宝藿甙-Ⅰ,Ⅵ,Ⅶ和宝藿素的分离和结构研究

自宝兴淫羊藿(Epimedium davidii Franch)中分离出8个黄酮类化合物,根据理化数据、光谱分析(UV,IR,¹HNMR,¹³CNMR,MS)和水解实验证明,其中E₃,E₁₃和E₈分别为已知成分淫羊藿甙、淫羊藿素和苜蓿素。E₁,E₁₁、E₁₆和E₁₅是新黄酮类化合物,并证明结构,分别命名为宝藿甙-Ⅰ(baohuoside Ⅰ),宝藿甙-Ⅵ(baohuoside Ⅵ),宝藿甙-Ⅶ(baohuo side Ⅶ)和宝藿素(baohuosu)。E¹⁷的结构待定。     

Oestradiol Protects Against the Harmful Effects of Fluoride More by Increasing Thiol Group Levels than Scavenging Hydroxyl Radicals

Abstract: The aim of the study was to investigate the role of oestrogens in free radical detoxication upon exposure to fluoride. Interactions between xenobiotics and oestrogens need to be investigated, especially as many chemicals interact with the oestrogen receptor. It is still unknown whether free radical‐generating xenobiotics can influence the antioxidative ability of oestradiol (E₂). In an in vitro examination of human placental mitochondria, thiobarbituric active reagent species (TBARS), hydroxyl radical (^?OH) generation and protein thiol (–SH) groups were detected. 17β‐E₂ was examined in physiological (0.15–0.73 nM) and experimental (1–10 µM) concentrations and sodium fluoride (NaF) in concentrations of 6–24 µM. E₂ in all the concentrations significantly decreased lipid peroxidation measured as the TBARS level, in contrast to NaF, which increased lipid peroxidation. Lipid peroxidation induced by NaF was decreased by E₂. The influence of E₂ on ^?OH generation was not very significant and depended on the E₂ concentration. The main mechanism of E₂ protection in NaF exposure appeared to be connected with the influence of E₂ on thiol group levels, not ^?OH scavenging ability. The E₂ in concentrations 0.44–0.73 nM and 1–10 µM significantly increased the levels of –SH groups, in contrast to NaF, which significantly decreased them. E₂ at every concentration reversed the harmful effects of NaF on –SH group levels. No unfavourable interactions in the influence of E₂ and NaF on TBARS production, ^?OH generation, or –SH group levels were observed. The results suggest that postmenopausal women could be more sensitive to NaF‐initiated oxidative stress.     

1-methyl substituent and stereochemical effects of 2-phenylcyclopropylamines on the inhibition of rat brain mitochondrial monoamine oxidase A and B

(E)-2-Phenylcyclopropylamine ((E)-TCP), (Z)-2-phenylcyclopropylamine ((Z)-TCP), (E)-1-methyl-2-phenylcyclopropylamine ((E)-MTCP), and (Z)-1-methyl-2-phenylcyclopropylamine ((Z)-MTCP) were synthesized and used to determine to what extent 1-methyl substitution and stereochemistry of 2-phenylcyclopropylamines affect inhibition of monoamine oxidase (MAO). Inhibition of rat brain mitochondrial MAO-A and B by the compounds were measured using serotonin and benzylamine as the substrate, respectively and IC₅₀ values obtained with 95% confidence limits by the method of computation. For the inhibition of MAO-A, (E)-MTCP (IC₅₀=6.2×10^?8M) was found to be 37 times more potent than (Z)-MTCP (IC₅₀=2.3×10^?6 M), whereas the activity of (E)-TCP (IC₅₀=2.9×10^?7 M) was slightly less than that of (Z)-TCP (IC₅₀=2.3×10^?7 M). Similarly, for the inhibition of MAO-B, (E)-MTCP (IC₅₀=6.3×10^?8 M) was 7 times more potent than (Z)-MTCP (IC₅₀=4.7×10^?7 M) and (E)-TCP (IC₅₀=7.8×10^?8 M), 0.6 times as potent as (Z)-TCP (IC₅₀=4.4×10^?8 M). The results suggested that while without 1-methyl group, potency of a (Z)-isomer was comparable to that of (E)-isomer, the methyl group in its (Z)-position was very unfavorable to the inhibition of MAO and that in its (E)-position, the methyl group contributed positively to the potency as found by the fact that (E)-MTCP was 1–5 times more potent than (E)-TCP. In view of the selective inhibition of MAO-A or B, all compounds elicited 4–10 times higher preference for the inhibition of MAO-B over MAO-A and 1-methyl substitution as well as the stereochemical factors did not significantly influence the selectivity.     

