bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of dehydrodiisoeugenol in rat tissues using HPLC method
Authors: Li Fei , Yang Xiu‐wei 
Published: July 2008

AbstractDehydrodiisoeugenol (DDIE) is a bioactive neolignan from the seeds of Myristica fragrans Houtt., which exhibits good anti‐inflammatory activity. A rapid and simple high‐performance liquid chromatographic (HPLC) method has been developed for the determination of DDIE in rat tissues after intravenous administration. The tissue samples were processed by liquid–liquid extraction. The analyses were successfully carried out on a Diamonsil™ ODS C18 column (250 × 4.6 mm i.d., 5 µm) equipped with a C18 guard column (8 × 4.6 mm i.d., 5 µm). The mobile phase was the system of methanol–water (4:1, v/v). The UV detection was set at 270 nm. The calibration curves were linear from 0.4 to 200.0 µg/g with the correlation coefficients (r2) greater than 0.998. The intra‐ and inter‐day precisions in quality control samples were less than 10% and the accuracies were in the range 85.4–110.3%. The average recoveries from all the tissues were between 84.4 and 106.0%. This assay method has been successfully used to study the tissues distribution of DDIE in rats after intravenous administration. The result suggests that DDIE is distributed to rat tissues rapidly with possibly greater initial concentrations in liver and brain than in other tissues. Copyright © 2008 John Wiley & Sons, Ltd.
High‐throughput LC‐MS/MS assay for 6‐methoxy‐2‐naphthylacetic acid, an active metabolite of nabumetone in human plasma and its application to bioequivalence study
Authors: Patel Bhavin N. , Sharma Naveen , Sanyal Mallika , Prasad Arpana , Shrivastav Pranav S. 
Published: July 2008

AbstractA simple, precise and accurate assay for the determination of 6‐methoxy‐2‐naphthylacetic acid (6‐MNA), an active metabolite of nabumetone in human plasma, was developed and validated using liquid chromatography–tandem mass spectrometry (LC‐MS/MS). The analyte (6‐MNA) and propranolol (internal standard, IS) were extracted from 200 µL aliquot of human plasma via solid‐phase extraction employing HLB Oasis cartridges and separated on a Discovery® HS C18 (50 × 4.6 mm, 5 µm) column. Detection of analyte and IS was done by tandem mass spectrometry with a turbo ion spray interface operating in positive ion and multiple reaction monitoring acquisition mode. The total chromatographic runtime was 3.0 min with retention time for 6‐MNA and IS at 1.97 and 1.26 min, respectively. The method was validated over a dynamic linear range of 0.20–60.00 µg/mL for 6‐MNA with mean correlation coefficient r ≥ 0.9986. The intra‐batch and inter‐batch precision (%CV) across five validation runs (lower limit of quantiation, low‐, medium‐ and high‐quality controls and upper limit of quantitation) was less than 7.5%. The accuracy determined at these levels was within −5.8 to +0.2% in terms of percentage bias. The method was successfully applied for a bioequivalence study of 750 mg nabumetone tablet formulation in 12 healthy Indian male subjects under fasted condition. Copyright © 2008 John Wiley & Sons, Ltd.
Application of RP‐TLC technique for the determination of dissociation constants of 1‐substituted pyrrolidin‐2‐one derivatives
Authors: Kulig Katarzyna , Rybicka Karolina , Malawska Barbara 
Published: July 2008

AbstractThe procedures for measuring dissociation constants (pKa) of twenty 1‐substituted pyrrolidin‐2‐one derivatives are described. The dissociation constants of the compounds tested were determined using potentiometric titration, reversed‐phase thin‐layer chromatography (RP‐TLC) and calculated using Pallas and Marvin programs. It was found that the RP‐TLC method of determination of pKa could be considered as a feasible alternative to potentiometric titration. The Marvin program is a better tool for preliminary estimation of dissociation constant than the Pallas one. Copyright © 2008 John Wiley & Sons, Ltd.
Structural elucidation of in vitro metabolites of emodin by liquid chromatography–tandem mass spectrometry
Authors: Song Rui , Xu Fengguo , Zhang Zunjian , Liu Ying , Dong Haijuan , Tian Yuan 
Published: July 2008

