With the rise of capillary HPLC systems, open tubular liquid chromatography (OTLC) has been garnering more attention due to the possible fundamental advantages of open tubular systems over conventional packed or monolithic systems. Performance has yet to reach its potential due in part to a variety of technical challenges, resulting in the need for very small injection volumes and sensitive detection. In this work, we have shown that with modern HPLC sample introduction and detection systems, along with careful fabrication of polymer stationary phases, that reverse phase open tubular liquid chromatography may be within reach. We have shown that, with small diameter (i.d. 30m) open tubular columns, complex multi-component mixtures (EPA 610, in-house drug mixture) can be separated. We have also shown that these columns are robust and can function over a wide range of flow rates (200-1000 nl/min), and may be useful for general reverse phase separation in the future. However, currently, more stationary phase development and procedure refinement is needed. Microstructured fibres (MSFs), a relatively new class of optical fibre which confine light within fibres through a refractive index change caused by the use of parallel air channels running throughout the length of the fibre, are explored as a new support material for open tubular liquid chromatography. The fine channel structures of MSFs enable reasonable sample volumes to be used compared to conventional open tubular systems, while offering a similar plug-like flow profile through the fibre. With current sample introduction and flow technologies, we have shown that the potential advantages of MSF columns is great even when simple C18 stationary phases are used; this was able to separate a four PAH mixture. However, a distribution in channel sizes caused by current manufacturing standards and a limited ability to evenly deposit polymer stationary phases in the fibres has kept MSF columns from reaching their full potential. / Thesis (Master, Chemistry) -- Queen's University, 2011-09-14 11:52:41.23

No description available.

The overall aims of this project were to assess the pharmaceutical quality and consistency of commercially available solid dose Sutherlandia frutescens containing products (viz. tablets & capsules) by exploring the use of monitoring the pharmaceutical presentation, flavonoid profile and antioxidant activity levels and to develop/or adapt methods and specifications that may be used for the quality control of such products.Stability tests were conducted on all of the selected SCP. The products were stored under elevated temperatures and environmental humidity conditions and total phenol, antioxidant and chromatographic analysis was conducted on these samples. Samples of each of the SCP were hydrolyzed using HCL and then analyzed using HPLC to test the stability of the flavonoids present in each product. The SCP investigated in this study physically appeared to be of quite good “pharmaceutical” quality, but generally lacked information on the date of manufacture and lacked package inserts, or when these were present they contained insufficient information.Based on the results obtained, it is recommended that, the manufacturers of SCP pay more attention to the information provided on the package inserts and the storage conditions for their products. Further the levels of antioxidant activity, total phenols and flavonoid (sutherlandins A to D) be used as specifications to control the quality of commercially available solid dose Sutherlandia frutescens containing preparations on an individual basis.

Résumé: Les dommages à la cytosine, spontanés et induits par des oxydants, sont probablement la principale cause des transitions GC vers AT, la mutation du génome la plus commune chez les organismes aérobiques. Ces dommages sont impliqués dans le processus de mutagenèse, dans le vieillissement et dans le cancer. Les dommages à la cytosine par les oxydants et les radicaux libres sont nombreux et ont été découverts et étudiés dans les monomères de cytosines et dans de courts oligonucléotides. Dans cette étude, nous avons développé une méthode d'analyse par HPLC-MS/MS des plus importants produits d'oxydation de la cytosine dans l'ADN. Cette méthode permet l'analyse de la formation de 5-hydroxy-2'-désoxycytidine (5-OH-dC), de 5,6-dihydroxy-5,6-dihydro-2'-désoxyuridine (dUg), de 1-(2-désoxyribose)-5-hydroxyhydantoïne (HdU) et de 3-(2-désoxyribose)-1-carbamoy1-4,5-dihydroxy-2-oxo-imidazolidine (C422-dC) lors d'irradiation aux rayons gamma par réaction de type fenton et par ozonolyse. Les résultats de l'irradiation de l'ADN aux rayons gamma (en modifications/106bases/Gy) sont de 1.62 pour la 5-OH-dC, de 1.48 pour le dUg, de 7.43 pour la HdU et de 1.38 pour la C422-dC. La réaction de type fenton avec le cuivre donne une formation de dommages environ 25 fois plus grande qu'avec le fer et les deux types (cuivre et fer) donnent des ratios de produits semblables à ceux par les rayons gamma avec une augmentation de la 5- OH-dC et une diminution de la HdU. L'exposition .de l'ADN à l'ozone donne une très grande formation de la HdU et une faible formation des autres produits d'oxydation.//Abstract: The damages to cytosine, spontaneous and inducted by oxidants, are probably the principal cause of the GC to AT transition, the most important mutation of the genome for the aerobic organisms. Those damages are involved in the process of mutagenesis, aging and cancer. The damages to cytosine by oxidants and fre radicals are numerous and have been discovered and studied in monomers of cytosine and in short oligonucleotides. In this study, we have developed a analysis method of the most important oxidation products of cytosine in DNA by HPLC-MS/MS. This method allows the analysis of the formation of 5-hydroxy-2'-deoxycytidine (5-OH-dC), de 5,6-dihydroxy-5,6-dihydro-2'-desxyuridine (dUg), de 1-(2-deoxyribose)-5-hydroxyhydantoin (HdU) et de 3-(2-deoxyribose)- 1-carbamoyl-4,5-dihydroxy-2-oxo-imidazolidine (C422-dC) after irradiation by gamma rays, by fenton type reaction and ozonolysis. The results of the irradiation of DNA by gamma rays (in modifications10[indice supérieur 6] bases/Gy) are of 1.62 for 5-OH-dC, of 1.48 for dUg, of 7.43 for HdU and of 1.38 for C422-dC. The fenton type reaction with copper gives a formation of damages about 25 times higher than with ferrous and both kind gives a ratio of formation similar to the the ones by gamma rays with a increase of 5-OH-dC and a decrease of HdU. The exposition of DNA to ozone gives a strong formation of HdU and a small formation of the other modifications. [symboles non conformes]

