Asiatic acid and madecassic acid cause cardiotoxicity via inflammation and production of excessive reactive oxygen species in zebrafish.

Centella asiatica (L.) Urban is a famous Chinese traditional medicine, which is widely used for treating various chronic inflammatory diseases. Although there are reports that Centella total glycosides exhibit heart-protective properties, our previous experiment showed that it has cardiac toxic effects in zebrafish. The components of Centella total glycosides are complex, so we recommend further research to determine their key components and mechanisms. In this study, sample quantification was done using liquid chromatography-tandem mass spectrometry. The cardiotoxicity of Centella total glycosides, asiaticoside, madecassoside, asiatic acid, and madecassic acid was evaluated using zebrafish and cell models. The zebrafish oxidative stress model and myocarditis model were used to explore further the mechanisms through which cardiotoxicity is achieved. Asiatic acid and madecassic acid caused zebrafish cardiotoxicity and H9C2 cell death. However, no toxicity effects were observed for asiaticoside and madecassoside in zebrafish, until the solution was saturated. The results from the cell model study showed that asiatic acid and madecassic acid changed the expression of apoptosis-related genes in myocardial cells. In the zebrafish model, high concentrations of these components raised the levels of induced systemic inflammation, neutrophils gathered in the heart, and oxidative stress injury. Asiatic acid and madecassic acid are the main components causing cardiotoxicity in zebrafish. This may be due to enhanced inflammation and reactive oxygen species injury, which causes myocardial cell apoptosis, which further leads to cardiac toxicity.

Glabrol impurity exacerbates glabridin toxicity in zebrafish embryos by increasing myofibril disorganization.

ETHNOPHARMACOLOGICAL RELEVANCE: Glabridin, extracted from Glycyrrhiza glabra L., is widely used for the treatment of hyperpigmentation because of its anti-inflammatory and antioxidant activities and its ability to inhibit melanin synthesis. This led to the strict regulation of its quality and safety. However, traditional quality control methods used for plant extracts cannot reflect the product quality owing to multiple unknown impurities, which necessitates the further analysis of impurities. AIM OF THE STUDY: The study identified the toxic impurities of glabridin and their toxicological mechanism. MATERIALS AND METHODS: In total, 10 glabridin samples from different sources were quantified using high-performance liquid chromatography. Sample toxicities were evaluated using zebrafish and cell models. To identify impurities, samples with different toxicity were analyzed by ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry. The toxicity of related impurities was verified in the zebrafish model. Phalloidin stain was used to evaluate subtle changes in myofibril alignment. RESULTS: Although glabridin content in the samples was similar, there were significant differences in toxicity. The results were verified using four different mammalian cell lines. Higher contents of glabrone and glabrol were identified in the sample with the highest toxicity. In the zebrafish model, the addition of glabrol reduced the LC50 of glabridin to 9.224, 6.229, and 5.370 µM at 48, 72, and 96 h post-fertilization, respectively, whereas glabrone did not have any toxic effect. Phalloidin staining indicated that a glabrol impurity exacerbates the myotoxicity of glabridin in zebrafish embryos. CONCLUSION: Glabrol, but not glabrone, was identified as a key impurity that increased glabridin toxicity. This finding indicates that controlling glabrol content is necessary during glabridin product production.

Identification and characterization of microRNAs in phloem and xylem from ramie (Boehmeria nivea).

Ramie (Boehmeria nivea) is a widely cropped species in southern China due to its high economic value of natural fiber for industry. Development of phloem and xylem is key evidence for generating fiber. However, the MicroRNA (miRNA) profiles of phloem and xylem in ramie have not been reported yet. miRNA belong to a small RNA family which has been recognized as an important regulator for various biological processes. In the present study, we aimed to identify differently expressed miRNAs between phloem and xylem in adult ramie. The results showed that 137 and 122 unique conserved miRNAs were identified from phloem and xylem libraries, respectively. Meanwhile, 4 novel miRNAs were identified from ramie by miRDeep2. Of these miRNAs, 77 conserved miRNAs in ramie were differentially expressed. Among the differentially expressed miRNAs, 44 miRNAs and 33 miRNAs were up-regulated and down-regulated in phloem compared to that in xylem, respectively. The functions of differentially expressed miRNAs were associated with regulating the development and differentiation of phloem and xylem. The present study provides a glance of miRNA profiles for further understanding of miRNA role in ramie development.

