The Glitazone Class of Drugs as Carbonic Anhydrase Inhibitors-A Spin-Off Discovery from Fragment Screening.

The approved drugs that target carbonic anhydrases (CA, EC 4.2.1.1), a family of zinc metalloenzymes, comprise almost exclusively of primary sulfonamides (R-SO2NH2) as the zinc binding chemotype. New clinical applications for CA inhibitors, particularly for hard-to-treat cancers, has driven a growing interest in the development of novel CA inhibitors. We recently discovered that the thiazolidinedione heterocycle, where the ring nitrogen carries no substituent, is a new zinc binding group and an alternate CA inhibitor chemotype. This heterocycle is curiously also a substructure of the glitazone class of drugs used in the treatment options for type 2 diabetes. Herein, we investigate and characterise three glitazone drugs (troglitazone 11, rosiglitazone 12 and pioglitazone 13) for binding to CA using native mass spectrometry, protein X-ray crystallography and hydrogen-deuterium exchange (HDX) mass spectrometry, followed by CA enzyme inhibition studies. The glitazone drugs all displayed appreciable binding to and inhibition of CA isozymes. Given that thiazolidinediones are not credited as a zinc binding group nor known as CA inhibitors, our findings indicate that CA may be an off-target of these compounds when used clinically. Furthermore, thiazolidinediones may represent a new opportunity for the development of novel CA inhibitors as future drugs.

Ability of two new thiazolidinediones to downregulate proinflammatory cytokines in peripheral blood mononuclear cells from children with asthma

Allergic asthma is a chronic, complex inflammatory disease of the airway. Despite extensive studies on the immunomodulation of T helper (Th) cell pathways (i.e., Th1 and Th2) in asthma, little is known about the effects of Th17 pathway modulation, particularly that involving peroxisome proliferator-activated receptors (PPARs). In response, two new thiazolidinedione derivatives-namely, LPSF-GQ-147 and LPSF-CR-35 were synthesized and evaluated for their immunomodulatory effects on Th17-related cytokines, including interferon γ (IFNγ), interleukin IL-6, IL-17, and IL-22 in the peripheral blood mononuclear cells of asthmatic children. Both compounds were nontoxic even at high concentrations (i.e., 100 µM). The LPSF-CR-35 compound significantly reduced the levels of IL-17A (p = .039) and IFNγ (p = .032) at 10 µM. For IL-22 and IL-6, significant reduction occurred at 100 µM (p = .039 and p = .02, respectively). Conversely, LPSF-GQ-147 did not significantly inhibit the production of the tested cytokines, the levels of all of which were more efficiently reduced by LPSF-CR-35 than methylprednisolone, the standard compound. Real-time polymerase chain reaction assay confirmed that LPSF-GQ-147 has significant PPARγ modulatory activity. Such data indicate that both LPSF-CR-35 and LPSF-GQ-147 are promising candidates as drugs for treating inflammation and asthma

Absorbance detector for high performance liquid chromatography based on a deep-UV light-emitting diode at 235nm.

In this communication, we describe a flow-through optical absorption detector for HPLC using for the first time a deep-UV light-emitting diode with an emission band at 235nm as light source. The detector is also comprised of a UV-sensitive photodiode positioned to enable measurement of radiation through a flow-through cuvette with round aperture of 1mm diameter and optical path length of 10mm, and a second one positioned as reference photodiode; a beam splitter and a power supply. The absorbance was measured and related to the analyte concentration by emulating the Lambert-Beer law with a log-ratio amplifier circuitry. This detector showed noise levels of 0.30mAU, which is comparable with our previous LED-based detectors employing LEDs at 280 and 255nm. The detector was coupled to a HPLC system and successfully evaluated for the determination of the anti-diabetic drugs pioglitazone and glimepiride in an isocratic separation and the benzodiazepines flurazepam, oxazepam and clobazam in a gradient elution. Good linearities (r>0.99), a precision better than 0.85% and limits of detection at sub-ppm levels were achieved.

Simultaneous spectrophotometric determination of glimepiride and pioglitazone in binary mixture and combined dosage form using chemometric-assisted techniques.

