Alterations in gp120 glycans or the gp41 fusion peptide-proximal region modulate the stability of the human immunodeficiency virus (HIV-1) envelope glycoprotein pretriggered conformation.

The human immunodeficiency virus (HIV-1) envelope glycoprotein (Env) trimer mediates entry into host cells by binding receptors, CD4 and CCR5/CXCR4, and fusing the viral and cell membranes. In infected cells, cleavage of the gp160 Env precursor yields the mature Env trimer, with gp120 exterior and gp41 transmembrane Env subunits. Env cleavage stabilizes the State-1 conformation, which is the major target for broadly neutralizing antibodies, and decreases the spontaneous sampling of more open Env conformations that expose epitopes for poorly neutralizing antibodies. During HIV-1 entry into cells, CD4 binding drives the metastable Env from a pretriggered (State-1) conformation into more "open," lower-energy states. Here, we report that changes in two dissimilar elements of the HIV-1 Env trimer, namely particular gp120 glycans and the gp41 fusion peptide-proximal region (FPPR), can independently modulate the stability of State 1. Individual deletion of several gp120 glycans destabilized State 1, whereas removal of a V1 glycan resulted in phenotypes indicative of a more stable pretriggered Env conformation. Likewise, some alterations of the gp41 FPPR decreased the level of spontaneous shedding of gp120 from the Env trimer and stabilized the pretriggered State-1 Env conformation. State-1-stabilizing changes were additive and could suppress the phenotypes associated with State-1-destabilizing alterations in Env. Our results support a model in which multiple protein and carbohydrate elements of the HIV-1 Env trimer additively contribute to the stability of the pretriggered (State-1) conformation. The Env modifications identified in this study will assist efforts to characterize the structure and immunogenicity of the metastable State-1 conformation. IMPORTANCE The elicitation of antibodies that neutralize multiple strains of HIV-1 is an elusive goal that has frustrated the development of an effective vaccine. The pretriggered shape of the HIV-1 envelope glycoprotein (Env) spike on the virus surface is the major target for such broadly neutralizing antibodies. The "closed" pretriggered Env shape resists the binding of most antibodies but is unstable and often assumes "open" shapes that elicit ineffective antibodies. We identified particular changes in both the protein and the sugar components of the Env trimer that stabilize the pretriggered shape. Combinations of these changes were even more effective at stabilizing the pretriggered Env than the individual changes. Stabilizing changes in Env could counteract the effect of Env changes that destabilize the pretriggered shape. Locking Env in its pretriggered shape will assist efforts to understand the Env spike on the virus and to incorporate this shape into vaccines.

Exploring efficient strategies for air quality improvement in China based on its regional characteristics and interannual evolution of PM2.5 pollution.

Fine particulate matter (PM2.5) harms human health and hinders normal human life. Considering the serious complexity and obvious regional characteristics of PM2.5 pollution, it is urgent to fill in the comprehensive overview of regional characteristics and interannual evolution of PM2.5. This review studied the PM2.5 pollution in six typical areas between 2014 and 2022 based on the data published by the Chinese government and nearly 120 relevant literature. We analyzed and compared the characteristics of interannual and quarterly changes of PM2.5 concentration. The Beijing-Tianjin-Hebei region (BTH), Yangtze River Delta (YRD) and Pearl River Delta (PRD) made remarkable progress in improving PM2.5 pollution, while Fenwei Plain (FWP), Sichuan Basin (SCB) and Northeast Plain (NEP) were slightly inferior mainly due to the relatively lower level of economic development. It was found that the annual average PM2.5 concentration change versus year curves in the three areas with better pollution control conditions can be merged into a smooth curve. Importantly, this can be fitted for the accurate evaluation of each area and provide reliable prediction of its future evolution. In addition, we analyzed the factors affecting the PM2.5 in each area and summarize the causes of air pollution in China. They included primary emission, secondary generation, regional transmission, as well as unfavorable air dispersion conditions. We also suggested that the PM2.5 pollution control should target specific industries and periods, and further research need to be carried out on the process of secondary production. The results provided useful assistance such as effect prediction and strategy guidance for PM2.5 pollution control in Chinese backward areas.

