Comparison of chiral electrophoretic separation methods for phenethylamines and application on impurity analysis

A chiral microemulsion electrokinetic chromatography method has been developed for the separation of the enantiomers of the phenethylamines ephedrine, N-methylephedrine, norephedrine, pseudoephedrine, adrenaline (epinephrine), 2-amino-1-phenylethanol, diethylnorephedrine, and 2-(dibutylamino)-1-phenyl-1-propanol, respectively. The separations were achieved using an oil-in-water microemulsion consisting of the oil-component ethyl acetate, the surfactant sodium dodecylsulfate, the cosurfactant 1-butanol, the organic modifier propan-2-ol and 20 mM phosphate buffer pH 2.5 as aqueous phase. For enantioseparation sulfated β-cyclodextrin was added. The method was compared to an already described CZE method, which made use of heptakis(2,3-di-O-diacetyl-6-O-sulfo)-β-cyclodextrin (HDAS) as chiral selector. Additionally, the developed method was successfully applied to the related substances analysis of noradrenaline, adrenaline, dipivefrine, ephedrine and pseudoephedrine monographed in the European Pharmacopoeia 6.     

制首乌中两个新化合物

目的：研究制首乌(Radix Polygoni multiflori Preparata)化学成分。方法：应用硅胶、Sephadex、反相硅胶柱色谱对制首乌正丁醇萃取部分中化学成分进行分离纯化,应用理化常数测定和光谱(IR,MS,¹HNMR,¹³CNMR,2D-NMR)分析技术鉴定结构。结果：分离并鉴定了5个单体化合物：大黄素甲醚-8-O-β-D-葡糖苷(Ⅰ)、大黄素-8-O-β-D-葡糖苷(Ⅱ)、决明蒽酮-8-O-β-D-葡糖苷(Ⅲ)、6-甲氧基-2-乙酰基-3-甲基-1,4-萘醌-8-O-β-D-葡糖苷(Ⅳ)、2,3,5,4′-四羟基二苯乙烯-2-O-(2″-O-乙酰基)-β-D-葡糖苷(Ⅴ)。结论：Ⅳ和Ⅴ为新化合物。     

Evaluation of cholesterol depletion as a marker of nephrotoxicity in vitro for novel β-cyclodextrin derivatives

Cyclodextrins (CDs) have been shown to improve physicochemical and biopharmaceutical properties of drugs when low solubility and low safety limit their use in the pharmaceutical field. Recently, we have developed new multi-substituted-β-CDs, hydroxypropyl-sulfobutyl ether-β-cyclodextrin (HPn-SBEm-β-CD). HPn-SBEm-β-CD exhibit low hemolysis, good solubility, strong inclusion ability, and an appropriate average molecular weight. In this study, we chose two products of HPn-SBEm-β-CD (HP₃-SBE₂-β-CD and HP₂-SBE₃-β-CD) and compared their effects to sulfobutyl ether-β-cyclodextrin (SBE₇-β-CD), methyl-β-cyclodextrin (M-β-CD) and 2,6-di-O-methyl-β-cyclodextrin (DM-β-CD). We evaluated viability, membrane damage, induction of apoptosis and necrosis, cholesterol depletion, and morphological changes in human embryonic kidney 293A cells (HEK293A) in vitro. CDs caused a reduction of cell viability and increased LDH levels in a concentration-dependent manner. The effect of HP₃-SBE₂-β-CD or HP₂-SBE₃-β-CD on cell viability, membrane damage, and the induction of apoptosis and necrosis resembled that of SBE₇-β-CD, whereas the effects were significantly lower for M-β-CD or DM-β-CD. HP₃-SBE₂-β-CD and HP₂-SBE₃-β-CD exhibited morphological changes at high concentrations. In conclusion, the results showed that cholesterol depletion may be as a marker for evaluating the cytotoxicity of novel β-CD derivatives. These results will provide useful information for HPn-SBEm-β-CD as a promising safe adjuvant for intravenous administration in the future.     

Two new constituents from Rheum sublanceolatum

The chemical investigation of Rheum sublanceolatum has led to the isolation of two new constituents, the structures of which were identified on the basis of physical and spectroscopic analysis as 2-acetyl-3-methyl-6,8-dihydroxy-2,3,4,4-tetrahydronaphthalene-1-one-6-O-β-d-glucopyranoside (1) and 2,5-dimethyl-7-hydroxychromone-7-O-β-d-(6′-O-galloyl)-glucopyranoside (2).     