In the present work, pioglitazone and glimepiride, 2 widely used antidiabetics, were simultaneously determined by a chemometric-assisted UV-spectrophotometric method which was applied to a binary synthetic mixture and a pharmaceutical preparation containing both drugs. Three chemometric techniques - Concentration residual augmented classical least-squares (CRACLS), principal component regression (PCR), and partial least-squares (PLS) were implemented by using the synthetic mixtures containing the two drugs in acetonitrile. The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbencies in the range between 215 and 235nm in the intervals with Δλ=0.4nm in their zero-order spectra. Then, calibration or regression was obtained by using the absorbance data matrix and concentration data matrix for the prediction of the unknown concentrations of pioglitazone and glimepiride in their mixtures. The described techniques have been validated by analyzing synthetic mixtures containing the two drugs showing good mean recovery values lying between 98 and 100%. In addition, accuracy and precision of the three methods have been assured by recovery values lying between 98 and 102% and R.S.D. % ˂0.6 for intra-day precision and ˂1.2 for inter-day precision. The proposed chemometric techniques were successfully applied to a pharmaceutical preparation containing a combination of pioglitazone and glimepiride in the ratio of 30: 4, showing good recovery values. Finally, statistical analysis was carried out to add a value to the verification of the proposed methods. It was carried out by an intrinsic comparison between the 3 chemometric techniques and by comparing values of present methods with those obtained by implementing reference pharmacopeial methods for each of pioglitazone and glimepiride.

RP-HPTLC Data in Correlation Studies of a 5-Arylidene-2,4-Thiazolidinedione Derivatives.

Thiazolidinediones show a large scale of biological activities as a result of ability to perform interactions with a variety of biological targets. Modeling properties of newly synthesized thiazolidinediones is important for both understanding their activity and predicting their interactions. In the paper the chromatographic retention data determined in various RP chromatographic systems (stationary phases RP-CN and RP-18; six aqueous binary mobile phases modified with acetonitrile, methanol, ethanol, propanol, acetone and dioxane) were considered for 13 new 5-arylidene-2,4-thiazolidinediones. In this article, three attempts to find suitable quantitative structure-retention relationship (QSRR) models that quantify retention as a function ofmolecular descriptors had been presented. Models built for RP-18 show generally better multiple R but are also mostly monoparametric with logP as the dominant descriptor. More informative from the standpoint of molecular interactions are QSRR models for RP-CN. The quality of those models depends of the mobile phase modifier (the best was obtained for acetone and the worst for propanol as modifier). Since all QSRR models use extrapolated retention as a property which is indirectly connected with plasma protein binding further assessment of plasma protein binding should be based on extrapolated retention on a RP-CN stationary phase instead of standard RP-18.

A highly sensitive LC-MS/MS method for concurrent determination of sildenafil and rosiglitazone in rat plasma.

Patients with pulmonary arterial hypertension (PAH) are currently treated with more than one drug. Sildenafil, a phosphodiesterase type 5 (PDE-5) inhibitor, and rosiglitazone, a peroxisome proliferator-activated receptor γ (PPAR-γ) activator, is one of those combinations that could be used in PAH. To monitor the pharmacokinetics of sildenafil in the presence of rosiglitazone, we have developed and validated a sensitive, specific and rapid liquid chromatography-tandem mass spectrometric (LC-MS/MS) method. We have used this validated method to study the pharmacokinetics of sildenafil and rosiglitazone after intravenous administration of sildenafil alone or a combination of sildenafil plus rosiglitazone to adult male Sprague-Dawley rats. Sildenafil and rosiglitazone were extracted from plasma by protein precipitation with methanol. With an octadeuterated sildenafil as the internal standard, the drugs were separated via gradient elution using a C18 column and formic acid in methanol or in water as the mobile phase with a flow rate of 0.25mL/min. Both sildenafil and rosiglitazone samples in rat plasma produced linear response, when the concentration ranged between 5 and 1000ng/mL (r(2)>0.99). The pharmacokinetics study suggests that intravenous co-administration rosiglitazone plus sildenafil increases the plasma concentration of sildenafil and extends the drug's elimination half-life.

Simultaneous Determination of Metformin, Glipizide, Repaglinide, and Glimepiride or Metformin and Pioglitazone by a Validated LC Method: Application in the Presence of Metformin Impurity (1-Cyanoguanidine).