AbstractLiquid chromatography–electrospray ionization tandem mass spectrometry (LC‐ESI‐MS/MS) was employed to investigate the in vitro metabolism of emodin. Emodin was incubated with rat liver microsomes in the presence of a NADPH‐generating system, followed by extraction with ethyl acetate. After separation on a reversed‐phase C18 analytical column with a linear gradient elution of methanol and 0.1% formic acid in water, negative electrospray ionization tandem mass spectrometry experiments were performed. As a result, the parent drug and its six metabolites were detected from rat liver microsomal incubations. The identification of the metabolites and elucidation of their structure were performed by comparing the changes in molecular masses (ΔM), retention times and MS2 spectral patterns of metabolites with those of parent drug. Besides three mono‐hydroxylated metabolites (ω‐hydroxyemodin, 2‐hydroxyemodin, 4‐hydroxyemodin), three other metabolites were identified, which were emodic acid, 3‐carbomethoxy‐6‐methoxy‐1,8‐dihydroxyanthraquinone and physcion, respectively. Copyright © 2008 John Wiley & Sons, Ltd.
Improved HPLC method for doxorubicin quantification in rat plasma to study the pharmacokinetics of micelle‐encapsulated and liposome‐encapsulated doxorubicin formulations
Authors: Wei Guangli , Xiao Shuhua , Si Duanyun , Liu Changxiao 
Published: July 2008

AbstractAn improved simple, rapid and accurate HPLC method for quantification of doxorubicin derived from micelle‐encapsulated or liposome‐encapsulated doxorubicin formulation in rat plasma was described. The mobile phase consisting of a mixture of methanol–water [containing 0.1% formic acid anhydrous and 0.1% ammonia solution (25%), pH 3.0], 60:40, was delivered at a flow rate of 1.0 mL/min. Sample preparation for micelle‐ or liposome‐encapsulated doxorubicin in rat plasma were achieved directly by protein precipitation with acetonitrile. Doxorubicin and daunorubicin (internal standard, IS) were separated on a C18 reversed‐phase HPLC column and quantified by a fluoresence detection with an excitation wavelength of 475 nm and an emission wavelength of 580 nm. The linearity was obtained over the range of 5.0–1000.0 ng/mL and 1.0–200.0 µg/mL for doxorubicin and the lower limit of quantitation was 5.0 ng/mL. For each level of quality control samples, inter‐ and intra‐assay precision was less than 9.6 and 5.1% (relative standard deviation), respectively, and percentage error was within ±2.6%. The extraction recoveries of doxorubicin in the range of 10 ng/mL to 100 µg/mL in rat plasma were between 94.1 and 105.6%. This method was successfully applied to the pharmacokinetic study of doxorubicin formulations after i.v. administration to rats. Copyright © 2008 John Wiley & Sons, Ltd.
Development of a pretreatment method for amyloid β‐protein analysis based on the effect of acetic acid on the dissolution of plasma polypeptides
Authors: Goda Ryoya , Masumoto Hiroshi , Okazaki Osamu , Sudo Kenichi 
Published: July 2008

AbstractDuring the evaluation of a pretreatment method for the simultaneous quantification of four amyloid β‐protein fragments in transgenic mice plasma by a new gradient system, we have found that acetic acid has potency to completely dissolve plasma polypeptides in the presence of an organic solvent. Based on this observation, we designed a simple pretreatment method using an ultrafiltration membrane. An analysis of the filtrate obtained by this method suggests the possibility that acetic acid inhibits the interaction between amyloid β‐protein fragments and plasma polypeptides, which leads to a higher recovery of the amyloid β‐protein fragments from mouse plasma. In addition, higher dilution of mouse plasma using a dilution solution produced higher recovery as well. The highest recovery of amyloid β‐protein 1–38, 1–40, 1–42 and 1–43 fragments was 101.7, 94.9, 96.2 and 84.8%, respectively. Furthermore, calibration curves with the lower limit of quantification of 0.65 nm were successfully constructed with good accuracy using the developed method. Consequently, a pretreatment method using an ultrafiltration membrane is a powerful tool to determine the amyloid β‐protein fragments in transgenic mice plasma containing an abundance of plasma polypeptides such as albumin. Copyright © 2008 John Wiley & Sons, Ltd.
Simultaneous quantification of acylated and desacylated ghrelin in biological fluids
Authors: Aydin Suleyman , Karatas Fikret , Geckil Hikmet 
Published: July 2008