Interindividual variation in the enzymatic 15-keto-reduction of 13,14-dihydro-15-keto-prostaglandin E1 in human liver and in human erythrocytes

Objective: The therapeutic response to PGE₁ is highly variable, and a contribution by variable formation of its active tertiary metabolite PGE₀ is in question. Hence, the objective of this study was to assess the person-to-person variation of the reduction of the inactive intermediate metabolite 15-KD PGE₁ by human liver and human erythrocytes in forming the active metabolite PGE₀. Methods: Source of enzyme was lysed erythrocytes from 29 donors, and a bank of 37 donor livers including specimens from 15 children. Tritium-labelled 13,14-dihydro-15-keto-prostaglandin E₁ (15-KD PGE₁) was used at low nanomolar concentrations and found to be converted almost exclusively to the more polar compound 13,14-dihydro-prostaglandin E₁ (PGE₀) by an NADPH-dependent carbonyl reductase. The identity of the product PGE₀ was established by comparison of its chromatographic and mass spectral characteristics with authentic PGE₀. Results: Lysed erythrocytes had readily measurable enzymatic activity; differences between the preparations from 29 subjects were very small with only a twofold range of variation. In contrast to lysed erythrocytes, intact erythrocytes did not catalyse the reaction so that the erythrocyte activity should be medically immaterial. 15-KD PGE₁ 15-ketoreductase activity of liver cytosol averaged 61.1 fmol · min⁻¹ · mg⁻¹ protein in preparations from 37 human livers. Individual activities varied over an almost tenfold range, with indications of a non-normal distribution. Kinetic studies of selected specimens showed substantially different V_max values but indistinguishable k _M values, suggesting that the individual variation in 15-KD PGE₁ 15-ketoreduction is the result of differences in enzyme concentration rather than of structural enzyme variations. The activity in 15 livers from children was significantly lower than in those from adults. Inhibition data suggest that both the liver and the erythrocyte enzymes belong to the class of carbonyl reductases. Conclusions: The variations in hepatic enzyme activity may be expected to affect the transformation of 15-KD PGE₁ to the active metabolite PGE₀ in vivo. The clinical significance remains to be explored. Received: 5 July 1996 / Accepted in revised form: 18 November 1996     

Endocrine disrupting chemicals, 4‐nonylphenol,bisphenol A and butyl benzyl phthalate,impair metabolism of estradiol in male and female rats as assessed by levels of 15α‐hydroxyestrogens and catechol estrogens in urine

Bisphenol A (BPA), 4‐nonylphenol (NP) and butyl benzyl phthalate (BBP), termed endocrine‐disrupting chemicals, are known to mimic estrogen activity. The effects of these chemicals on 17β‐estradiol (E₂) metabolism in vivo in rats were examined. Male and female rats were given NP (250 mg kg^–1 day^–1), BPA (250 μg kg^–1 day^–1) or BBP (500 mg kg^–1 day^–1) by gavage for 14 days, followed by a single intraperitoneal injection of E₂ (5 mg kg^–1) on the final day. The urinary excretion over 72 hours of 2‐hydroxyestrone 1‐N‐acetylcysteine thioether, 2‐hydroxyestrone 4‐N‐acetylcysteine thioether, 4‐hydroxyestrone 2‐N‐acetylcysteine thioether, 2‐hydroxy‐17β‐estradiol (2‐OHE₂), 2‐hydroxyestrone (2‐OHE₁), 4‐hydroxy‐17β‐estradiol, 4‐hydroxyestrone, 15α‐hydroxyestriol (E₄), 15α‐hydroxy‐17β‐estradiol and 15α‐hydroxyestrone was measured. Increases in urinary excretion of 2‐OHE₁ and decreases in E₄ were observed in males treated with NP or BBP. Decreases in urinary excretion of 2‐OHE₂ and E₄ were observed in males treated with BPA. Decreases in urinary excretion of 2‐OHE₁ and 2‐OHE₂ were observed in females treated with BBP. Normalized liver and weights were increased in both sexes treated with NP or BBP. Histologic observations revealed marked changes in the distal tubules and collecting ducts in the kidneys of rats exposed to NP and BBP, and hypertrophy in the hepatocytes of the centrilobular zone of the liver. No BPA‐related effects on organ weight and on liver or kidney histopathology were found. These results suggest that the 14 day oral dosing of NP and BBP disrupted E₂ metabolism, resulting from marked morphological and functional alterations in the liver and kidneys. In addition, BPA could induce metabolic and endocrine disruption.     

