Evaluation of the stiffness of normal cervix and its change with different factors using transvaginal two-dimensional shear wave elastography under strict quality control.

BACKGROUND: The usefulness of transvaginal two-dimensional shear wave elastography (2D SWE) for cervical lesions is still uncertain. This study was to explore the value of transvaginal 2D SWE in the evaluation of the stiffness of normal cervix and its change with different factors under strict quality control (QC). METHODS: Two hundred patients with normal cervix were included in this study and were examined using quantitative 2D SWE to evaluate cervical stiffness and its change with different factors under strict QC. RESULTS: Intra-observer concordance of transvaginal 2D SWE parameters in midsagittal planes were acceptable with intraclass correlation coefficients higher than 0.5. Transvaginal 2D SWE parameters were significantly higher than the corresponding transabdominal parameters. 2D SWE parameters of internal cervical os were significantly higher than the corresponding parameters of external cervical os in a transvaginal midsagittal plane. 2D SWE parameters of external cervical os increased significantly over 50 years old, while these parameters of internal cervical os didn't change significantly with increasing age. 2D SWE parameters of internal cervical os of horizontal position cervix were significantly higher than those of vertical position cervix. SWE parameters of normal cervix did not change according to different menstrual cycles, parities and human papilloma virus test results. CONCLUSIONS: Transvaginal 2D SWE under strict QC could provide quantitative, repeatable and reliable cervical stiffness information. Internal cervical os was stiffer than external cervical os. Menstrual cycles, parities and human papilloma virus test results wouldn't affect cervical stiffness. However, age and cervical positions should be taken into condition while interpreting 2D SWE results of cervical stiffness.

Influenza a virus triggers acute exacerbation of chronic obstructive pulmonary disease by increasing proinflammatory cytokines secretion via NLRP3 inflammasome activation.

BACKGROUND: Influenza A virus (IAV) triggers acute exacerbation of chronic obstructive pulmonary disease (AECOPD), but the molecular mechanisms remain unclear. In this study, we investigated the role of IAV induced NLRP3 inflammasome activation to increase airway inflammation response in the progression of AECOPD. METHODS: Human bronchial epithelial cells were isolated and cultured from normal and COPD bronchial tissues and co-cultured with IAV. The NLRP3 inflammasome associated genes were identified using RNA sequencing, and the expressions of NLRP3 inflammasome components were measured using qRT-PCR and western blot after cells were transfected with siRNA and treated with MCC950. Moreover, IAV-induced COPD rat models were established to confirm the results; 37 AECOPD patients were included to measure the serum and bronchoalveolar lavage fluid (BALF) of interleukin (IL)-18 and IL-1ß. RESULTS: Increased levels of NLRP3 inflammasome components were not seen until 6 h post-inoculation in normal cells. However, both cell groups reached peak NLRP3 level at 12 h post-inoculation and maintained it for up to 24 h. ASC, Caspase-1, IL-1ß and IL-18 were also elevated in a similar time-dependent pattern in both cell groups. The mRNA and protein expression of the NLRP3 inflammasome components were decreased when COPD cells treated with siRNA and MCC950. In COPD rats, the NLRP3 inflammasome components were elevated by IAV. MCC950 alleviated lung damage, improved survival time, and reduced NLRP3 inflammasome components expression in COPD rats. Additionally, the serum and BALF levels of IL-1ß and IL-18 were increased in AECOPD patients. CONCLUSIONS: NLRP3 inflammasome is activated in COPD patients as a pre-existing condition that is further exacerbated by IAV infection.

