Results in pharma sciences最新文献

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Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/S2211-2863(11)00017-0
{"title":"Advisory Board","authors":"","doi":"10.1016/S2211-2863(11)00017-0","DOIUrl":"https://doi.org/10.1016/S2211-2863(11)00017-0","url":null,"abstract":"","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Page i"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S2211-2863(11)00017-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136974586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Study of particle rearrangement, compression behavior and dissolution properties after melt dispersion of ibuprofen, Avicel and Aerosil 布洛芬、Avicel和Aerosil熔体分散后颗粒重排、压缩行为和溶解性能的研究
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.05.003
Subrata Mallick , Saroj Kumar Pradhan , Muronia Chandran , Manoj Acharya , Tanmayee Digdarsini , Rajaram Mohapatra
{"title":"Study of particle rearrangement, compression behavior and dissolution properties after melt dispersion of ibuprofen, Avicel and Aerosil","authors":"Subrata Mallick ,&nbsp;Saroj Kumar Pradhan ,&nbsp;Muronia Chandran ,&nbsp;Manoj Acharya ,&nbsp;Tanmayee Digdarsini ,&nbsp;Rajaram Mohapatra","doi":"10.1016/j.rinphs.2011.05.003","DOIUrl":"10.1016/j.rinphs.2011.05.003","url":null,"abstract":"<div><p>Particle rearrangements, compaction under pressure and in vitro dissolution have been evaluated after melt dispersion of ibuprofen, Avicel and Aerosil. The Cooper–Eaton and Kuno equations were utilized for the determination of particle rearrangement and compression behavior from tap density and compact data. Particle rearrangement could be divided into two stages as primary and secondary rearrangement. Transitional tapping between the stages was found to be 20–25 taps in ibuprofen crystalline powder, which was increased up to 45 taps with all formulated powders. Compaction in the rearrangement stages was increased in all the formulations with respect to pure ibuprofen. Significantly increased compaction of ibuprofen under pressure can be achieved using Avicel by melt dispersion technique, which could be beneficial in ibuprofen tablet manufacturing by direct compression. SEM, FTIR and DSC have been utilized for physicochemical characterization of the melt dispersion powder materials. Dissolution of ibuprofen from compacted tablet of physical mixture and melt dispersion particles has also been improved greatly in the following order: Ibc&lt;Ibsmd<sub>1</sub>&lt;Ibsmd<sub>2</sub>&lt;Ibsmp<sub>10</sub>&lt;Ibsmd<sub>5</sub>&lt;Ibsmd<sub>10</sub>.</p></div>","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Pages 1-10"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.05.003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32992934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 24
Effects of doxorubicin-encapsulating AG73 peptide-modified liposomes on tumor selectivity and cytotoxicity 阿霉素包封AG73肽修饰脂质体对肿瘤选择性和细胞毒性的影响
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.10.001
Yoichi Negishi , Nobuhito Hamano , Daiki Omata , Azusa Fujisawa , Maya Manandhar , Motoyoshi Nomizu , Yukihiko Aramaki
{"title":"Effects of doxorubicin-encapsulating AG73 peptide-modified liposomes on tumor selectivity and cytotoxicity","authors":"Yoichi Negishi ,&nbsp;Nobuhito Hamano ,&nbsp;Daiki Omata ,&nbsp;Azusa Fujisawa ,&nbsp;Maya Manandhar ,&nbsp;Motoyoshi Nomizu ,&nbsp;Yukihiko Aramaki","doi":"10.1016/j.rinphs.2011.10.001","DOIUrl":"10.1016/j.rinphs.2011.10.001","url":null,"abstract":"<div><p>Doxorubicin-encapsulating liposomal formulations, known as Doxil, have been used for the treatment of Kaposi’s sarcoma and ovarian cancer. However, there is still a need for a drug delivery system for doxorubicin that limits the treatment’s side effects, namely, mucositis and hand-and-foot syndrome. The AG73 peptide derived from the laminin α1 chain is a ligand for syndecans, and syndecan-2 is highly expressed in some cancer cells. In this study, to develop a safer and more selective liposomal formulation, we prepared doxorubicin-encapsulating AG73 peptide-modified liposomes (AG73–Dox). First, we assessed the selectivity of AG73–Dox for cancer cells, including syndecan-2 over-expressing cells, using flow cytometry and confocal microscopy. AG73–Dox