A Redox-Based Chemical Delivery System that Enhances Estradiol Distribution to the Brain: Disposition Studies in the Rat

The disposition of a chemical delivery system for estradiol (E₂-CDS) which is based on a redox dihydropyridine-pyridinium salt conversion was investigated in rats. Tissue and plasma concentrations of E₂-CDS and the oxidized metabolite (E₂-Q ⁺ ) were evaluated at times ranging from 1 to 14 days after intravenous administration of E₂-CDS formulated as a modified cyclodextrin inclusion complex. While E₂-CDS levels were below HPLC assay detection limits for all samples by 1 day postdosing, E₂-Q⁺ was readily quantified. The calculated half-life of E₂-Q⁺ was longest in brain tissue, significantly shorter in heart, lung, and kidney tissues, and shortest in plasma. There was a linear relationship between administered E₂-CDS dose and oxidized metabolite measured in brain as well as in other tissues collected 24 hr after drug administration. Coadministration of high doses of a similarly oxidizable dihydropyridine, l-methyl-1,4-dihydronicotinamide (NMN), in a dimethylsulfoxide (DMSO) vehicle decreased E₂-Q⁺ measured in brain and other tissues without significantly affecting the relative patterns of distribution in these tissues. Brain tissue E₂Q⁺ levels were not detected after dosing with the oxidized metabolite.     

Dose and Time-Course Evaluation of a Redox-Based Estradiol-Chemical Delivery System for the Brain. I. Tissue Distribution

Brain-enhanced delivery and sustained release of estradiol (E₂) may be potentially useful in the treatments of vasomotor hot flushes and prostatic adenocarcinoma and for fertility regulation. Therefore, we have evaluated a redox-based estradiol-chemical delivery system (E₂-CDS) for the brain. The mechanism of this drug delivery is based on an interconvertible dihydropyridinepyridinium salt redox reaction. In this study, we investigated the dose- and time-dependent effects of E₂-CDS on the tissue distribution of E₂-Q⁺ and E₂, the inactive (intermediate) and active metabolites, respectively, of the E₂-CDS. Ovariectomized rats received a single iv injection of E₂-CDS at 0.01, 0.1, or 1.0 mg/kg or an E₂ dose of 0.7 mg/kg or the drug's vehicle, 2-hydroxypropyl--cyclodextrin (HPCD), on day 0. Tissue samples including brain and peripheral tissues were then analyzed for both E₂-Q⁺ and E₂ at 1, 7, 14, 21, or 28 days following the E₂-CDS administration. Initially, both E₂-Q⁺ and E₂ were detected in all tissues analyzed. The dose-distribution and time-course study demonstrates that (1) at 24 hr (1 day) after administration of E₂-CDS, all tissues showed a dose-proportional increase in concentrations of E₂-Q⁺ and E₂; (2) the enzymatic oxidation of E₂-CDS to E₂-Q⁺ was dose dependent over the 100-fold dose range examined; and (3) the disappearance of E₂-Q⁺ as well as E₂ was slow in whole brain and hypothalamus, with an apparent t = 8–9 days, while both of these metabolites were rapidly cleared from plasma, liver, fat, anterior pituitary, kidney, lung, heart, and uterus. Finally, when the kinetic behaviors of E₂-CDS and E₂ were compared on molar basis, the E₂-CDS (1.0-mg/kg dose) produced E₂ concentrations in brain tissue which were 81- and 182-fold greater than those achieved following equimolar E₂ (0.7 mg/kg) injection at 1 and 7 days, respectively. These data demonstrate that the E₂-CDS is much more effective than E₂ itself in delivering the estrogen to the brain. Collectively, these data support the concept of the brain-enhanced delivery and sustained release of E₂ using the redox-based chemical delivery system.     