Correlation Analysis of Lignin Accumulation and Expression of Key Genes Involved in Lignin Biosynthesis of Ramie (Boehmeria nivea).

The phloem of the stem of ramie (Boehmeria nivea) is an important source of natural fiber for the textile industry. However, the lignin content in the phloem affects the quality of ramie phloem fiber. In this study, the lignin content and related key gene expression levels were analyzed in the phloem and xylem at different developmental periods. The results showed that the relative expression levels of lignin synthesis-related key genes in the xylem and phloem of the stem gradually decreased from the fast-growing period to the late maturation period, but the corresponding lignin content increased significantly. However, the relative expression levels of a few genes were the highest during the maturation period. During all three periods, the lignin content in ramie stems was positively correlated with the expression of genes, including PAL, C4H and 4CL1 in the phenylpropanoid pathway, F5H and CCoAOMT in the lignin-specific synthetic pathway, and CAD in the downstream pathway of lignin synthesis, but the lignin content was negatively correlated with the expression of genes including 4CL3 in the phenylpropanoid pathway and UDP-GT in the shunt pathway of lignin monomer synthesis. The ramie 4CL3 recombinant protein prefers cinnamic acid as a substrate during catalysis, and it negatively regulates lignin synthesis. It is speculated that ramie 4CL3 is mainly involved in the synthesis of ramie flavonoid compounds, and that 4CL1 is mainly involved in lignin synthesis.

Electrochemical Reduction of CO2 on Hollow Cubic Cu2O@Au Nanocomposites.

Surfactant-free and low Au loading Cu2O@Au and Au hollow cubes, based on electrodeposited Cu2O cubes as sacrificed templates, were prepared by means of a galvanic replacement reaction (GRR). The electrocatalytical performance of the as-prepared catalysts towards carbon dioxide (CO2) electrochemical reduction was evaluated. The experimental results show that Cu2O@Au catalyst can convert CO2 to carbon monoxide (CO) with a maximum Faradaic efficiency (FE) of ~ 30.1% at the potential of - 1.0 V (vs. RHE) and is about twice the FE of the other catalysts at the same potential. By comparison, such electrocatalytical enhancement is attributed to the metal-oxide interface in Cu2O@Au.

The effects of long-term low selenium diet on the expression of CHST-3, CHST-12 and UST in knee cartilage of growing rats.

OBJECTIVES: To investigate the effect of low selenium diet on rat´s knee cartilage and expression of chondroitin sulfate (CS) sulfated enzymes in articular and epiphyseal-plate cartilage of rats' femur and tibia. METHODS: Twenty-four SD rats were randomly divided into two groups with six female and six male in each group: control group (selenium 0.18 mg/kg), and low selenium group (selenium 0.02 mg/kg). After 109 days, the rats were sacrificed. The ultrastructural changes in chondrocytes of rat knee cartilage were observed by transmission electron microscopy (TEM). The morphology and pathology changes of knee cartilage were examined by hematoxylin-eosin (HE) and toluidine blue (TB) staining. The localization and expression of enzymes involved in CS sulfation, including chondroitin 6-O-sulfotransferase 1 (CHST-3), chondroitin 4-O-sulfotransferase 2 (CHST-12) and uronyl 2-O-sulfotransferase (UST) were examined by immunohistochemical staining and semi-quantitative analysis. RESULTS: In low selenium group, ultrastructural changes of chondrocytes were observed in articular cartilage of femur (AF), articular cartilage of tibia (AT), epiphyseal-plate cartilage of femur (EF) and epiphyseal-plate cartilage of tibia (ET); however, no significant changes in chondrocytes number were observed in the above AF, AT, EF or ET. Moreover, reduced thickness of cartilage layer in AF, EF and ET was detected along with reduced staining areas of sulfated glycosaminoglycan in EF and ET in low selenium group. In addition, positive staining rate of CHST-3 was lower in AF, AT and EF, while positive staining rates of CHST-12 and UST were lower in AF, AT, EF and ET in low selenium group when compared with control group. CONCLUSIONS: Low selenium undermines the ultrastructure of chondrocytes, inhibits the normal development of cartilage and the expression of CS sulfated enzymes.

