Physical-Chemical Coupling Coassembly Approach to Branched Magnetic Mesoporous Nanochains with Adjustable Surface Roughness

Self-assembly processes triggered by physical or chemical driving forces have been applied to fabricate hierarchical materials with subtle nanostructures. However, various physicochemical processes often interfere with each other, and their precise control has remained a great challenge. Here, in this paper, a rational synthesis of 1D magnetite-chain and mesoporous-silica-nanorod (Fe3O4&mSiO2) branched magnetic nanochains via a physical-chemical coupling coassembly approach is reported. Magnetic-field-induced assembly of magnetite Fe3O4 nanoparticles and isotropic/anisotropic assembly of mesoporous silica are coupled to obtain the delicate 1D branched magnetic mesoporous nanochains. The nanochains with a length of 2-3 µm in length are composed of aligned Fe3O4@mSiO2 nanospheres with a diameter of 150 nm and sticked-out 300 nm long mSiO2 branches. By properly coordinating the multiple assembly processes, the density and length of mSiO2 branches can well be adjusted. Because of the unique rough surface and length in correspondence to bacteria, the designed 1D Fe3O4&mSiO2 branched magnetic nanochains show strong bacterial adhesion and pressuring ability, performing bacterial inhibition over 60% at a low concentration (15 µg mL-1). This cooperative coassembly strategy deepens the understanding of the micro-nanoscale assembly process and lays a foundation for the preparation of the assembly with adjustable surface structures and the subsequent construction of complex multilevel structures.

Identification of a broad sarbecovirus neutralizing antibody targeting a conserved epitope on the receptor-binding domain

Omicron, as the emerging variant with enhanced vaccine tolerance, has sharply disrupted most therapeutic antibodies. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) belongs to the subgenus Sarbecovirus, members of which share high sequence similarity. Herein, we report one sarbecovirus antibody, 5817, which has broad-spectrum neutralization capacity against SARS-CoV-2 variants of concern (VOCs) and SARS-CoV, as well as related bat and pangolin viruses. 5817 can hardly compete with six classes of receptor-binding-domain-targeted antibodies grouped by structural classifications. No obvious impairment in the potency is detected against SARS-CoV-2 Omicron and subvariants. The cryoelectron microscopy (cryo-EM) structure of neutralizing antibody 5817 in complex with Omicron spike reveals a highly conserved epitope, only existing at the receptor-binding domain (RBD) open state. Prophylactic and therapeutic administration of 5817 potently protects mice from SARS-CoV-2 Beta, Delta, Omicron, and SARS-CoV infection. This study reveals a highly conserved cryptic epitope targeted by a broad sarbecovirus neutralizing antibody, which would be beneficial to meet the potential threat of pre-emergent SARS-CoV-2 VOCs.

RBD class 1 and 2 antibody epitopes elicit around 70% neutralizing capacity against SARS-CoV-2 virus following boosting with inactivated virus vaccine

A third dose of inactivated virus vaccine (IVV) boosts neutralizing antibodies, reducing SARS-CoV-2 transmission rate and COVID-19 severity. However, the impact of RBD-elicited antibodies and their neutralizing activity by the boost of IVV is unknown. We investigated the impact of IVV's boost shot on RBD-elicited antibodies and their neutralizing activity in 18 subjects receiving the second and third IVV doses. Using an RBD antibodies depletion assay, we assessed the neutralizing activity of RBD-elicited antibodies. After the second dose, RBD-antigen elicitation accounted for ∼60% of neutralizing activity, which increased to 82% after the IVV boost against ancestral SARS-CoV-2. Depleting class 3 and class 4-specific antibodies with the Beta-RBD protein revealed that NAbs targeting RBD class 1 and class 2 subdomains increased from 57% to 75% post-boost. These findings highlight the significant enhancement of RBD-specific antibodies, especially against RBD class 1 and class 2, with IVV booster doses. Our study offers valuable insights for optimizing COVID-19 vaccine strategies.

