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Discovery of direct inhibitors of Keap1-Nrf2 protein-protein interaction as potential therapeutic and preventive agents.

Dhulfiqar Ali ABED ; Melanie GOLDSTEIN ; Haifa ALBANYAN ; Huijuan JIN ; Longqin HU ;

Acta Pharmaceutica Sinica B.2015;5(4):285-299. doi:10.1016/j.apsb.2015.05.008

The Keap1-Nrf2-ARE pathway is an important antioxidant defense mechanism that protects cells from oxidative stress and the Keap1-Nrf2 protein-protein interaction (PPI) has become an important drug target to upregulate the expression of ARE-controlled cytoprotective oxidative stress response enzymes in the development of therapeutic and preventive agents for a number of diseases and conditions. However, most known Nrf2 activators/ARE inducers are indirect inhibitors of Keap1-Nrf2 PPI and they are electrophilic species that act by modifying the sulfhydryl groups of Keap1׳s cysteine residues. The electrophilicity of these indirect inhibitors may cause "off-target" side effects by reacting with cysteine residues of other important cellular proteins. Efforts have recently been focused on the development of direct inhibitors of Keap1-Nrf2 PPI. This article reviews these recent research efforts including the development of high throughput screening assays, the discovery of peptide and small molecule direct inhibitors, and the biophysical characterization of the binding of these inhibitors to the target Keap1 Kelch domain protein. These non-covalent direct inhibitors of Keap1-Nrf2 PPI could potentially be developed into effective therapeutic or preventive agents for a variety of diseases and conditions.

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Ginsenoside Rg1 protects against transient focal cerebral ischemic injury and suppresses its systemic metabolic changes in cerabral injury rats.

Mingbao LIN ; Wei SUN ; Wan GONG ; Yasi DING ; Yuanyan ZHUANG ; Qi HOU

Acta Pharmaceutica Sinica B.2015;5(3):277-284. doi:10.1016/j.apsb.2015.02.001

Ginsenoside Rg1 (GR), a major bioactive compound of traditional Chinese medicine, such as Panax ginseng or Radix Notoginseng, has been shown to exert neuroprotective effects against ischemic stroke. However, pharmacokinetic studies have suggested that GR could not be efficiently transported through the blood-brain barrier. The mechanism by which GR attenuates cerebral ischemic injury in vivo remains largely unknown. Therefore, this study explored potential neuro-protective effects of GR through its systemic metabolic regulating mechanism by using mass spectrometry-based metabolomic profiling. Rats with middle cerebral artery occlusion (MCAO) were treated with GR intravenously. Their metabolic profiles in serum were measured by gas chromatography coupled with mass spectrometry on 1 and 3 days after MCAO. GR exhibited a potent neuro-protective effect by significantly decreasing the neurological scores and infarct volume in the MCAO rats. Moreover, 18 differential metabolites were tentatively identified, all of which appeared to correlate well with these disease indices. Our findings suggested that GR carries a therapeutic potential in stroke possibly through a feed-back mechanism by regulating systematic metabolic mediation.

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Synchrotron radiation-based Fourier-transform infrared spectromicroscopy for characterization of the protein/peptide distribution in single microspheres.

Manli WANG ; Xiaolong LU ; Xianzhen YIN ; Yajun TONG ; Weiwei PENG ; Li WU ; Haiyan LI ; Yan YANG ; Jingkai GU ; Tiqiao XIAO ; Min CHEN ; Jiwen ZHANG ;

Acta Pharmaceutica Sinica B.2015;5(3):270-276. doi:10.1016/j.apsb.2015.03.008

The present study establishes a visualization method for the measurement of the distribution and localization of protein/peptide constituents within a single poly-lactide-co-glycolide (PLGA) microsphere using synchrotron radiation-based Fourier-transform infrared spectromicroscopy (SR-FTIR). The representative infrared wavenumbers specific for protein/peptide (Exenatide) and excipient (PLGA) were identified and chemical maps at the single microsphere level were generated by measuring and plotting the intensity of these specific bands. For quantitative analysis of the distribution within microspheres, Matlab software was used to transform the map file into a 3D matrix and the matrix values specific for the drug and excipient were extracted. Comparison of the normalized SR-FTIR maps of PLGA and Exenatide indicated that PLGA was uniformly distributed, while Exenatide was relatively non-uniformly distributed in the microspheres. In conclusion, SR-FTIR is a rapid, nondestructive and sensitive detection technology to provide the distribution of chemical constituents and functional groups in microparticles and microspheres.

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Site-specific PEGylation of lidamycin and its antitumor activity.

