Directed evolution of dibenzocyclooctyne-reactive peptide tags for protein labeling.

Protein labeling with a functional molecule is a technique widely used for protein research. The covalent reaction of self-labeling peptide tags with synthetic probe-modified small molecules enables tag-fused protein labeling with chemically diverse molecules, including fluorescent probes. We report the discovery, by in vitro directed evolution, of a novel 23-mer dibenzocyclooctyne (DBCO)-reactive peptide (DRP) tag using Systematic Evolution of Ligands by EXponential enrichment (SELEX) with a combination of a reconstituted cell-free translation system (PURE system) and cDNA display. The N- and C-terminal DRP truncations created a shorter 16-mer DBCO-reactive peptide (sDRP) tag without significant reactivity reduction. By fusing the sDRP tag to a model protein, we showed the chemical labeling and in-gel fluorescence imaging of the sDRP-fused protein using a fluorescent DBCO probe. Results showed that sDRP tag-mediated protein labeling has potential for use as a basic molecular tool in a variety of applications for protein research.

Candidate genes involved in the biosynthesis of lignan in Schisandra chinensis fruit based on transcriptome and metabolomes analysis.

Schisandra chinensis Turcz. (Baill.) is a plant species with fruits that have been well known in Far Eastern medicine for a long time. It has traditionally been used as a stimulating and fortifying agent in cases of physical exhaustion and to inhibit fatigue. The major bioactive compounds found in S. chinensis are lignans with a dibenzocyclooctadiene skeleton, but little is known about their biosynthesis in plants. S. chinensis is the ideal medicinal plant for studying the biosynthesis of lignans, especially the dibenzocyclooctadiene skeleton. Genomic information for this important herbal plant is unavailable. To better understand the lignan biosynthesis pathway, we generated transcriptome sequences from the fruit during ripening and performed de novo sequence assembly, yielding 136 843 unique transcripts with N50 of 1778 bp. Putative functions could be assigned to 41 824 transcripts (51.57%) based on BLAST searches against annotation databases including GO (Gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes). Furthermore, 22 candidate cytochrome P450 genes and 15 candidate dirigent proteins genes that were most likely involved in the lignan biosynthesis pathway were discovered based on transcriptome sequencing of S. chinensis. The genomic data obtained from S. chinensis, especially the identification of putative genes involved in the lignan biosynthesis pathway, will facilitate our understanding of lignan biosynthesis at the molecular level. The lignan metabolite profiles were analyzed by metabolomes, the accumulation patterns of 30 metabolites involved in the lignan pathway were studied. Co-expression network of lignan contents and transcriptional changes showed 355 strong correlations (correlation coefficient, R2 > 0.9) between 21 compounds and 153 transcripts. Furthermore, the comprehensive analysis and characterization of the genes involved in lignan pathways and the metabolite profiles of lignans are expected to provide better insight regarding the diversity of the chemical composition, synthetic characteristics, and regulatory mechanisms of this medical herb.

Effects of 27 natural products on drug metabolism genes in channel catfish (Ictalurus punctatus) cell line.

Pregnane X receptor (PXR) as a ligand dependent transcription factor, is capable of regulating gene expression of cytochromes P450 and transporters involved in xenobiotic/drug metabolism and elimination. Due to the species differences in the regulatory specificity of PXR, gene regulation should not be extrapolated from mammal to fish without research data.The aim of present study was to investigate the effect of 27 natural products on PXR, CYP3A30 and MDR1 genes in channel catfish (Ietalurus punetaus) kidney cells (CC-K). The results showed that bisdemethoxycurcumin, glycyrrhetnic acid, rotenone, artemisinin, dihydroartemisinin, ligustilide and matrine strongly induced the mRNA levels of PXR. Additionally, the up-regulation of CYP3A30 gene ran parallel with PXR gene after the treatment of demethoxycurcumin, glycyrrhetnic acid, artemisinin, matrine, baicalein, schisantherin A, ligustilide, and dihydroartemisinin. Moreover, we found that natural products schisandrin A, schisandrin B, schisandrol A, and schisandrol B significantly up-regulated the mRNA level of MDR1 gene.Our work with a view to provide experimental data support for further research, which will make for the rational application of natural products in channel catfish, such as to avoid adverse herb-drug interactions or accelerating the residue elimination of chemical medicine.