showed selective cellular uptake on cancer cells and enhancement of the intracellular uptake. Next, we examined the cytotoxicity of AG73–Dox using a WST assay. AG73–Dox exhibited a higher cytotoxicity against cancer cells than other control liposomes. In addition, we showed that the antitumor efficacy of AG73–Dox <em>in vivo</em> was better than that of free Dox. When we examined the biodistribution of liposomes, AG73 peptide-modified liposomes (AG73-L) tended to bind to intratumoral vessels and extravasated in the tumor tissue. Thus, further optimization of AG73-L toward tumor targeting may lead to a development of a useful tool for cancer therapy.</p></div>","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Pages 68-75"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.10.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32998623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 9
Publisher Note 出版商记
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.05.002
{"title":"Publisher Note","authors":"","doi":"10.1016/j.rinphs.2011.05.002","DOIUrl":"10.1016/j.rinphs.2011.05.002","url":null,"abstract":"","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Page ii"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.05.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32998627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Nanosized ethosomes bearing ketoprofen for improved transdermal delivery 含酮洛芬的纳米酶体改善透皮给药
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.10.002
Manish K. Chourasia , Lifeng Kang , Sui Yung Chan
{"title":"Nanosized ethosomes bearing ketoprofen for improved transdermal delivery","authors":"Manish K. Chourasia ,&nbsp;Lifeng Kang ,&nbsp;Sui Yung Chan","doi":"10.1016/j.rinphs.2011.10.002","DOIUrl":"10.1016/j.rinphs.2011.10.002","url":null,"abstract":"<div><p>The potential of ethosomes for delivering ketoprofen via skin was evaluated. The ethosomes were prepared, optimized and characterized. Vesicular shape, size and entrapment efficiency were determined by transmission electron microscopy, dynamic light scattering and minicolumn centrifugation technique, respectively. Vesicle sizes varied from 120.3±6.1 to 410.2±21.8<!--> <!-->nm depending on the concentrations of soya phosphatidyl choline (SPC) and ethanol. Entrapment efficiency increased with concentrations of SPC and ethanol. The formulations exhibited entrapment efficiencies of 42–78%. <em>In vitro</em> release through cellophane membrane showed sustained release of drug from ethosomal formulations in contrast to hydroalcoholic drug solution (HA), which released most of the drug within 2–3<!--> <!-->h. <em>In vitro</em> drug permeation across human skin revealed improved drug permeation and higher transdermal flux with ethosomal formulations compared to hydroethanolic drug solution. Kinetics of in vitro skin permeation showed zero order drug release from formulations. Based on in vitro transdermal flux, the estimated steady state <em>in vivo</em> plasma concentration from ethosomes attained therapeutic drug levels whereas hydroalcoholic drug solution exhibited sub therapeutic drug concentration with a patch size of 50<!--> <!-->cm<sup>2</sup>. Skin permeation of ethosomal formulations assessed by confocal microscopy revealed enhanced permeation of Rhodamine 123 loaded formulation in comparison to the hydroalcoholic solution.</p></div>","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Pages 60-67"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.10.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32998624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 151
The application of co-melt-extruded poly(ε-caprolactone) as a controlled release drug delivery device when combined with novel bioactive drug candidates: Membrane permeation and Hanson dissolution studies 共熔挤压聚(ε-己内酯)与新型生物活性候选药物联合作为控释药物递送装置的应用:膜渗透和汉森溶出研究
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.11.002
Stephen J. Gardyne , Michael R. Mucalo , Michael J. Rathbone