An enzyme-free and label-free fluorescent biosensor for small molecules by G-quadruplex based hybridization chain reaction.

An enzyme-free and label-free fluorescent biosensor is developed by G-quadruplex-based hybridization chain reaction (HCR) for small molecules, using adenosine triphosphate (ATP) as the model. Aptamer probes for the recognition of small molecules are hybridized with blocking probes. The G-quadruplex sequences are incorporated into one of the two HCR hairpin probes. In the presence of small molecules (ATP), the formation of aptamer-ATP bioaffinity complexes induces the release of blocking probes; the released blocking probes initiate HCR and numerous G-quadruplexes along DNA nanowires are self-assembled after the HCR process. Using N-methyl mesoporphyrin IX (NMM) as the fluorophore, a "turn-on" fluorescence response can be achieved and detected as low as 15 µmol L(-1) of ATP. This biosensor is applied to detect ATP in biologic samples with satisfactory results.

Label-free and enzyme-free sensitive fluorescent detection of human immunodeficiency virus deoxyribonucleic acid based on hybridization chain reaction.

A label-free and enzyme-free sensitive fluorescent detection of human immunodeficiency virus (HIV) deoxyribonucleic acid (DNA) based on isothermal hybridization chain reaction (HCR) was developed. A G-quadruplex sequence which was incorporated into one of the two hairpin probes was inactive in the absence of target DNA. However, at the presence of target DNA numerous G-quadruplexes along DNA nanowires were self-assembled through HCR. Using N-methyl mesoporphyrin IX (NMM) as the fluorophore, a "turn-on" fluorescent response would be achieved and detected as low as 0.5 nmol L(-1) of HIV DNA. This proposed method was applied to detect HIV DNA in biologic samples with satisfactory results.

Transcriptome sequencing and profiling of expressed genes in phloem and xylem of ramie (Boehmeria nivea L. Gaud).

Ramie (Boehmeria nivea L. Gaud) is a highly versatile herbaceous plant which is widely cropped in southern China. The success of this herbaceous plant relies on wide use in modern industry. Understanding the profiling of expressed genes in phloem and xylem of ramie is crucial for improving its industrial performance. Herein, we uncover the transcriptome profile in phloem and xylem in present study. Using Illumina paired-end sequencing technology, 57 million high quality reads were generated. De novo assembly yielded 87,144 unigenes with an average length of 635 bp. By sequence similarity searching for public databases, a total of 32,541 (41.77%) unigenes were annotated for their function. Among these genes, 57,873 (66.4%) and 28,678 (32.9%) unigenes were assigned to categories of Gene Ontology and Orthologous Groups database, respectively. By searching against the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG), 18,331 (21.0%) unigenes were mapped to 125 pathways. The metabolic pathways were assigned the most unigene (4,793, 26.2%). Furthermore, Pol II and Pol III subunits as well as the genes of Galactose metabolism pathway had higher expression in phloem compared to xylem. In addition, fatty acid metabolism pathway genes showed more abundant in xylem than phloem. These results suggest that high activities of RNA synthesis and Galactose metabolism pathway promises fiber synthesis in phloem. The present study is the initial exploration to uncover the fiber biosynthesis difference between phloem and xylem in ramie through the analysis of deep sequencing data.

Visual detection of blood glucose based on peroxidase-like activity of WS2 nanosheets.

Tungsten disulfide (WS2) nanosheets were discovered to possess intrinsic peroxidase-like activity and catalyze the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) to produce a color reaction in the presence of H2O2. Based on this finding, a colorimetric method and a portable test kit for the visual detection of blood glucose have been developed by using glucose oxidase (GOx) and WS2 nanosheets-catalyzed reactions. The linear range for glucose was ranged from 5 to 300 µM (R(2)=0.999) with the detection limit of 2.9 µM. The portable test kit was successfully evaluated glucose levels in serum samples from normal persons and diabetes persons by the observable color change from pale yellow to yellow-green, blue-green.

