Miranda Sertić

Simultaneous determination of lovastatin and citrinin in red yeast rice supplements by micellar electrokinetic capillary chromatography

Lovastatin is a main component of Monascus purpureus fermented red rice contributing to the lipid-lowering effect. Citrinin is a toxic fermentation by-product which can be found as a contaminant. An accurate, simple and rapid micellar electrokinetic capillary chromatographic method was developed for the first time for simultaneous determination of lovastatin present in lactone and hydroxy acid forms and citrinin in red rice products provided by different manufacturers and formulated in various dosage forms. Separation was achieved within only 2 min using 20 mM of phosphate buffer at pH 7.0 and 30 mM of sodium dodecyl sulphate at an applied voltage of 25 kV. Sensitivity crucial for detecting citrinin was enhanced by using an extended light path capillary. The results showed that the content of lovastatin and its acid form in dietary supplements were considerably different indicating the need for improved standardization in order to ensure efficiency and safety of these products.

Development of a Rapid LC/DAD/FLD/MSn Method for the Simultaneous Determination of Monacolins and Citrinin in Red Fermented Rice Products

Red fermented rice is used worldwide by many patients as an alternative therapy for hyperlipidemia; however, the discovery of a toxic fermentation byproduct, citrinin, causes much controversy about the safety of red mold rice products. A new and fast high-performance liquid chromatography method was developed and validated for simultaneous determination of cholesterol-lowering compounds monacolin K (lovastatin), monacolin K hydroxy acid, and other monacolins present in red fermented rice as well as nephrotoxic mycotoxin citrinin in a single run using connected diode array and fluorescence and mass spectrometric detectors. The proposed method was successfully applied for the analysis of red fermented rice food samples and various dietary supplements also containing other natural lipid-lowering agents. The deviations between label content and levels of active compounds found in investigated samples as well as high batch-to-batch variation found in one product indicate that the regular quality control of red fermented rice products is of great importance.

Multi-walled carbon nanotubes/Nafion composite film modified electrode as a sensor for simultaneous determination of ondansetron and morphine.

The electrochemical behavior of ondansetron was studied on the multi-walled carbon nanotubes/Nafion polymer composite modified glassy carbon electrode (MWCNTs-Nafion/GCE). The oxidation peak potential was shifted from 1.32 V to 1.18 V compared to the bare electrode indicating excellent electrocatalytic activity of immobilized film toward drug molecule. The modified electrode exhibited a remarkable enhancement effect on voltammetric response due to the synergistic effect of nanomaterial and cation-exchange polymer on the electron transfer rate, the effective electrode area and the accumulation capability. After optimizing the experimental parameters, adsorptive stripping procedure was used for the determination of ondansetron in pharmaceutical formulation. The results were satisfactory in comparison with those obtained by high-performance liquid chromatography. In addition, the MWCNTs-Nafion/GCE exhibited high selectivity in the voltammetric measurements of ondansetron and co-administrated drug morphine with potential difference of 430 mV. The response peak currents had linear relationship with drug concentration in the range of 1.0 × 10(-7)-5.0 × 10(-6)M and 1.0 × 10(-7)-4.0 × 10(-6)M with detection limits 3.1 × 10(-8) and 3.2 × 10(-8)M for ondansetron and morphine, respectively. The electrode was successfully applied for simultaneous electrochemical sensing of both drugs in human serum samples after selective accumulation at the electrode surface.

A Review of Current Trends and Advances in Analytical Methods for Determination of Statins: Chromatography and Capillary Electrophoresis

Statins are the most effective drugs currently available for treating hypercholesterolemia, as they reduce the level of total and low-density lipoprotein cholesterol, triglycerides and apolipoprotein B in plasma of patients at risk of cardiovascular disease, even they are currently among the most widely prescribed drugs. They are specific and competitive inhibitors of 3-hydroxy-3-methlyglutaryl coenzyme A (HMG-CoA) reductase, which is a key enzyme that catalyzes the conversion of HMG-CoA to mevalonate. This is an early rate-limiting step in the cholesterol biosynthetic pathway. Statins include natural (lovastatin), semi-synthetic (simvastatin, and pravastatin) and synthetic compounds (fluvastatin, atorvastatin, rosuvastatin and pitavastatin). All statins share an HMG-like pharmacophore, which may be present in the active hydroxy acid form or in the inactive lactone form. Lovastatin and simvastatin are administered as lactone prodrugs and subsequently hydrolyzed to active metabolites, while other statins are formulated in β-hydroxy acid form. The interconversion between lactone and hydroxy acid forms of statin molecules is a highly pH dependent. Statin use has soared over the last decade, and is expected to increase further in the years ahead because high cholesterol and cardiovascular diseases are being diagnosed more frequently. For this reason, rapid and effective ways for the identification and determination of these drugs are highly required. The therapy with statins is considered for the long-term use and the purity evaluation of these drugs is of great significance. Bioanalytical methods are necessary for the clinical trials, for therapeutic drug monitoring and individual dosage scheme adjustment of statins. High performance liquid chromatography with various types of detection is the technique of choice in developing new methods for analysis of statin molecules. This chapter presents recent trends and advances in chromatographic and capillary electrophoretic methods for the determination of statin drugs in various fields of application.