{"title":"The application of co-melt-extruded poly(ε-caprolactone) as a controlled release drug delivery device when combined with novel bioactive drug candidates: Membrane permeation and Hanson dissolution studies","authors":"Stephen J. Gardyne ,&nbsp;Michael R. Mucalo ,&nbsp;Michael J. Rathbone","doi":"10.1016/j.rinphs.2011.11.002","DOIUrl":"10.1016/j.rinphs.2011.11.002","url":null,"abstract":"<div><p>Eight bioactive drug compounds (abamectin, amoxicillin, dexamethasone, dexamethasone valerate, ketoprofen, melatonin, oestradiol 17β, and oestradiol benzoate) were combined via melt extrusion and disc pressing processes with a polycaprolactone (PCL) matrix and were then evaluated and compared via membrane diffusion and Hanson dissolution studies. This investigation was to determine the potential of this matrix to act as a controlled release drug delivery vehicle for a number of drugs not previously combined with PCL in a melt extrusion mix. The inclusion of the progesterone/PCL system, for which the drug release behaviour has been well studied before was intended for comparison with the PCL systems incorporating drugs that have received little research attention in the past. Initial studies centred on an evaluation of the permeation ability of the bioactive drugs dissolved in aqueous cyclodextrin solutions through a poly(ε-caprolactone) (PCL) membrane using Valia-Chien side-by-side cells. Permeation rates were mostly low and found to range from 0 to 122<!--> <!-->μg<!--> <!-->h<sup>−1</sup> with only ketoprofen, melatonin, and progesterone displaying rates exceeding 20<!--> <!-->μg<!--> <!-->h<sup>−1</sup>. Hanson dissolution release profiles in aqueous alcohol were subsequently measured for the 9 melt extruded PCL/drug combinations and led to Hanson release rates of 0–556<!--> <!-->μg<!--> <!-->cm<sup>−2</sup> <!-->h<sup>−0.5</sup> with dexamethasone, dexamethasone valerate, ketoprofen, melatonin, and progesterone giving values exceeding 100<!--> <!-->μg<!--> <!-->cm<sup>−2</sup> <!-->h<sup>−0.5</sup>. A number of drugs such as the dexamethasones probably performed better than they did in the permeability rate measurements because of the less polar aqueous alcoholic solvent used. In searching for useful correlations between the drug physicochemical properties and release rate, only a moderate correlation (<em>R</em><sup>2</sup>=0.5675) between Hanson dissolution release rate and permeation rate was found. This suggests that the release rate and the permeation are both controlled by the rate of drug diffusion through the PCL with release rate involving an additional dissolution process (of the drug) before permeation occurs accounting for the moderate correlation. In general, of the eight drugs considered, it was clear that the oestradiol-based drugs, abamectin, and amoxicillin were generally not suited to drug delivery via PCL under the conditions used. However, ketoprofen was found to be very suitable as a drug candidate for melt extrusion with PCL with dexamethasone valerate, dexamethasone, and melatonin also showing potential as candidates though to a much lesser extent.</p></div>","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Pages 80-87"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.11.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32998626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
A microdialysis study of topically applied diclofenac to healthy humans: Passive versus iontophoretic delivery 双氯芬酸局部应用于健康人的微透析研究:被动与离子透送
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.11.001
Birgit Falk Riecke , Else Marie Bartels , Søren Torp-Pedersen , Søren Ribel-Madsen , Henning Bliddal , Bente Danneskiold-Samsøe , Lars Arendt-Nielsen
{"title":"A microdialysis study of topically applied diclofenac to healthy humans: Passive versus iontophoretic delivery","authors":"Birgit Falk Riecke ,&nbsp;Else Marie Bartels ,&nbsp;Søren Torp-Pedersen ,&nbsp;Søren Ribel-Madsen ,&nbsp;Henning Bliddal ,&nbsp;Bente Danneskiold-Samsøe ,&nbsp;Lars Arendt-Nielsen","doi":"10.1016/j.rinphs.2011.11.001","DOIUrl":"10.1016/j.rinphs.2011.11.001","url":null,"abstract":"<div><p>Topical application of NSAIDs is an alternative route to systemic administration when a local anti-inflammatory effect of the underlying tissue is a treatment option. The aim of the present microdialysis study was to assess and compare plasma and tissue levels of diclofenac when topically applied with or without iontophoresis in healthy adults. Fourteen healthy adults (26±9.4 years) were randomized to diclofenac applied by iontophoresis, or by a gel, in a crossover design. Diclofenac concentrations were measured in plasma and in microdialysis perfusates from the underlying tissues. Iontophoretic application resulted in the highest plasma concentration of 3.4±0.5<!