Kinetics of interconversion of sulphamethoxydiazine crystal forms

A quantitative Nujol mull technique is described for the determination of sulphamethoxydiazine crystal forms in mixtures, so that the rates of their interconversion may be determined. The technique is applied to the transformations taking place in the more thermo-dynamically active as well as biologically available crystal form (Form II). Kinetic parameters indicate a highly temperature dependent transformation (E_a ? 100 kcal mol^?1; 418·6 kJ mol^?1) of Form II to the more stable Form I. Suspension in water results in a much faster transformation of Form II (E_a ? 20 kcal mol^?1; 83·7 kJ mol^?1, t_1/2 ? 15 min) to the water-stable Form III. Water and water vapour are shown to be important factors in the transformation of Form II at room temperature.     

Developmental effects of oral exposure to diethylstilbestrol on mouse placenta

Placental growth and function are of biological significance in that placental tissue promotes prenatal life and the maintenance of pregnancy. Exposure to synthetic estrogens causes embryonic mortality and placental growth restriction in mice. The aim of the present study was to examine the effects of diethylstilbestrol (DES) on placenta in mice. DES at 1, 5, 10 or 15 µg kg^–1 day^–1, or 17β‐estradiol (E₂) at 50 µg kg^–1 day^–1, was administered orally to ICR mice on days 4 through to 8 of gestation. Expression of ERα, ERβ, ERRβ or ERRγ mRNA in the junctional or labyrinth zone of the placentas on day 13 was assessed using RT‐PCR, as well as the embrynic mortality, embryonic and placental weight, histological changes of labyrinth and ultrastructural changes of the trophoblast giant cells (TGCs). Embryo mortalities in the DES 10 and 15 µg kg^–1 day^–1 groups were markedly increased. No significant changes in embryonic and placental weight were observed in any DES‐ or E₂‐exposed groups. Expression of ERα mRNA in the junctional zone with male embryos in the 5 µg kg^–1 day^–1 group was significantly higher than that in the control, whereas expression was not determined in the 15 µg kg^–1 day^–1 group. Histological observation revealed that the placentas exposed to DES at 10 µg kg^–1 day^–1 lacked the developing labyrinth. Ultrastructural observation of the TGCs showed poor rough‐surfaced endoplasmic reticulum in the DES 10 µg kg^–1 day^–1 group. The present data suggest that developmental changes induced by DES may be related to interference with the nutrition and oxygen exchange between mother and embryo or decreased protein synthesis, resulting in a high frequency of embryo mortality. Copyright © 2012 John Wiley & Sons, Ltd.     

Temporal linear mode complexity as a surrogate measure of the effect of remifentanil on the central nervous system in healthy volunteers

AIMS

Previously, electroencephalographic approximate entropy (ApEn) effectively described both depression of central nervous system (CNS) activity and rebound during and after remifentanil infusion. ApEn is heavily dependent on the record length. Linear mode complexity, which is algorithmatically independent of the record length, was investigated to characterize the effect of remifentanil on the CNS using the combined effect and tolerance, feedback and sigmoid E_max models.

METHODS

The remifentanil blood concentrations and electroencephalographic data obtained in our previous study were used. With the recording of the electroencephalogram, remifentanil was infused at a rate of 1, 2, 3, 4, 5, 6, 7 or 8 µg kg⁻¹ min⁻¹ for 15–20 min. The areas below (AUC_effect) or above (AAC_rebound) the effect vs. time curve of temporal linear mode complexity (TLMC) and ApEn were calculated to quantitate the decrease of the CNS activity and rebound. The coefficients of variation (CV) of median baseline (E₀), maximal (E_max), and individual median E₀ minus E_maxvalues of TLMC were compared with those of ApEn. The concentration–TLMC relationship was characterized by population analysis using non-linear mixed effects modelling.

RESULTS

Median AUC_effectand AAC_reboundwere 1016 and 5.3 (TLMC), 787 and 4.5 (ApEn). The CVs of individual median E₀ minus E_max were 35.6, 32.5% (TLMC, ApEn). The combined effect and tolerance model demonstrated the lowest Akaike information criteria value and the highest positive predictive value of rebound in tolerance.

CONCLUSIONS

The combined effect and tolerance model effectively characterized the time course of TLMC as a surrogate measure of the effect of remifentanil on the CNS.     