Graphite-like carbon nitrides as peroxidase mimetics and their applications to glucose detection.

g-C3N4 was found to possess intrinsic peroxidase-like activity, and could catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction. Using g-C3N4 peroxidase-like catalytic activity and glucose oxidase (GOx), a colorimetric method for glucose detection in serum samples has been developed. The linear range for glucose was from 5 to 100 µM (R(2)=0.9987) and the limit of detection was as low as 1.0 µM. The proposed method was applied to detect glucose in serum samples by the naked eyes.

Mussel-inspired polydopamine coated mesoporous silica nanoparticles as pH-sensitive nanocarriers for controlled release.

A novel pH-sensitive controlled release system is proposed by using mussel-inspired polydopamine (PDA) coated mesoporous silica nanoparticles (MSNs) as nanocarriers. MSNs with a large pore diameter are synthesized by using 1,3,5-trimethylbenzene as a pore-expanding agent and are modified with a PDA coating by virtue of oxidative self-polymerization of dopamine in neutral pH. PDA coated MSNs are characterized by FTIR, TEM, N2 adsorption and XPS techniques. The PDA coating can work as pH-sensitive gatekeepers to control the release of drug molecules from MSNs in response to the pH-stimulus. Doxorubicin (DOX, an anticancer drug) can be released in the acid media and blocked in the neutral media.

Amplified colorimetric detection of mercuric ions through autonomous assembly of G-quadruplex DNAzyme nanowires.

An amplified colorimetric detection of Hg(2+) is proposed by combining T-Hg(2+)-T base pairs and hybridization chain reaction (HCR). Two hairpins consisting of three-fourths and one-fourth of the horseradish peroxidase (HRP)-mimicking DNAzyme in inactive configuration are used as functional elements. In the presence of Hg(2+), one of the hairpins is opened by an assistant probe with the help of T-Hg(2+)-T base pairs and this triggers an autonomous cross-opening of the two hairpins using the strand displacement principle, resulting in the formation of DNA nanowires consisting of numerous reunited Q-quadruplex DNAzyme units. The resulting catalytically active hemin/G-quadruplex HRP-mimicking DNAzymes catalyze the oxidation of ABTS(2-) by H2O2 into a green-colored cationic radical ABTS(•+) for the colorimetric readout. This "turn-on" sensing system enables the high sensitive and selective detection of aqueous Hg(2+) with a detection limit of 9.7 pM.

Binding of dihydromyricetin and its metal ion complexes with bovine serum albumin.

The binding mechanisms of the interaction of three dihydromyricetin (DMY)-metal complexes (DMY-Cu (II) complex, DMY-Mn (II) complex, DMY-Zn (II) complex) and DMY with bovine serum albumin (BSA) were investigated using fluorescence and ultraviolet spectroscopy at different temperatures. The results indicated some differences in the binding process between different DMY-metal complexes and BSA compared with that of free DMY. All of the complexes and DMY quenched the fluorescence of BSA based on static mode combined with radiationless energy transfer, yet having different binding distance based on the Förster theory. Different DMY-metal complexes can change the binding constants. The binding constants increase for DMY-Cu (II) and DMY-Mn (II) complexes, whereas the opposite is true for the DMY-Zn (II) complex compared to the one with free DMY. The DMY-metal complexes can also affect the types of the interaction. The van der Waals forces and hydrogen bonding may play a major role in the interaction of free DMY with BSA, while for the three complexes, the nature of the binding forces lies in hydrophobic forces and hydrogen bonding based on the thermodynamic parameters.

A pH-responsive controlled release system using layered double hydroxide (LDH)-capped mesoporous silica nanoparticles.

A pH-responsive controlled release system is proposed using acid-decomposable layered double hydroxides (LDHs) as inorganic nanovalves by virtue of the electrostatic adsorption of LDH nanosheets on the surface of mesoporous silica nanoparticles (MSNs). Guest molecules (Ru(bpy)3Cl2 in this case) are loaded and encapsulated in a neutral environment. The dissolution of the LDH coatings in an acidic environment triggers the release of the guest molecules from the MSNs.