Cichoric acid from extracted Echinacea purpurea induces the proliferation and apoptosis of peripheral blood mononuclear cells from yaks

BACKGROUND: Cichoric acid (CA) is extracted from Echinacea purpurea. It is well known and widely used for its immunological function. However, the effect of CA on peripheral blood mononuclear cells (PBMCs) from yaks is still unclear. This study investigated the potential influences of CA on the proliferation, cytokine induction, and apoptosis of PBMCs from Datong yak in vivo, and aimed to provide a basis for exploring the pharmacological activities of CA on yaks. RESULTS: In this study, CA promoted PBMCs proliferation by combining concanavalin A (Con A) and exhibited a dose-dependent effect as demonstrated by a Cell Counting Kit-8. The concentration of 60 µg/ml CA was the best and promoted the transformation from the G0/G1 phase to the S and G2/M phases with Con A. Furthermore, 60 µg/ml CA significantly increased IL-2, IL-6, and IFN-γ levels and PCNA, CDK4 and Bcl-2 expression levels, but it significantly inhibited the TP53, Bax, and Caspase-3 expression levels. Transcriptome analysis revealed a total of 6807 differentially expressed genes (DEGs) between the CA treatment and control groups. Of these genes, 3788 were significantly upregulated and 3019 were downregulated. Gene Ontology and pathway analysis revealed that DEGs were enriched in cell proliferation and immune function signaling pathways. The expression level of some transcription factors (BTB, Ras, RRM_1, and zf-C2H2) and genes (CCNF, CCND1, and CDK4) related to PBMCs proliferation in yaks were significantly promoted after CA treatment. By contrast, anti-proliferation-associated genes (TP53 and CDKN1A) were inhibited. CONCLUSIONS: In summary, CA could regulate the immune function of yaks by promoting proliferation and inhibiting inflammation and apoptosis of PBMCs.

A signal peptide derived from Hsp60 induces protective cytotoxic T lymphocyte immunity against lymphoid malignancies independently of TAP and classical MHC-I.

Hsp60sp, a signal peptide derived from the leader sequence of heat shock protein 60 kDa (Hsp60), is a Qa-1/HLA-E-binding peptide. We previously showed that Hsp60sp-specific CD8+ T cells are involved in the immunoregulation of autoimmune diseases by controlling the response of self-reactive lymphocytes. Here, we report that Hsp60sp-specific CD8+ T cells killed malignant lymphocytes in vitro independently of transporter associated with antigen processing (TAP) and classical MHC-I expression. Induction of this cytotoxic T lymphocyte (CTL) response in vivo, either by adoptive transfer of in vitro-amplified CTLs or peptide-loaded dendritic cell immunization, resulted in effective control of lymphoid tumors, including TAP- or classical MHC-I-deficient cells. Hsp60sp-specific immune activation combined with programmed cell death protein 1 (PD-1) blocking synergistically restrained mouse lymphoma development. Importantly, Hsp60sp-specific CD8+ T cells did not negatively affect normal tissues and cells. Our data suggest that Hsp60sp-based immunotherapy is an inviting strategy to control lymphoid malignancies.

Metallic iron in cornflakes.

Iron is an essential element, and cornflake-style cereals are typically fortified with iron to a level up to 14 mg iron per 100 g. Even single cornflakes exhibit magnetic behaviour. We extracted iron microparticles from samples of two own-brand supermarket cornflakes using a strong permanent magnet. Synchrotron iron K-edge X-ray absorption near-edge spectroscopic data were consistent with identification as metallic iron, and X-ray diffraction studies provided unequivocal identification of the extracted iron as body-centred cubic (BCC) α-iron. Magnetometry measurements were also consistent with ca. 14 mg per 100 g BCC iron. These findings emphasise that attention must be paid to the speciation of trace elements, in relation to their bioavailability. To mimic conditions in the stomach, we suspended the iron extract in dilute HCl (pH 1.0-2.0) at 310 K (body temperature) and found by ICP-MS that over a period of 5 hours, up to 13% of the iron dissolved. This implies that despite its metallic form in the cornflakes, the iron is potentially bioavailable for oxidation and absorption into the body.

Strategies for conjugating iridium(III) anticancer complexes to targeting peptides via copper-free click chemistry.