Screening and Identification of the Main Metabolites of Schisantherin a In Vivo and In Vitro by Using UHPLC-Q-TOF-MS/MS.

Schisantherin A is an active ingredient originating from Schisandra chinensis (Turcz.) which has hepatoprotective and anti-oxidation activities. In this study, in vitro metabolisms investigated on rat liver microsomes (RLMs) and in vivo metabolisms explored on male Sprague Dawley rats of Schisantherin A were tested, respectively. The metabolites of Schisantherin A were identified using ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS). Based on the method, 60 metabolites were successfully identified and structurally characterized including 48 phase-I and 12 phase-II metabolites. Among the metabolites, 45 metabolites were reported for the first time. Moreover, 56 and eight metabolites were detected in urine and bile and 19 metabolites were identified in rats' plasma. It demonstrated that hepatic and extra-hepatic metabolic pathways were both involved in Schisantherin A biotransformation in rats. Five in vitro metabolites were structurally characterized for the first time. The results indicated that the metabolic pathways mainly include oxidation, reduction, methylation, and conjugation with glucuronide, taurine, glucose, and glutathione groups. This study provides a practical strategy for rapidly screening and identifying metabolites, and the results provide basic data for future pharmacological and toxicology studies of Schisantherin A and other lignin ingredients.

Wuzhi capsule and haemoglobin influence tacrolimus elimination in paediatric kidney transplantation patients in a population pharmacokinetics analysis: A retrospective study.

WHAT IS KNOWN AND OBJECTIVES: Tacrolimus is widely used for kidney transplantation in children. However, the narrow therapeutic window and considerable interindividual and intraindividual variabilities make tacrolimus untoward to design an optimum dosage for paediatric personalized medicine. Our research aims to establish the tacrolimus population pharmacokinetics (PPK) of Chinese paediatric kidney transplantation patients and to distinguish covariates impacting variabilities. METHODS: Chinese paediatric kidney transplantation patients treated with tacrolimus between January 2014 and April 2018 from Children's Hospital of Fudan University were retrospectively analysed. A total of 51 Chinese paediatric kidney transplantation patients were analysed using non-linear mixed effects modelling (NONMEM). The effects of population characteristics, biological features and drug combination were assessed. The final PPK model was evaluated using visual inspection of routine diagnostic plots and the internal validation method of bootstrap. RESULTS: Our data met the condition of a one-compartment model, and the final model was CL/F = 32.7 × (WT/70)0.75  × (1 - WZ × 0.341) × (HGB/97)-0.508 ; V/F = 1890 × (WT/70) × (POD/57)0.816 , where WT, WZ, HGB and POD were weight, Wuzhi capsule (extracted from schisandra sphenanthera, whose primary efficient constituents are schisantherin A, schisandrol B, schisandrin etc, and often used to treat drug-induced hepatitis in Chinese organ transplant patients), haemoglobin and post-transplant day, respectively. WHAT IS NEW AND CONCLUSION: The tacrolimus PPK model in Chinese paediatric kidney transplantation patients was developed, and Wuzhi capsule and haemoglobin influence tacrolimus elimination in paediatric kidney transplantation patients.

Pharmacokinetics and distribution of schisandrol A and its major metabolites in rats.

1. Schizandrol A is an active component in schisandra, also the representative component for the identification of schisandra. 2. A rapid resolution liquid chromatography coupled with quadruple-time-of-flight mass spectrometry (RRLC-QTOF/MS) was developed to investigate the pharmacokinetics of schizandrol A after its intragastric administration (50 mg/kg) in rats. 3. Schizandrol A was rapidly absorbed (T max = 2.07 h), with a longer duration (t 1/2 = 9.48 h) and larger apparent volume of distribution (Vz/F = 111.81 l/kg) in rats. Schizandrol A can be detected in main organs and the order of its distribution was in the liver > kidney > heart > spleen > brain, particularly higher in the liver. 4. Five schizandrol A metabolites were identified, including 2-demethyl-8(R)-hydroxyl-schizandrin, 3-demethyl-8(R)-hydroxyl-schizandrin, hydroxyl-schizandrin, demethoxy-schizandrin, 2, 3-demethyl-8(R)-hydroxyl-schizandrin, indicating that the hydroxylation and demethylation may be the major metabolic way of schizandrol A. 5. This study defined the pharmacokinetic characteristics of schizandrol A in vivo, and the RRLC-QTOF/MS is more sensitive and less limited by conditions, and needs less samples, which may be a useful resource for the further research and development of schisandrol A.

