Aggregation-caused dual-signal response of gold nanoclusters for ratiometric optical detection of cysteine.

Designing ratiometric sensors for cysteine (Cys) monitoring with high accuracy is of great significance for disease diagnosis and biomedical studies. The current ratiometric methods mainly rely on multiplex probes, which not only complicates the operation but also increases the cost, making it difficult for quantitative Cys detection in resource-limited areas. Herein, one-pot prepared gold nanoclusters (Au NCs) that glow red fluorescent were synthesized by employing glutathione as the stabilizer and reducing agent. When Fe3+ is present with Au NCs, the fluorescence is quenched and the scattering is strong because of the aggregation of Au NCs. With introduction of Cys, Cys can efficiently compete with glutathione-modified Au NCs for Fe3+, which leads to increase of fluorescence and decrease of scattering. The ratiometric determination of Cys can be thereby realized by collecting the fluorescence and SRS spectrum simultaneously. The linear range for Cys was 5-30 µM with a detection limit of 1.5 µM. In addition, the sensing system exhibits good selectivity for Cys and shows potential application in biological samples.

Ratiometric optical detection of pyrophosphate based on aggregation-caused dual-signal response of gold nanoclusters.

Sensing of pyrophosphate ion (PPi) has received much attention due to the strong demand for clinical diagnostics. Here, based on gold nanoclusters (Au NCs), a ratiometric optical detection method for PPi is developed by simultaneously detecting the dual signals of fluorescence (FL) and second-order scattering (SOS). The PPi is detected by inhibiting the formation of aggregates of Fe3+ with Au NCs. Binding of Fe3+ to Au NCs causes aggregation of Au NCs, which leads to fluorescence quenching and scattering increasing. The presence of PPi can competitively bind Fe3+ to re-disperse the Au NCs and finally recover the fluorescence and reduce the scattering signal. The designed PPi sensor shows a high sensitivity with a linear range 5-50 µM and a detection limit of 1.2 µM. In addition, the assay has excellent selectivity for PPi, which makes its application in real biological samples extremely valuable.

Exploring the Inhibition of Quercetin on Acetylcholinesterase by Multispectroscopic and In Silico Approaches and Evaluation of Its Neuroprotective Effects on PC12 Cells.

This study investigated the inhibitory mechanism of quercetin in acetylcholinesterase (AChE) and its neuroprotective effects on ß-amyloid25-35-induced oxidative stress injury in PC12 cells. Quercetin inhibited AChE in a reversible mixed manner with an IC50 of 4.59 ± 0.27 µM. The binding constant of quercetin with AChE at 25 °C was (5.52 ± 0.05) × 104 L mol-1. Hydrogen bonding and van der Waals forces were the main interactions in forming the stable quercetin-AChE complex. Computational docking revealed that quercetin was dominant at the peripheral aromatic site in AChE and induced enzymatic allosterism; meanwhile, it extended deep into the active center of AChE and destabilized the hydrogen bond network, which caused the constriction of the gorge entrance and prevented the substrate from entering the enzyme, thus resulting in the inhibition of AChE. Molecular dynamics (MD) simulation emphasized the stability of the quercetin-AChE complex and corroborated the previous findings. Interestingly, a combination of galantamine hydrobromide and quercetin exhibited the synergistic inhibition effect by binding to different active sites of AChE. In a ß-amyloid25-35-induced oxidative stress injury model in PC12 cells, quercetin exerted neuroprotective effects by increasing the glutathione level and reducing the malondialdehyde content and reactive oxygen species levels. These findings may provide novel insights into the development and application of quercetin in the dietary treatment of Alzheimer's disease.

Utilizing dual carriers assisted by enzyme digestion chemiluminescence signal enhancement strategy simultaneously detect tumor markers CEA and AFP.

To measure two tumor biomarkers, alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA), a dual-carrier CL sensor with restriction enzyme digestion (Exo I) and aptamer technology utilizing gold nanoparticles (hydroxylamine amplification) and horseradish peroxidase (HRP) as the CL signal enhancement in the sensing strategy was formed. These nanoparticles and nano-enzyme were precisely detected and tagged to the appropriate position attributable to the particular recognition of biotin and streptavidin. In this sensing strategy, target markers were further enriched and recognized sensitively by CL following enrichment, and matching strong chemical signals were collected under luminol catalysis, allowing for marker identification. For CEA (0.1-80 ng/mL) and AFP (2-500 ng/mL), the proposed method has a large linear range, with detection limits of 36.6 pg/mL and 0.94 ng/mL, respectively.

Antipyretic Mechanism Exploration of HuanglianShangqing Pill Based on Metabolomics and Network Pharmacology.