We report the synthesis and characterization of novel pentamethylcyclopentadienyl (Cp*) iridium(III) complexes [(Cp*)Ir(4-methyl-4'-carboxy-2,2'-bipyridine)Cl]PF6 (Ir-I), the product (Ir-II) from amide coupling of Ir-I to dibenzocyclooctyne-amine, and its conjugate (Ir-CP) with the cyclic nona-peptide c(CRWYDENAC). The familiar three-legged 'piano-stool' configuration for complex Ir-I was confirmed by its single crystal X-ray structure. Significantly, copper-free click strategy has been developed for site-specific conjugation of the parent complex Ir-I to the tumour targeting nona-cyclic peptide. The approach consisted of two steps: (i) the carboxylic acid group of the bipyridine ligand in complex Ir-I was first attached to an amine functionalized dibenzocyclooctyne group via amide formation to generate complex Ir-II; and (ii) the alkyne bond of dibenzocyclooctyne in complex Ir-II underwent a subsequent strain-promoted copper-free cycloaddition with the azide group of the modified peptide. Interestingly, while complex Ir-I was inactive towards A2780 human ovarian cancer cells, complex Ir-II exhibited moderate cytotoxic activity. Targeted complexes such as Ir-CP offer scope for enhanced activity and selectivity of this class of anticancer complexes.

Ligand-Controlled Reactivity and Cytotoxicity of Cyclometalated Rhodium(III) Complexes.

We report the synthesis, characterisation and cytotoxicity of six cyclometalated rhodium(III) complexes [CpXRh(C^N)Z]0/+, in which CpX = Cp*, Cpph, or Cpbiph, C^N = benzo[h]quinoline, and Z = chloride or pyridine. Three x-ray crystal structures showing the expected "piano-stool" configurations have been determined. The chlorido complexes hydrolysed faster in aqueous solution, also reacted preferentially with 9-ethyl guanine or glutathione compared to their pyridine analogues. The 1-biphenyl-2,3,4,5,-tetramethylcyclopentadienyl complex [CpbiphRh(benzo[h]quinoline)Cl] (3a) was the most efficient catalyst in coenzyme reduced nicotinamide adenine dinucleotide (NADH) oxidation to NAD+ and induced an elevated level of reactive oxygen species (ROS) in A549 human lung cancer cells. The pyridine complex [CpbiphRh(benzo[h]quinoline)py]+ (3b) was the most potent against A549 lung and A2780 ovarian cancer cell lines, being 5-fold more active than cisplatin towards A549 cells, and acted as a ROS scavenger. This work highlights a ligand-controlled strategy to modulate the reactivity and cytotoxicity of cyclometalated rhodium anticancer complexes.

Ligand-centred redox activation of inert organoiridium anticancer catalysts.

Organometallic complexes with novel activation mechanisms are attractive anticancer drug candidates. Here, we show that half-sandwich iodido cyclopentadienyl iridium(iii) azopyridine complexes exhibit potent antiproliferative activity towards cancer cells, in most cases more potent than cisplatin. Despite their inertness towards aquation, these iodido complexes can undergo redox activation by attack of the abundant intracellular tripeptide glutathione (GSH) on the chelated azopyridine ligand to generate paramagnetic intermediates, and hydroxyl radicals, together with thiolate-bridged dinuclear iridium complexes, and liberate reduced hydrazopyridine ligand. DFT calculations provided insight into the mechanism of this activation. GS- attack on the azo bond facilitates the substitution of iodide by GS-, and leads to formation of GSSG and superoxide if O2 is present as an electron-acceptor, in a largely exergonic pathway. Reactions of these iodido complexes with GSH generate Ir-SG complexes, which are catalysts for GSH oxidation. The complexes promoted elevated levels of reactive oxygen species (ROS) in human lung cancer cells. This remarkable ligand-centred activation mechanism coupled to redox reactions adds a new dimension to the design of organoiridium anticancer prodrugs.