Drug-drug interation prediction between ketoconazole and anti-liver cancer drug Gomisin G.

BACKGROUND: Gomisin G, isolated from herb Schisandra chinensis, exhibits anti-tumor activities. Therefore, Gomisin G is a drug candidate for anti-liver cancer therapy. AIMS: To predict the metabolic behavior and metabolism-based drug-drug interaction of gomisin G. METHODS: Molecular docking method was used. The crystal structure of CYP3A4 with the ligand ketoconazole was chosen from protein data bank (http://www.rcsb.org/pdb). Chemdraw software was used to draw the two-dimensional structure of gomisin G with standard bond lengths and angles. RESULTS: Gomisin G can be well docked into the activity site of CYP3A4, and distance between gomisin G the heme active site was 2.75 Å. To evaluate whether the inhibitors of CYP3A4 can affect the metabolism of gomisin G, co-docking of gomisin G and ketoconazole was further performed. The distance between ketoconazole and activity center (2.10 Å) is closer than the distance between gomisin G and activity center of CYP3A4, indicating the easy influence of CYP3A4's strong inhibitor towards the metabolism of gomisin G. CONCLUSION: Gomisin G is a good substrate of CYP3A4, and CYP3A4 inhibitors easily affect the metabolism of Gomisin G.

[Effect of forchlorfenuron on fruit morphology and lignans content of Schisandra chinensis].

The effect of plant growth regulator forchlorfenuron (CPPU) 1 x 10(-6), 0.67 x 10(-6), 0.5 x 10(-6) on fruit morphology and effective components lignans was studied. Those morphologies were the combination of four basic morphological changes. The result showed, diametre were increased and longitudinal diametre of fruits were inhibited by foliage fertilizers including CPPU. At the same time, 1 000-grain weight and yield showed the varying degrees increase under CPPU. The order of the degree was 0.5 x 10(-6) > 1 x 10(-6) > 0.67 x 10(-6). Six lignans content of Schisandra chinensis of different harvest time and different CPPU processing groups were determined, the results showed that lignans accumulation occurred mainly in periods of premature the half mature fruiting stages. Under the 0.67 x 10(-6) CPPU treatment, schisandrol B, schisandrin B, schisandrin C content of S. chinensis showed different increase.

Screening of herbal components for attenuating amiodarone-induced hepatotoxicity on gel-entrapped rat hepatocytes.

Amiodarone (AMD) is a hepatotoxic drug that has been widely used as a class III antiarrhythmic drug. Because, to date, only a few kinds of protectants are able to reduce AMD hepatotoxicity, this article utilized gel-entrapped rat hepatocytes to screen effective protectants from a series of herbal compounds for their effects against AMD-induced toxicity. Herbal compounds, including matrine, silibinin, glycyrrhizic acid, schisandrin B, epigallocatechin gallate and anisodamine, were cotreated with AMD to assess their protective effect, whereas vitamin E, which has been shown to be protective in rats, was selected as a control. It was found that vitamin E, as with its function in rats, provided the best protection in gel-entrapped rat hepatocytes, whereas silibinin, a major component of silymarin, could largely reduce AMD-induced hepatotoxicity, performing a similar function as silymarin in rats. The results illustrated that gel-entrapped hepatocytes may reflect the protective effects of drugs and serve as a reliable model for screening hepatoprotectants. Moreover, matrine, a widely used monomer of the traditional Chinese medicine, Sophora flavescens, for treatment of arrhythmia, was evidenced to show some effective protections against AMD hepatotoxicity. Taken together, gel-entrapped rat hepatocytes may provide a platform for screening effective candidates from the herbal component library.

Effect of acupuncture on target tissue distribution of Schisandra lignans.

