stimuli of the host oxylipin-mediated defense response played important roles.

Amino acid-catalyzed formation of 2-vinylfuran from lipid-derived 4-oxo-2-hexenal.

The formation of 2-vinylfuran from the corresponding 4-oxo-2-hexenal (OHE, a lipid oxidation product) under the catalysis of amino acid were studied. The effects of amino acids, reaction temperature, reaction time, water content, pH, metallic ions and some food additives on the formation of 2-vinylfuran were investigated. Amino acids promoted the formation of 2-vinylfuran except aspartic acid, histidine and glutamine. Cysteine showed the strongest catalytic activity among the amino acids tested. Further investigation indicated that the intermediate 1-(furan-2-yl)ethanol played an very important role in the formation of 2-vinylfuran. Both higher temperature and acidic condition favored the transformation of OHE into 2-vinylfuran. The reaction time, water content, metallic ions and food additives also influenced the reaction to certain extent.

Postligation-desulfurization: a general approach for chemical protein synthesis.

Native chemical ligation, involving regioselective and chemoselective coupling of two unprotected peptide segments, enabled the synthesis of polypeptide with more than 200 amino acids. However, cysteine was indispensable in this synthetic technique in its initial format, which limited its further application. Thus, considerable effort has been put into breaking the restriction of cysteine-containing ligation. As a consequence, postligation-desulfurization, concerning thiol-mediated ligation followed by desulfurization, was developed. This review describes the development and recent progress on the chemical synthesis of peptides and proteins encompassing postligation-desulfurization at alanine, valine, lysine, threonine, leucine, proline, arginine, aspartic acid, glutamate, phenylalanine, glutamine, and tryptophan.

Collective synthesis of 4-hydroxy-2-pyridone alkaloids and their antiproliferation activities.

A collective synthesis of 4-hydroxy-2-pyridone alkaloids--specifically, pretenellin B, prebassianin B, farinosone A, militarione D, pyridovericin, and torrubiellone C--has been achieved. Key steps include using a strategic convergent method to synthesize the densely substituted pyridone key intermediate by Suzuki-Miyaura cross-coupling reaction, a divergent synthesis approach of target molecules by aldol condensation of pyridone intermediate with homologous aldehydes, and an iterative synthesis of homologous aldehydes with all-trans-polyene backbones. Interestingly, among the six tumor cell lines investigated, torrubiellone C was found to induce potent and apoptotic inhibitory activities on Jurkat T cells with IC50 values of 7.05 µM. Hence, this approach could potentially contribute to the synthesis of bioactive small-molecule libraries as well as drug discovery.