philippe hennig - Academia.edu (original) (raw)

Papers by philippe hennig

Research paper thumbnail of A reinvestigation of the intramolecular Buchner reaction of 1-diazo-4-phenylbutan-2-ones leading to 2-tetralones

Journal of the Chemical Society, 1993

Research paper thumbnail of 19F nuclear magnetic resonance screening of glucokinase activators

Analytical Biochemistry, 2015

Research paper thumbnail of ChemInform Abstract: A Reinvestigation of the Intramolecular Buchner Reaction of 1‐Diazo‐4‐ phenylbutan‐2‐ones Leading to 2‐Tetralones

ChemInform, 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Research paper thumbnail of New substrate analogues of human serotonin N‐acetyltransferase produce in situ specific and potent inhibitors

European Journal of Biochemistry, 2004

Melatonin is synthesized by an enzymatic pathway, in which arylalkylamine (serotonin) N‐acetyltra... more Melatonin is synthesized by an enzymatic pathway, in which arylalkylamine (serotonin) N‐acetyltransferase catalyzes the rate‐limiting step. A previous study [Khalil, E.M., De Angelis, J., Ishii, M. & Cole, P.A. (1999) Proc. Natl Acad. Sci. USA96, 12418–12423] reported the discovery of bromoacetyltryptamine (BAT), a new type of inhibitor of this enzyme. This compound is the precursor of a potent bifunctional inhibitor (analogue of the transition state), capable of interfering with both the substrate and the cosubstrate binding sites. This inhibitor is biosynthesized by the enzyme itself in the presence of free coenzyme A. In the present report, we describe the potency of new N‐halogenoacetyl derivatives leading to a strong in situ inhibition of serotonin N‐acetyltransferase. The new concept behind the mechanism of action of these precursors was studied by following the biosynthesis of the inhibitor from tritiated‐BAT in a living cell. The fate of tritiated‐phenylethylamine (PEA), a n...

Research paper thumbnail of Solution conformation by NMR and molecular modeling of three sulfide-free somatostatin octapeptide analogs compared to angiopeptin

Journal of Computer-Aided Molecular Design, 1996

The conformation in dimethylsulfoxide of the somatostatin derivative angiopeptin and of three dis... more The conformation in dimethylsulfoxide of the somatostatin derivative angiopeptin and of three disulfide-free analogs was estimated by two-dimensional nuclear magnetic resonance spectroscopy at room temperature. The resulting 3D molecular graphics were compared and shown to reflect the observed differences in the inhibition of restenosis after rat aorta balloon injury by these octapeptide inhibitors. Angiopeptin and its active analog 2 displayed a relatively rigid conformation of the cyclic hexapeptide backbone due to the presence of two well-defined hydrogen bonds, further stabilized by a third hydrogen bond outside the ring. No such constraints were detected for the two biologically inactive analogs, which, compared to 2, had a two-atom longer or shorter hexapeptide ring. The well-defined structure of compound 2 may serve as an improved pharmacophore for this new class of drugs.

Research paper thumbnail of A zinc chelator inhibiting gelatinases exerts potent in vitro anti-invasive effects

European Journal of Pharmacology, 1998

Matrix metalloproteinases are zinc metalloenzymes involved in remodelling of the extracellular ma... more Matrix metalloproteinases are zinc metalloenzymes involved in remodelling of the extracellular matrix. We compared the anti-invasive properties of a zinc ejector matrix metalloproteinase inhibitor with those of reference compounds (hydroxamic acid-based BB-94 and Ro-31-9790) which form inactive ternary complexes with the enzymes and the catalytic zinc. We show that the compound undecadenedioic acid bis-[[2-(3 H-imidazol-4-yl)-ethyl]-amide] (S 30372) is active against gelatinases, chelates zinc and exhibits enzymatic features compatible with the potential to extract zinc from gelatinases. We then used five invasive cell lines in the Matrigel invasion chamber assay (NIH-3T3 fibroblasts, Lewis lung carcinoma cells, EJ138 and J82 bladder carcinoma and HT1080 fibrosarcoma cells). With the exception of J82 cells which were unaffected by the three inhibitors, all remaining cells were substantially more sensitive to S 30372 in terms of maximal inhibition of invasion attained. This suggests that matrix metalloproteinase inhibitors with zinc chelating/ejecting properties may be more efficient in preventing tumor progression.