Transplanted MSCs promote alveolar bone repair via hypoxia-induced extracellular vesicle secretion.

OBJECT: Mesenchymal stem cell (MSC) therapy is a potential strategy for promoting alveolar bone regeneration. This study evaluated the effects and mechanisms of transplanted MSCs on alveolar bone repair. METHODS: Mouse alveolar bone defect model was treated using mouse bone marrow mesenchymal stem cell (BMSC) transplantation. The bone repair was evaluated by micro-CT and Masson staining. The conditioned medium of hypoxia-treated BMSCs was co-cultured with normal BMSCs in vitro to detect the regulatory effect of transplanted MSCs on the chemotactic and migratory functions of host cells. The mechanisms were investigated using Becn siRNA transfection and western blotting. RESULTS: BMSC transplantation promoted bone defect regeneration. The hypoxic microenvironment induces BMSCs to release multiple extracellular vesicle (EV)-mediated regulatory proteins that promote the migration of host stem cells. Protein array analysis, western blotting, GFP-LC3 detection, and Becn siRNA transfection confirmed that autophagy activation in BMSCs plays a key role during this process. CONCLUSION: The local hypoxic microenvironment induces transplanted MSCs to secrete a large number of EV-mediated regulatory proteins, thereby upregulating the migration function of the host stem cells and promoting alveolar bone defect regeneration. This process depends on the autophagy-related mechanism of the transplanted MSCs.

Direct imaging of intraflagellar-transport turnarounds reveals that motors detach, diffuse, and reattach to opposite-direction trains.

Intraflagellar transport (IFT), a bidirectional intracellular transport mechanism in cilia, relies on the cooperation of kinesin-2 and IFT-dynein motors. In Caenorhabditis elegans chemosensory cilia, motors undergo rapid turnarounds to effectively work together in driving IFT. Here, we push the envelope of fluorescence imaging to obtain insight into the underlying mechanism of motor turnarounds. We developed an alternating dual-color imaging system that allows simultaneous single-molecule imaging of kinesin-II turnarounds and ensemble imaging of IFT trains. This approach allowed direct visualization of motor detachment and reattachment during turnarounds and accordingly demonstrated that the turnarounds are actually single-motor switching between opposite-direction IFT trains rather than the behaviors of motors moving independently of IFT trains. We further improved the time resolution of single-motor imaging up to 30 ms to zoom into motor turnarounds, revealing diffusion during motor turnarounds, which unveils the mechanism of motor switching trains: detach-diffuse-attach. The subsequent single-molecule analysis of turnarounds unveiled location-dependent diffusion coefficients and diffusion times for both kinesin-2 and IFT-dynein motors. From correlating the diffusion times with IFT train frequencies, we estimated that kinesins tend to attach to the next train passing in the opposite direction. IFT-dynein, however, diffuses longer and lets one or two trains pass before attaching. This might be a direct consequence of the lower diffusion coefficient of the larger IFT-dynein. Our results provide important insights into how motors can cooperate to drive intracellular transport.

The value of bioimpedance analysis in the assessment of hydration and nutritional status in children on chronic peritoneal dialysis.

Bioimpedance analysis (BIA)-body composition monitoring (BCM) has been used to evaluate the hydration and nutritional status of adults and children on dialysis. However, its clinical application still has challenges, so further exploration is valuable. We used BIA-BCM to evaluate the hydration and nutritional status of children undergoing chronic peritoneal dialysis from 1 July 2021 to 31 December 2022 in the Children's Hospital of Fudan University to explore the clinical value of this method. A total of 84 children on chronic peritoneal dialysis (PD) were included. In the PD group, 16 (19.05%) and 31 (36.90%) had mild and severe overhydration (OH), respectively; 41.27% (26/63) had a low lean tissue index (LTI). In the PD group, patients with relative OH (Re-OH) > 5.6% had significantly higher systolic blood pressure (SBP) and SBP z score (SBPz). Patients with LTI > 12% had significantly higher body mass index (BMI) and BMI z score (BMIz). Canonical correlation analysis indicated a linear relationship (ρ = 0.708) between BIA-BCM hydration and the clinical hydration indicator and a linear relationship (ρ = 0.995) between the BIA-BCM nutritional indicator and the clinical nutritional indicator. A total of 56% of children on chronic peritoneal dialysis had OH, and 41% had a low LTI. In PD patients, SBP and SBPz were correlated with BIA-BCM Re-OH, and BMI and BMIz were correlated with BIA-BCM LTI. BIA-BCM indicators have good clinical value in evaluating hydration and nutrition.