A rapid, simple, and precise RPLC method was developed for the simultaneous determination of the widely used oral antidiabetic, metformin hydrochloride (MTF), with some commonly coadministered oral antidiabetics from different pharmacological classes-glipizide (GPZ), pioglitazone hydrochloride (PGZ), glimepiride (GLM), and repaglinide (RPG)-in bulk, laboratory-prepared mixtures and pharmaceutical formulations in the presence of metformin-reported impurity [1-cyanoguanidine (CNG)]. Chromatographic separation was achieved using isocratic elution mode with a mobile phase of acetonitrile: 0.02 M potassium dihydrogen phosphate (pH 3.17; 50-50, v/v) flowing through a CN Phenomenex column (Phenosphere Next, 250 × 4.6 mm, 5 µm) at a rate of 1.5 mL/min at ambient temperature. UV detection was carried out at 220 nm. The method was validated according to International Conference on Harmonization guidelines. Linearity, accuracy, and precision were satisfactory for concentration ranges: 0.175-350 µg/mL for MTF, 0.0525-105 µg/mL for GPZ, 0.125-250 µg/mL for PGZ, and 0.05-100 µg/mL for GLM and RPG. Correlation coefficients were >0.99 for all analytes. LOQs were 0.009 µg/mL for MTF, 0.009 µg/mL for GPZ, 0.04 µg/mL for GLM, 0.124 µg/mL for PGZ, and 0.044 µg/mL for RPG. The developed method is specific, accurate, and suitable for the QC and routine analysis of the cited drugs in their pharmaceutical products.

A guide for using experimental design in chromatographic method development: applied to the analysis of selected anti-diabetic pharmaceutical combinations.

A guide experimental design in chromatographic method development was described and applied successfully to the analysis of different recently approved anti-diabetic pharmaceutical combinations. Enhancement of UHPLC analysis of alogliptin benzoate either with pioglitazone hydrochloride or with metformin hydrochloride was achieved. The optimal chromatographic conditions were not attained by trial and error that requires a large number of experiments. Alternatively, a computer program was used as a systematic optimization strategy for the design of the experiment which accurately predicts the combined effect of different factors simultaneously. Resolution between peaks was studied by the proposed fractional factorial design approach performed by the Minitab® Program using screening and optimization steps. Application of the central composite design was implemented. A Pareto chart was used to exclude the insignificant variables. Linearity ranges were found to be 0.5-40 µg ml-1, 1-20 µg ml-1 and 1-32 µg ml-1 for alogliptin benzoate, pioglitazone hydrochloride and metformin hydrochloride, respectively. The proposed method is applicable for the analysis of six pharmaceutical dosage forms namely, Nesina®, Actos®, Glucophage®, Oseni®, Kazano® and Actoplus MET® tablets.

Analytical approaches to investigate salt disproportionation in tablet matrices by Raman spectroscopy and Raman mapping.

It has always been challenging to use spectroscopic methods to analyze salt disproportionation in a multi-component tablet matrix due to the spectral interference generated by the various excipients. Although combining Raman spectroscopy and chemometrics can be a powerful approach to study the extent of salt disproportionation, it was found in the present study that bulk measurements and chemometric modeling have obvious limitations when the targeted component is present at low levels in the tablet. Hence, a two-step Raman mapping approach was developed herein to investigate salt disproportionation in tablets with a low drug loading (5% w/w). The first step is to locate the area of interest where the drug particles reside throughout the tablet surface by using a statistically optimized sampling method termed deliberate sub-sampling. The second step, referred to herein as close-step mapping, utilize a step by step mapping of the targeted area to find more details of salt disproportionation in the tablet regions where the drug is concentrated. By using this two-step Raman mapping approach, we successfully detected the existence of minor species embedded in multi-component low drug loading tablet matrices, where bulk measurements from routine techniques usually lack of sensitivity. This approach will help formulation scientists detect and understand salt disproportionation and in situ drug-excipients compatibility issues in low dose solid dosage formulations.

Detection of structurally similar adulterants in botanical dietary supplements by thin-layer chromatography and surface enhanced Raman spectroscopy combined with two-dimensional correlation spectroscopy.