AbstractThis study reports simultaneous quantification of both acylated and desacylated forms of ghrelin in biological samples, utilizing a reverse‐phase high‐performance liquid chromatography (HPLC) system. The HPLC assay was also compared with RIA assays in use. Biological samples (serum, saliva, urine, milk) known for the presence of ghrelin were collected from a total of eight post‐partum women and eight male volunteers. Analysis of ghrelin with HPLC was also validated for linearity, precision, detection limit and accuracy. An elution time of 6 min was observed for pure (commercial) desacylated human ghrelin and for the same form of the hormone from all body fluids studied. The elution time for acylated pure human ghrelin and that in body fluids, however, was around 16 min. The mean recovery rate was over 90% for both forms with no significant interference. The lowest detectable levels for acylated and desacylated ghrelin with the method used here were 11 (±2) and 14 (±3) pg mL−1, respectively. Given its simplicity, accuracy, time and cost‐effectiveness, the HPLC method described here for determination of two forms of ghrelin (active and inactive) might prove useful for certain diagnostic purposes. Copyright © 2008 John Wiley & Sons, Ltd.
LC/MS/MS for identification of in vivo and in vitro metabolites of jatrorrhizine
Authors: Zhang Yi , Wu Wenhua , Han Fengmei , Chen Yong 
Published: July 2008

AbstractThe in vivo and in vitro metabolism of jatrorrhizine has been investigated using a specific and sensitive LC/MS/MS method. In vivo samples including rat feces, urine and plasma collected separately after dosing healthy rats with jatrorrhizine (34 mg/kg) orally, along with in vitro samples prepared by incubating jatrorrhizine with rat intestinal flora and liver microsome, respectively, were purified using a C18 solid‐phase extraction cartridge. The purified samples were then separated with a reversed‐phase C18 column with methanol–formic acid aqueous solution (70:30, v/v, pH3.5) as mobile phase and detected by on‐line MS/MS. The structural elucidation of the metabolites was performed by comparing their molecular weights and product ions with those of the parent drug. As a result, seven new metabolites were found in rat urine, 13 metabolites were detected in rat feces, 11 metabolites were detected in rat plasma, 17 metabolites were identified in intestinal flora incubation solution and nine metabolites were detected in liver microsome incubation solution. The main biotransformation reactions of jatrorrhizine were the hydroxylation reaction, the methylation reaction, the demethylation reaction and the dehydrogenation reaction of parent drug and its relative metabolites. All the results were reported for the first time, except for some of the metabolites in rat urine. Copyright © 2008 John Wiley & Sons, Ltd.
Aib Residues in Peptaibiotics and Synthetic Sequences: Analysis of Nonhelical Conformations
Authors: Aravinda Subrayashastry , Shamala Narayanaswamy , Balaram Padmanabhan 
Published: July 2008