Individual bat virome analysis reveals co-infection and spillover among bats and virus zoonotic potential

Bats are reservoir hosts for many zoonotic viruses. Despite this, relatively little is known about the diversity and abundance of viruses within individual bats, and hence the frequency of virus co-infection and spillover among them. We characterize the mammal-associated viruses in 149 individual bats sampled from Yunnan province, China, using an unbiased meta-transcriptomics approach. This reveals a high frequency of virus co-infection (simultaneous infection of bat individuals by multiple viral species) and spillover among the animals studied, which may in turn facilitate virus recombination and reassortment. Of note, we identify five viral species that are likely to be pathogenic to humans or livestock, based on phylogenetic relatedness to known pathogens or in vitro receptor binding assays. This includes a novel recombinant SARS-like coronavirus that is closely related to both SARS-CoV and SARS-CoV-2. In vitro assays indicate that this recombinant virus can utilize the human ACE2 receptor such that it is likely to be of increased emergence risk. Our study highlights the common occurrence of co-infection and spillover of bat viruses and their implications for virus emergence.

Spike substitution T813S increases Sarbecovirus fusogenicity by enhancing the usage of TMPRSS2

SARS-CoV Spike (S) protein shares considerable homology with SARS-CoV-2 S, especially in the conserved S2 subunit (S2). S protein mediates coronavirus receptor binding and membrane fusion, and the latter activity can greatly influence coronavirus infection. We observed that SARS-CoV S is less effective in inducing membrane fusion compared with SARS-CoV-2 S. We identify that S813T mutation is sufficient in S2 interfering with the cleavage of SARS-CoV-2 S by TMPRSS2, reducing spike fusogenicity and pseudoparticle entry. Conversely, the mutation of T813S in SARS-CoV S increased fusion ability and viral replication. Our data suggested that residue 813 in the S was critical for the proteolytic activation, and the change from threonine to Serine at 813 position might be an evolutionary feature adopted by SARS-2-related viruses. This finding deepened the understanding of Spike fusogenicity and could provide a new perspective for exploring Sarbecovirus' evolution.

Comparative global B cell receptor repertoire difference induced by SARS-CoV-2 infection or vaccination via single-cell V(D)J sequencing

Dynamic changes of the paired heavy and light chain B cell receptor (BCR) repertoire provide an essential insight into understanding the humoral immune response post-SARS-CoV-2 infection and vaccination. However, differences between the endogenous paired BCR repertoire kinetics in SARS-CoV-2 infection and previously recovered/naïve subjects treated with the inactivated vaccine remain largely unknown. We performed single-cell V(D)J sequencing of B cells from six healthy donors with three shots of inactivated SARS-CoV-2 vaccine (BBIBP-CorV), five people who received the BBIBP-CorV vaccine after having recovered from COVID-19, five unvaccinated COVID-19 recovered patients and then integrated with public data of B cells from four SARS-CoV-2-infected subjects. We discovered that BCR variable (V) genes were more prominently used in the SARS-CoV-2 exposed groups (both in the group with active infection and in the group that had recovered) than in the vaccinated groups. The VH gene that expanded the most after SARS-CoV-2 infection was IGHV3-33, while IGHV3-23 in the vaccinated groups. SARS-CoV-2-infected group enhanced more BCR clonal expansion and somatic hypermutation than the vaccinated healthy group. A small proportion of public clonotypes were shared between the SARS-CoV-2 infected, vaccinated healthy, and recovered groups. Moreover, several public antibodies had been identified against SARS-CoV-2 spike protein. We comprehensively characterize the paired heavy and light chain BCR repertoire from SARS-CoV-2 infection to vaccination, providing further guidance for the development of the next-generation precision vaccine.

Biodegradation Mn-CoS@carbon di-shell nanoheterostructure with enhanced nanozyme-mediated phototherapy

The efficacy of phototherapy is dependent on intracellular O₂ concentration and NIR harvest. Here, a simple nanoplatform with nanoenzyme mediated phototherapy enhances anticancer capacity. Mn-CoS@carbon (CMS/C) di-shell hollow nanospheres (50 nm) are synthesized successfully through two-step consecutive Kirkendall process. The nanoheterostructure reveals the higher near-infrared (NIR) light absorption and photothermal conversion rate of 66.3% than pure CoS (45.5%), owing to the decreased band gap and multi-reflection of incident light in the hollow structure. And CMS/C reveals the reactive oxygen species (ROS) production and nanoenzyme activities (mimic peroxidase and catalase) that are 6 and 2 times than those of pure CoS. Furthermore, the nanoenzyme exhibits NIR-enhanced abilities to produce more OH and O₂ facilitating anticancer. In addition, it also depletes glutathione (mimicking glutathione oxidase), to disturb intracellular redox-homeostasis, boosting the increase of oxidative stress. With grafting bovine serum albumin (BSA) and drug loading, CMS/C@BSA-Dox integrated multi-therapy make the great anticancer effect in vitro and vivo. After that, the nanocomposite could be biodegraded and eliminated via urinary and feces within 14 days. Based on this work, the efficient charge-separation can be designed to reveal high performance nanoenzymes as well as photosensitizers for anticancer.