Thin-layer chromatography (TLC) coupled with surface enhanced Raman spectroscopy (SERS) has been widely used for the study of various complex systems, especially for the detection of adulterants in botanical dietary supplements (BDS). However, this method is not sufficient to distinguish structurally similar adulterants in BDS since the analogs have highly similar chromatographic and/or spectroscopic behaviors. Taking into account the fact that higher cost and more time will be required for comprehensive chromatographic separation, more efforts with respect to spectroscopy are now focused on analyzing the overlapped SERS peaks. In this paper, the combination of a TLC-SERS method with two-dimensional correlation spectroscopy (2DCOS), with duration of exposure to laser as the perturbation, is applied to solve this problem. Besides the usual advantages of the TLC-SERS method, such as its simplicity, rapidness, and sensitivity, more advantages are presented here, such as enhanced selectivity and good reproducibility, which are obtained by 2DCOS. Two chemicals with similar structures are successfully differentiated from the complex BDS matrices. The study provides a more accurate qualitative screening method for detection of BDS with adulterants, and offers a new universal approach for the analysis of highly overlapped SERS peaks.

Atividade de novos derivados de tiazolidinodionas sobre a diferenciação de pré-osteoblastos e pré-adipócitos / Activity of new derivatives of thiazolidinediones on differentiation of preosteoblasts and preadipocytes

As tiazolidinodionas (TZDs) são sensibilizadores de insulina utilizados no tratamento do diabetes mellitus tipo 2. Contudo, apesar dos efeitos benéficos sobre a glicemia, importantes efeitos adversos incluindo perda óssea e aumento de adiposidade são relatados com o uso clínico das TZDs. Assim, é necessário o desenvolvimento de novos derivados de TZDs com potenciais efeitos benéficos sobre a hiperglicemia e menos efeitos adversos. Neste estudo, investigamos os efeitos de 5 novos derivados de TZDs (LYSO-7, GQ-89, GQ-150, GQ-177 e SF-3) sobre a diferenciação celular de pré-osteoblastos murinos MC3T3-E1, pré-adipócitos murinos 3T3-L1 e pré-adipócitos SGBS de linhagem humana. Seus potenciais efeitos sobre a utilização de glicose, a produção de adipocinas e mediadores pró-inflamatórios também foram avaliados, utilizando linhagens murinas e humanas de adipócitos, e macrófagos THP-1 de linhagem humana. O principal achado de nosso estudo foi que os novos derivados de TZDs estimulam a utilização celular de glicose, porém não alteram o processo de diferenciação celular de pré-osteoblastos e pré-adipócitos, quando comparados com a TZD clássica Rosiglitazona. Conforme esperado, o tratamento com Rosiglitazona na concentração de 5 µM inibiu a osteogênese de pré-osteoblastos murinos MC3T3-E1. No entanto, o tratamento com 2 novos derivados de TZDs (GQ-89 e GQ-177) na mesma concentração não afetou a diferenciação celular, sendo possível observar níveis de mineralização de matriz extracelular similares aos do grupo controle. Além disso, enquanto a GQ-89 estimulou a atividade da fosfatase alcalina, a GQ-177 não modulou sua atividade enzimática e induziu a expressão gênica de osteocalcina. Contudo, ambos inibiram a expressão de Runx2 e colágeno. Por sua vez, quando os efeitos foram avaliados sobre a diferenciação de adipócitos, foi possível observar que ao contrário do efeito pró-adipogênico constatado com a Rosiglitazona na concentração de 1 µM, as TZDs GQ-150, GQ-177, LYSO-7 e SF-3 foram incapazes de induzir o acúmulo lipídico em pré-adipócitos murinos e humanos. Além disso, a GQ-150 inibiu a expressão gênica de C/EBPα, assim como a expressão gênica e os níveis protéicos de CD36, enquanto que a SF-3 estimulou a expressão gênica de C/EBPα e de FABP4 e diminuiu a expressão gênica e os níveis protéicos de CD36, os quais não foram modificados pela LYSO-7 em pré-adipócitos murinos 3T3-L1. No entanto, em pré-adipócitos SGBS de linhagem humana, nenhum efeito sobre os marcadores de fenótipo adipogênico C/EBPα e FABP4 foi observado com os novos derivados de TZDs. Ademais, os novos derivados de TZDs não interferiram na via de sinalização de Wnt, não apresentaram qualquer efeito sobre a expressão de adipocinas (adiponectina, resistina e leptina) e mediadores pró-inflamatórios (IL-6, CCL2/MCP-1, TNF-α e JNK), bem como não ativaram o fator de transcrição PPARγ no ensaio de gene repórter. Por sua vez, a LYSO-7, GQ-150 e SF-3 aumentaram o consumo de glicose em presença de insulina em adipócitos 3T3-L1 e modificaram a atividade de enzimas mitocondriais em adipócitos SGBS e macrófagos THP-1. Entretanto, o efeito sensibilizador de insulina foi confirmado somente com a GQ-177 pelo aumento da captação de glicose e somente a LYSO-7 e a SF-3 foram capazes de inibir o consumo de oxigênio e modificar a taxa de glicólise em macrófagos, sugerindo que também poderiam alterar os níveis de ATP/ADP. Considerando que baixos níveis de ATP estimulam a via de sinalização de AMPK, essa via também foi investigada em nosso estudo. Entretanto, os resultados sobre a ativação de AMPK foram inconclusivos. Desse modo, nossos resultados apontam que os novos derivados de TZDs não atuam como ligantes de PPARγ, apresentam atividade sensibilizadora de insulina in vitro, e que exercem menores efeitos antiosteoblásticos e adipogênicos quando comparados com a Rosiglitazona. Mais estudos são necessários para elucidar os mecanismos responsáveis por esses efeitos, bem como para estabelecer se os novos derivados de TZDs são mais seguros in vivo, com relação ao risco de fraturas ósseas e ganho de massa adiposa