BACKGROUND AND OBJECTIVE: HuanglianShangqing pill (HLSQ), a well-known traditional Chinese medicine (TCM), has been used to treat fever in China for a long time. Our previous study had demonstrated that a total of 45 prototype components of HLSQ could be absorbed into the plasma of rats after intragastric administration. However, the detailed mechanisms related to the antipyretic effects of HLSQ were still unclear. METHODS: In the present work, urinary metabolomics coupled with network pharmacology were employed to evaluate the mechanisms of HLSQ in the treatment of fever compared with ibuprofen (IBU) and paracetamol (APAP). RESULTS: In pyrexia rats, a total of 11 potential metabolites and a disturbed TCA cycle were found. The metabolic regulation effects of HLSQ on fever rats were similar to APAP and could make the TCA cycle disorder return to normal by reducing citrate, ß-hydroxybutyrate, succinate. In addition, HLSQ could adjust the intestinal microbial disorder and inhibit inflammatory factors, including IL6, TNF, VEGFA, TP53, STAT3, etc. There were 40 components acting on fever targets in HLSQ; among them, luteolin, apigenin, ursolic acid, kaempferol, wogonin, daidzein, baicalein, emodin, berberine, and oroxylin A were the main active compounds of HLSQ in the treatment of fever. CONCLUSION: The antipyretic mechanisms of HLSQ are inhibition of inflammatory factors, action on the TCA cycle, and regulation of gut microbiota.

Synthesis and biological evaluation of aminobenzamides containing purine moiety as class I histone deacetylases inhibitors.

The aminobenzamide is selective to class I histone deacetylases (HDACs) and displays unique tight-binding/slow-off HDAC-binding mechanism. Herein, we report a series of 9-substituted purine aminobenzamides that selectively inhibit class I HDACs. The activities in vitro showed compound 9d exhibited 12 folds more potent than MS-275 against HDAC1 isoform and showed excellent inhibitory activity on cancer cells, including HCT-116, MDA-MB-231, K562 cell lines. The metabolic stability of 9d was much better than that of the well-known HDAC inhibitor SAHA. Pulse exposure test of western blot assay demonstrated that 9a, 9d induced histone acetylation in a similar manner to MS-275. Further biological validation demonstrated that 9d prevented cell transition from G1 phase to S phase by reducing Cyclin D1, CDK2 and lifting p21, induced early apoptosis by upregulating BAX and downregulating Bcl-2 in HCT-116 cells.

Smartphone assisted colorimetric and fluorescent triple-channel signal sensor for ascorbic acid assay based on oxidase-like CoOOH nanoflakes.

Ascorbic acid (AA) is an important diet-derived antioxidant to human body. Thus, efficient and accurate detection of AA is of considerable significance in food analysis. Herein, smartphone assisted colorimetric and fluorescent triple-channel signal sensor has been developed for AA monitoring based on oxidase-like CoOOH nanoflakes. CoOOH nanoflakes can efficiently catalyze the oxidation of p-phenylenediamine (p-PD) into reddish brown p-PDox. The carbon dots (C-dots) are further introduced, of which the fluorescence can be quenched by p-PDox. However, in the presence of AA, the CoOOH nanoflakes is reduced and thus collapsed. As a result, the oxidation of p-PD is restrained, and thus the fluorescence of C-dots keeps strong. Based on AA induced light color, low absorbance, and strong fluorescence, triple-channel signal sensor has been proposed for AA determination. The AA assay shows a dynamic response range from 0.5 to 10 µM with a detection limit of 0.09 µM. The method assay allows detection of AA in real samples such as fruit juices. Combination with portable smartphone, the developed sensor is potential for AA determination in resource-poor settings.

Resonance Rayleigh Scattering as a Tool for Isoelectric Point Monitoring and Iron(III) Cation Determination.

A resonance Rayleigh scattering (RRS) technique was utilized as a tool for isoelectric point monitoring and iron(III) cation determination. The spectral properties of some amphoteric molecules (proteins and a DNA sequence) were investigated using the RRS technique. When the pH values were kept at around their isoelectric points, especially high RRS signals could be obtained, which were much stronger than those at other pH values. By using the C30 DNA sequence as a probe, the iron(III) cation can be detected rapidly. After iron(III) was added to a C30 solution, a significantly decreased RRS signal was obtained. The sensing process can be finished within 10 min with a detection limit of 0.9 µM. Thus, a sensitive, selective, and label-free method was successfully developed for iron(III) detection.

Use of UHPLC-QTOF-MS/MS with combination of in silico approach for distributions and metabolites profile of flavonoids after oral administration of Niuhuang Shangqing tablets in rats.

