Papers by Isabelle Forfar
Analytical and Bioanalytical Chemistry, 2015
Gliomas are brain tumours classified into four grades with increasing malignancy from I to IV. Th... more Gliomas are brain tumours classified into four grades with increasing malignancy from I to IV. The development and the progression of malignant glioma largely depend on the tumour vascularization. Due to their tissue heterogeneity, glioma cases can be difficult to classify into a specific grade using the gold standard of histological observation, hence the need to base classification on a quantitative and reliable analytical method for accurately grading the disease. Previous works focused specifically on vascularization study by Fourier transform infrared (FTIR) spectroscopy, proving this method to be a way forward to detect biochemical changes in the tumour tissue not detectable by visual techniques. In this project, we employed FTIR imaging using a focal plane array (FPA) detector and globar source to analyse large areas of glioma tumour tissue sections via molecular fingerprinting in view of helping to define markers of the tumour grade. Unsupervised multivariate analysis (hierarchical cluster analysis and principal component analysis) of blood vessel spectral data, retrieved from the FPA images, revealed the fine structure of the borderline between two areas identified by a pathologist as grades III and IV. Spectroscopic indicators are found capable of discriminating different areas in the tumour tissue and are proposed as biomolecular markers for potential future use of grading gliomas. Graphical Abstract Infrared imaging of glioma blood vessels provides a means to revise the pathologists' line of demarcation separating grade III (GIII) from grade IV (GIV) parts.
Tetrahedron, 1999
The two isomeric 7-benzyl-2-(phenoxymethyl)-2,3,6,7,8,9-hexahydro-5H-[1,3]oxazolo[3,2-a] pyrido[4... more The two isomeric 7-benzyl-2-(phenoxymethyl)-2,3,6,7,8,9-hexahydro-5H-[1,3]oxazolo[3,2-a] pyrido[4,3-d]pyrimidin-5-one 3 and 7-benzyl-2-(phenoxymethyl)-1,2,6,7,8,9-hexahydro-5H-[1 ,3]oxazolo[3,2-a]pyrido[3,4-e]pyrimidin-5-one 4 were synthesized by a one-step ...
Journal of Pharmaceutical and Biomedical Analysis, 2004
A rapid and sensitive high-performance liquid chromatography method with UV detection was develop... more A rapid and sensitive high-performance liquid chromatography method with UV detection was developed for the determination of clonazepam in human plasma using 3-methylclonazepam, as internal standard. A one-step extraction of both compounds was performed with a mixture of hexane/ethyl acetate (90:10, v/v). The HPLC analysis was carried out on a Nova Pak((R)) C(18) reversed-phase column with a mobile phase of acetonitrile-0.01 M sodium acetate adjusted to pH 7 with dilute acetic acid (40:60, v/v). A linear response was observed over the concentration range 5-100 ng/mL. Intra- and inter-day assay precision and accuracy fulfilled the international requirements. The lower limit of quantification was 5 ng/mL without interference of endogenous components. For analytical purpose, the stability of clonazepam in bidistilled water and plasma has been studied. A rapid degradation was noticed when clonazepam was stored in bidistilled water at the daylight following a first-order kinetic rate with a 87 min half life whereas no significant degradation was observed in plasma. This method was applied to measure plasma concentrations of clonazepam either in patients receiving therapeutic doses or in poisoning cases.
Journal of Liquid Chromatography & Related Technologies, 1998
ABSTRACT The effect of pH on the stability of 5-(1-phenyl-4-piperazinyl)methyl-2-amino-2-oxazolin... more ABSTRACT The effect of pH on the stability of 5-(1-phenyl-4-piperazinyl)methyl-2-amino-2-oxazoline (COR 3224), a novel antidepressant, was determined by HPLC at different pH (1, 3, 6, 7.4) at 100°C. One degradation product was isolated at pH 1 and identified as the 5-(1-phenyl-4-piperazinyl)methyl-2-oxazol-idinone. A hydrolysis kinetic study was carried out over a range of pH (1-7.4). The degradation followed a pseudo-first-order kinetics with respect to COR 3224 and was accelerated by an increase in pH.
Heterocyclic Communications, 2000
Heterocyclic Communications, 2000
European Journal of Medicinal Chemistry, 1994
ABSTRACT
Biomedical Chromatography, 2002
A rapid high-performance liquid chromatographic method for the determination of buflomedil in hum... more A rapid high-performance liquid chromatographic method for the determination of buflomedil in human plasma is described. It requires a single liquid-liquid extraction step from 1 mL of plasma with diethyl ether followed by chromatography on a Nova Pak C(18) reversed-phase column and detection by ultaviolet light. Metoclopramide was used as internal standard. The method is sensitive with a quantification limit at 500 ng/mL. It was used for the determination of buflomedil in biological fluids in poisoning cases.