Epigallocatechin-3-gallate is an inhibitor of Na,K-ATPase by favoring the E1 conformation

Four catechins, epigallocatechin-3-gallate, epigallocatechin, epicatechin-3-gallate, and epicatechin, inhibited activity of the Na⁺,K⁺-ATPase. The two galloyl-type catechins were more potent inhibitors, with IC₅₀ values of about 1 μM, than were the other two catechins. Inhibition by epigallocatechin-3-gallate was noncompetitive with respect to ATP. Epigallocatechin-3-gallate reduced the affinity of vanadate, shifted the equilibrium of E₁P and E₂P toward E₁P, and reduced the rate of the E₁P to E₂P transition. Epigallocatechin-3-gallate potently inhibited membrane-embedded P-type ATPases (gastric H⁺,K⁺-ATPase and sarcoplasmic reticulum Ca²⁺-ATPase) as well as the Na⁺,K⁺-ATPase, whereas soluble ATPases (bacterial F₁-ATPase and myosin ATPase) were weakly inhibited. Solubilization of the Na⁺,K⁺-ATPase with a nonionic detergent reduced sensitivity to epigallocatechin-3-gallate with an elevation of IC₅₀ to 10 μM. These results suggest that epigallocatechin-3-gallate exerts its inhibitory effect through interaction with plasma membrane phospholipid.     

Pharmacokinetic-pharmacodynamic modelling of the anti-lipolytic and anti-ketotic effects of the adenosine A1-receptor agonist N6-(p-sulphophenyl)adenosine in rats

1. The purpose of this study was to develop and validate an integrated pharmacokinetic-pharmacodynamic model for the anti-lipolytic effects of the adenosine A₁-receptor agonist N⁶-(p-sulphophenyl)adenosine (SPA). Tissue selectivity of SPA was investigated by quantification of haemodynamic and anti-lipolytic effects in individual animals.
2. After intravenous infusion of SPA to conscious normotensive Wistar rats, arterial blood samples were drawn for determination of blood SPA concentrations, plasma non-esterified fatty acid (NEFA) and β-hydroxybutyrate levels. Blood pressure and heart rate were monitored continuously.
3. The relationship between the SPA concentrations and the NEFA lowering effect was described by the indirect suppression model. Administration of SPA at different rates and doses (60 μg kg⁻¹ in 5 min and 15 min, and 120 μg kg⁻¹ in 60 min) led to uniform pharmacodynamic parameter estimates. The averaged parameters (mean±s.e., n=19) were E_max: −80±2% (% change from baseline), EC₅₀: 22±2 ng ml⁻¹, and Hill factor: 2.2±0.2.
4. In another group, given 400 μg kg⁻¹ SPA in 15 min, pharmacodynamic parameters for both heart rate and anti-lipolytic effect were derived within the same animal. The reduction in heart rate was directly related to blood concentration on the basis of the sigmoidal E_max model. SPA inhibited lipolysis at concentrations lower than those required for an effect on heart rate. The EC₅₀ values (mean±s.e., n=6) were 131±31 ng ml⁻¹ and 20±3 ng ml⁻¹ for heart rate and NEFA lowering effect, respectively.
5. In conclusion, the relationship between blood SPA concentrations and anti-lipolytic effect was adequately described by the indirect suppression model. For SPA a 6 fold difference in potency was observed between the effects on heart rate and NEFAs, indicating some degree of tissue selectivity in vivo.

     

A Redox-Based System that Enhances Delivery of Estradiol to the Brain: Pharmacokinetic Evaluation in the Dog

The pharmacokinetics of a dihydropyridine–pyridinium salt-type chemical delivery system (CDS) for brain-targeted delivery of estradiol (E₂) were examined in dogs. Parameters evaluated in vitro included stability in buffers and biological fluids and plasma protein binding. In vivo studies examined drug and metabolite concentrations in plasma, urine, and cerebrospinal fluid as well as in selected brain regions. The administered lipophilic E₂-CDS disappeared very quickly from plasma and was not detected in urine. The oxidized drug form, E₂-Q⁺, was excreted unchanged or as a conjugate in the urine for as long as 2 weeks. Plasma levels were below assay detection limits at later times. Pharmacokinetic analysis of urine E₂-Q⁺ levels allowed estimation of a half-life of 2.2 days. Amounts of E₂-Q⁺ excreted into the urine were proportional to the dose but averaged only 13.9% of the dose, indicating that other routes of excretion must be considered. CSF levels were below the limit of detection for both E₂-CDS and E₂-Q⁺, however, brain tissue concentrations of E₂-Q⁺ were similar in several brain regions of individual animals examined 1 or 3 days after drug dosing.     