--> <!-->ng/ml (SEM given) compared to 0.4<!--> <!-->ng/ml (at the detection limit) with gel, whereas no differences were observed between tissue concentrations for the two application methods, both being very low, below or around the detection limit. Iontophoresis caused skin reactions in 25% of the participants. Iontophoresis of diclofenac as compared to traditional topical application was not superior in order to increase the NSAID concentration locally and appears to have a higher frequency of skin reactions.</p></div>","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Pages 76-79"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.11.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32998625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 12
A simple protocol for preparation of a liposomal vesicle with encapsulated plasmid DNA that mediate high accumulation and reporter gene activity in tumor tissue 一个简单的方案制备脂质体囊泡包被质粒DNA介导高积累和报告基因活性在肿瘤组织
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.08.001
Torben Gjetting , Thomas Lars Andresen , Camilla Laulund Christensen , Frederik Cramer , Thomas Tuxen Poulsen , Hans Skovgaard Poulsen
{"title":"A simple protocol for preparation of a liposomal vesicle with encapsulated plasmid DNA that mediate high accumulation and reporter gene activity in tumor tissue","authors":"Torben Gjetting ,&nbsp;Thomas Lars Andresen ,&nbsp;Camilla Laulund Christensen ,&nbsp;Frederik Cramer ,&nbsp;Thomas Tuxen Poulsen ,&nbsp;Hans Skovgaard Poulsen","doi":"10.1016/j.rinphs.2011.08.001","DOIUrl":"10.1016/j.rinphs.2011.08.001","url":null,"abstract":"<div><p>The systemic delivery of gene therapeutics by non-viral methods has proven difficult. Transfection systems that are performing well <em>in vitro</em> have been reported to have disadvantageous properties such as rapid clearance and short circulation time often resulting in poor transfection efficiency when applied <em>in vivo</em>. Large unilaminary vesicles (LUV) with encapsulated nucleic acids designated stabilized-plasmid-lipo-particle (SPLP) have showed promising results in terms of systemic stability and accumulation in tumor tissue due to the enhanced permeability and retention effect (EPR). We have developed a simple protocol for the research-scale preparation of SPLPs from commercially available reagents with high amounts of encapsulated plasmid DNA. The SPLPs show properties of promising accumulation in tumor tissue in comparison to other organs when intravenously injected into xenograft tumor-bearing nude mice. Although transcriptionally targeted suicide gene therapy was not achieved, the SPLPs were capable of mediating reporter gene transfection in subcutaneous flank tumors originating from human small cell lung cancer.</p></div>","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Pages 49-56"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.08.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32992939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 13
Comparative evaluation of humic substances in oral drug delivery 腐殖质物质在口服给药中的比较评价
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.06.001
Mohd. Aamir Mirza , Niyaz Ahmad , Suraj Prakash Agarwal , Danish Mahmood , M. Khalid Anwer , Z. Iqbal
{"title":"Comparative evaluation of humic substances in oral drug delivery","authors":"Mohd. Aamir Mirza ,&nbsp;Niyaz Ahmad ,&nbsp;Suraj Prakash Agarwal ,&nbsp;Danish Mahmood ,&nbsp;M. Khalid Anwer ,&nbsp;Z. Iqbal","doi":"10.1016/j.rinphs.2011.06.001","DOIUrl":"10.1016/j.rinphs.2011.06.001","url":null,"abstract":"<div><p>Major and biologically most explored components of natural organic matter (NOM) are humic acid (HA) and fulvic acid (FA). We have explored rock shilajit as a source of NOM. On the other hand carbamazepine (CBZ) is a well known anticonvulsant drug and has a limited accessibility to brain. Bioavailability and pharmacokinetic profiles of CBZ have been improved by complexation and different techniques also.