Metallodrugs are unique: opportunities and challenges of discovery and development.

Metals play vital roles in nutrients and medicines and provide chemical functionalities that are not accessible to purely organic compounds. At least 10 metals are essential for human life and about 46 other non-essential metals (including radionuclides) are also used in drug therapies and diagnostic agents. These include platinum drugs (in 50% of cancer chemotherapies), lithium (bipolar disorders), silver (antimicrobials), and bismuth (broad-spectrum antibiotics). While the quest for novel and better drugs is now as urgent as ever, drug discovery and development pipelines established for organic drugs and based on target identification and high-throughput screening of compound libraries are less effective when applied to metallodrugs. Metallodrugs are often prodrugs which undergo activation by ligand substitution or redox reactions, and are multi-targeting, all of which need to be considered when establishing structure-activity relationships. We focus on early-stage in vitro drug discovery, highlighting the challenges of evaluating anticancer, antimicrobial and antiviral metallo-pharmacophores in cultured cells, and identifying their targets. We highlight advances in the application of metal-specific techniques that can assist the preclinical development, including synchrotron X-ray spectro(micro)scopy, luminescence, and mass spectrometry-based methods, combined with proteomic and genomic (metallomic) approaches. A deeper understanding of the behavior of metals and metallodrugs in biological systems is not only key to the design of novel agents with unique mechanisms of action, but also to new understanding of clinically-established drugs.

[Bmi-1 as A Molecular Marker for Prognosis of Pediatric ALL].

OBJECTIVE: To study whether the Bmi-1 gene can be a biomarker for analysis of clinical risk stratification and prognosis of ALL patients. METHODS: The expression level of Bmi-1 gene in bone marrow samples from 127 cases of newly diagnosed ALL was detected by qRT-PCR, at the same time the expression level of Bmi-1 protein in bone marrow samples from above-mentioned cases was detected by Western blot. The collected samples were divided into 3 groups: high, intermediate and low risk according to clinical risk stratfication, the relationship between Bmi-1 expression and risk grade of ALL patients was analyzed; at the same time the collected samples were divided into 2 groups: prednisone good response (PGR) and prednisone poor respouse (PPR) according to the sensitivity of prednison test, and the sensitivily to prednisone in 2 groups was compared; moreover, the collected samples were divided into 2 groups: high level and low level according to median of Bmi-1 level, and the relation of Bmi-1 level with prognosis of patients was analyzed by using the Kaplan-Meier method. RESULTS: The expression level of Bmi-1 in low risk group was lowest, while that in high risk group was highest, however that in intermediat risk group was between the low and high risk groups, statistical analysis showed significant difference (P＜0.05). The expression level of Bmi-1 in PPR group was significantly higher than that in PGR group (P＜0.001). The Kaplan-Meier analysis showed that the RFS rate in Bmi-1 high expression group was significantly lower than that in Bmi-1 low expression group (73.0% vs 90.6%) (P＜0.001). CONCLUSION: The Bmi-1 can be used as a molecular marker for the analysis of chinical risk and prognosis of pediatric ALL.

KRT1 gene silencing ameliorates myocardial ischemia-reperfusion injury via the activation of the Notch signaling pathway in mouse models.