Thiazolidinediones (TZDs) are insulin sensitizers used in the treatment of type 2 diabetes mellitus. However, despite the beneficial effects on blood glucose, significant adverse effects including bone loss and increased adiposity are reported with the clinical use of TZDs. Thus, it is necessary to develop new derivatives of TZDs with potential beneficial effects on hyperglycemia and fewer adverse effects. In this study, we investigated the effects of 5 new derivatives of TZDs (LYSO-7, GQ-89, GQ-150, GQ-177 e SF-3) on cellular differentiation in murine MC3T3-E1 preosteoblasts, murine 3T3-L1 preadipocytes, and SGBS preadipocytes from human lineage. Potential effects on glucose consumption, adipokines, and pro-inflammatory mediators were also assessed using murine and human strains of adipocytes, and macrophages from human THP-1 lineage. The main finding of this study was that new derivatives of TZDs stimulate glucose consumption, but do not change the cell differentiation process of preosteoblasts and preadipocytes compared to classical TZD Rosiglitazone. As expected, the treatmet with Rosiglitazone, at 5µM, inhibited the osteogenesis in murine MC3T3-E1 preosteoblasts. However, the treatment with 2 new derivatives of TZDs (GQ-89 and GQ-177) at the same concentration did not affect cell differentiation, and levels of mineralization of the extracellular matrix similar to the control group were observed. In addition, whereas the GQ-89 stimulated the activity of alkaline phosphatase, GQ-177 does not modulate its enzymatic activity and induced gene expression of osteocalcin. However, both of them inhibit the expression of Runx2 and collagen. In turn, when the effects were assessed on the adipocyte differentiation, unlike the proadipogenic effect observed with Rosiglitazone at a concentration of 1 µM, the new TZDs GQ-150, GQ-177, LYSO-7 and SF-3 were unable to induce lipid accumulation in human and murine preadipocytes. In addition, GQ-150 inhibited the gene expression of C/EBPα , as well as the gene expression and protein levels of CD36, whereas SF-3 stimulated the gene expression of C/EBPα and FABP4 and decreased gene expression and protein levels of CD36, which was not modified by LYSO-7 on murine 3T3- L1 preadipocytes. However, no effect on markers of adipogenic phenotype C/EBPα and FABP4 has been observed with the novel derivatives of TZDs in human SGBS preadipocytes. Furthermore, the new derivatives of TZDs do not interfere with the Wnt signaling pathway, showed no effect on the adipokines expression (adiponectin, resistin and leptin) and proinflammatory mediators (IL-6, CCL2 / MCP-1, TNF α and JNK) and did not activate the transcription factor PPARγ in the gene reporter assay. In turn, LYSO-7, GQ-150, and SF-3 increased glucose consumption in the presence of insulin in 3T3-L1 adipocytes and modified the activity of mitochondrial enzymes in SGBS adipocytes and THP-1 macrophages. However, the effect on insulin sensitization was confirmed only to GQ-177 that increased glucose uptake and just LYSO-7 and SF-3 were able to inhibit oxygen consumption and modify the rate of glycolysis in macrophages, suggesting that they could also alter the levels of ATP/ADP. Since low levels of ATP could stimulate AMPK pathway, this signaling pathway was also investigated in our study. However, the results on the AMPK activation were inconclusive. Thus, our results demonstrate that the new derivatives of TZDs do not act as PPARγ ligands, present insulin sensitizing activity in vitro, and display minor antiosteoblastic and adipogenic effects when compared to Rosiglitazone. More studies are needed to elucidate the exact mechanisms responsible for these effects, as well as to establish whether the safety of the new TZDs with respect to the risk of bone fractures and body mass gain using in vivo models

Rapid on-site TLC-SERS detection of four antidiabetes drugs used as adulterants in botanical dietary supplements.