Simultaneous analysis of mitotane and its main metabolites in human blood and urine samples by SPE‐HPLC technique

Adrenocortical carcinoma (ACC) is a rare malignancy with an incompletely understood pathogenesis and a poor prognosis. The adrenalytic activity of mitotane has made it the most important single drug in the treatment of ACC. Unfortunately, the exact mechanism of mitotane action is still unknown. It is believed that mitotane belongs to the class of drugs that require metabolic transformation by cytochrome P450 for therapeutic action; therefore determination of plasma levels of not only mitotane but also its metabolites would help in carrying out the treatment. The objective of this work was to develop and validate an SPE-HPLC method for simultaneous determination of mitotane and its metabolites in different biological fluids. The sample preparation consisted of a solid-phase extraction on a Discovery DSC(18) cartridge, while analysis of extracts was performed on a Symmetry C(18) column. The usefulness of the proposed method was confirmed by analysis of plasma, red cell and urine samples from patient chronically treated with 1.5 g of mitotane. The patient involved in this study had a high plasma concentration of mitotane and none of the investigated metabolites were found. In order to investigate whether the polymorphism of CYP2C9 and CYP2C19 enzymes could be related to the metabolism of mitotane, RT-PCR analysis was performed.

Quality assessment of liquid pharmaceutical preparations by HSS-GC-FID

A new headspace gas chromatographic method with flame ionization detection (HSS-GC-FID) was developed and validated for the determination of methanol as the main volatile impurity present in ethanolic pharmaceutical preparations. The use of static headspace sampling minimized the interference of other volatile matrix components and provided satisfactory results in purity assessment of different complex samples. The developed procedure revealed to be rapid, sensitive, reproducible and accurate. The detection and quantification limits of methanol were 0.0003 and 0.0011% (v/v), respectively, and were sufficiently low to enable the estimation of organic volatile impurity according to the ICH guideline as well as the examination of methanol limit specified in European Pharmacopoeia for liquid pharmaceutical preparations. The proposed method was successfully applied to the analysis of diverse alcoholic herbal extracts and tinctures as well as ethanolic dermatological lotions.

Chromatographic and mass spectrometric solutions to improve quality and safety of food and dietary supplements