Research paper thumbnail of Identification and characterisation of the isomers of cyclothiazide responsible for potentiating ampa current

Bioorganic & Medicinal Chemistry Letters, 1994

ABSTRACT

Research paper thumbnail of Combinatorial Peptide Libraries: Robotic Synthesis and Analysis by Nuclear Magnetic Resonance, Mass Spectrometry, Tandem Mass Spectrometry, and High-Performance Capillary Electrophoresis Techniques

Analytical Biochemistry, 1996

Research paper thumbnail of Isolation, sequence, and conformation of seven trichorzianines from Trichoderma harzianum

International Journal of Peptide and Protein Research, 2009

From the antagonistic fungus Triclroderma harzianum, a group of acidic new peptides, trichorziani... more From the antagonistic fungus Triclroderma harzianum, a group of acidic new peptides, trichorzianines B (TB), was isolated in addition to neutral trichorzianines A (TA) previously studied. TA and TB exhibit various biological activities related to their membrane properties and a different behaviour of the two groups was noticed. As observed for other peptaibols, TB consist in a microheterogeneous mixture which was resolved into pure peptides by reversed‐phase C18 HPLC. The sequence of the seven main isolated TB, namely TB IIa, TB IIIc, TB IVb. TB Vb. TB VIa. TB VIb, TB VII, was determined by the combined use of positive ion FAB mass spectrometry and 2D 1H n.m.r. spectroscopy, including COSY and NOESY experiments. TB differ from the corresponding TA only by the replacement of Gln 18 in the TA sequence by a glutamic acid. The 1H n.m.r. data suggested that the TB are mainly organized in an α helix.

Research paper thumbnail of Effect of dilution solvent and injection volume on the analysis of basic hydrophilic therapeutic polypeptide salts with pressurized carbon dioxide mobile phases

Journal of Chromatography B

Research paper thumbnail of Analysis of short-chain bioactive peptides by unified chromatography-electrospray ionization mass spectrometry. Part I. Method development

Journal of Chromatography A, 2021

A method to analyse short-chain bioactive peptides (MW < 800 Da) and their impurities was deve... more A method to analyse short-chain bioactive peptides (MW < 800 Da) and their impurities was developed with a unified chromatography (UC) analysis, including a wide mobile phase gradient ranging from supercritical fluid to near-liquid conditions, with UV and electrospray ionization mass spectrometry detection (ESI-MS). Four stationary phases and three mobile phase compositions were examined. Ten model peptides were first selected to identify the best operating conditions, including five linear tripeptides and five cyclic pentapeptides, with log P values ranging from -5.9 to 3.6, and including isomeric species. Derringer desirability functions were designed to identify optimal operating conditions based on 7 criteria, namely the number of peaks detected (including all impurities resolved), the proportion of the chromatogram occupied by target peaks, the least favourable resolution observed between the main peptide and impurities, peak shape features (asymmetry and peak width at half height), and finally the signal-to-noise ratio observed both with UV (210 nm) and ESI-MS in positive ionization mode. The optimum conditions were obtained on Ascentis Express OH5 stationary phase, with a mobile phase composed of carbon dioxide and methanol, comprising 2% water and 20 mM ammonium hydroxide. The final gradient program ranged from 5 to 80% co-solvent in CO2, with a reversed flow rate gradient ranging from 3.0 to 1.5 mL/min. Back-pressure was set at 120 bar and the column oven temperature at 60°C. Optimal conditions were applied to a large set of 76 peptides (34 linear tripeptides and 42 cyclic pentapeptides) and provided adequate scattering of the peaks in the retention space, together with some separation of isomeric species, particularly for the cyclic peptides.

Research paper thumbnail of Purification of drug degradation products supported by analytical and preparative supercritical fluid chromatography

Journal of Pharmaceutical and Biomedical Analysis, 2019

A stressed degradation (oxidation) was employed to produce metabolites from an active pharmaceuti... more A stressed degradation (oxidation) was employed to produce metabolites from an active pharmaceutical ingredient (API) with large molecular weight (about 900 g/mol). An analytical chromatographic method was desired to compare the products generated by different degradation methods while a multi-gram-scale preparative chromatographic method was necessary to purify the produced metabolites. Supercritical fluid chromatography (SFC) was selected for both tasks as no other chromatographic method had achieved the resolution of the API and metabolites (two isomeric mono-oxide species and one dioxide). First, an analytical-scale method was developed with ultra-high performance supercritical fluid chromatography (UHPSFC). Achiral stationary phases containing sub-2 μm fully porous particles or sub-3 μm superficially porous particles, and chiral phases containing 3 and 5 µm fully porous particles were selected for a first screening with gradient elution (carbon dioxidemethanol containing additives). The stationary phase providing the most promising results was ACQUITY Torus 2-PIC (100 x 3 mm, 1.7 μm, Waters). A central composite design (CCD) was conducted to optimize the gradient program and oven temperature. Final gradient conditions were as follows: 50 to 70 % methanol in 3.8 min with oven temperature set at 36°C, back-pressure set at 11 MPa and flow-rate at 0.8 mL/min. The optimized method was employed to analyze samples obtained with different degradation conditions. Then the method was adapted and transferred to preparativescale SFC on a 5 μm-particles Torus 2-PIC stationary phase (150 x 30 mm). The method was modified to comprise an isocratic step followed by a gradient, favoring peak shape of the last eluting compound and minimal volume of collected fractions. Batch injections in gradient mode were carried out to purify six grams of crude product.