A novel facile method has been established for rapid on-site detection of antidiabetes chemicals used to adulterate botanical dietary supplements (BDS) for diabetes. Analytes and components of pharmaceutical matrices were separated by thin-layer chromatography (TLC) then surface-enhanced Raman spectroscopy (SERS) was used for qualitative identification of trace substances on the HPTLC plate. Optimization and standardization of the experimental conditions, for example the method used for preparation of silver colloids, the mobile phase, and the concentration of colloidal silver, resulted in a very robust and highly sensitive method which enabled successful detection when the amount of adulteration was as low as 0.001 % (w/w). The method was also highly selective, enabling successful identification of some chemicals in extremely complex herbal matrices. The established TLC-SERS method was used for analysis of real BDS used to treat diabetes, and the results obtained were verified by liquid chromatography-triple quadrupole mass spectrometry (LC-MS-MS). The study showed that TLC-SERS could be used for effective separation and detection of four chemicals used to adulterate BDS, and would have good prospects for on-site qualitative screening of BDS for adulterants.

[Pioglitazone hydrochloride a instrumental analytical perspective by Raman spectroscopy and HPLC]. / Clorhidrato de pioglitazona: una perspectiva analítico-instrumental por espectroscopia Raman y HPLC.

INTRODUCTION: The thiazolidinediones (pioglitazone) increases the action of insulin and produces the glycemic control in the patients with type 2 diabetes mellitus. Also, the pharmacological effect may be affected by the purity and pioglitazone plasma concentration. Therefore, the instrumental techniques offer a tool for characterization, identification and/or quantification of the pioglitazone; Raman spectroscopy offers several advantages due to its easy application methodology and structural analysis and the HPLC technique is the gold standard vs. other qualitative and quantitative techniques. OBJECTIVE: The aim of this work is to develop and validate analytical techniques for the characterization of pioglitazone hydrochloride by Raman spectroscopy and quantitative analysis in human plasma by HPLC. MATERIAL AND METHODS: The pioglitazone hydrochloride was analyzed by Raman spectroscopy with a 678 mW power and 3 integration time seconds. The analytical method for quantification by HPLC was validated with the guidelines of the NOM-177SSAl-1998. RESULTS: The Raman technique allowed us to elucidate the functional groups of the pioglitazone hydrochloride and the HPLC technique was linear, accurate, precise, specific and sensitive in the range of 30 to 2000 ng/mL under the chromatographic conditions specified. CONCLUSIONS: The structure analysis by Raman spectroscopy allowed us a complete characterization of the functional groups of pioglitazone hydrochloride effectively and non-destructively. Likewise, the analytical technique for the pioglitazone hydrochloride quantification by HPLC was linear, accurate, precise and sensitive in the range of 30 to 2000 ng/mL under the guidelines.

RP-HPLC method development and validation for simultaneous estimation of atorvastatin calcium and pioglitazone hydrochloride in pharmaceutical dosage form.

A simple, selective, rapid, precise and economical reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for simultaneous estimation of atorvastatin calcium (ATV) and pioglitazone hydrochloride (PIO) from pharmaceutical formulation. The method is carried out on a C8 (25 cm × 4.6 mm i.d., 5 µm) column with a mobile phase consisting of acetonitrile (ACN):water (pH adjusted to 6.2 using o-phosphoric acid) in the ratio of 45:55 (v/v). The retention time of ATV and PIO is 4.1 and 8.1 min, respectively, with the flow rate of 1 mL/min with diode array detector detection at 232 nm. The linear regression analysis data from the linearity plot showed good linear relationship with a correlation coefficient (R(2)) value for ATV and PIO of 0.9998 and 0.9997 in the concentration range of 10-80 µg mL(-1), respectively. The relative standard deviation for intraday precision has been found to be <2.0%. The method is validated according to the ICH guidelines. The developed method is validated in terms of specificity, selectivity, accuracy, precision, linearity, limit of detection, limit of quantitation and solution stability. The proposed method can be used for simultaneous estimation of these drugs in marketed dosage forms.