Myocardial ischemia and reperfusion injury (MIRI) includes major drawbacks, such as excessive formation of free radicals and also overload of calcium, which lead to cell death, tissue scarring, and remodeling. The current study aims to explore whether KRT1 silencing may ameliorate MIRI via the Notch signaling pathway in mouse models. Myocardial tissues were used for the determination of the positive rate of KRT1 protein expression, apoptosis of myocardial cells, creatine kinase (CK) and lactate dehydrogenase (LDH) expression, expression of related biomarkers as well as myocardial infarction area. The transfected myocardial cells were treated with KRT1-siRNA, Jagged1, and DAPT (inhibitor of Notch-1 signaling pathway). The expression of KRT1, NICD, Hes1, Bcl-2, and Bax protein was detected. The MTT assay was applied for cell proliferation and flow cytometry was used for cell apoptosis. Mice with MIRI had a higher positive rate of KRT1 protein expression, apoptosis of myocardial cells, CK and LDH expression, myocardial infarction area, increased expression of MDA, NO, SDH, IL-1, IL-6, TNF-α, CRP, KRT1, Bax protein, CK, and LDH, and decreased expression of SOD, NICD, Hes1, and Bcl-2. The downregulation of KRT1 led to decreased expression of KRT1 and Bax protein, increased expression of NICD, Hes1, and Bcl-2, decreased cell apoptosis, and improved cell proliferation. The inhibition of the Notch signaling pathway leads to reduced expression of Bax, increased expression of NICD, Hes1, and Bcl 2, and also decreased cell apoptosis and increased cell proliferation. Our data conclude that KRT1 silencing is able to make MIRI better by activating the Notch signaling pathway in mice.

[Lithium chloride arrests HK-2 cell cycle in G2 phase through AKT/GSK-3ß signal pathway].

OBJECTIVE: To investigate the effect of lithium chloride (LiCl) on cell cycle of HK-2 cells and explore the possible pathways involved. METHODS: HK-2 cells were treated with LiCl at different concentrations (5, 12.5, 20, and 25 mmol/L) for 12, 24, 48, or 72 h, and the changes in cell cycle and viability were detected using flow cytometry and CCK-8 assay, respectively. Western blotting was used to analyze the changes in the expressions of cyclin B1 and CDK1 (the two G2 phase-related proteins) and those of AKT/GSK-3ß signaling pathway-related proteins in the treated cells. RESULTS: LiCl treatment time- and concentration-dependently increased HK-2 cell percentage in G2 phase and decreased the cell vitality. The expressions of cyclin B1, CDK1, p-GSK-3ß, and ß-catenin increased and the expression of p-AKT decreased significantly in the cells as LiCl treatment time and concentration increased. CONCLUSION: LiCl may cause HK-2 cell cycle arrest in G2 phase through activation of the AKT/GSK-3ß signaling pathway.

Exogenous hydrogen sulfide ameliorates high glucose-induced myocardial injury & inflammation via the CIRP-MAPK signaling pathway in H9c2 cardiac cells.

AIMS: Hydrogen sulfide (H2S) is a novel signaling molecule with potent cytoprotective actions. In this study, we hypothesize that exogenous H2S may protect cardiac cells against high glucose (HG)-induced myocardial injury and inflammation with the involvement of the CIRP-MAPK signaling pathway. MAIN METHODS: H9c2 cardiac cells cultured under HG conditions were transfected with siRNA and different inhibitor for detecting the effects of sodium hydrogen sulfide (NaHS) (a H2S donor) on cell biological processes. The cardiac cell viability and LDH activity were determined by CCK-8 and LDH kit. ELISA was employed to measure the levels of inflammatory factors, while 2',7'-dichlorofluorescein diacetate (DCFH-DA) to evaluate reactive oxygen species (ROS). Mitochondrial membrane potential (MMP) was identified by rhodamine 123 staining. TUNEL staining and Hoechst 33258 staining were employed to observe cardiac cell apoptosis. Besides, we determined the expression of CIRP-MAPK signaling pathway- and apoptosis-related factors by protein immunoblot analysis. KEY FINDINGS: HG culturing induced toxicity, LDH, higher level of inflammatory factors, ROS, MMP, and apoptosis in cardiac cells, attenuated the viability of cardiac cells, and activated the CIRP-MAPK signaling pathway. Notably, CIRP silencing aggravated the above condition. H2S or blockade of the MAPK signaling pathway reversed the above conditions induced by HG. SIGNIFICANCE: The present study provides evidence for the protective effect of exogenous H2S on HG-induced myocardial injury and inflammation in H9c2 cardiac cells and suggests that the activation of CIRP-MAPK signaling pathway might be one of the mechanisms underlying the protective effect of H2S.