Convergent synthesis of 2-thioether-substituted (N)-methanocarba-adenosines as purine receptor agonists

A linear route has been used to prepare (N)-methanocarba-nucleoside derivatives, which serve as purine receptor ligands having a pre-established, receptor-preferred conformation. To introduce this rigid ribose substitute, a Mitsunobu reaction of a [3.1.0]bicyclohexane 5′-trityl intermediate 3 with a nucleobase is typically followed by functional group modifications. We herein report an efficient scalable convergent synthesis for 2-substituted (N)-methanocarba-adenosines, which were demonstrated to bind to the A₃ adenosine receptor. The adenine moiety was pre-functionalized with 2-thioethers and other groups before coupling to the bicyclic precursor (3) as a key step to facilitate a high yield Mitsunobu product. This new approach provided the (N)-methanocarba-adenosines in moderate to good yield, which effectively increased the overall yield compared to a linear synthesis and conserved a key intermediate 3 (a product of nine sequential steps). The generality of this convergent synthesis, which is suitable as an optimized preclinical synthetic route, was demonstrated with various 2-thioether and 2-methoxy substituents.

Enabling efficient synthesis of rigid methanocarba nucleotides and nucleosides as clinically promising purinergic receptor ligands.

Immobilizing of palladium on melamine functionalized magnetic chitosan beads: A versatile catalyst for p-nitrophenol reduction and Suzuki reaction in aqueous medium

In this study, an environmental-friendly palladium catalyst with high efficiency, magnetic, recoverability, reusability, and excellent stability was prepared and thoroughly characterized by the Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), X-ray diffraction (XRD), Elemental mapping, Thermogravimetric analysis (TGA) and Energy-dispersive X-ray spectroscopy (EDX). Results demonstrates that melamine provides a coordination point on the surface of chitosan microspheres, which provides a platform for the uniform distribution of palladium (II) and combines with palladium (II) firmly to avoid unnecessary leaching of nanoparticles. Besides, Fe₃O₄/CS-Me@Pd microcapsules exhibited high catalytic performance in reducing p-NP in water at room temperature (150-300 s). This composite was also effective in the Suzuki-Miyaura coupling reaction under mild conditions with high catalytic performance (TON = 3.8 × 10⁴, TOF = 7.6 × 10⁴). Reproducibility experiments also showed that Fe₃O₄/CS-Me@Pd microcapsules have high recovery efficiency and can work at least six times during these two catalytic reactions. The hot filtration test indicated that the catalyst has heterogeneous nature.

Extracellular vesicles promote esophageal cancer progression by delivering lncZEB1-AS1 between cells

OBJECTIVE

To explore the expression of extracellular vesicle-derived lncZEB1-AS1 in esophageal cancer and its role in esophageal cancer progression.

PATIENTS AND METHODS

The extracellular vesicles (EVs) from esophageal cancer patients (n = 26) and normal subjects (n = 26) were isolated by differential centrifugation. The expression of lncZEB1-AS1 in EVs was detected by Real-time PCR (polymerase chain reaction). The clinical data of normal subjects and patients were analyzed. In addition, the concentration of EVs and lncZEB1-AS1 in blood samples from normal subjects and esophageal cancer patients were assessed. After co-culture of esophageal cancer cell line EC109 and EVs with or without lncZEB1-AS1 knockdown, cell proliferation was detected by CCK-8 assay. The possible target microRNAs of lncZEB1-AS1 in cytoplasm were predicted with miRcode, followed by correlation analysis of lncZEB1-AS1 and miR-214. Through literature review, lncZEB1-AS1 positively regulates ZEB1 expression, which was consistent with our result.