A Penicillium sp. F33 metabolite and its synthetic derivatives inhibit acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase (a key enzyme in platelet-activating factor biosynthesis) and carrageenan-induced paw edema in mice

Acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine (lyso-PAF) acetyltransferase is a key enzyme in the biosynthesis of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) in inflammatory cells. Substances which inhibit this enzyme are of therapeutic interest. In this study, we screened for new inhibitors of lyso-PAF acetyltransferase with anti-inflammatory effects. In a metabolite from Penicillium sp. F33, we isolated an acetyltransferase inhibitor identified as dihydrofumigatin (2-methoxy-1,3,4-trihydroxy-5-methylbenzene) from high resolution mass spectrometer and NMR data. Dihydrofumigatin had strong acetyltransferase inhibitory activity, but was not stable in aqueous solution. Thus, we chemically synthesized its oxidized form fumigatin (3-hydroxy-2-methoxy-5-methyl-1,4-benzoquinone) and derivatives thereof, and evaluated their inhibitory effects. Strong inhibitory activity was observed for saturated fatty acid esters of fumigatin; the order of inhibition was 3-decanoyloxy-2-methoxy-5-methyl-1,4-benzoquinone (termed FUD-7, IC₅₀ = 3 μM) > 2-methoxy-5-methyl-3-tetradecanoyloxy-1,4-benzoquinone (termed FUD-8, IC₅₀ = 20 μM) > 3-hexanoyloxy-2-methoxy-5-methyl-1,4-benzoquinone (IC₅₀ = 139 μM). Interestingly, these compounds also significantly suppressed the gene expression of lyso-PAF acetyltransferase/LPCAT2 in mouse bone marrow-derived macrophages stimulated by lipopolysaccharide (LPS). We further evaluated the effect of these substances on anti-inflammatory activity in vivo using the carrageenan-induced mouse paw edema test. FUD-7 and FUD-8 at 2.5 mg/kg showed significant, 47.9–51.7%, inhibition stronger than that of prednisolone at 10 mg/kg (41.9%). These results suggest that FUD-7 and FUD-8 are potent inhibitors with anti-inflammatory activity.     

Inhibitory effect of ethanol extract of Magnolia officinalis and 4-O-methylhonokiol on memory impairment and neuronal toxicity induced by beta-amyloid

The components of the herb Magnolia officinalis have exhibited antioxidant and neuroprotective activities. In this study, we investigated effects of ethanol extract of M.officinalis and its major component 4-O-methylhonokiol on memory dysfunction and neuronal cell damages caused by Aβ. Oral pretreatment of ethanol extract of M. officinalis (2.5, 5 and 10 mg/kg) and 4-O-methylhonokiol (1 mg/kg) into drinking water for 5 weeks suppressed the intraventricular treatment of Aβ_1-42 (0.5 μg/mouse, i.c.v.)-induced memory impairments. In addition, 4-O-methylhonokiol prevented the Aβ_1-42-induced apoptotic cell death as well as β-secretase expression. 4-O-methylhonokiol also inhibited H₂O₂ and Aβ_1-42-induced neurotoxicity in cultured neurons as well as PC12 cells by prevention of the reactive oxygen species generation. 4-O-methylhonokiol also directly inhibited β-secretase activity and Aβ fibrilization in vitro. Thus, ethanol extract of M. officinalis may be useful for prevention of the development or progression of AD, and 4-O-methylhonokiol may be a major active component.     