Antitumor Activity of Intratumoral Ethanol Injection in an Orthotopic Pancreatic Cancer Cell Mouse Xenograft Model.

PURPOSE: Pancreatic cancer is a lethal disease and usually is diagnosed at advanced stages of disease. This study assessed the effects of intratumoral ethanol injection using an endoscopic ultrasound (EUS) probe on the control of pancreatic cancer in a mouse orthotopic xenograft model. MATERIALS AND METHODS: The subcutaneous and orthotopic human pancreatic cancer cell mouse xenograft models were established. Different concentrations of ethanol (0-95%) were injected into subcutaneous xenograft tumors. In the orthotopic tumor model, ethanol was injected into the tumor lesions under the guidance of a high-frequency EUS probe. Tumor volume, relative tumor volume (RTV), and histopathology were evaluated. The serum amylase level was analyzed at baseline and 24 h after treatment in the orthotopic tumor model. RESULTS: Injection of 40-95% ethanol induced tumor necrosis in the subcutaneous tumor model, while there was no statistical difference between the RTVs of the two groups (P = 0.81). In the orthotopic tumor model, the RTV of the 80% ethanol treatment group was less than that of the saline injection group (P < 0.01); and histologically, there was a large area of necrosis observed in the 80% ethanol group. The serum amylase level was slightly elevated at 24 h after injection and returned to the baseline level at 7 days. CONCLUSION: Injection of 80% ethanol into xenograft tumor lesions of orthotopic pancreatic cancer resulted in tumor necrosis, and the procedure was safe and effective. Future studies will further confirm its antitumor activity as well as assess its safety and feasibility.

[Application of non-invasive microelectrode ion flux estimation technique in crop stress physiology.] / éžæŸä¼¤ç¦»å­æµæ£€æµ‹æŠ€æœ¯åœ¨ä½œç‰©é€†å¢ƒç ”ç©¶ä¸­çš„åº”ç”¨.

Non-invasive microsensing technique has been widely used in evaluating the adaptive responses of plant cells and tissues to abiotic stresses. One of the representative techniques is the microelectrode ion flux estimation (MIFE), which allows concurrent quantification of net fluxes with high spatial and temporal resolution. More importantly, this technique permits simultaneous recording of ion concentration and mobility with less intervention to the in situ physiological status. With the availability of such advanced technique, the last three decades have seen a significant progress towards the role of ion signaling in a variety of abiotic stresses including salinity, extreme temperature, osmotic stress, hypoxia, and drought. In this review, we gave a brief introduction of the MIFE working principles and focused on its applications in detecting ion responses to various abiotic stresses.

Excessive activated T-cell proliferation after anti-CD19 CAR T-cell therapy.

Excessive activated T-cell proliferation was observed in vivo in one patient after an anti-CD19-chimeric antigen receptor (CAR) T-cell infusion. The patient, who had chemotherapy refractory and CD19+ diffuse large B-cell lymphoma (DLBCL), received an anti-CD19 CAR T-cell infusion following conditioning chemotherapy (fludarabine/cyclophosphamide). The lymphocyte count in the peripheral blood (PB) increased to 77 × 109/L on day 13 post infusion, and the proportion of CD8+ actived T cells was 93.06% of the lymphocytes. Then, the patient suffered from fever and hypoxaemia. Significant increases in serum cytokine, lactate dehydrogenase, aspartate aminotransferase (AST), alanine transaminase (ALT), and glutamic-oxalacetic transaminase (γ-GT) levels were observed. A high-throughput sequencing analysis for T-cell receptors (TCRs) and whole-genome sequencing were used to explore the mechanisms underlying this excessive T-cell proliferation. TCR diversity was demonstrated, but no special gene mutation was found. The patient was found to be infected with the John Cunningham polyomavirus (JCV). It cannot be ruled out the bystander activation pathway induced by JCV infections related the excessive activated T-cell proliferation. Although the clinical and laboratory data do not fully explain the reason for excessive T-cell proliferation after the anti-CD19 CAR T-cell infusion, the risk of this type of toxicity should be emphasized. This study was registered at www.clinicaltrials.gov as NCT01864889.