宝藿甙Ⅱ,Ⅲ,Ⅳ,Ⅴ的分离和结构研究

自宝兴淫羊藿(Epimedium davidii Franch)全草中分离得十七个黄酮类化合物。确定了E₂,E₄,E₅,E₆,E₇,E₉,E₁₀,E₁₂和E₁₄的化学结构。其中五个为已知成分,即E₅为淫羊藿甙-C,E₉为淫羊藿甙-A,E₁₂为去甲淫羊藿素,E₄为金丝桃甙,E₁₄为山柰素-3-双鼠李糖甙。E₂,E₆,E₇和E₁₀是首次从植物中分离到的黄酮醇甙,分别命名为宝藿甙-Ⅱ,宝藿甙-Ⅲ,宝藿甙-Ⅳ和宝藿甙-Ⅴ。E₄和E₁₄在本属植物中系首次发现。     

Dose and Time-Course Evaluation of a Redox-Based Estradiol-Chemical Delivery System for the Brain. II. Pharmacodynamic Responses

Clinically, brain-enhanced delivery and sustained release of estradiol (E₂) are desirable for effective treatments of menopausal hot flushes and prostatic adenocarcinoma and for fertility regulation. Thus, we conducted studies to determine the dose- and time-dependent effects of a brain-enhanced estradiol-chemical delivery system (E₂-CDS) on anterior pituitary hormones secretion in ovariectomized (OVX) rats. The E₂-CDS has consistently demonstrated preferential retention of its intermediate metabolite (E₂-Q⁺ ), with slow release of E₂ in the brain but rapid clearance from peripheral tissues. Animals received a single iv injection of E₂-CDS at doses of 0.01, 0.1, or 1.0 mg/kg or an E₂ dose of 0.7 mg/kg on day 0. The responses of plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), and prolactin (PRL) were then evaluated at 1, 7, 14, 21, or 28 days after drug administration. The E₂-CDS caused a dose- and time-dependent suppression of LH and FSH throughout the time course studied. The maximum LH and FSH reduction occurred at 7 days postinjection. Plasma LH and FSH were significantly suppressed by 86 and 58% on day 7, respectively, and were suppressed by 35% (LH) or were at preinjection levels (FSH) at 28 days following the single injection of a 1.0-mg E₂-CDS dose. An equimolar E₂ dose suppressed LH and FSH by only 29 and 20% on day 7, respectively which were not significantly different from time 0 values. Plasma PRL increased significantly on day 14 with the 1.0-mg E₂-CDS dose but levels returned to preinjection values by 28 days after drug administration. Lower doses of the E₂-CDS did not affect PRL concentrations. Plasma GH concentrations were not altered in response to the E₂-CDS at any dose or time. Also, anterior pituitary and uterine weights increased in a dose- and time-dependent manner in response to E₂-CDS administration. Collectively, these data demonstrate that the E₂-CDS effects on gonadotropins suppression are dose and time dependent and this duration of suppression is consistent with the long half-lives of the E₂-CDS metabolites in the brain.     

Synthesis of stable isotopes of auxinic herbicides 4‐amino‐3,5,6‐trichloropicolinic acid and 4‐amino‐3,6‐dichloropicolinic acid

Pentachloropyridine serves as a key intermediate in the synthesis of 4‐amino‐3,5,6‐trichloropicolinic acid (picloram) and 4‐amino‐3,6‐dichloropicolinic acid (aminopyralid). An M+3 stable isotope of pentachloropyridine (1, pentachloropyridine‐1‐¹⁵N‐2,6‐¹³C₂) was prepared from K¹³C¹⁵N. Isotopically labeled pentachloropyridine was then carried through a seven‐step synthesis to give an M+3 stable isotope of 4‐amino‐3,5,6‐trichloropicolinic acid (2, picloram‐1‐¹⁵N‐2,6‐¹³C₂) in an overall yield of 42%. The chlorine atom in the 5‐position of 2 was selectively removed via electrochemical reduction. Carrying out the electrochemical reduction in water provided an M+3 stable isotope of 4‐amino‐3,6‐dichloropicolinic acid (3, aminopyralid‐1‐¹⁵N‐2,6‐¹³C₂), whereas conducting the reduction in deuterium oxide produced an M+4 stable isotope (4, aminopyralid‐1‐¹⁵N‐2,6‐¹³C₂‐5‐²H). Copyright © 2009 John Wiley & Sons, Ltd.     