AbstractThe α‐aminoisobutyric (Aib) residue has generally been considered to be a strongly helicogenic residue as evidenced by its ability to promote helical folding in synthetic and natural sequences. Crystal structures of several peptide natural products, peptaibols, have revealed predominantly helical conformations, despite the presence of multiple helix‐breaking Pro or Hyp residues. Survey of synthetic Aib‐containing peptides shows a preponderance of 310‐, α‐, and mixed 310/α‐helical structures. This review highlights the examples of Aib residues observed in nonhelical conformations, which fall ‘primarily’ into the polyproline II (PII) and fully extended regions of conformational space. The achiral Aib residue can adopt both left (αL)‐ and right (αR)‐handed helical conformations. In sequences containing chiral amino acids, helix termination can occur by means of chiral reversal at an Aib residue, resulting in formation of a Schellman motif. Examples of Aib residues in unusual conformations are illustrated by surveying a database of Aib‐containing crystal structures.
Conformational Effects on the Electron‐Transfer Efficiency in Peptide Foldamers Based on α,α‐Disubstituted Glycyl Residues
Authors: Gatto Emanuela , Porchetta Alessandro , Stella Lorenzo , Guryanov Ivan , Formaggio Fernando , Toniolo Claudio , Kaptein Bernard , Broxterman Quirinus B. , Venanzi Mariano 
Published: July 2008

AbstractPeptide foldamers based on α,α‐disubstituted glycyl residues were synthesized and chemically characterized to investigate the effects of the electric field generated by a 310‐helix on the rate of intramolecular photoinduced electron‐transfer reactions. To this end, two new octapeptides having identical sequences were suitably side‐chain functionalized with the same electron‐transfer donor–acceptor pair, but inverting the position of the pair along the main chain. The electron‐transfer rate constants, measured by time‐resolved spectroscopy techniques (nanosecond transient absorption and time‐resolved fluorescence), indicated that, in the case of the 310‐helix, the electrostatic effect is significant, but smaller than that obtained for α‐helical peptides. This finding can be likely ascribed to the distortion of the H‐bond network with respect to the helical axis taking place in the former secondary structure. Overall, these results could have implications on electron‐transfer phenomena in model and biomembranes facilitated by peptaibiotics.
Two New Bromotyrosine Derivatives from the Marine Sponge Pseudoceratina sp.
Authors: Ma Ke , Yang Yi , Deng Zhiwei , de Voogd Nicole J. , Proksch Peter , Lin Wenhan 
Published: July 2008

AbstractTwo new bromotyrosine alkaloids, purealidins T and U (1 and 2, resp.), along with five known bromotyrosines 3–7, were isolated from marine sponge Pseudoceratina sp. Their structures were elucidated on the basis of extensive spectroscopic data (CD, IR, 1D‐ and 2D‐NMR, and MS) analysis.
Leaf Essential Oil Composition of Three Species of Myrcianthes from Monteverde, Costa Rica
Authors: Cole Ramona A. , Haber William A. , Lawton Robert O. , Setzer William N. 
Published: July 2008

AbstractTo examine the chemical diversity of essential oils from Myrcianthes species (Myrtaceae) as well as potential chemotaxonomic relationships between them, the leaf essential oils of M. fragrans (Sw.) McVaugh, M. rhopaloides (Kunth) McVaugh, and an undescribed species, Myrcianthes ‘black fruit’, from Monteverde, Costa Rica, were isolated by hydrodistillation and analyzed by GC/MS. The most abundant components of the essential oil of M. fragrans were 1,3,5‐trimethoxybenzene (15.7%), (Z)‐hex‐3‐en‐1‐ol (10.0%), α‐cadinol (10.4%), eudesma‐4(15),7‐dien‐1β‐ol (9.0%), caryophyllene oxide (7.8%), and spathulenol (7.5%). The leaf oils of two different samples of Myrcianthes rhopaloides were quantitatively different with one sample composed mostly of linalool (17.7%), α‐cadinol (14.4%), spathulenol (11.1%), τ‐cadinol (9.6%), and 1‐epicubenol (6.9%), and the other was made up largely of (E)‐hex‐2‐enal (46.1%), 1,8‐cineole (12.5%), linalool (9.1%), α‐cadinol (6.7%), and α‐terpineol (4.4%). The major components in the leaf essential oil of Myrcianthes ‘black fruit’ were 1,8‐cineole (38.3%), α‐terpineol (21.2%), heptan‐2‐ol (15.5%), terpinen‐4‐ol (4.2%), and β‐pinene (3.8%). The leaf oil compositions of Myrcianthes in this study are very different from leaf oils from other members of Myrcianthes reported in the literature. A cluster analysis reveals large chemical variation not only between members of the genus, but also between samples of the same species.
A New Indole Alkaloid and Anti‐Inflammatory Constituents from Strychnos cathayensis
Authors: Chen Jih‐Jung , Luo Yu‐Ting , Hwang Tsong‐Long , Sung Ping‐Jyun , Wang Tai‐Chi , Chen Ih‐Sheng 
Published: July 2008