</p><p>Present study has assessed the comparative abilities of FA and HA as complexing agent for CBZ in order to enhance pharmacokinetic profile of CBZ and accessibility to the brain. These two complexing agents have been compared on various indices such as their abilities to cause complexation and enhance solubility, permeability and dissolution. The present study also compared pharmacodynamic and biochemical profiles after oral administration of complexes. With the help of various pharmaceutical techniques such as freeze drying, physical mixture, kneading and solvent evaporation, two molar ratios (1:1 and 1:2) were selected for complexation and evaluated for conformational analysis (molecular modeling). Complex formed was further characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), mass spectroscopy and X-ray diffraction (XRD).</p><p>Preclinical study on rodents with CBZ–HA and CBZ–FA has yielded appreciable results in terms of their anticonvulsant and antioxidants activities. However, CBZ–HA (1:2) demonstrated better result than any other complex.</p></div>","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Pages 16-26"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.06.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32992936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 37
Stabilizing effect of citrate buffer on the photolysis of riboflavin in aqueous solution 柠檬酸缓冲液对核黄素光解的稳定作用
Results in pharma sciences Pub Date : 2011-05-01 DOI: 10.1016/j.rinphs.2011.06.002
Iqbal Ahmad, Muhammad Ali Sheraz, Sofia Ahmed, Sadia Hafeez Kazi, Tania Mirza, Mohammad Aminuddin
{"title":"Stabilizing effect of citrate buffer on the photolysis of riboflavin in aqueous solution","authors":"Iqbal Ahmad,&nbsp;Muhammad Ali Sheraz,&nbsp;Sofia Ahmed,&nbsp;Sadia Hafeez Kazi,&nbsp;Tania Mirza,&nbsp;Mohammad Aminuddin","doi":"10.1016/j.rinphs.2011.06.002","DOIUrl":"10.1016/j.rinphs.2011.06.002","url":null,"abstract":"<div><p>In the present investigation the photolysis of riboflavin (RF) in the presence of citrate species at pH 4.0–7.0 has been studied. A specific multicomponent spectrophotometric method has been used to assay RF in the presence of photoproducts during the reactions. The overall first-order rate constants (<em>k</em><sub><em>obs</em></sub>) for the photolysis of RF range from 0.42 to 1.08×10<sup>–2</sup> <!-->min<sup>−1</sup> in the region. The values of <em>k</em><sub><em>obs</em></sub> have been found to decrease with an increase in citrate concentration indicating an inhibitory effect of these species on the rate of reaction. The second-order rate constants for the interaction of RF with total citrate species causing inhibition range from 1.79 to 5.65×10<sup>–3</sup> <!-->M<sup>−1</sup> <!-->min<sup>−1</sup> at pH 4.0–7.0. The log<!--> <em>k</em>–pH profiles for the reactions at 0.2–1.0<!--> <!-->M citrate concentration show a gradual decrease in <em>k</em><sub><em>obs</em></sub> and the value at 1.0<!--> <!-->M is more than half compared to that of <em>k</em><sub>0</sub>, i.e., in the absence of buffer, at pH 5.0. Divalent citrate ions cause a decrease in RF fluorescence due to the quenching of the excited singlet state resulting in a decrease in the rate of reaction and consequently leading to the stabilization of RF solutions. The greater quenching of fluorescence at pH 4.0 compared to that of 7.0 is in accordance with the greater concentration of divalent citrate ions (99.6%) at that pH. The trivalent citrate ions exert a greater inhibitory effect on the rate of RF photolysis compared to that of the divalent citrate ions probably as a result of excited triplet state quenching. The values of second-order rate constants for the interaction of divalent and trivalent citrate ions are 0.44×10<sup>–2</sup> and 1.06×10<sup>–3</sup> <!-->M<sup>–1</sup> <!-->min<sup>–1</sup>, respectively, indicating that the trivalent ions exert a greater stabilizing effect, compared to the divalent ions, on RF solutions.</p></div>","PeriodicalId":89718,"journal":{"name":"Results in pharma sciences","volume":"1 1","pages":"Pages 11-15"},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.rinphs.2011.06.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32992935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 25
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