Hydrocarbon adsorption mechanism of modern automobile engines and methods of reducing hydrocarbon emissions during cold start process: A review.

With the global emphasis on environmental protection and increasingly stringent emission regulations for internal combustion engines, there is an urgent need to overcome the problem of large hydrocarbon (HC) emissions caused by unstable engine cold starts. Synergistic engine pre-treatment (reducing hydrocarbon production) as well as after-treatment devices (adsorbing and oxidizing hydrocarbons) is the fundamental solution to emissions. In this paper, the improvement of hydrocarbon emissions is summarized from two aspects: pre-treatment and after-treatment. The pre-treatment for engine cold start mainly focuses on summarizing the intake control, fuel, and engine timing parameters. The after-treatment mainly focuses on summarizing different types of adsorbents and modifications (mainly including different molecular sieve structures and sizes, preparation conditions, silicon aluminum ratio, ion exchange modification, and heterogeneity, etc.), adsorptive catalysts (mainly including optimization of catalytic performance and structure), and catalytic devices (mainly including coupling with thermal management equipment and HC trap devices). In this paper, a SWOT (strength, weakness, opportunity, and threat) analysis of pre-treatment and after-treatment measures is conducted. Researchers can obtain relevant research results and seek new research directions and approaches for controlling cold start HC emissions.

Localized Medium Concentration Electrolyte with Fast Kinetics for Lithium Metal Batteries.

Localized high-concentration electrolyte is widely acknowledged as a cutting-edge electrolyte for the lithium metal anode. However, the high fluorine content, either from high-concentration salts or from highly fluorinated diluents, results in significantly higher production costs and an increased environmental burden. Here, we have developed a novel electrolyte termed "Localized Medium-Concentration Electrolyte" (LMCE) to effectively address these issues. This LMCE is designed and produced by diluting a medium concentration (0.5 M-1.5 M) electrolyte which is incompatible with lithium metal anode before diluting. It has ultralow concentration (0.1 M) and demonstrates remarkable compatibility with lithium metal anode. Surprisingly, our LMCE, despite having an ultralow concentration (0.1 M), exhibits excellent kinetics in Li/Cu, Li/Li, LiFePO4 /Li, and NCM811/Li batteries. Additionally, LMCE effectively inhibits the corrosion of the Al current collector caused by LiTFSI salt under high voltage (>4 V) conditions. This groundbreaking LMCE design transforms the seemingly "incompatible" into the "compatible", opening up new avenues for exploring various electrolyte formulations, including all liquid electrolyte-based batteries.

Rolling Circle Amplification-Based DNA Nano-Assembly for Targeted Drug Delivery and Gene Therapy.

Combining the killing ability of chemotherapy drugs on tumor cells with the inhibiting ability of genetic drugs on tumor cell growth, a dual drug delivery system loaded with therapy drugs and siRNA has gradually received more and more research and extensive attention. In this paper, we designed a DNA nano-assembly based on rolling circle amplification that can co-deliver doxorubicin (Dox) and siRNA simultaneously. In order to fully exploit the potential of the dual loading system in cancer treatment, we selected STAT3 gene as a target and used siRNA to target STAT3 of mRNA and reduce the STAT3 expression in mouse melanoma cell line (B16); meanwhile, Dox as a chemotherapy drug was combined with multivalent aptamers specifically targeting B16 to achieve efficient delivery of siRNA and Dox. The results showed that the synergistic delivery system could achieve high efficiency in targeting and inhibiting proliferation in mouse melanoma cells. In addition, the synergistic effect of the dual delivery system on apoptosis of cancer cells was significantly better than that of single drug delivery systems.