健康志愿者单次和多次口服美敏伪麻缓释胶囊的药动学研究

目的研究美敏伪麻缓释胶囊经单、多次给药后的药动学特征,评估其在健康志愿者体内的安全性。方法 22例受试者随机、开放试验设计,研究单、多次给药药动学特征。血浆中氯苯那敏、伪麻黄碱、右美沙芬、右啡烷采用LC-MS/MS法测定,药动学参数采用Win Nonlin软件计算。安全性特征以记录到的所有不良事件来进行评价。结果整个研究过程中没有严重不良事件报告。单次口服美敏伪麻缓释胶囊后,伪麻黄碱、氯苯那敏、右美沙芬和右啡烷均在3~5 h达峰,t1/2分别为6.30±1.17、23.3±6.91、10.4±2.19、8.62±3.04 h,Cmax分别为203±40.4、5.05±1.39、4.29±3.95、1.95±0.72 ng/m L,AUClast分别为2 050±559、137±47.5、61.3±67.5、17.2±6.58μg·h/L,AUCinf分别为2 140±570、161±63.8、17.6±6.65、62.8±69.3μg·h/L。在2次/d,连续给药4 d后基本达到稳态血药浓度,伪麻黄碱、氯苯那敏、右美沙芬和右啡烷的Cmax、Cmin、AUCtau,ss与单次给药比较均有不同程度的升高,波动系数的平均值为107%~271%。结论美敏伪麻缓释胶囊多次给药后4 d达到稳态血药浓度,暴露均较单次给药后有所增高,在健康志愿者体内安全性良好。     

Pharmacokinetic-pharmacodynamic modelling as a tool to evaluate the clinical relevance of a drug-food interaction for a nisoldipine controlled-release dosage form

Objective: Nisoldipine, a calcium antagonist of the dihydropyridine class, has been used in the treatment of hypertension and angina pectoris. A new controlled-release dosage form (nisoldipine coat-core, NCC) has been developed to allow once daily dosing. In addition to a formal food interaction study as requested by regulatory authorities for controlled-release dosage forms, a subsequent study was conducted to determine the clinical relevance of the changes in nisoldipine plasma concentration vs time profiles seen in the food effect study. Methods: After a placebo run-in phase of 6 days, 12 hypertensive patients started treatment with 20 mg NCC once daily (days 0–3, 5–6, 8–9). On days 4, 7 and 10 the NCC was substituted for 5, 10 and 20 mg nisoldipine solution, respectively, in order to obtain nisoldipine plasma concentration vs time profiles comparable to the ones resulting from the concomitant intake of food and NCC. Simultaneous measurements of blood pressure (BP) and nisoldipine concentration were performed on days 3, 4, 7 and 10. Results: The relationship between nisoldipine plasma concentrations and percentage reduction in BP [diastolic (DBP) and systolic (SBP), supine and standing] could be described by an E_max model. The mean maximum reduction (E_max) relative to baseline was about 36.4% and 37.7% (DBP, supine and standing) and 27.9% and 29.2% (SBP, supine and standing), respectively. The interindividual variability (% CV) in E_max was low, ranging from 17.6% to 28.8%. The mean nisoldipine plasma concentration corresponding to 50% of the maximum effect (EC₅₀) ranged between 0.99 and 2.62 μg · l^–1 with a pronounced interindividual variability (% CV) of 89.5–108.8%. Mean C_max values after administration of the 30 and 40 mg NCC together with food were 4.5 and 7.5 μg · l^–1, respectively. Based on the concentration-effect relationship established in the present study, the effect achieved with a concentration of 7.5 μg · l^–1 will be about 77% of E_max for DBP and about 88% of E_max for SBP, respectively. Conclusion: At the time of maximum plasma concentration the additional decrease in BP relative to baseline due to the food effect will be about 7–15% for DBP and 3–9% for SBP. After administration of the 10␣mg solution with a mean C_max of 8.7 μg · l^–1, only headache and flush with mild severity have been reported as adverse events. These maximum concentrations are comparable to C_max values seen after intake of 40 mg NCC with food. With regard to heart rate (HR) there were distinct differences between the two formulations: Following administration of 5, 10 and 20 mg nisoldipine solution, there were dose-dependent increases in HR by a maximum of 4, 12 and 16 beats · min⁻¹, respectively, whereas the HR profile for the NCC was similar to that seen under placebo treatment. Received: 28 December 1995 / Accepted in revised form: 19 August 1996     