Liang LI ; Boyang SHANG ; Lei HU ; Rongguang SHAO ; Yongsu ZHEN

Acta Pharmaceutica Sinica B.2015;5(3):264-269. doi:10.1016/j.apsb.2015.03.006

In this study, N-terminal site-specific mono-PEGylation of the recombinant lidamycin apoprotein (rLDP) of lidamycin (LDM) was prepared using a polyethyleneglycol (PEG) derivative (M w 20 kDa) through a reactive terminal aldehyde group under weak acidic conditions (pH 5.5). The biochemical properties of mPEG-rLDP-AE, an enediyne-integrated conjugate, were analyzed by SDS-PAGE, RP-HPLC, SEC-HPLC and MALDI-TOF. Meanwhile, in vitro and in vivo antitumor activity of mPEG-rLDP-AE was evaluated by MTT assays and in xenograft model. The results indicated that mPEG-rLDP-AE showed significant antitumor activity both in vitro and in vivo. After PEGylation, mPEG-rLDP still retained the binding capability to the enediyne AE and presented the physicochemical characteristics similar to that of native LDP. It is of interest that the PEGylation did not diminish the antitumor efficacy of LDM, implying the possibility that this derivative may function as a payload to deliver novel tumor-targeted drugs.

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Pharmacokinetic analysis and tissue distribution of Vam3 in the rat by a validated LC-MS/MS method.

Ruixia ZHANG ; Ping MAO ; Tingting ZHANG ; Chen MA ; Bo JIN ; Tong LI

Acta Pharmaceutica Sinica B.2015;5(3):254-263. doi:10.1016/j.apsb.2015.03.011

Vam3 is a potential pharmacologically active ingredient isolated from Vitis amurensis Rupr. A rapid, simple and sensitive method to determine Vam3 levels in rat plasma and tissue was developed based on LC-MS/MS. Vam3 and an internal standard (IS) were chromatographed on a C18 short column with acetonitrile-0.1% formic acid in water by gradient elution. MS detection was performed by electrospray ionization in negative ion multiple reaction-monitoring modes. This method monitored the transitions m/z 451.0→345.0 and m/z 301.0→164.0 for Vam3 and IS, respectively. The calibration curve was linear over a concentration range of 1.64-1000 ng/mL. The inter-day and intra-day variabilities in precision was less than 12.8%, while the inter-day and intra-day accuracies ranged from -10.60% to 9.08% in plasma and tissue homogenates. This method was applied to investigate the pharmacokinetics and tissue distribution of Vam3 in rats. The results indicated that Vam3 had poor absorption into systemic circulation and extensive tissue distribution after oral administration, and the absolute bioavailability was low (0.79%). Vam3 had a relatively long terminal elimination half-life in lung, and the highest concentration was found in small intestinal tissue. The developed method and the pharmacokinetic data can provide a basis for further studies on the bioactivity of Vam3.

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Pharmacokinetic study of salvianolic acid D after oral and intravenous administration in rats.

Junke SONG ; Wen ZHANG ; Jialin SUN ; Xiaona XU ; Xue ZHANG ; Li ZHANG ; Zhangying FENG ; Guan-Hua DU

Acta Pharmaceutica Sinica B.2015;5(3):246-253. doi:10.1016/j.apsb.2015.03.015

A sensitive, specific and rapid LC-MS method was developed and validated for the determination of salvianolic acid D (SalD) in rat plasma. This method used a single quadrupole mass spectrometer with an electrospray ionization (ESI) source. A single ion monitoring scanning (SIM) mode was employed. It showed good linearity over the concentration range from 3.3 to 666.7 ng/mL for the determination of SalD. The R.S.D.% of intra-day and inter-day precision values were no more than 7.69%, and the accuracy was within 91%-104% at all quality control levels. This LC-MS method was applied to the pharmacokinetic study of SalD in rats. A two-compartmental model analysis was employed. The plasma concentrations at 2 min (C 2min) were 5756.06±719.61, 11,073.01±1783.46 and 21,077.58±5581.97 μg/L for 0.25, 0.5 and 1 mg/kg intravenous injection, respectively. The peak plasma concentration (C max) was 333.08±61.21 μg/L for 4 mg/kg oral administration. The area under curve (AUC0-t ) was 14,384.379±8443.184, 22,813.369±11,860.823, 46,406.122±27,592.645 and 8201.740±4711.961 μg/L·h for intravenous injection (0.25, 0.5 and 1 mg/kg) and oral administration (4 mg/kg), respectively. The bioavailability of SalD was calculated to be 4.159%±0.517%.

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Study on pharmacokinetics and tissue distribution of the isocorydine derivative (AICD) in rats by HPLC-DAD method.