Pectin mediates the mechanism of host blood glucose regulation through intestinal flora.

Pectin is a complex polysaccharide found in plant cell walls and interlayers. As a food component, pectin is benefit for regulating intestinal flora. Metabolites of intestinal flora, including short-chain fatty acids (SCFAs), bile acids (BAs) and lipopolysaccharides (LPS), are involved in blood glucose regulation. SCFAs promote insulin synthesis through the intestine-GPCRs-derived pathway and hepatic adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathway to promote hepatic glycogen synthesis. On the one hand, BAs stimulate intestinal L cells and pancreatic α cells to secrete Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) through receptors G protein-coupled receptor (TGR5) and farnesoid X receptor (FXR). On the other hand, BAs promote hepatic glycogen synthesis through AMPK pathway. LPS inhibits the release of inflammatory cytokines through Toll-like receptors (TLRs)-myeloid differentiation factor 88 (MYD88) pathway and mitogen-activated protein kinase (MAPK) pathway, thereby alleviating insulin resistance (IR). In brief, both SCFAs and BAs promote GLP-1 secretion through different pathways, employing strategies of increasing glucose consumption and decreasing glucose production to maintain normal glucose levels. Notably, pectin can also directly inhibit the release of inflammatory cytokines through the -TLRs-MYD88 pathway. These data provide valuable information for further elucidating the relationship between pectin-intestinal flora-glucose metabolism.

A nucleolin-activated polyvalent aptamer nanoprobe for the detection of cancer cells.

Sensitive detection of cancer cells plays a critical role in early cancer diagnosis. Nucleolin, overexpressed on the surface of cancer cells, is regarded as a candidate biomarker for cancer diagnosis. Thus, cancer cells can be detected through the detection of membrane nucleolin. Herein, we designed a nucleolin-activated polyvalent aptamer nanoprobe (PAN) to detect cancer cells. In brief, a long single-stranded DNA with many repeated sequences was synthesized through rolling circle amplification (RCA). Then the RCA product acted as a scaffold chain to combine with multiple AS1411 sequences, which was doubly modified with fluorophore and quenching group, respectively. The fluorescence of PAN was initially quenched. Upon binding to target protein, the conformation of PAN changed, leading to the recovery of fluorescence. The fluorescence signal of cancer cells treated with PAN was much brighter compared with that of monovalent aptamer nanoprobes (MAN) at the same concentration. Furthermore, the binding affinity of PAN to B16 cells was proved to be 30 times higher than that of MAN by calculating the dissociation constants. The results indicated that PAN could specifically detect target cells, and this design concept has potential to become promising in cancer diagnosis.

Phase wavefront perturbation calculation model for spectroscopic refractive index matching of hybrid materials.

A low-cost flexible spectroscopic refractive index matching (SRIM) material with bandpass filtering properties without incidence angle and polarization dependence by randomly dispersing inorganic C a F 2 particles in organic polydimethylsiloxane (PDMS) materials was proposed in our previous study. Since the micron size of the dispersed particles is much larger than the visible wavelength, the calculation based on the commonly used finite-difference time-domain (FDTD) method to simulate light propagation through the SRIM material is too bulky; however, on the other hand, the light tracing method based on Monte Carlo theory in our previous study cannot adequately explain the process. Therefore, a novel approximate calculation model, to the best of our knowledge, based on phase wavefront perturbation is proposed that can well explain the propagation of light through this SRIM sample material and can also be used to approximate the soft scattering of light through composite materials with small refractive index differences, such as translucent ceramics. The model simplifies the complex superposition of wavefront phase disturbances and the calculation of scattered light propagation in space. The scattered and nonscattered light ratios; the light intensity distribution after transmission through the spectroscopic material; and the influence of absorption attenuation of the PDMS organic material on the spectroscopic performance are also considered. The simulation results based on the model are in great agreement with the experimental results. This work is important to further improve the performance of SRIM materials.