Niuhuang Shangqing tablet (NHSQT), a well-known traditional Chinese medicine preparation, has been used as an over- the- counter drug for the treatment of headache, dizziness in China. The flavonoids are the main active components in NHSQT, however, there have no reports about their distribution and metabolic fate in vivo after oral administration of NHSQTs so far. An novel UHPLC-QTOF-MS/MS method combined with in silico approach was applied to identify the flavonoids and metabolites profiling in biological samples following oral administration NHSQTs for the first time. As a result, 127 compounds including 34 original compounds of flavonoids and 93 metabolites were identified. There were 20 flavones, 9 flavonols, 4 flavanones and 1 flavan-3, 4-diol found in biological samples. Rutin, wogonoside, apigenin, baicalein, wogonin, oroxylin A, quercetin and acacetin were considered as the potential flavonoids in NHSQT against brain diseases. The docking-based metabolism models were established and applied to propose the sites of hydroxylation of flavonoids, which indicated baicalin was engaged in dihydroxylation at C2', C3', tilianin was engaged in hydroxylation at C3, wogonin and wogonside were engaged in dihydroxylation at C3', C4'. Some novel metabolic pathways were discovered for oroxylin A, acacetin, diosmetin, tilianin. The metabolic spots and pathways of flavonoids vary as much between flavones, flavonols and flavanones. The results presented here would be helpful for the further study of pharmacokinetics and quality control of NHSQT.

Syntheses and Biological Evaluation of Novel Hydroxamic Acid Derivatives Containing Purine Moiety as Histone Deacetylase Inhibitors.

The novel hydroxamates containing purine scaffold were designed, synthesized and screened for their biological activities as histone deacetylase (HDAC) inhibitors. Some of them exhibited excellent acti-HDACs activities and antiproliferative activities, the most promising compound was 7m'. Western blot analysis indicated the compounds 7f', 7l', 7m', 7o' could increase histone H3 acetylation levels in HCT116 and K562 cell lines, and 7m' increased the level of acetyl histone H3 in a dose-dependent manner, which is similar to the behavior of suberoylanilide hydroxamic acid (SAHA). Molecular docking study revealed that the conformation of 7m' in the active site of HDAC2 was similar to positive drug SAHA, which were oriented with the hydroxamic acid towards the catalytic center and formed metal binding with zinc ion.

Identification of the constituents and metabolites in rat plasma after oral administration of HuanglianShangqing pills by ultra high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.

An ultra high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry method was established to detect and identify the chemical constituents and metabolites of HuanglianShangqing pill (HLSQ) in vitro and in vivo. A total of 96 compounds were characterized in HLSQ extracts. In vivo, 45 prototype components and 53 metabolites of HLSQ were detected in rat plasma and tentatively identified, three of which are new. The novel metabolic pathways of rhein and hesperetin were revealed. The bioactive compounds of HLSQ undergo phase I metabolic routes of hydrogenation, hydroxylation, hydrolysis, demethylation and phase II metabolic routes of glucuronide, sulfation, acetylation and methylation. Among these, glucuronide conjugation is the main metabolic pathway of the active compounds of HLSQ in rat plasma.

Synthesis, Anticancer Evaluation and Docking Study of 3- Benzyloxyhydantoin Derivatives.

A series of 3-benzyloxyhydantoin derivatives were designed and synthesized by introducing hydroxyurea pharmacophore into hydantoin rigid scaffold. The cytotoxic activities of the target compounds were evaluated in vitro against three cancer cell lines. Compounds 5b, 5c, 5e, 5g, 6c and 6g displayed high activity on all of the three cancer cell lines and the most promising compounds were 5g, 6g with IC50 values of 0.04 and 0.01µM. Binding of derivatives for the ribonucleotide reductase (RR) was investigated by use of molecular docking studies. Our findings show that modification at the C5 position of hydantoin with isopropyl or isobutyl was favorable to increasing binding affinity to the active site of the RR receptor and antiproliferative activity.

[Study on HPLC Fingerprint of Kanggongyan Series].

OBJECTIVE: To establish analysis methods for fingerprint of Kanggongyan series by HPLC. METHODS: A Shiseido CAP-CELL PAK C18(250 mm x 4. 6 mm, 3 µm) column was used with acetonitrile-0. 5% phosphoric acid as the mobile phase by gradient elution. The flow rate was 0. 8 mL/min, the column temperature was 30 °C, and the detection wavelength was set at 280 nm during 0 ~ 44 min and at 332 nm during 44 ~ 115 min. RESULTS: Ten common peaks were selected as characteristic peaks in the chromatogram of Kanggongyan particles, eleven common peaks were selected as characteristic peaks in the chromatogram of Kanggongyan tablets and capsules ,the similarities were greater than 0. 9 among all batches. CONCLUSION: The method is simple, steady and repeatable. It provides a basis for the quality control of Kanggongyan series.