Cyclosporine forms the cornerstone of therapy to prevent rejection after organ transplantation. However, the clinical use of the drug is compromised by a narrow therapeutic window and a wide inter- and intra-individual variation in metabolism. Cyclosporine is metabolised by the CYP3A4 isoenzymes in both the liver and intestine, while it has been reported that the metabolism of the drug can be inhibited by certain furocoumarin derivatives in grapefruit juice. Methoxsalen (8-methoxypsoralen) is a furocoumarin and a potent inhibitor of the cytochrome P450 system in both the liver and intestine. The study was conducted to investigate the possibility whether methoxsalen may inhibit the metabolism of cyclosporine and thereby increase the bioavailability of the drug. The interaction is of clinical relevance since both drugs are used in the treatment of psoriases. The study, conducted in 12 healthy male volunteers, was a three-way comparative bioavailability study with a wash out period of one week between treatments. The patients received 40 mg methoxsalen, 200 mg cyclosporine or a combination of the two on three separate occasions. Blood samples of 10 ml were collected by venupuncture at the following times: 0, 0.5, 1, 1.5, 2, 2.5, 3.4, 5,6, 8, 12 and 24 hours after drug administration. Methoxsalen was analysed by a high pressure liquid chromatograph method (HPLC) with UV detection (LOQ = 10 ng/ml), while cyclosporine was analysed using a fluorescence polarisation immunoassay (FPIA) technique. There was a statistical significant difference in AUCo-00 and Cmax ' for cyclosporine when methoxsalen was added to the drug regimen. When the methoxsalen levels were compared with those in the presence of cyclosporine, the levels were lower, although the difference was not statistical significant. We conclude that methoxsalen increase the levels of cyclosporine by inhibiting the P450 system enzymes in the liver and intestine. However, the absorption of methoxsalen is highly variable in the same individual which needs to be considered before this interaction can be regarded as being of any clinical relevance. / Thesis (M.Sc.(Pharmacology))--North-West University, Potchefstroom Campus, 2004.

Darbo tikslas: optimizuoti metodiką, kuria būtų galima atlikti antihistamininių vaistų mišinio, sudaryto iš klemastino fumarato, loratadino ir desloratadino, ekstrakciją iš kraujo plazmos ir kokybinį nustatymą efektyviosios skysčių chromatografijos metodu. Darbo uždaviniai: Atlikti mokslinės literatūros analizę siekiant įvertinti antihistamininių vaistų savybes ir pasirinktų junginių ekstrakcijos iš kraujo plazmos ir tapatybės nusatymo metodikas. Optimizuoti ir validuoti ESC metodiką kokybiniam pasirinktų preparatų mišinio nustatymui iš kraujo plazmos. Parinkti klemastino fumarato, loratadino ir desloratadino skysčių – skysčių ekstrakcijos iš kraujo plazmos sąlygas. Apibendrinti gautus ekstrakcijos ir ESC rezultatus. Metodai: skysčių – skysčių ekstrakcija ir ESC. Tyrimo objektas: kraujo plazma, į kurią įterpti antihistamininiai vaistai klemastino fumaratas, loratadinas, desloratadinas ir jų mišinys. Rezultatai: tiriamųjų medžiagų sulaikymo laikai: desloratatadino apie – 5,9 min, loratadino – apie 11,4 min, klemastino fumarato – apie 13,2 min. Validuota ESC atlikimo metodika. Atliekant ekstrakciją su trichlormetanu neišsiekstrahavo nei vienas tiriamasis junginys, su dichlormetanu – loratadinas, su dietileteriu ir cikloheksanu – visi trys tiriamieji junginiai. Išvados: 1. Atlikta mokslinės literatūros analizė, apžvelgiant antihistamininių vaistų savybes, ekstrakcijos iš kraujo plazmos būdus bei identifikavimo metodus, didžiausią dėmesį skiriant efektyviajai skysčių... [toliau žr. visą tekstą] / Aim: to optimise a method, by which mixture of antihistamines containing clemastine fumarate, loratadine and desloratadine could be extracted from human plasma and qualitative determination using high performance liquid chromatogrophy could be made. Tasks: to carry out analysis of scientific literature and evaluate characteristics of antihistamines and methods of chosen compounds extraction from human plasma and identity determination. Optimise and validate HPLC method for qualitative determination of chosen medicines. Select conditions suitable for chosen antihistamines liquid – liquid extraction from human plasma. Carry out qualitative determination of clemastine fumarate, loratadine and desloratadine in human plasma using validated HPLC method. Summarize results of extraction and HPLC. Methods: liquid – liquid extraction and HPLC. Object: human plasma with embedded antihistamines: clemastine fumarate, loratadine, deloratadine and their mixture. Results: retention times of test substances: desloratadine – 5,9 min, loratadine – 11,4 min, clemastine fumarate – 13,2 min. HPLC method was validated. None of the compounds were extracted using trichlormethan. Only loratadine was extracted using dichlormethan. All three compounds were extracted using diethyl ether and cyclohexane. Conclusions: 1. Analysis of scientific literature was caried out, characteristics of antihistamines, methods of extraction from human plasma and identity determination of chosen compounds were overviewed... [to full text]