Simultaneous quantitation of levodopa and 3-O-methyldopa in human plasma by HPLC-ESI-MS/MS: application for a pharmacokinetic study with a levodopa/benserazide formulation

A sensitive and simple method was developed for the quantitation of levodopa and its metabolite 3-O-methyldopa, in human plasma, after oral administration of tablet formulations containing levodopa (200 mg) and benserazide (50 mg). The analytes were extracted by a protein precipitation procedure, using carbidopa as an internal standard. A mobile phase consisting of 0.2% formic acid and acetonitrile (94:6, v/v) was used and chromatographic separation was achieved using ACE C₁₈ column (50 mm × 4.6 mm i.d.; 5 μm particle size). Selected reaction monitoring was performed using the fragmentation transitions m/z 198 → m/z 107, m/z 212 → m/z 166 and m/z 227 → m/z 181 for levodopa, 3-O-methyldopa and carbidopa, respectively. Calibration curves were constructed over the range 50.0-6000.0 ng/mL for levodopa and 25.0-4000.0 ng/mL for 3-O-methyldopa. The method shown to be specific, precise, accurate and provided recovery rates higher than 85% for all analytes. No matrix effect was detected in the samples. The validated method was applied in a pharmacokinetic study with a levodopa/benserazide tablet formulation in healthy volunteers.     

Improving the Affinity of SL0101 for RSK Using Structure-Based Design

l-rhamnopyranoside)) has been shown to be an RSK selective inhibitor. However, the K_i for SL0101 is 1 μM with a half-life of less than 30 min in vivo. To identify analogues with improved efficacy we designed a set of analogues based on the crystallographic model of SL0101 in complex with the RSK2 N-terminal kinase domain. We identified an analogue with a 5″-n-propyl group on the rhamnose that has >40-fold improved affinity for RSK relative to SL0101 in an in vitro kinase assay. This analogue preferentially inhibited the proliferation of the human breast cancer line, MCF-7, versus the normal untransformed breast line, MCF-10A, which is consistent with results using SL0101. However, the efficacy of the 5″-n-propyl analogue to inhibit MCF-7 proliferation was only 2-fold better than for SL0101, which we hypothesize is due to limited membrane permeability. The improved affinity of the 5″-n-propyl analogue for RSK will aid in the design of future compounds for in vivo use.     

Evaluation of the mutagenic effects of myosmine in human lymphocytes using the HPRT gene mutation assay

The minor tobacco alkaloid myosmine is implicated in DNA damage through pyridyloxobutylation similar to the tobacco-specific nitrosamines (TSNA). In contrast to TSNA, occurrence of myosmine is not restricted to tobacco. Myosmine is genotoxic to human cells in the comet assay. In this study, the mutagenic effect of myosmine was evaluated using the cloning hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene mutation assay. Four hour exposure of isolated peripheral blood lymphocytes from 14 subjects homozygous for the Leu84 wild-type of the O⁶-methylguanine-DNA-methyltransferase (MGMT) gene to 1 mM of myosmine increased mutant frequency from 0.73 ± 0.58 × 10⁻⁶ in control to 1.14 ± 0.89 × 10⁻⁶ lymphocytes (P < 0.05). These new data further confirm the mutagenic effects of myosmine.     

Two new anthraquinone glycosides from the roots of Rheum palmatum

Two new anthraquinone glycosides, named 1-methyl-8-hydroxyl-9,10-anthraquinone-3-O-β-d-(6′-O-cinnamoyl)glucopyranoside (1) and rhein-8-O-β-d-[6′-O-(3″-methoxyl malonyl)]glucopyranoside (2), have been isolated from the roots of Rheum palmatum, together with seven known compounds, rhein-8-O-β-d-glucopyranoside (3), physcion-8-O-β-d-glucopyranoside (4), chrysophanol-8-O-β-d-glucopyranoside (5), aleo-emodin-8-O-β-d-glucopyranoside (6), emodin-8-O-β-d-glucopyranoside (7), aleo-emodin-ω-O-β-d-glucopyranoside (8), and emodin-1-O-β-d-glucopyranoside (9). Their structures were elucidated on the basis of chemical and spectral analysis.     

柱前手性衍生化反相高效液相色谱法拆分地佐西平对映异构体的研究

用乙酰葡萄糖异硫氰酸酯(GITC)作柱前手性衍生化试剂,以反相高效液相色谱法成功地拆分了地佐西平对映异构体。在此基础上建立了地佐西平对映异构体纯度和血药浓度测定方法。已用于测定右旋地佐西平的光学纯度和小鼠血药浓度。     

Inhibitory activity of quercetin and its metabolite on lipopolysaccharide-induced activation of macrophage U937 cells