RP-LC method for the simultaneous determination of gliquidone, pioglitazone hydrochloride, and atorvastatin in formulations and human serum.

The objective of this research was to develop and validate a rapid, economical, and sensitive HPLC method for quantitative determination of gliquidone, pioglitazone hydrochloride, and atorvastatin in tablets and serum. Due to drug combination of these formulations, there has been a need for a reliable quantitative method to determine these drugs in commercial samples and human serum. The chromatographic separation was carried out at ambient temperature with a mobile phase consisting of methanol-water (90 + 10, v/v), with pH adjusted to 3.50 with phosphoric acid. The pump was operated at a flow rate of 1 mL/min, and all analytes were detected at 235 nm. The method was linear over the concentration range of 5-50 microg/mL for all the drugs. The LOD of gliquidone, pioglitazone hydrochloride, and atorvastatin was 0.30, 1.30, and 0.57 microg/mL and LOQ was 0.98, 4.28, and 1.90 microg/mL, respectively. The proposed method was successfully applied to the determination of these drugs in commercial tablets and human serum. The established method was validated with respect to specificity, linearity, precision, accuracy, and ruggedness.

Combination of hollow-fiber liquid-phase microextraction and capillary electrophoresis for pioglitazone and its main metabolites determination in rat liver microsomal fraction.

Pioglitazone (PGZ), a thiazolidinedione antidiabetic agent, is reported as a potent and selective activator of peroxisome proliferator-activated receptor γ (PPAR γ). This drug has been widely prescribed for the treatment of Type 2 diabetes mellitus. In this regard, this manuscript presents, for the first time, an alternative electrophoretic method for PGZ and its main metabolites determination in rat liver microsomal fraction. The electrophoretic analyses were performed using an uncoated fused-silica capillary of 50 µm id, 48 cm in total length and 40 cm in effective length, and 50 mmol/L sodium phosphate buffer solution (pH 2.5). All experiments were carried out under the normal mode. The capillary temperature was set at 35°C and a constant voltage of +30 kV was applied during the analyses. Samples were introduced into the capillary by hydrodynamic injection (50 mbar, 15 s) and detection was performed at 190 nm. The sample preparation procedure, based on hollow-fiber liquid-phase microextraction, was optimized using multifactorial experiments. Next, the following optimal condition was established: sample agitation at 1500 rpm, extraction for 15 min, 0.01 mol/L hydrochloric acid as acceptor phase, 1-octanol as organic phase, and donor phase pH adjustment to 6.0. The method demonstrated LOQs of 200 ng/mL. Additionally, it was linear over the concentration range of 200-25,000 ng/mL for PGZ and 200-2000 ng/mL for the metabolites. Finally, the validated method was employed to study the in vitro metabolism of PGZ using rat liver microsomal fraction.

Co-culture of bovine muscle satellite cells with preadipocytes increases PPARγ and C/EBPß gene expression in differentiated myoblasts and increases GPR43 gene expression in adipocytes.

We hypothesized that preadipocyte differentiation would be depressed by differentiating myoblasts, whereas preadipocytes would promote adipogenic gene expression in myoblasts in a co-culture system. We also determined the effects of arginine, a biological precursor of nitric oxide, and/or trans-10, cis-12 conjugated linoleic acid (CLA) on adipogenic gene expression during differentiation of bovine preadipocytes and myoblasts. Bovine semimembranosus satellite cells (BSC) and subcutaneous preadipocytes were isolated from crossbred steers and cultured with 10% fetal bovine serum (FBS)/Dulbecco's modified Eagle medium (DMEM) and 1% antibiotics during the 3-day proliferation period. After proliferation, BSC and preadipocytes were treated for 3 days with 3% horse serum/DMEM and 5% FBS/DMEM with antibiotics, respectively. Media also contained 100 µM oleic acid, 10 µg/ml insulin, 1 µg/ml pioglitazone and 1 µg/ml dexamethasone. Subsequently, the differentiating myoblasts and adipocytes were cultured in their respective media with 5 mM arginine and/or 40 µM trans-10, cis-12 CLA for 4 days. Finally, myoblasts and adipocytes were single- or co-cultured for 2 h singly or in combination. Arginine stimulated SCD gene expression, whereas CLA depressed SCD gene expression in adipocytes and myoblasts (P=.002). Co-culture of adipocytes and myoblasts elicited an increase in C/EBPß and PPARγ gene expression in differentiated myoblasts (P≤.01) and an increase in GPR43 gene expression in adipocytes (P=.01). Expression of AMPKα and CPT1ß was unaffected by co-culture, although SCD gene expression tended (P=.12) to be depressed by co-culture. These experiments demonstrated that co-culture of adipocytes with myoblasts increased adipogenic gene expression in the myoblastic cells.