RESULTS

Quantitative Real-time PCR showed that the serum levels of EVs and the content of lncZEB1-AS1 in EVs from esophageal cancer patients were significantly higher than those in normal controls. LncZEB1-AS1 was overexpressed in esophageal cancer cells co-cultured with EVs of esophageal cancer patients. CCK-8 results indicated that EC109 cells co-cultured with EVs of esophageal cancer patients had stronger proliferative capacity. miRcode showed that miR-214 ranked the first of microRNAs that lncZEB1-AS1 might target, and miR-214 expression was significantly increased after lncZEB1-AS1 knockdown in EC109. After overexpressing lncZEB1-AS1 in EC109 or co-culturing EVs of esophageal cancer patients with EC109 cells, we found that lncZEB1-AS1 positively regulates ZEB1. In contrast, interfering with the expression of lncZEB1-AS1 in esophageal cancer cell lines can effectively reduce the expression of ZEB1.

CONCLUSIONS

EVs in the peripheral blood from esophageal cancer patients promote esophageal cancer progression by delivering lncZEB1-AS1 to esophageal cancer cells and targeting miR-214.

Effects of habitat fragmentation on the genetic diversity and differentiation of Dendrolimus punctatus (Lepidoptera: Lasiocampidae) in Thousand Island Lake, China, based on mitochondrial COI gene sequences

Thousand Island Lake (TIL) is a typical fragmented landscape and an ideal model to study ecological effects of fragmentation. Partial fragments of the mitochondrial cytochrome oxidase subunit I gene of 23 island populations of Dendrolimus punctatus in TIL were sequenced, 141 haplotypes being identified. The number of haplotypes increased significantly with the increase in island area and shape index, whereas no significant correlation was detected between three island attributes (area, shape and isolation) and haplotype diversity. However, the correlation with number of haplotypes was no longer significant when the 'outlier' island JSD (the largest island) was not included. Additionally, we found no significant relationship between geographic distance and genetic distance. Geographic isolation did not obstruct the gene flow among D. punctatus populations, which might be because of the high dispersal capacity of this pine moth. Fragmentation resulted in the conversion of large and continuous habitats into isolated, small and insular patches, which was the primary effect on the genetic diversity of D. punctatus in TIL. The conclusion to emphasize from our research is that habitat fragmentation reduced the biological genetic diversity to some extent, further demonstrating the importance of habitat continuity in biodiversity protection.

Lead-free silver-antimony halide double perovskite quantum dots with superior blue photoluminescence

Sb-based lead-free double perovskite Cs₂AgSbX₆ (X = Cl, Br or I) quantum dots exhibiting excellent air stability and blue emission with photoluminescence quantum yields of 31.33% were synthesized firstly using surfactant-assisted method.

Synthesis of 1β-hydroxydeoxycholic acid in H-2 and unlabeled forms

1β-hydroxydeoxycholic acid in unlabeled and stable isotope labeled forms was required for use as a biomarker for Cytochrome P450 3A4/5 activity. A lengthy synthesis was undertaken to deliver the unlabeled compound and in the process, to develop a route to the deuterium labeled compound. The synthesis of the unlabeled compound was completed but in a very low yield. Concurrent with the synthetic approach, a biosynthetic route was pursued and this approach proved to be much more rapid and afforded the compound in both unlabeled and deuterium labeled forms in a 1-step oxidation from deoxycholic acid and [D₄ ]deoxycholic acid, respectively.

One-pot rota-crystallized hollownest-structured Ti-zeolite: a calcination-free and recyclable catalytic material

A hydrothermal rota-crystallization method is developed for the one-step synthesis of a hollownest-structured zeolite precursor with the shell composed of autogenously-intergrown MWW nanosheet crystals containing a large number of stacking-pores without any porogen or hard scaffold.

A hydrothermal rota-crystallization method is developed for the one-step synthesis of a hollownest-structured zeolite precursor with the shell composed of autogenously-intergrown MWW nanosheet crystals containing a large number of stacking-pores without using any porogen or hard scaffold. This material possesses a large external surface area. By simple acid washing, the resultant Ti-containing catalyst can be directly used in the epoxidation of alkenes with hydrogen peroxide. The excellent catalytic activity over the Ti-HSZ catalyst is assumed to be due to the exposure of more Ti active sites over the MWW nanosheet crystals in the shell of the catalyst. More importantly, this Ti-HSZ catalyst washed with H₂O₂/ethanol solution has been reused 6 times without an appreciable decrease in both the conversion of the allyl chloride and the selectivity of the epichlorohydrin, which is ascribed to the structural stability of the hollownest-structured zeolite.