BACKGROUND: Recently, the combination of acupuncture and Chinese medicine as a practical strategy to treat diseases is receiving considerable attention worldwide as they are usually found to exhibit intriguing therapeutic effectiveness. The current study aimed to study the adjunct effect of acupuncture on target tissue distribution of schisandra lignans when acupuncture is combined with Schisandra chinensis. METHODS: A simple and reliable high performance liquid chromatography-electrospray tandem-mass spectrometry (HPLC-ESI-MS) method for simultaneous analysis of three bioactive lignans (schisandrin, deoxyschisandrin and schisandrin B) in rat tissues was established. Using this analytical method we evaluated whether acupuncture had a synergistic effect on the tissue distribution of schisandra lignans. RESULTS: Tissue concentrations of the three lignans in the group receiving acupuncture were significantly higher than those in the schisandra only group, suggesting that acupuncture may potently increase tissue concentrations of schisandra lignans. The highest concentrations of the three lignans occurred in the liver compared with other tissues, and tissue concentrations in the heart, spleen, lungs and kidneys were increased by 315%, 203%, 250% and 224%, respectively. In addition, retention times of the lignans in tissues were prolonged for a relative long time. CONCLUSIONS: Our date indicate that the combined use of acupuncture and Schisandra chinensis could produce a synergistic effect which could play a beneficial role on promoting the tissue distribution of lignans. This has supported our initial hypothesis. The HPLC-MS method showed good sensitivity in quantifying the three schisandra lignans in different tissues.

Schisandrin B protects against solar irradiation-induced oxidative stress in rat skin tissue.

Schisandrin B (Sch B) and schisandrin C (Sch C), but not schisandrin A and dimethyl diphenyl bicarboxylate, protected rat skin tissue against solar irradiation-induced oxidative injury, as evidenced by a reversal of solar irradiation-induced changes in cellular reduced glutathione and α-tocopherol levels, as well as antioxidant enzyme activities and malondialdehyde production. The cytochrome P-450-mediated metabolism of Sch B or Sch C caused ROS production in rat skin microsomes. Taken together, Sch B or Sch C, by virtue of its pro-oxidant action and the subsequent eliciting of a glutathione antioxidant response, may prevent photo-aging of skin.

[Research on liposoluble ingredients of Quchiling].

OBJECTIVE: To study the liposoluble ingredients of Quchiling (LQ), which enter the blood and the brain,and to confirm the active ingredients of LQ in vivo. METHOD: Serum pharmacochemistry and gas chromatography mass spectroscopy were used to analyze ingredients of LQ entering the blood and the brain. RESULT: There were eleven ingredients of LQ to enter the blood and six ingredients of LQ to enter the brain. CONCLUSION: It is confirmed that eleven ingredients of LQ entered the blood, which are beta-asarone, schisandrol A, schisandrol B, deoxyschisandrin, schisandrin B, schisantherrin A, schisantherrin B, schisantherrin C, delta-cadinene, delta-cadinol and calamendiol in the blood, and that six ingredients are beta-asarone, schisandrol A, schisandrol B, deoxyschisandrin, schisandrin B and calamendiol in the brain.

[Enzyme kinetics of schizandrin metabolism and sex differences in rat liver microsomes].

To study the enzyme kinetics of schizandrin metabolism in different gender in rat liver microsomes, liver microsomes were prepared from male or female rats. Schizandrin was incubated with rat liver microsomes. Schizandrin and its metabolites were isolated and identified by HPLC-UV method. Vmax, Km and Cl(int) of schizandrin in male and female rat liver microsomes were (21.88 +/- 2.30) and (0.61 +/- 0.07) micromol x L(-1) x min(-1) x mg(-1) (protein), (389.00 +/- 46.26) and (72.64 +/- 13.61) micromol x L(-1), (0.0563 +/- 0.0007) and (0.0084 +/- 0.0008) min x mg(-1) (protein), respectively. The major metabolites of schizandrin in female and male rat liver microsomes were 7,8-dihydroxy-schizandrin (M1) and 7, 8-dihydroxy-2-demethyl schizandrin (M2b), respectively. Ketoconazole, quinidine, and orphenadrine had different level effects on schizandrin metabolism in both male and female rat liver microsomes, and cimetidine still had some inhibitory effect in male liver microsomes. CYP3A and CYP2C11 may be the main P450 enzymes in schizandrin metabolism and their difference in rat liver microsomes may be the main reason for the sex difference of metabolic enzyme kinetics and metabolites of schizandrin in rats.