Therapeutic drug monitoring of free vancomycin concentration in practice: A new analytical technique based on the HFCF-UF sample separation method.

The aim of this study was to establish a method for free vancomycin concentration determination in human plasma and apply it to clinical therapeutic drug monitoring (TDM). The unbound vancomycin in plasma was separated by the hollow fiber centrifugal ultrafiltration (HFCF-UF) technique and analyzed by HPLC. Chromatographic conditions were optimized, the specificity, linearity, precision, recovery and stability of the method were examined, and plasma samples of patients were measured. The standard curve for free vancomycin is y = 0.0277x - 0.0080 with good linearity within 0.25-50 µg·mL-1 . The relative and absolute recovery rates for vancomycin were 98.63-101.0% and 88.41-101.2%, respectively. The intraday and interday precision RSDs were <10%. Plasma was stable under several conditions. The TDM value of the free vancomycin concentration of 20 patients was 0.99-38.51 µg·mL-1 , and the correlation between the free and total concentrations was not significant. The unbound fraction of vancomycin ranged from 25.5 to 84.8%, with large variation. The operation of free vancomycin separation by HFCF-UF was simple and suitable for TDM in practice. The unbound fraction of vancomycin in clinical samples varied significantly between individuals. It is recommended to perform free concentration TDM in critically ill patients.

Separation and Purification of Hydroxyl-α-Sanshool from Zanthoxylum armatum DC. by Silica Gel Column Chromatography.

Hydroxyl-α-sanshool is the main alkylamide produced by Zanthoxylum armatum DC., and it is responsible for numbness after consuming Z. armatum-flavored dishes or food products. The present study deals with the isolation, enrichment, and purification of hydroxyl-α-sanshool. The results indicated that the powder of Z. armatum was extracted with 70% ethanol and then filtrated; the supernatant was concentrated to get pasty residue. Petroleum ether (60-90 °C) and ethyl acetate at a 3:2 ratio, with an Rf value of 0.23, were chosen as the eluent. Petroleum ether extract (PEE) and ethyl acetate-petroleum ether extract (E-PEE) were used as the suitable enriched method. Afterward, the PEE and E-PEE were loaded onto silica gel for silica gel column chromatography. Preliminary identification was carried out by TLC and UV. The fractions containing mainly hydroxyl-α-sanshool were pooled and dried by rotary evaporation. Lastly, all of the samples were determined by HPLC. The yield and recovery rates of hydroxyl-α-sanshool in the p-E-PEE were 12.42% and 121.65%, respectively, and the purity was 98.34%. Additionally, compared with E-PEE, the purity of hydroxyl-α-sanshool in the purification of E-PEE (p-E-PEE) increased by 88.30%. In summary, this study provides a simple, rapid, economical, and effective approach to the separation of high-purity hydroxyl-α-sanshool.

Antibiofilm Activity and Mechanism of Linalool against Food Spoilage Bacillus amyloliquefaciens.

Pellicle biofilm-forming bacteria Bacillus amyloliquefaciens are the major spoilage microorganisms of soy products. Due to their inherent resistance to antibiotics and disinfectants, pellicle biofilms formed are difficult to eliminate and represent a threat to food safety. Here, we assessed linalool's ability to prevent the pellicle of two spoilage B. amyloliquefaciens strains. The minimum biofilm inhibitory concentration (MBIC) of linalool against B. amyloliquefaciens DY1a and DY1b was 4 µL/mL and 8 µL/mL, respectively. The MBIC of linalool had a considerable eradication rate of 77.15% and 83.21% on the biofilm of the two strains, respectively. Scanning electron microscopy observations revealed that less wrinkly and thinner pellicle biofilms formed on a medium supplemented with 1/2 MBIC and 1/4 MBIC linalool. Also, linalool inhibited cell motility and the production of extracellular polysaccharides and proteins of the biofilm matrix. Furthermore, linalool exposure reduced the cell surface hydrophobicity, zeta potential, and cell auto-aggregation of B. amyloliquefaciens. Molecular docking analysis demonstrated that linalool interacted strongly with quorum-sensing ComP receptor and biofilm matrix assembly TasA through intermolecular hydrogen bonds, hydrophobic contacts, and van der Waals forces interacting with site residues. Overall, our findings suggest that linalool may be employed as a potential antibiofilm agent to control food spoilage B. amyloliquefaciens.