Archiv der Pharmazie, 1994
A series of 5-(1-aryl-4-piperazino)methyl-2-amino-2-oxazolines has been prepared and screened for... more A series of 5-(1-aryl-4-piperazino)methyl-2-amino-2-oxazolines has been prepared and screened for antidepressant activity. Their lipophilic behaviour has been discussed in relation to the nature and the position of substituents on the aromatic ring. The influence of steric effects on the pharmacological activity has been investigated using experimental methods (X-ray diffraction, NMR) and theoretical calculations (semi-empirical quantum mechanics). The ortho-substitution on the phenyl ring or the C-alpha substitution on the piperazine ring by a methyl group results in the same effects i.e. an increase of the angle between the two rings up to 64 degrees (X-ray and calculation) and a loss of the antidepressant activity. Using NMR, only the influence of the ortho-substitution has been observed.
Antimicrobial Agents and Chemotherapy, 2007
A series of 11 pyrrolo[1,2-a]quinoxaline derivatives, 1a to 1k, sharing structural analogies with... more A series of 11 pyrrolo[1,2-a]quinoxaline derivatives, 1a to 1k, sharing structural analogies with omeprazole, a eukaryotic efflux pump inhibitor (EPI) used as an antiulcer agent, was synthesized. Their inhibitory effect was evaluated using Staphylococcus aureus strain SA-1199B overexpressing NorA. By determinations of the MIC of norfloxacin in the presence of these EPIs devoid of intrinsic antibacterial activity and used at 128 g/ml, and by the checkerboard method, compound 1e (MIC decrease, 16-fold; fractional inhibitory concentration index [⌺FIC], 0.18) appeared to be more active than compounds 1b to 1d, reserpine, and omeprazole (MIC decrease, eightfold; ⌺FIC, 0.31), followed by compounds 1a and 1f (MIC decrease, fourfold; ⌺FIC, 0.37) and 1g to 1k (MIC decrease, twofold; ⌺FIC, 0.50 to 0.56). By time-kill curves combining norfloxacin (1/4 MIC) and the most efficient EPIs (128 g/ml), compound 1e persistently restored the bactericidal activity of norfloxacin (inoculum reduction, 3 log 10 CFU/ml at 8 and 24 h), compound 1f led to a delayed but progressive decrease in the number of viable cells, and compounds 1b to 1d and omeprazole acted synergistically (inoculum reduction, 3 log 10 CFU/ml at 8 h but further regrowth), while compound 1a and reserpine slightly enhanced norfloxacin activity. The bacterial uptake of norfloxacin monitored by high-performance liquid chromatography confirmed that compounds 1a to 1f increased antibiotic accumulation, as did reserpine and omeprazole. Since these EPIs did not disturb the ⌬ and ⌬pH, they might directly interact with the pump. A structure-activity relationships study identified the benzimidazole nucleus of omeprazole as the main structural element involved in efflux pump inhibition and highlighted the critical role of the chlorine substituents in the stability and efficiency of compounds 1e to 1f. However, further pharmacomodulation is required to obtain therapeutically applicable derivatives.
Analytical Methods, 2014
The yeast Saccharomyces cerevisiae is widely used as a biological eukaryotic model and also serve... more The yeast Saccharomyces cerevisiae is widely used as a biological eukaryotic model and also serves as a production organism in biotechnology. One of the methods used to avoid degradation of the yeast cell content is lyophilization. The use of lyophilized yeast cells has several advantages over fresh ones: samples can be easily transported and/or stored and variations of their metabolomic profiles do not occur during transport or storage. Fourier transform infrared (FTIR) spectroscopy is one of the most emerging approaches in modern biology that permits operation on very small quantities of whole cells without the need for extractions or purifications. This technique is very sensitive and not only allows the discrimination between different cell genotypes but also between different growth conditions. FTIR spectra provide interesting data on the metabolic status of the whole cell. Modern multivariate data processing was applied to analyse live fresh or lyophilized S. cerevisiae cells from different growth media.