AbstractA new indole alkaloid, 11,12‐dimethoxyhenningsamine (1), was isolated from the roots of Strychnos cathayensis, together with 19 known compounds. The structure of this new compound was determined through spectroscopic and mass‐spectrometric analyses. Among the isolated compounds, 11‐methoxyhenningsamine (3) and aesculetin dimethyl ether (4) exhibited potent inhibition (IC50<5.5 μg/ml) on superoxide‐anion generation and elastase release by human neutrophils in response to fMet‐Leu‐Phe/cytochalasin B.
Natural Inhibitors of DNA Topoisomerase I with Cytotoxicities
Authors: Han Hong‐Jin , Tan Ning‐Hua , Zeng Guang‐Zhi , Fan Jun‐Ting , Huang Huo‐Qiang , Ji Chang‐Jiu , Jia Rui‐Rui , Zhao Qin‐Shi , Zhang Ying‐Jun , Hao Xiao‐Jiang , Wang Li‐Qin 
Published: July 2008

AbstractDNA Topoisomerase I can cause DNA breaks and play a key role during cell proliferation and differentiation. It is an important target for anticancer agents. While screening for anticancer compounds, seven natural compounds, 1–7, showed potent cytotoxicities against a panel of ten cancer cell lines. Moreover, an inhibition assay demonstrated that they are also DNA topoisomerase I inhibitors, in which inhibitors 1–5 are new ones.
Two New Triterpene Saponins from the Anti‐Inflammatory Saponin Fraction of Ilex pubescens Root
Authors: Wang Jing‐Rong , Zhou Hua , Jiang Zhi‐Hong , Liu Liang 
Published: July 2008

AbstractThe saponin fraction from the ethanolic extracts of the root of Ilex pubescens Hook. et Arn. (Ilexaceae) was found to exhibit potent anti‐inflammatory effects on carrageenan‐induced paw edema in rats. Two novel triterpene saponins, pubescenosides C and D (1 and 2, resp.), together with five known saponins were isolated from this saponin fraction. The structures of 1 and 2 were elucidated as (20β)‐3‐O‐[β‐D‐glucopyranosyl‐(1→2)‐β‐D‐xylopyranosyl]ursa‐12,18‐dien‐28‐oic acid 28‐O‐β‐D‐glucopyranosyl ester, and (20β)‐3‐O‐[α‐L‐rhamnopyranosyl‐(1→2)‐β‐D‐glucopyranosyl‐(1→2)‐β‐D‐xylopyranosyl]ursa‐ 12,18‐dien‐28‐oic acid 28‐O‐β‐D‐glucopyranosyl ester, respectively, on the basis of chemical and spectroscopic data. Five known saponins isolated from the saponin fraction were identified as ilexsaponin B1, B2, B3, A1, and chikusetsusaponin IVa (3–7, resp.).
A New Dihydroagarofuranoid Sesquiterpene and Antituberculosis Constituents from the Root of Microtropis japonica
Authors: Chou Tsung‐Hsien , Chen Ih‐Sheng , Peng Chien‐Fang , Sung Ping‐Jyun , Chen Jih‐Jung 
Published: July 2008

AbstractA new dihydroagarofuran‐based sesquiterpene, 15‐acetoxyorbiculin A (1), was isolated from the root of Microtropis japonica, together with 13 known compounds. Their structures were determined through in‐depth spectroscopic and mass‐spectrometric analyses. Among the isolated compounds, celahin C (6) and salasol A (7) exhibited potent in vitro antituberculosis activity, both with an MIC value of 15.0 μg/ml against Mycobacterium tuberculosis H37Rv.
Biochemistry of PUFA Double Bond Isomerases Producing Conjugated Linoleic Acid
Authors: Liavonchanka Alena , Feussner Ivo 
Published: July 2008