The potential of quercetin and its metabolite 3-O-methyl quercetin in inhibiting lipopolysaccharide (LPS)-mediated activation of macrophage U937 cells was investigated. Cells were pre-incubated for different periods with 100 ng/mL phorbol myristate acetate (PMA), and later with LPS and quercetin or 3-O-methyl quercetin (30 μM). Later, the supernatant of each cell culture was assessed for catalase activity, nitric oxide, and the production of tumour necrosis factor-α (TNF-α), interleukin 6 (IL-6), and interleukin 1 (IL-1). The results showed that when the cells were incubated with LPS, there were elevations in the levels of all the markers over the cells not incubated with LPS (P < 0.05). For the cells that were incubated with LPS, there were significant differences between the various cells when they were pre-incubated with PMA for various periods (P < 0.05). However, greatest production of the markers was attained when the cells were pre-treated with PMA for 48 h. Both quercetin and 3-O-methyl quercetin (at 30 mM) reduced the levels of all the markers with 3-O-methyl quercetin possessing more inhibitory potential (P < 0.05). This suggests that the flavonoids possessed significant immunomodulatory activities which depend on methylation especially at position 3.     

Quantitative relationship between guanine O-alkyl lesions produced by Onrigin™ and tumor resistance by O-alkylguanine-DNA alkyltransferase

O⁶-Alkylguanine-DNA alkyltransferase (AGT) mediates tumor resistance to alkylating agents that generate guanine O⁶-chloroethyl (Onrigin™ and carmustine) and O⁶-methyl (temozolomide) lesions; however, the relative efficiency of AGT protection against these lesions and the degree of resistance to these agents that a given number of AGT molecules produces are unclear. Measured from differential cytotoxicity in AGT-ablated and AGT-intact HL-60 cells containing 17,000 AGT molecules/cell, AGT produced 12- and 24-fold resistance to chloroethylating (90CE) and methylating (KS90) analogs of Onrigin™, respectively. For 50% growth inhibition, KS90 and 90CE generated 5,600 O⁶-methylguanines/cell and ∼300 O⁶-chloroethylguanines/cell, respectively. AGT repaired O⁶-methylguanines until the AGT pool was exhausted, while its repair of O⁶-chloroethylguanines was incomplete due to progression of the lesions to AGT-irreparable interstrand DNA cross-links. Thus, the smaller number of O⁶-chloroethylguanine lesions needed for cytotoxicity accounted for the marked degree of resistance (12-fold) to 90CE produced by AGT. Transfection of human or murine AGT into AGT deficient transplantable tumor cells (i.e., EMT6, M109 and U251) generated transfectants expressing AGT ranging from 4,000 to 700,000 molecules/cell. In vitro growth inhibition assays using these transfectants treated with 90CE revealed that AGT caused a concentration dependent resistance up to a level of ∼10,000 AGT molecules/cell. This finding was corroborated by in vivo studies where expression of 4,000 and 10,000 murine AGT molecules/cell rendered EMT6 tumors partially and completely resistant to Onrigin™, respectively. These studies imply that the antitumor activity of Onrigin™ stems from guanine O⁶-chloroethylation and define the threshold concentration of AGT that negates its antineoplastic activity.     

土茯苓化学成分的分离与鉴定

目的对土茯苓的化学成分进行分离和鉴定,为土茯苓药材的质量控制提供依据。方法采用大孔树脂、硅胶、聚酰胺、ODS和Sephadex LH-20柱色谱方法进行分离,根据IR、1H-NMR、13C-NMR等谱学方法对化合物进行结构鉴定。结果从土茯苓中分离得到9个化合物,分别鉴定为β-谷甾醇棕榈酸酯(β-sitosterol palmitate,1)、β-谷甾醇(β-sitosterol,2)、胡萝卜苷(daucosterol,3)、1-棕榈酰基-3-O-β-D-半乳糖基甘油酯(1-O-hexadecanoyl-3-O-β-D-galactop yranosyl-glycerol,4)、落新妇苷(astilbin,5)、槲皮素(quercetin,6)、花旗松素(taxilfolin,7)、槲皮素-4′-O-β-D-吡喃葡萄糖苷(quercetin-4′-O-β-D-pyranglucoside,8)、异落新妇苷(isoastilbin,9)。结论化合物1、4为首次从菝葜属中分离得到,化合物8为首次从该植物中分离得到。     