Yali CHEN ; Qian YAN ; Mei ZHONG ; Quanyi ZHAO ; Junxi LIU ; Duolong DI ; Jinxia LIU

Acta Pharmaceutica Sinica B.2015;5(3):238-245. doi:10.1016/j.apsb.2015.03.012

A simple and effective high-performance liquid chromatography with diode-array detection method coupled with a liquid-liquid extraction pretreatment has been developed for determining the pharmacokinetics and tissue distribution of a novel structurally modified derivative (8-acetamino-isocorydine) of isocorydine. According to the in vivo experiments data calculations by DAS 2.0 software, a two-compartment metabolic model was suitable for describing the pharmacokinetic of 8-acetamino-isocorydine in rats. 8-Acetamino-isocorydine was absorbed well after oral administration, and the absolute bioavailability was 76.5%. The half-life of 8-acetamino-isocorydine after intravenous and oral administration was 2.2 h and 2.0 h, respectively. In vivo, 8-acetamino-isocorydine was highly distributed in the lungs, kidney and liver; however, relatively little entered the brain, suggesting that 8-acetamino-isocorydine could not easily pass through the blood brain barrier. Our work describes the first characterization of the pharmacokinetic parameters and tissue distribution of 8-acetamino-isocorydine. The acquired data will provide useful information for the in vivo pharmacology of 8-acetamino-isocorydine, and can be applied to new drug research.

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Development of a new ferulic acid certified reference material for use in clinical chemistry and pharmaceutical analysis.

Dezhi YANG ; Fengfeng WANG ; Li ZHANG ; Ningbo GONG ; Yang LV

Acta Pharmaceutica Sinica B.2015;5(3):231-237. doi:10.1016/j.apsb.2015.03.009

This study compares the results of three certified methods, namely differential scanning calorimetry (DSC), the mass balance (MB) method and coulometric titrimetry (CT), in the purity assessment of ferulic acid certified reference material (CRM). Purity and expanded uncertainty as determined by the three methods were respectively 99.81%, 0.16%; 99.79%, 0.16%; and 99.81%, 0.26% with, in all cases, a coverage factor (k) of 2 (P=95%). The purity results are consistent indicating that the combination of DSC, the MB method and CT provides a confident assessment of the purity of suitable CRMs like ferulic acid.

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Effects of antibiotic antitumor drugs on nucleotide levels in cultured tumor cells: an exploratory method to distinguish the mechanisms of antitumor drug action based on targeted metabolomics.

Fang WANG ; Xi LIU ; Cuichai LIU ; Zheng LIU ; Lixin SUN

Acta Pharmaceutica Sinica B.2015;5(3):223-230. doi:10.1016/j.apsb.2015.03.010

Nucleotide pools in mammalian cells change due to the influence of antitumor drugs, which may help in evaluating the drug effect and understanding the mechanism of drug action. In this study, an ion-pair RP-HPLC method was used for a simple, sensitive and simultaneous determination of the levels of 12 nucleotides in mammalian cells treated with antibiotic antitumor drugs (daunorubicin, epirubicin and dactinomycin D). Through the use of this targeted metabolomics approach to find potential biomarkers, UTP and ATP were verified to be the most appropriate biomarkers. Moreover, a holistic statistical approach was put forward to develop a model which could distinguish 4 categories of drugs with different mechanisms of action. This model can be further validated by evaluating drugs with different mechanisms of action. This targeted metabolomics study may provide a novel approach to predict the mechanism of action of antitumor drugs.

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Acetylenes and fatty acids from Codonopsis pilosula.

Yueping JIANG ; Yufeng LIU ; Qinglan GUO ; Zhibo JIANG ; Chengbo XU ; Chenggen ZHU ; Yongchun YANG ; Sheng LIN ; Jiangong SHI

Acta Pharmaceutica Sinica B.2015;5(3):215-222. doi:10.1016/j.apsb.2015.03.005

Four new acetylenes (1-4) and one new unsaturated ω-hydroxy fatty acid (5), together with 5 known analogues, were isolated from an aqueous extract of Codonopsis pilosula roots. Their structures were determined by spectroscopic and chemical methods. The new acetylenes are categorized as an unusual cyclotetradecatrienynone (1), tetradecenynetriol (2), and rare octenynoic acids (3 and 4), respectively, and 3 and 4 are possibly derived from oxidative metabolic degradation of 1 and/or 2. The absolute configuration of 1 was assigned by comparison of the experimental circular dichroism (CD) spectrum with the calculated electronic circular dichroism (ECD) spectra of stereoisomers based on the quantum-mechanical time-dependent density functional theory, while the configuration of 2 was assigned by using modified Mosher׳s method based on the MPA determination rule of Δδ RS values for diols.

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