AbstractThe biotransformation of linoleic acid (LA) into conjugated linoleic acid (CLA) by microorganisms is a potentially useful industrial process. In most cases, however, the identities of proteins involved and the details of enzymatic activity regulation are far from clear. Here we summarize available data on the reaction mechanisms of CLA‐producing enzymes characterized until now, from Butyrivibrio fibrisolvens, Lactobacillus acidophilus, Ptilota filicina, and Propionibacterium acnes. A general feature of enzymatic LA isomerization is the protein‐assisted abstraction of an aliphatic hydrogen atom from position C‐11, while the role of flavin as cofactor for the double bond activation in CLA‐producing enzymes is also discussed with regard to the recently published three‐dimensional structure of an isomerase from P. acnes. Combined data from structural studies, isotopic labeling experiments, and sequence comparison suggest that at least two different prototypical active site geometries occur among polyunsaturated fatty acid (PUFA) double bond isomerases.
SAR by Oxime‐Containing Peptide Libraries: Application to Tsg101 Ligand Optimization
Authors: Liu Fa , Stephen Andrew G. , Waheed Abdul A. , Aman M. Javad , Freed Eric O. , Fisher Robert J. , Burke Terrence R. 
Published: July 2008

AbstractHIV‐1 viral assembly requires a direct interaction between a Pro‐Thr‐Ala‐Pro (“PTAP”) motif in the viral protein Gag‐p6 and the cellular endosomal sorting factor Tsg101. In an effort to develop competitive inhibitors of this interaction, an SAR study was conducted based on the application of post solid‐phase oxime formation involving the sequential insertion of aminooxy‐containing residues within a nonamer parent peptide followed by reaction with libraries of aldehydes. Approximately 15–20‐fold enhancement in binding affinity was achieved by this approach.
An evidence‐based approach to the use of rotational and directional coronary atherectomy in the era of drug‐eluting stents: When does it make sense?
Authors: Tran Trung , Brown Michael , Lasala John 
Published: July 2008

AbstractAdvances in percutaneous interventions have profoundly changed the way we manage patients with coronary and peripheral arterial disease. Though the use of stents, particularly drug‐eluting stents, is the preferred method for revascularization because of ease of use and lower restenosis rates, there are many short comings. Ostial and bifurcation lesions as well as heavily calcified and tortuous arteries remain problematic. Mechanical debulking with rotational and direct coronary atherectomy may be beneficial in these situations. In this review, we present the general concepts of mechanical debulking and attempt to summarize the available data on its use in the setting of drug‐eluting stents. In addition, we will discuss its special role in the management of peripheral arterial disease. © 2008 Wiley‐Liss, Inc.
Radiation‐induced peripheral artery disease
Authors: Jurado Javier A. , Bashir Riyaz , Burket Mark W. 
Published: July 2008

AbstractRadiation therapy is a cause of cardiovascular morbidity and mortality. This is due to the significant degree of atherosclerosis seen in the vessels in the vicinity of the area being irradiated. Radiation‐induced peripheral arterial disease is increasingly being recognized as large populations of cancer patients survive longer, yet it is a problem that is often under reported. Although it has most commonly been associated with carotid artery disease, all vascular beds are prone to this form of injury. The injury is accelerated by usual risk factors for atherosclerosis. Developing a healthy lifestyle, dietary prudence and the aggressive treatment of hypertension, diabetes mellitus, and dyslipidemia should all be encouraged in this patient population. When revascularization strategies are warranted, the percutaneous approach may be superior to open surgery as technical difficulties may arise in the fibrotic, scarred tissue. Stenting with distal embolic protection devices should be considered as the treatment of choice for patients with radiation‐induced carotid artery disease. Several reports also suggest good results with balloon angioplasty with or without stenting in the case of radiation‐induced renal, iliac, and femoral artery disease. Lifelong antiplatelet therapy may be appropriate. © 2008 Wiley‐Liss, Inc.