Two cassava varieties TMS98/0505 (white) and TMS05/0473 (yellow) were processed into four different products each. The microbiological analysis and sensory properties of the products from both cassava varieties (Garri, fufu, flour and tapioca) were examined. Microorganisms identified and isolated from the samples include; Enterobacter spp., Staphylococcus spp., Klebsiella spp., Bacillus, Lactobacillus, Proteus vulgaris, Micrococcus spp., for bacteria identification while the fungi identified include Penicillium spp., Aspergillus spp., Rhizopus spp., Mucor spp. These microbial composition and the sensory properties were evaluated. The total microbial count ranged from 9.0×10 2 cfug-1 for sample 1 (produced from white cassava variety) to 4.8×10 2 cfug -1 in sample 5 (flour produced using white cassava variety). The samples showed combined positivity and negativity to the morphological, microscopic and biochemical test processes for bacteria and fungi. The sensory properties evaluation had values of results ranging from 6.3±1.2 to 2.61±1.2 with sample 4 having the highest value while sample 2 had the lowest value and differing significantly (p>0.05) texture ranged from 6.1±1.7 to 4.07±1.8. However, overall acceptability ranged from 6.31±1.8 to 4.10±1.2 for sample 8 and sample 6 respectively. The overall acceptability showed significant difference at (p<0.05) among all other samples.P the shelf life of food is one of the biggest challenges the food industry is facing, which when improved could decrease food decomposition, add value and also help ease food sustainability concerns. This talk would present a possible methodology for integrating antimicrobial functionality onto some of the existing polymer based food wrapping materials. The antimicrobial activity of nanoparticles, including silver, that have been integrated onto the polymer substrates using some green chemicals, would be discussed along with the pros and cons of using it for food packaging based on results.In recent years, chromatography and mass spectrometry have gained a wide recognition as a sensitive, selective and fast techniques for the analysis of a wide range of food and dietary supplement (DS) products. An overview of our recently developed chromatographic and mass spectrometric methods used in food and DS analysis will be given. As counterfeiting of DS has become an important health and economic problem, a fast-screening DI-MS method for identification of various pharmacologically active ingredients was developed. Red fermented rice is used worldwide as an alternative therapy for hyperlipidemia. The recent discovery of a mycotoxin, citrinin, causes much controversy about the safety of these products. The LC/DAD/FLD/MSn method for determination of 5 monacolins and citrinin in a single run in food and DS have shown high deviations between labeled and found content. Despite recent efforts of regulatory authorities to improve the safety of DS, evaluation of ethanol is not harmonized. The sHSS-GC-FID method was applied for analysis of 93 samples. High amounts of ethanol were found in products for young children as well as in ˝alcohol-free˝ products. GC and HPLC methods for evaluation of the volatile compounds and food additives in blackberry wine were developed. Devastating results were obtained as several samples contained methanol above the permissible limits. Although olive growing is a traditional agricultural sector in Mediterranean countries, most of oil is obtained by small producers without production control. A low cost sHSS-GC-FID method may be used for evaluaton of volatile compounds, possible indicators of olive oil quality.Zhaowei Zhang1 and Peiwu Libcde 1Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, P.R.China b Laboratory of Risk Assessment for Oilseeds Products (Wuhan), Ministry of Agriculture, 430062, P.R.China c Key Laboratory of Detection for Mycotoxins, Ministry of Agriculture, Wuhan, 430062, P.R.China d Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan, 430062, P.R.China e Quality Inspection and Test Center for Oilseeds Products, Ministry of Agriculture, Wuhan, 430062, P.R. ChinaI recent times maize has become first among other grains and cereals in terms of annual area planted in Ghana. Unfortunately, the crop suffers several losses, such as aflatoxin contamination along the maize post-harvest value chain which affect both quality and quantity before reaching the final consumer. A study was carried out to assess the qualitative and quantitative losses of maize along the maize value chain in two regions, Brong-Ahafo and Eastern Regions of Ghana. Questionnaires administered to key informant of the value chain established the main causative factors of post-harvest losses; these include losses due to the effects of insects, rodents, monkeys, birds, bushfires, ruminants (sheep and goats) and rainfall causing grains to grow mould since most farmers allowed drying on stalk before harvesting. Laboratory analyses showed the presence of free fatty acids and high levels of aflatoxins in most maize sampled, indicating poor storage. Changes in moisture content reduced the volume and weight of the grains and was perceived as source of losses, hence the need for maize variety with less moisture content. The study revealed that even though responses from these value chain actors indicated that with the help of the extension workers they are abreast with several technologies to prevent losses, most value actors are not implementing what they learnt. There is therefore the need to use more innovative to help value chain actors in the maize industry to adopt methods for reducing post-harvest losses in the sector.

Analysis of aucubin and catalpol content in different plant parts of four Globularia species

Iridoids are plant secondary metabolites that are gaining more scientific interest due to the wide range of their observed biological activities such as neuroprotective, anti-inflammatory, immunomodulatory, hepatoprotective and cardioprotective. The presence and content of aucubin and catalpol, two iridoid glucosides frequently present in iridoid-containing plants, was studied in methanolic extracts of leaves, flowers, woody stems and underground parts of four Globularia L. species, including the medicinal plant Globularia alypum L., using a specific and reliable HPLC-DAD-ESI/MS method. Aucubin was found in all four species, while catalpol was found only in G. alypum and G. punctata . Flowers contained the highest amounts of investigated iridoids, with catalpol content reaching 1.6% in G. punctata flowers. Comparing to the medicinal plant G. alypum , related species contained higher amounts of investigated iridoids, which makes them interesting candidates for further biological activity investigations. The online version of this article (doi: 10.5073/JABFQ.2015.088.030) contains supplementary files .