Two novel heterozygous HTRA1 mutations in two pedigrees with cerebral small vessel disease families.

Heterozygous HTRA1 mutations, recently, have been reported as a cause of autosomal dominant hereditary cerebral small vessel disease (CSVD). We herein describe clinical and neuroimaging findings in two familial CSVD with two different heterozygous HTRA1 mutations. Detailed clinical and neuroimaging examination were conducted in probands and their available family members. A next-generation sequencing-based comprehensive gene panel was used to investigate their causative mutations. A novel heterozygous missense variant c.527T>C (p.V176A) and a novel heterozygous nonsense variant c.589C>T (p.R197X) in HTRA1 gene were detected in probands of family 1 and family 2, respectively. Co-segregation analysis in family 1 showed eight family members were mutation carriers. All alive male patients showed typical clinical and neuroimaging features of CSVD. All alive female mutation carriers were clinical or neuroimaging asymptomatic. Screening of HTRA1 should be considered in patients with familial CSVD. A male predominance may exist in patients with heterozygous HTRA1 mutations and need to be further investigated.

[Optimize excipients for Yinsang hypoglycemic granules by using multiple indexes].

Optimal excipients were screened by studying the effect of different excipients on the hygroscopicity of the extract, testing polysaccharide in the preparation and blood glucose value. Single factor tests were performed with hygroscopicity, formability and fluidity as the indexes, and the moisture content, granule yield and angle of repose were combined with physical characters of the materials to screen the proportioning and dosage of excipients. Then the critical relative humidity of preferred Yinsang granules were measured. The optimum excipients for Yinsang hypoglycemic granules were mulberry leaf paste-microcrystalline cellulose-mactra veneriformis crude polysaccharides (10∶9∶1.67). The obtained granules had good formability and fluidity, which were not easy to absorb moisture for liquefaction, with a critical relative humidity of 73%. This formation process was reasonable and feasible, suitable for industrial production, which can significantly improve hygroscopicity and liquefaction properties of extracts, improve stability of Yinsang granules, and provide reference for screening of excipients for other preparations.

Determination of a natural DNMT1 inhibitor, peperomin E, in rat plasma by UFLC-MS/MS and method application in a pharmacokinetic study.

Peperomin E (PepE), a naturally occurring secolignan isolated from Peperomia dindygulensis, has drawn much attention recently owing to its anticancer and DNA methyltransferase 1 (DNMT1) inhibitory activity. Here, a simple and sensitive ultra-fast liquid chromatography-tandem mass spectrometry method was developed and validated for the determination of PepE in rat plasma for the first time. Samples were prepared by simple protein precipitation. Separation was performed on an XBridge™ C18 column using a mobile phase of acetonitrile and 0.1% (v/v) aqueous formic acid. PepE and the internal standard arctigenin were detected in a positive-ion mode using multiple reaction monitoring of the transitions at m/z 413.2 → 261.0 and 373.2 → 137.2, respectively. The calibration curve for PepE was linear over the range of concentrations of 1.46-6000 ng/mL, with a lower limit of quantitation of 1.46 ng/mL. Both intra- and interday precisions were within 11.05%, and the accuracy ranged from -11.5 to 5.51%. The extraction recovery and matrix effect were within acceptable limits. Stability tests showed that PepE remained stable throughout the analytical procedure. The validated method was then used to analyze the pharmacokinetics of PepE administered to rats orally (12.5 and 25 mg/kg) or intravenously (6.25 and 12.5 mg/kg).