Random color filters based on an all-dielectric metasurface for compact hyperspectral imaging.

Metasurface filters are a compact, lightweight, and inexpensive solution for the miniaturized hyperspectral imaging system. However, the emerging applicability of these filters is limited by the trade-off between spatial and spectral resolutions. In this study, we establish and experimentally demonstrate a compact hyperspectral photodetection method using random all-dielectric metasurface filters that are directly integrated on the detectors. Based on compressive sensing algorithms, the compact photodetectors can accurately reconstruct the incident spectrum in the visible range. The minimum full width at half maximum (FWHM) of the spectrum reconstructed is 4.8 nm, which fully satisfies the requirements of hyperspectral imaging. The proposed method may be applied in the design, development, and measurement of compact hyperspectral imaging systems.

"Willow Branch" DNA Self-Assembly for Cancer Dual-Target and Proliferation Inhibition.

DNA nanotechnology is beginning to yield unique advantages in the area of drug delivery. For the dual-targeting and proliferation suppression of cancer cells, a "willow branch" DNA assembly based on rolling circle amplification (RCA) was built. Three single-stranded DNAs, including antibody modified cDNAs, aptamer cDNAs, and simple cDNAs, were employed in the DNA self-assembly, along with the RCA scaffolds (every 63 bases is a repeat unit). "Willow branch" DNA (WB DNA) assembly successfully linked multiple antibodies and aptamers together to achieve dual targeting of cancer cells. Binding of CD44 antibodies and S2.2 aptamers to receptors on the cell membrane inhibits both pathways, ß-catenin signaling and nuclear factor-kappa B-specific transcription activity, through feedback regulation. Results demonstrated that WB DNA assembly could effectively exert multivalency clustering cell-surface receptors, modulating signal pathways and inhibiting proliferation. This study proposes a new approach for cancer dual-target and proliferation inhibition by clustering multivalent receptors.

Viral neutralization by antibody-imposed physical disruption.

In adaptive immunity, organisms produce neutralizing antibodies (nAbs) to eliminate invading pathogens. Here, we explored whether viral neutralization could be attained through the physical disruption of a virus upon nAb binding. We report the neutralization mechanism of a potent nAb 8C11 against the hepatitis E virus (HEV), a nonenveloped positive-sense single-stranded RNA virus associated with abundant acute hepatitis. The 8C11 binding flanks the protrusion spike of the HEV viruslike particles (VLPs) and leads to tremendous physical collision between the antibody and the capsid, dissociating the VLPs into homodimer species within 2 h. Cryo-electron microscopy reconstruction of the dissociation intermediates at an earlier (15-min) stage revealed smeared protrusion spikes and a loss of icosahedral symmetry with the capsid core remaining unchanged. This structural disruption leads to the presence of only a few native HEV virions in the ultracentrifugation pellet and exposes the viral genome. Conceptually, we propose a strategy to raise collision-inducing nAbs against single spike moieties that feature in the context of the entire pathogen at positions where the neighboring space cannot afford to accommodate an antibody. This rationale may facilitate unique vaccine development and antimicrobial antibody design.

Effects of vindoline on rat cytochrome P450 isoform activities in vitro.