Analytical Methods, 2013
Glioblastoma, the most malignant brain tumor in humans, is characterized by being severely angiog... more Glioblastoma, the most malignant brain tumor in humans, is characterized by being severely angiogenic and an increase in vascularization generally worsens the prognosis of patients. Finding the best approach to characterize glioma blood vessels (BVs) is very important in view of helping to determine any specific biomolecular markers of these tumors. In previous work by conventional FTIR spectroscopy we were able to discriminate some molecular markers in order to differentiate between normal and tumor BVs in glioma tissue sections. The aim of the present study was to assess whether FTIR microspectroscopy using a synchrotron radiation (SR) source could provide advantages over a classical globar IR source for detailed spectral analysis on such small features like micro-BVs. Using chemometric analysis such as PCA and HCA, the results show that a high brilliant SR beam provides a very satisfying quality signal compared with the globar source to study spectral images for relevant analysis of glioma big and micro-BVs and determination of subtle molecular markers characterizing them from the surrounding tissue.
Analytical and Bioanalytical Chemistry, 2014
It has been widely reported that the tear film, which is crucially important as a protective barr... more It has been widely reported that the tear film, which is crucially important as a protective barrier of the eye, undergoes biochemical changes as a result of a wide range of ocular pathology. This tends to suggest the possibility of early detection of ocular diseases on the basis of biochemical analysis of tears. However, studies of tears by conventional methods of biomolecular and biochemical analysis are often limited by methodological difficulties. Moreover, such analysis could not be applied in the clinic, where structural and morphological analyses by, mainly, slit-lamp biomicroscopy remains the recommended method. In this study, we assessed, for the first time, the potential of FTIR spectroscopy combined with advanced chemometric processing of spectral data for analysis of raw tears for diagnosis purposes. We first optimized sampling and spectral acquisition (tears collection method, tear sample volume, and preservation of the samples) for accurate spectral measurement. On the basis of the results, we focused our study on the possibility of discriminating tears from normal individuals from those of patients with different ocular pathologies, and showed that the most discriminating spectral range is that corresponding to variations of CH2 and CH3 of lipid aliphatic chains. We also report more subtle discrimination of tears from patients with keratoconus and those from patients with non-specific inflammatory ocular diseases, on the basis of variations in spectral ranges attributed notably to lipid and carbohydrate vibrations. Finally, we also succeeded in distinguishing tears from patients with early-stage and late-stage keratoconus on the basis of spectral features attributed to protein structure. Therefore, this study strongly suggests that FTIR spectral analysis of tears could be developed as a valuable and cost-saving tool for biochemical-based detection of ocular diseases, potentially before the appearance of the first morphological signs of diseases. Combined with supervised modelling methods and with use of a spectral data base acquired for representative patients, such a spectral approach could be a useful addition to current methods of clinical analysis for improvement of patient care.
Analytical and Bioanalytical Chemistry, 2012
The PI3K/Akt-signaling pathway, associated with cancer development and disease progression, is re... more The PI3K/Akt-signaling pathway, associated with cancer development and disease progression, is recognized to be an anti-tumor drug target that could present important therapeutic benefit. However, no targeted Akt medicines have been commercialized yet, reflecting that drug selection procedures requires significant improvement from early research to clinical trials. Thus, new methods permitting both the evaluation of cytotoxic and proliferation inhibition effect on cancer cells but also to provide a global fingerprint of the drug action mechanism of new Akt inhibitor candidates are of major interest. Because it can detect very subtle molecular changes and could provide a global fingerprint of drug effects on cells, Fourier-transform infrared (FTIR) spectroscopy appears to be a promising method to develop new time-and cost-saving tools for chemical library screening improvements. In this study, we combine FTIR spectroscopy, advanced chemometrics analysis and cross-validation by standard biological assays to establish a basis of a midthroughput methodology for rapid and automated assessment of cell response to Akt inhibitors and quantitative evaluation of their anti-proliferative effects. Our results shows that our methodology is able (1) to detect cell response to an Akt inhibitor exposure even for very low doses, (2) to provide biochemical information of interest about its effects on the cell metabolism, lipidome, and proteome, (3) to predict accurately resulting cell proliferation inhibition rate. Thus, further based on a large spectral data base, our methodology could contribute to facilitate preliminary screening of chemical libraries and improving the selection procedure of drug candidates in laboratory routine.