Regioselective sulfonation of dopamine by SULT1A3 in vitro provides a molecular explanation for the preponderance of dopamine-3-O-sulfate in human blood circulation

SULT1A3 is an enzyme that catalyzes the sulfonation of many endogenous and exogenous phenols and catechols. The most important endogenous substrate is dopamine (DA), which is often used as a probe substrate for SULT1A3. We developed a new method for analyzing the SULT1A3 reaction products by high-performance liquid chromatography (HPLC) with electrochemical detection. The sulfonate donor 3′-phosphoadenosine-5′-phosphosulfate (PAPS), DA and the two dopamine sulfates, DA-3-O-sulfate and DA-4-O-sulfate, can be separated within 3 min. This enables quantitation of the sulfates without radioactive PAPS or the precipitation of unreacted PAPS. Both sulfates were synthesized as reference substances and characterized by ¹H and ¹³C nuclear magnetic resonance (NMR), mass spectrometry (MS) and tandem mass spectrometry (MS/MS). The purity of the dopamine sulfates was estimated by HPLC using a diode array detector. We determined the enzyme kinetic parameters for formation of DA-3-O-sulfate and DA-4-O-sulfate using purified recombinant human SULT1A3. The reactions followed Michaelis-Menten kinetics up to 50 μM DA concentration, and strong substrate inhibition was observed at higher concentrations. The apparent K_m values for sulfonation at both hydroxy groups were similar (2.21 ± 0.764 and 2.59 ± 1.06 μM for DA-4-O-sulfate and DA-3-O-sulfate, respectively), but the V_max was approximately six times higher for the formation of the 3-O-sulfate (344 ± 139 nmol/min/mg protein) than the 4-O-sulfate (45.4 ± 16.5 nmol/min/mg protein). These results are in accordance with the observation that DA-3-O-sulfate is more abundant in human blood than DA-4-O-sulfate and that in the crystal structure of SULT1A3 with dopamine bound to the active site, the 3-hydroxy group is aligned to form hydrogen bonds with catalytic residues of the enzyme.     

银杏叶中的黄酮醇苷类成分

目的　对银杏（Ginkgo biloba L.）叶的化学成分进行分离、鉴定。方法　采用各种色谱技术进行分离,用IR,UV,MS,¹HNMR,¹³CNMR和2DNMR光谱技术确定化合物的结构。结果　分得8个黄酮醇苷类成分：槲皮素-3-O-β-D-葡糖苷（1）,山奈酚-3-O-β-D-葡糖苷（2）,芦丁（3）,山奈酚-3-O-β-D-芸香糖苷（4）,异鼠李素-3-O-β-D-芸香糖苷（5）,槲皮素-3-O-β-D-葡萄糖基(1-2)-α-L-鼠李糖苷（6）,山奈酚-3-O-β-D-葡萄糖基(1-2)-α-L-鼠李糖苷（7）,异鼠李素-3-O-β-D-葡萄糖基(1-2)-α-L-鼠李糖苷（8）。结论　化合物8为新化合物。     

羟丙基-β-环糊精对兰索拉唑的增溶作用 及其包合物的制备

目的 研究羟丙基－β－环糊精（HP-β-CD）对难溶性药物兰索拉唑（LPZ）的包合作用。方法 绘制相溶解度图,考察pH变化、碳酸氢钠的加入对LPZ的增溶作用。采用共蒸发法（CE）和喷雾干燥法（SD）按照LPZ: HP-β-CD量比为1：1或1：1.5的比例制备LPZ/HP-β-CD包合物,测定其溶出度,并利用差示扫描量热法（DSC）和傅立叶红外光谱法（FTIR）对SD法制备的包合物进行结构表征。结果 在pH 11条件下,HP-β-CD与NaHCO3对LPZ的协同增溶效果最好。体外溶出实验表明：CE法和SD法制备的包合物溶出均优于LPZ与HP-β-CD的物理混合物。结论 HP-β-CD能明显提高LPZ的溶解度和溶出度。     

Simultaneous determination of vitexin-4″-O-glucoside and vitexin-2″-O-rhamnoside from hawthorn leaves flavonoids in rat plasma by HPLC method and its application to pharmacokinetic studies