High-performance liquid chromatography quadrupole time-of-flight mass spectrometry method for the analysis of antidiabetic drugs in aqueous environmental samples.

Antidiabetic compounds are among the most prescribed pharmaceuticals. Nevertheless, their presence in the environment has been scarcely evaluated as there is no method for their determination in environmental samples. This paper reports the development of an analytical method for the determination of traditionally used antidiabetics (metformin and glibenclamide) and novel antidiabetics (vildagliptin, sitagliptin and pioglitazone). The method is based on solid-phase extraction and determination by high-performance liquid chromatography quadrupole time-of-flight mass spectrometry. The method was applied to effluent wastewater, river water and tap water. Mean recoveries of glibenclamide, vildagliptin, sitagliptin and pioglitazone in the matrices evaluated were in the range 78-83%; limits of quantification were in the range 0.4-4.3 ng L(-1); and precision values were in the range 2.2-13%. The high hydrophilicity and polarity of metformin complicated its simultaneous extraction. Chromabond Tetracycline cartridges and sample pH 8.5 were applied to the extraction of glibenclamide, vildagliptin, sitagliptin and pioglitazone. Oasis HLB cartridges, neutral sample pH and SDS as ion-pair reagent were used for the extraction of metformin. Validation results of metformin were not as favorable as those of the other antidiabetic drugs but were comparable with others previously reported. The developed method was applied to the first-time determination of the concentrations of the five antidiabetic drugs in wastewater, river water and tap water. Metformin was the antidiabetic drug at the highest concentration in wastewater and surface water (up to 253 ng L(-1) and 104 ng L(-1), respectively). Two of the antidiabetic drugs of recent prescription, sitagliptin and vildagliptin, were found in effluent wastewater at concentrations of 117 ng L(-1) and 12 ng L(-1), respectively, and in river water at concentrations of 35 ng L(-1) and 6 ng L(-1), respectively, whereas the classic antidiabetic drug glibenclamide and the novel drug pioglitazone were not detected.

Multi-objective optimization strategy based on desirability functions used for electrophoratic separation and quantification of rosiglitazone and glimepiride in plasma and formulations.

Multiple response simultaneous optimization employing Derringer's desirability function was used for the development of a capillary electrophoresis method for the simultaneous determination of rosiglitazone (RSG) and glimepiride (GLM) in plasma and formulations. Twenty experiments, taking the two resolutions, the analysis time, and the capillary current as the responses with three important factors--buffer morality, volte and column temperature--were used to design mathematical models. The experimental responses were fitted into a second order polynomial and the six responses were simultaneously optimized to predict the optimum conditions for the effective separation of the studied compounds. The separation was carried out by using capillary zone electrophoresis (CZE) with a silica capillary column and diode array detector at 210 nm. The optimum assay conditions were 52 mmol l⁻¹ phosphate buffer, pH 7, and voltage of 22 kV at 29 °C. The method showed good agreement between the experimental data and predictive value throughout the studied parameter space. The assay limit of detection was 0.02 µg ml⁻¹ and the effective working range at relative standard deviation (RSD) of ≤ 5% was 0.05-16 µg ml⁻¹ (r = 0.999) for both drugs. Analytical recoveries of the studied drugs from spiked plasma were 97.2-101.9 ± 0.31-3.0%. The precision of the assay was satisfactory; RSD was 1.07 and 1.14 for intra- and inter-assay precision, respectively. The proposed method has a great value in routine analysis of RSG and GLM for its therapeutic monitoring and pharmacokinetic studies.

Direct, metal-free amination of heterocyclic amides/ureas with NH-heterocycles and N-substituted anilines in POCl3.

A POCl(3)-mediated, direct amination reaction of heterocyclic amides/ureas with NH-heterocycles or N-substituted anilines is described. Compared to the existing methods, this operationally simple protocol provides unique reactivity and functional group compatibility because of the metal-free, acidic reaction conditions. The yields are generally excellent.