A specific ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) method has been described for the simultaneous determination of the metabolites of tacrine, bupropion, diclofenac, dextromethorphan and midazolam, which are the five probe drugs of the five cytochrome P450 (CYP450) isoforms CYP1A2, CYP2B, CYP2C11, CYP2D1 and CYP3A4. The inhibition degree was determined by calculating the IC50 . The chromatographic separation was performed on a C18 column with a mobile phase consisting of 0.1% formic acid and acetonitrile. The mass spectrometric analysis was conducted in positive electrospray ionization mode. The IC50 values of CYP1A2, CYP2B, CYP2C11, CYP2D1 and CYP3A were 113.4, 83.78, 22.50, 9.081 and 52.76 µmol L-1 , respectively. The in vitro results demonstrated that vindoline could inhibit CYP2D1 activity in rats, and weak inhibitory effect on CYP2C11 and CYP3A, but had no obvious effects on CYP1A2 and CYP2B.

Inhibition of imrecoxib on mRNA and protein expression of CYP2C11 enzyme in rats.

To evaluate the effect of imrecoxib on CYP2C11 enzyme activity, mRNA, and protein expression, a UPLC method was established. Tolbutamide was selected as the CYP2C11 enzyme-specific probe drug and incubated with imrecoxib in rat liver microsomes. The yield of 4-hydroxytolbutamide was measured using UPLC to investigate the effect of imrecoxib on CYP2C11 enzyme activity. Imrecoxib (10 mg/kg) was administered intragastrically twice daily. After 1, 7, and 14 days of administration, the liver tissues were analyzed. The expression of CYP2C11 enzyme mRNA was determined using reverse transcription-polymerase chain reaction, and its protein expression was determined using Western blot analysis. Imrecoxib concentration was inversely proportional to the production of 4-hydroxytolbutamide in liver microsomes. Imrecoxib demonstrated a dose-dependent inhibitory effect on CYP2C11 activity with IC50 = 74.77 µM. After administration, reverse transcription-polymerase chain reaction showed CYP2C11 enzyme mRNA expressions were 65% (P < 0.05), 35%, and 34% of the control group, respectively (P < 0.01). Western blot analysis showed CYP2C11 enzyme protein expressions were 80, 37, and 34% of the control group, respectively (P < 0.01). Imrecoxib can reduce mRNA and protein expression of CYP2C11 enzyme in rat liver and inhibit the activity of CYP2C11 enzyme in a dose-dependent manner. However, it does not produce clinically significant drug interactions.

A practical technique for rapid characterisation of ent-kaurane diterpenoids in Isodon serra (Maxim.) Hara by UHPLC-Q-TOF-MS/MS.

INTRODUCTION: The diterpenoids are the most important active constituents that contribute to the pharmacological efficacy of Isodon serra (Maxim.) Hara. Clinical studies have revealed that diterpenoids possess multiple features, e.g. antitumour, antitubercular and anti-ischemic activities. Therefore, the identification and detection of diterpenoids may be equally important for understanding the pharmacological basis of diterpenoids and enhancing the product quality control of I. serra. OBJECTIVES: The purpose of this study was to develop a practical analysis approach of rapid characterisation using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) for the structure characterisation of the ent-kaurane diterpenoids from I. serra. METHODOLOGY: The analytical strategy was as follows: first, ent-kaurane diterpenoids were detected by a novel on-line data acquisition approach, i.e. sequential window acquisition of all theoretical fragment-ion spectra (SWATH). Second, the MS of eight ent-kaurane diterpenoids was explored, and their mass spectrum cleavage pathways were summarised and determined. Finally, the methanol extract of I. serra was studied using SWATH and identified by extracted ion chromatography (XIC). RESULTS: Compared to the traditional information-dependent acquisition (IDA) method, SWATH significantly improved the hit rate of ent-kaurane diterpenoids. With support from UHPLC separation and specific detection by tandem mass spectrometry (MS/MS), 48 ent-kaurane diterpenoids were successfully characterised and classified as ent-kaurane diterpenoids from a complex matrix. CONCLUSIONS: These combined qualitative methods were used to provide a potential approach for the characterisation of traditional Chinese medicine (TCM) and its preparations. Meanwhile, the SWATH provided a novel and reliable method for the structural characterisation of ent-kaurane diterpenoids from other complicated TCMs.