USP4 inhibits p53 and NF-κB through deubiquitinating and stabilizing HDAC2

Histone deacetylases (HDACs) are major epigenetic modulators involved in a broad spectrum of human diseases including cancers. As HDACs are promising targets of cancer therapy, it is important to understand the mechanisms of HDAC regulation. In this study, we show that ubiquitin-specific peptidase 4 (USP4) interacts directly with and deubiquitinates HDAC2, leading to the stabilization of HDAC2. Accumulation of HDAC2 in USP4-overexpression cells leads to compromised p53 acetylation as well as crippled p53 transcriptional activation, accumulation and apoptotic response upon DNA damage. Moreover, USP4 targets HDAC2 to downregulate tumor necrosis factor TNFα-induced nuclear factor (NF)-κB activation. Taken together, our study provides a novel insight into the ubiquitination and stability of HDAC2 and uncovers a previously unknown function of USP4 in cancers.

Lentivirus-mediated knockdown of tumor protein D52-like 2 inhibits glioma cell proliferation

TPD52L2 (tumor protein D52-like 2) is a member of TPD52 family which has been implicated in multiple human cancers. Recently, TPD52 protein was shown to be associated with several malignancies, but very little is known about the function of TPD52L2 in cancers, especially in glioma to date, and its roles in glioma occurrence and progression remain to be elucidated. In the present study, we employed lentivirus-mediated RNA interference (RNAi) to knock down TPD52L2 expression in human glioma cell line U251. We found that knockdown of TPD52L2 significantly not only inhibited cell proliferation and colony formation, but also induced G0/G1 cell cycle arrest in vitro. Taken together, these findings suggest that TPD52L2 might play an important role in glioma tumorigenesis.

JNK phosphorylation promotes natural degeneration of cervical endplate chondrocytes by down-regulating expression of ANK

BACKGROUND

Endplate degeneration leads to accelerated degeneration of the intervertebral disc. The importance of endplate chondrocytes in this process is unclear. Many cellular processes in chondrocytes are controlled by activated c-Jun N-terminal kinases (JNK) and protein kinase B (AKT). However, the involvement of their pathways in the degeneration process needs to be elucidated.

AIM

To study activation of JNK and AKT signaling pathways and their significance for degeneration of endplate chondrocytes, as well as involvement of progressive ankylosis protein (ANK) in this process.

MATERIALS AND METHODS

Rat primary chondrocytes were grown to confluence and subcultured until passage 4. Morphological appearances (microscope, hematoxylin & eosin staining, toluidine blue staining) and proliferation rates of cells (MTT test) were observed. Further, levels of type II collagen, aggrecan, phosphorylated JNK and AKT, total JNK, AKT and ANK were evaluated by qPCR, flow cytometry and Western blot assays. Furthermore, inhibition experiments with SP600125, the JNK inhibitor, were carried out in the passage 4 cells to assess the effects of the JNK pathway on natural degeneration of endplate chondrocytes.

RESULTS

The proliferative speed of endplate chondrocytes progressively decreased during passaging. Expressions of type II collagen and aggrecan were significantly decreased with cells at higher passages. Furthermore, phosphorylation of JNK, but not AKT, was significantly up-regulated and accompanied by reduced ANK expression. Inhibition of the JNK pathway increased expression of type II collagen, aggrecan and ANK and facilitated proliferation rates.

CONCLUSIONS

Phosphorylation of JNK promotes natural degeneration of cervical endplate chondrocytes, likely by down-regulating ANK expression.

Contrast-enhanced ultrasound of hepatocellular carcinoma: Correlation of washout time and angiogenesis

BACKGROUND

The use of the pure blood pool ultrasound contrast agent SonoVue (Bracco, Italy) with specific ultrasound imaging software has enabled the dynamic visualization of tumor microcirculation.

AIM

The present study was designed to investigate the washout time of hepatocellular carcinoma (HCC) and correlate it with angiogenesis parameters.

METHODS

Thirty-one surgically confirmed HCC cases were prospectively evaluated with contrast-enhanced ultrasound (CEUS), and parameters such as wash-in time, peak enhancement time and washout time were determined offline. We also calculated microvessel density and the percentage of microvessel area (MVA) and compared CEUS parameters between a well differentiated group and a poorly to moderately differentiated group. The Spearman rank order correlation method was used to analyze the relationship between washout time and angiogenesis parameters.

RESULTS

The washout time was longer in well differentiated HCC patients compared to those with poorly to moderately differentiated HCC (p < 0.05). In addition, the washout time of HCC was positively correlated with the percentage of MVA (r = 0.510).