Journal of the Chemical Society, Perkin Transactions 2, 1997
The influence of the 1-adamantyl group on the structure and the proton transfer dynamics of N-uns... more The influence of the 1-adamantyl group on the structure and the proton transfer dynamics of N-unsubstituted pyrazoles has been determined. Four compounds have been labelled with 15 N and studied by variable temperature 15 N CP MAS NMR spectroscopy: 3(5)-(1-adamantyl)pyrazole 2, 4-(1adamantyl)pyrazole 3, 3,5-dimethyl-4-(1-adamantyl)pyrazole 4 and 3,5-di(1-adamantyl)pyrazole 5. Compound 2 (a 1 : 1 mixture of both tautomers) is a long chain of hydrogen bonded molecules ('catemer') and as in most catemers there is no proton transfer since it would imply an 'infinite' number of proton jumps. Compound 3, although also a 'catemer', is possibly an exception to this rule, in that it seems to show proton transfer. In the solid state, compounds 4 and 5 should be cyclic hydrogen-bonded structures, dimers or trimers, but the activation energies for proton transfer, about 39 kJ mol Ϫ1 , are quite low compared with those of 3,5-dimethylpyrazole. It appears that the quasi-spherical shape of the 1-adamantyl substituent and its solid-state plasticity may play a role in lowering these barriers. The crystal structure of 2 has been determined by X-ray analysis. Individual molecules of 2 form chains through N᎐H ؒ ؒ ؒ N hydrogen bonds ('catemers') very similar to those already described for 4-(1-adamantyl)pyrazole and for pyrazole itself; however, the packing of these catemers is different. Tautomers 2a and 2b are present in the crystal in a 1 : 1 ratio, forming alternating chains of hydrogen-bonded molecules (2a ؒ ؒ ؒ 2b ؒ ؒ ؒ 2a ؒ ؒ ؒ 2b ؒ ؒ ؒ); the NH hydrogen atoms are linked to both nitrogen positions (N1 and N2) and show a 1 : 1 disorder.
Analytical Sciences: X-ray Structure Analysis Online, 2005
ACS Chemical Biology, 2011
Inhibition of hemozoin biocrystallization is considered the main mechanism of action of 4-aminoqu... more Inhibition of hemozoin biocrystallization is considered the main mechanism of action of 4-aminoquinoline antimalarials including chloroquine (CQ) but cannot fully explain the activity of ferroquine (FQ) which has been related to redox properties and intramolecular hydrogen bonding. Analogues of FQ, methylferroquine (Me-FQ), ruthenoquine (RQ), and methylruthenoquine (Me-RQ), were prepared. Combination of physicochemical and molecular modeling methods showed that FQ and RQ favor intramolecular hydrogen bonding between the 4-aminoquinoline NH group and the terminal amino group in the absence of water, suggesting that this structure may enhance its passage through the membrane. This was further supported by the use of Me-FQ and Me-RQ where the intramolecular hydrogen bond cannot be formed. Docking studies suggest that FQ can interact specifically with the {0,0,1} and {1,0,0} faces of hemozoin, blocking crystal growth. With respect to the structure-activity relationship, the antimalarial activity on 15 different P. falciparum strains showed that the activity of FQ and RQ were correlated with each other but not with CQ, confirming lack of cross resistance. Conversely, Me-FQ and Me-RQ showed significant cross-resistance with CQ. Mutations or copy number of pfcrt, pfmrp, pfmdr1, pfmdr2, or pfnhe-1 did not exhibit significant correlations with the IC 50 of FQ or RQ. We next showed that FQ and Me-FQ were able to generate hydroxyl radicals, whereas RQ and me-RQ did not. Ultrastructural studies revealed that FQ and Me-FQ but not RQ or Me-RQ break down the parasite digestive vacuole membrane, which could be related to the ability of the former to generate hydroxyl radicals.
X-ray Structure Analysis Online, 2009
ABSTRACT 2, 3, 6, 7-Tetrahydro-7-methoxymethyl-4H-oxazolo[3, 2-a]-1, 3, 5-triazin-2, 4-diones (4)... more ABSTRACT 2, 3, 6, 7-Tetrahydro-7-methoxymethyl-4H-oxazolo[3, 2-a]-1, 3, 5-triazin-2, 4-diones (4), with potential anti-inflammatory activity, were synthesized. 2, 3, 6, 7-Tetrahydro-3-phenyl-7-methoxymethyl-4H-oxazolo[3, 2-a]-1, 3, 5-triazin-2, 4-dione (4a) was obtained in two steps from the 5-methoxymethyl-2-amino-2-oxazoline by acylation with phenyl isocyanate followed by a cyclization induced by heating. 2, 3, 6, 7-Tetrahydro-7-methoxymethyl-4H-oxazolo[3, 2-a]-1, 3, 5-triazin-2, 4-dione (4b) was prepared by oxidation of the corresponding 1, 3, 5-triazin-2-one-4-thione.
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Papers by Isabelle Forfar