The present study was to investigate the pharmacokinetics of the two similar flavonoid glycosides, vitexin-4″-O-glucoside (VGL) and vitexin-2″-O-rhamnoside (VRH) in rats after intravenous administration of hawthorn leaves flavonoids (HLF). Blood samples were collected via tail vein at time intervals after drug administration and the plasma concentrations of the studied ingredients were analyzed by HPLC after the plasma protein was precipitated directly with methanol. VGL and VRH were successfully separated using a C₁₈ column with a UV detection at 330 nm and a mobile phase of methanol–acetonitrile–tetrahydrofuran–0.5% acetic acid (1:1:19.4:78.6, v/v/v/v). The assay linearities of VGL and VRH were confirmed over the range 0.23–138.42 and 0.36–218.49 μg/ml, respectively. The accuracy and precision of the two analytes at high, medium and low concentration were within the range of −3.13% to 3.51% and below 4%, the mean assay recoveries of them (n = 5) ranged from 96.87% to 101.75% and 96.88% to 103.51% for intra- and inter-day assays and the mean extraction recoveries of them (n = 5) varied from 92.68% to 95.74% for VGL and 93.45% to 99.26% for VRH, respectively. After intravenous administration of HLF to rats over the doses range of 10–40 mg/kg, the plasma concentration–time curves of VGL and VRH were both conformed to the three-compartment open pharmacokinetic model and linear pharmacokinetic characteristics.     

Hemoglobin adducts as biomarkers of estrogen homeostasis: Elevation of estrogenquinones as a risk factor for developing breast cancer in Taiwanese Women

The aim of this study was to establish a methodology to analyze estrogen quinone-derived adducts, including 17β-estradiol-2,3-quinone (E₂-2,3-Q) and 17β-estradiol-3,4-quinone (E₂-3,4-Q), in human hemoglobin (Hb). The methodology was then used to measure the levels of these adducts in Hb derived from female breast cancer patients (n = 143) as well as controls (n = 147) in Taiwan. Our result confirmed that both E₂-2,3-Q- and E₂-3,4-Q-derived adducts, including E₂-2,3-Q-4-S-Hb and E₂-3,4-Q-2-S-Hb, were detected in all breast cancer patients with median levels at 434 (215–1472) and 913 (559–2384) (pmol/g), respectively. Levels of E₂-2,3-Q-4-S-Hb correlated significantly with those of E₂-3,4-Q-2-S-Hb (r = 0.622–0.628, p < 0.001). By contrast, median levels of these same estrogen quinone-derived adducts in healthy controls were 71.8 (35.7–292) and 139 (69.1–453) (pmol/g). This translated to ∼6-fold increase in mean values of E₂-2,3-Q-4-S-Hb and E₂-3,4-Q-2-S-Hb in breast cancer patients compared to those in the controls (p < 0.001). Our findings add further support to the theme that cumulative body burden of estrogen quinones is an important indicator of breast cancer risk. We hypothesize that combination of genetic events and environmental factors may modulate estrogen homeostasis and enhance the production of estrogen quinones which lead to subsequent generation of pro-mutagenic DNA lesions in breast cancer patients.     

毛细管电泳法测定(S)-2-(6-羟基-2,3-二氢苯并呋喃-3-基)乙酸甲酯中R异构体

目的建立毛细管电泳法测定(S)-2-(6-羟基-2,3-二氢苯并呋喃-3-基)乙酸甲酯中R异构体的方法。方法采用毛细管电泳法。以磺酸-β-环糊精(S-β-CD)为选择剂;25 mmol/L硼酸盐缓冲液(pH 8.9,含S-β-CD 1.8%)为运行缓冲液;运行电压为25 kV;柱温为15℃;检测波长:214 nm;3.4 kPa压力进样10 s。结果 (S)-2-(6-羟基-2,3-二氢苯并呋喃-3-基)乙酸甲酯与R异构体的分离度为2.9。R异构体在2~30μg/m L与峰面积线性关系良好(r=0.999 5),平均回收率为96.6%,RSD值为4.9%(n=6)。结论建立的毛细管电泳法操作简便,结果准确可靠,可用于(S)-2-(6-羟基-2,3-二氢苯并呋喃-3-基)乙酸甲酯中R异构体的控制。