Quantum chemical-based drug�Creceptor interaction of tetrahydroimidobenzodiazepinones (HIV-1-NNRTIs) with receptor (HIV-1-NNRTI-binding pocket)

The chemical forces responsible for interaction of drug (HIV-1-NNRTI) with receptor (HIV-1-NNRTI-binding pocket) have been studied by evaluating log P and SASA for the measurement of hydrophobic interaction; energy of protonation (ΔE) for the measurement of most favorable hydrogen bond acceptor site; bond length and bond strain for the measurement of strength of hydrogen bond formed between drug and receptor; ΔE _nm ^‡ = ∣E _n ^‡ − E _m ^‡∣ for the measurement of polar interaction. The molecular modeling and geometry optimization of the compounds (drugs) and receptor amino acids (Val, Met, and Tyr) have been done using MOPAC-2002 associated with CAChe software. Softness Calculator has been used to evaluate effective atomic softness (E _n ^‡ and E _m ^‡). The results indicate that there is strong and effective hydrophobic interaction between hydrophobic substituent at site-6 of the drug and Val-Y187 of the receptor; hydrophobic substituent at site-5 and Met-Y184. Similarly, hydrogen bonds are formed between N-atom (site-6) of the drug and H-atom of the phenolic group of the Tyr-Y188; between phenolic group of the Tyr-181 and H-atom (site-1) of the drug. Polar interaction (charge transfer) occurs between –C=O/S (site-2) of the drug and –CONH– of Asn-Y182-Tyr-Y183.     

Enantioselective pharmacokinetic and pharmacodynamic properties of carvedilol in spontaneously hypertensive rats: focus on blood pressure variability

The cardiovascular effects and pharmacokinetics of carvedilol were assessed in spontaneously hypertensive (SH) and Wistar Kyoto (WKY) animals with special focus on short-term blood pressure variability (BPV). Male SH and WKY rats were acutely treated with vehicle or carvedilol 1 or 5 mg kg⁻¹ (i.v.), and effects on blood pressure (BP), heart rate (HR) and BPV were recorded. Plasma pharmacokinetics of R- and S-carvedilol was studied by traditional blood sampling. Relationship between carvedilol concentrations and their hypotensive and bradycardic effects was established by pharmacokinetic–pharmacodynamic (PK–PD) modelling. Short-term BPV was assessed by standard deviation of BP recording. Vascular sympatholytic activity of carvedilol was studied by estimation of drug effects on ratio between low frequency (LF) and high frequency (HF) BPV (LF/HF ratio). Although pharmacokinetic properties of carvedilol remained mainly unaffected in SH rats with regard to WKY rats, hypertensive animals showed a reduction in drug clearance of R- and S-carvedilol after administration of 1 mg kg⁻¹ compared with WKY rats. PK–PD analysis of HR changes induced by S-carvedilol showed a greater maximal bradycardic response to carvedilol in SH rats (E _max, −27.6 ± 3.9%; p < 0.05) compared with WKY group (E _max, −13.4 ± 2.5%). SH rats showed a greater hypotensive effect of racemic carvedilol (E _max, −45.5 ± 5.0%; p < 0.05) with regard to WKY group (E _max, −17.9 ± 4.5%). Carvedilol induced a greater reduction of LF/HF ratio in SH rats compared with WKY rats. Short-term BPV was markedly reduced by carvedilol in WKY and SH rats. In conclusion, as a consequence of an enhanced bradycardic response and a greater vascular sympatholytic activity, carvedilol exerts a greater hypotensive response in SH rats compared with WKY animals and dramatically reduces short-term BPV.