Phytoestrogens are naturally occurring chemicals of plant origin that have the ability to cause estrogenic and/or anti-estrogenic effects due to their structural similarities to the human hormone oestradiol. It has been proposed that phytoestrogens protect against a wide range of ailments, including breast and prostate cancers, cardiovascular disease, osteoporosis, and menopausal symptoms. Daidzein, biochanin A and especially genistein which has been reported to be the most biologically active dietary phytoestrogen attract great deal of interest in today&rsquo / s researches. In this study, twenty different food items, including legumes, fruits, nuts and herbs, (haricot beans, chickpeas, green lentils, red lentils, soybeans, licorice root, yarrow, dried chestnuts, prunes, raisins, currants, black cumin, dried apricots, dried parsley, dried dates, dried figs, sage (from Aegean region), sage (from Mediterranean region), grapevine leaves, gilaburu) were selected. Following an extraction procedure employing acid hydrolysis and heating / they were analysed for their daidzein, genistein and biochanin A contents using a reversed-phase C18 column with linear gradient elution on a high-performance liquid chromatography (HPLC) coupled with diode-array detector (DAD). Soybeans were found to contain high amounts of daidzein (91.36 mg/100 g) and genistein (85.57 mg/100 g). Chickpeas were found to contain much less amount of genistein (0.89 mg/100 g) compared with that of soybeans and also biochanin A (0.95 mg/100 g) which was not detected in soybeans. None of daidzein, genistein and biochanin A was detected in the remaining eighteen food items.

This thesis describes the development of separate assays to measure coenzyme Q₁₀ (CoQ₁₀) and vitamin K. Coenzyme Q is essential for the mitochondrial electron transport chain, and vitamin K for the blood coagulation cascade. Vitamin K deficiency is associated with haemorrhagic disease of the new-born, and CoQ₁₀ deficiency with HMG-CoA-reductase inhibitor (statin) therapy and heart failure. Coenzyme Q and vitamin K are usually measured by HPLC, using electrochemical and ultraviolet, and electrochemical and fluorescence detection, respectively. For vitamin K1, the limit of detection achieved using fluorescence and electrochemical detection was 0.28 and 0.12 nmol/L, respectively. Sensitivity of fluorescence detection is improved by using protic solvents in the mobile phase, and platinum-black catalysed alcohol reduction. The lipophilicity and low endogenous concentrations of vitamin K1 hinder its measurement, and further work is required to produce a rapid, reliable and robust assay for its measurement in human plasma. The limits of detection achieved using fluorescence, ultraviolet and electrochemical detection to measure CoQ₁₀ were 29, 4.8, and 0.34 nmol/L, respectively. Plasma CoQ₁₀ is not stable during long term storage at -13 ℃, but at -80 ℃ it is stable for at least 18 months. The reference interval for plasma total CoQ₁₀ in the New Zealand population is 0.47 - 1.80 µmol/L. There is no clinical requirement for stratification of the reference interval according to gender. Coenzyme Q₁₀ in human plasma is homeostatically controlled, varying little over a two month interval in healthy young males. Coenzyme Q₁₀ supplements have significantly different bioavailability, with the median increase in plasma CoQ₁₀ ranging from 0.14 to 0.59 µmol/L for seven different supplement brands. There is a large inter-individual variation in CoQ₁₀ absorption, and hence plasma concentrations should be monitored during supplementation. A plateau in CoQ₁₀ absorption, from a single dose, at approximately 200 mg suggests that the maximum dose ingested at one time should be 200 mg or less. Q-Gel capsules containing 30 mg of CoQ₁₀ are twice as effective at raising blood CoQ₁₀ as 100 mg capsules. Plasma CoQ₁₀ in patients with chronic heart failure are significantly lowered by approximately 33% when these patients receive Atorvastatin for six weeks. The absolute decrease in CoQ₁₀ showed a significant correlation with worsening endothelial function (r = + 0.548, p = 0.011). Coenzyme Q₉ was shown to be present in human plasma with a reference interval of 8.8 - 47.0 nmol/L.

Zugl.: Stuttgart, Univ., Diss., 2005

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2008. / Härtill 5 uppsatser.