CONCLUSIONS

Given that the percentage of MVA was positively correlated with tumor blood volume, washout time may be associated with HCC blood volume.

Association of HLA genes with ankylosing spondylitis in Han population of eastern China

Ankylosing spondylitis (AS) is a chronic inflammatory disorder with a multifactorial genetic basis. HLA-B27 was reported with the greatest susceptibility to AS but did not act alone. The aim of this study was to search for other gene(s) associated with AS independently of HLA-B27 using 13 microsatellite markers spanning 1.5 Mb from locus TAP1 to HLA-Cw and a single-nucleotide polymorphism marker within NFkappaBIL1 gene promoter. Genotyping for microsatellites was performed in 175 AS patients of eastern Chinese and 219 ethnically matched healthy controls using polymerase chain reaction with fluorescence-labelled primers, whereas the SNP marker was genotyped by direct DNA sequencing. Allele as well as haplotype frequencies were compared between cases and controls, and a linkage disequilibrium analysis was performed to estimate the LD relationship between the candidate regions. The frequencies of alleles D6S2811*128, STR_MICA*A5.1 and D6S2672*109, as well as haplotypes D6S2811*128-D6S2927*213-D6S2810*340, D6S2927* 221-D6S2810*350-MICA*A5.1, and D6S2810*350-MICA*A5.1-D6S2800* 136 were significantly increased in B27-positive AS patients when compared with B27-positive controls. The results indicated that there may be other gene(s) within the HLA region, especially around locus HLA-B or HLA-Cw, with susceptibility to AS independently of HLA-B27.

Effects of a Single Nucleotide Polymorphism on the Expression of Human Tumor Necrosis Factor-alpha

Tumor necrosis factor (TNF)-alpha plays a prominent role in inflammations and is a proinflammatory cytokine that has been implicated in the pathogenesis of autoimmune and infectious diseases. Recent association studies have found that the TNF-alpha-857T allele was associated with several disorders. Here we demonstrate, with reporter genes under the control of the two allelic TNF-alpha promoters, that the minor allele -857T is a much stronger transcriptional activator than the major allele -857C in RAW264.7 cell line in response to lipopolysaccharide stimulation. However, the result was not consistent in HeLa cell line. Furthermore, for the quantitative analysis of TNF-alpha synthesis between the -857C/C genotype from healthy subjects and the -857C/T genotype from AS patients, the quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay were performed separately. There was no significant difference between the two groups at the level of mRNA and protein. These results show that this polymorphism may have a direct effect on TNF-alpha regulation in a tissue-specific manner, and apart from the polymorphism at -857 in the TNF-alpha promoter, there may be other factors affecting the expression of TNF-alpha.

Separation and determination of ephedrine alkaloids and tetramethylpyrazine in Ephedra sinica Stapf by gas chromatography-mass spectrometry

A simple, sensitive, and reliable method using gas chromatography (GC)-mass spectrometry (MS) is developed for the simultaneous determination of ephedrine alkaloids and 2,3,5,6-tetramethylpyrazine (TMP) in Ephedra sinica Stapf. The sample is extracted with ethyl ether and submitted to GC-MS for identification and quantitation without derivatization. The column used for GC is an HP-5 (30.0 m x 250 microm x 0.25 microm, 5% phenyl methyl siloxane), and the carrier gas is helium. The detection limits for ephedrine, pseudoephedrine, and TMP are 0.4 ng 0.7 ng, and 0.02 ng (signal-to-noise ratio of 3), respectively. The reproducibility of the total procedure is proved to be acceptable (RSD < 2%), and the recoveries are above 93%.

Analysis of tetramethylpyrazine in Ephedrae herba by gas chromatography-mass spectrometry and high-performance liquid chromatography

A simple and reliable HPLC method was developed for the determination of 2,3,5,6-tetramethylpyrazine (TMP) in Ephedrae herba. Further identification of TMP was achieved using GC-MS. The mobile phase used was methanol-water-35% acetic acid (35:65:0.5, v/v/v) at a flow-rate of 0.8 ml/min. The detection wavelength was set at 290 nm. The linear range of the peak area calibration curve of TMP was 2.64-264 mg/l (r=0.9987) and the recovery for TMP in Ephedrae herba extracts was 101.1-106.9%. The relative standard deviations of retention time and peak area were 0.18 and 1.5% (n=6), respectively. The detection limit of TMP was 0.03 mg/l. The contents of TMP in Ephedrae herba could easily be determined within 10 min.