Synthesis and anticancer evaluation of benzyloxyurea derivatives.

A series of novel benzyloxyurea derivatives was designed, synthesized by substituting different benzyls or phenyls on N,N'-positions of the hydroxyurea (HU). These target compounds were evaluated for their anticancer activity in vitro against human leukemia cell line K562 and murine leukemia cell line L1210 in comparison with HU by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Some of the compounds showed promising anticancer activity against the cells. Molecular docking experiments with Saccharomyces cerevisiae R1 domain indicated that 4a and 4f' have stronger affinity than 4m and 4n. Flow cytometry study showed that compound 4g exerted greater apoptotic activity against K562 cells line than HU.

[Chemical constituents of the roots of Vaccinium bracteatum].

OBJECTIVE: To study the chemical constituents of the roots of Vaccinium bracteatum. METHODS: The constituents were separated and purified with chromatographic methods (including silica gel, Sephadex LH-20 and RP-18 column chromatography), and their structures were determined by spectroscopic methods (including MS, 1H-NMR and 13C-NMR). RESULTS: 10 compounds were isolated from the roots of Vaccinium bracteatu and were elucidated as chlorogenic acid (1), pinoresinol (2), ferulic acid (3), kaempferol (4), trans-caffeic acid (5), beta-sitosterol (6), quercetin (7), oleanolic acid (8), apigenin (9) and luteolin (10). CONCLUSION: Compounds 1 -3 are obtained from this plant for the first time.

[FTIR fingerprints-chemical pattern recognition research of three kinds of Chimonanthus and fried samples].

OBJECTIVE: To classify the leaves of Chimonanthus nitens, Chimonanthus Salicifolius, Chimonanthus zhejiang and their fried samples, Discriminating equation was established to distinguish categories of raw materials. METHODS: The spectra of three kinds of Chimonanthus and fried samples were determined by FTIR. Principal component analysis, clustering analysis and discriminative analysis were applied to classify three kinds of Chimonanthus leaves and fried samples from different areas according to the relative absorbance of common peaks between 400 to 4000 cm(-1). RESULTS: 26 samples were divided into four classes, the discriminating accuracy was 96%. CONCLUSION: The method is rapid, simple and could be applied to evaluate the quality of Chimonanthus leaves without damaging to sample, and it is easy to identify the adulteration.

[Analysis of the chemical constituents of essential oil from Chimonanthus zhejiangensis by GC-MS].

OBJECTIVE: To analyze the chemical constituents of the essential oil from Chimonanthus zhejiangensis. METHODS: Steam distillation was employed to extract volatile compounds of essential oil from Chimonanthus zhejiangensis. Volatile compounds of essential oil were isolated and identified by capillary GC-MS-DS. RESULTS: 37 components were separated and 33 components were successfully identified. CONCLUSION: The main components were 1,4-Cineole (46.20%), 1,5,9-Undecatriene, 2,6, 10-trimethyl-, (Z)-(9.71%), Cyclohexane, 3,4-bis (1-methylethenyl) -1, 1-dimethyl-(7.42%), Trioctylamine (6.44%), alpha-Terpinyl propionate (4.01%), alpha-Pinene (3.92%).

Synthesis, antitumor evaluation and crystal structure of hydroxyurea derivatives.

A series of hydroxyurea derivatives have been synthesized and elucidated by means of FT-IR, (1)H-, (13)C-NMR and MS. The exact stereostructures of representative compounds have been determined by X-ray crystal structure analysis. In the crystals, inversion dimers linked by pairs of N-H...O hydrogen bonds occurred, and further N-H...O links led to chains of molecules. In vitro antitumor activities against Tca8113 human tongue cancer cells and L1210 murine leukemia cells were evaluated. A total of 8 of the 12 compounds had higher inhibitory activities than hydroxyurea against L1210 cells. Among them, the most promising compounds were 3e, 3d, 3a and 2d.

Synthesis of 1,3,4-thiadiazole derivatives as aminopeptidase N inhibitors.

Aminopeptidase N (APN) is a zinc-dependent ectopeptidase which plays an important role in the invasion of metastatic tumors. In this study, we report the synthesis and in vitro enzyme inhibition assay of 1,3,4-thiadiazole scaffold compounds. These new compounds have potent inhibitory activities toward APN with IC50 values in the micromolar range.

1-(3-Chloro-benz-yloxy)urea.

The asymmetric unit of the crystal structure of the title compound, C(8)H(9)ClN(2)O(2), contains four independent mol-ecules. The dihedral angles between the urea N-(C=O)-N planes and the benzene rings are 83.3 (3), 87.8 (1), 89.1 (1) and 17.5 (2)° in the four mol-ecules. Extensive N-H⋯O hydrogen bonding is present in the crystal structure.