Research paper thumbnail of Characterization of Retention Mechanisms in Mixed-Mode HPLC with a Bimodal Reversed-Phase/Cation-Exchange Stationary Phase

Chromatographia, 2018

Mixed-mode HPLC (MM-HPLC), combining different interactions or retention modes in a single column... more Mixed-mode HPLC (MM-HPLC), combining different interactions or retention modes in a single column, can be an interesting alternative to reversed-phase HPLC, notably to achieve the combined retention of polar and non-polar species. In the present fundamental study, we have selected one bimodal stationary phase allowing for both reversed-phase and weak cationexchange retention modes (Acclaim mixed-mode WCX-1 LC). First, the mobile phase buffer composition (buffer pH ranging from 5 to 7 and concentration ranging from 20 to 100 mM) was explored with a small set of probe compounds (15 acids, bases and neutrals) to ensure adequate retention and peak shapes for the target compounds, and to evaluate the relative contributions of reversed-phase and ion-exchange mechanisms. Second, retention values measured for 63 probe compounds with various proportions of acetonitrile (ranging from 30 to 80%) served to establish linear solvation energy relationships based on (a) the usual and (b) a modified version of the solvation parameter model comprising additional descriptors to take account of interactions with ionizable species to bring some insights into the retention mechanisms. Finally, temperature effects at the low (30%) and high (60%) proportions of acetonitrile were observed between 20 and 40 °C (with 5 °C increments) and Van't Hoff plots were drawn to measure the changes in interactions energies when the mobile phase composition changed.

Research paper thumbnail of Impurity profiling of drug candidates: Analytical strategies using reversed-phase and mixed-mode high-performance liquid chromatography methods

Journal of Chromatography A, 2018

Please cite this article in press as: E. Lemasson, et al., Impurity profiling of drug candidates:... more Please cite this article in press as: E. Lemasson, et al., Impurity profiling of drug candidates: Analytical strategies using reversed-phase and mixed-mode high-performance liquid chromatography methods,

Research paper thumbnail of Interest of achiral-achiral tandem columns for impurity profiling of synthetic drugs with supercritical fluid chromatography

Journal of Chromatography A, 2018

To achieve the most complete impurity profiling of synthetic drugs with a single chromatographic ... more To achieve the most complete impurity profiling of synthetic drugs with a single chromatographic technique, high resolution is required, which may be gained with a combination of high efficiency and versatile selectivity, allowing to separate most similar analytes. Compared to a single-column chromatographic method, coupling complementary stationary phases promises both an increase in efficiency and an increase in selectivity possibilities. With supercritical fluid chromatography (SFC), the use of long columns is facilitated by the low viscosity of the mobile phase. In this paper, we investigate the interest of coupling two achiral stationary phases (Acquity UPC 2 HSS C18 SB and Nucleoshell HILIC) that were previously observed to have excellent complementarity in SFC to carry out impurity profiling on 25 individual drug substances containing varied numbers and amounts of impurities. The single-column gradient methods are compared to tandem-column gradient methods with the two possible ordering of columns (C18 phase in first or second position) based on selectivity, peak capacity, sensitivity, UV-estimated purity of the active pharmaceutical ingredient and number of impurities detected with UV-estimated concentration >0.04 %. It appears that it could be more beneficial to have two

Research paper thumbnail of Characterization of Novel Polymer-Based Pyridine Stationary Phases for Supercritical Fluid Chromatography

Chromatographia, 2018

2-Ethylpyridine-bonded silica is one of the most famous stationary phases employed in supercritic... more 2-Ethylpyridine-bonded silica is one of the most famous stationary phases employed in supercritical fluid chromatography, especially for the analysis of basic compounds and even without an additive in the mobile phase. In the present paper, we present the synthesis and characterization of three original stationary phases based on poly(vinylpyridine) polymers supported on silica. The position of nitrogen atom relative to the polymer chain was varied to be in the 2, 3, or 4 position. All these phases were prototypes, while the poly(4-vinylpyridine) phase was subsequently commercialized (DCPak P4VP from Daicel Corporation). The stationary phases obtained are characterized in supercritical fluid chromatography with carbon dioxide-methanol mobile phase, with a modified version of the solvation parameter model, to take account of ionic interactions. The three phases are also compared to a 2-ethylpyridine-bonded silica phase and a 2-picolylamine-bonded silica phase. It appears that the polymer-based pyridine phases are significantly more retentive than brush-type pyridine phases and adequately shield residual silanol groups to prevent unwanted interactions with basic compounds. The different selectivities and chromatographic performances are also evidenced with sample applications on pharmaceutical compounds, notably with a selection of 140 drug candidates.

Research paper thumbnail of First inter-laboratory study of a Supercritical Fluid Chromatography method for the determination of pharmaceutical impurities

Journal of pharmaceutical and biomedical analysis, Jan 23, 2018

Supercritical Fluid Chromatography (SFC) has known a strong regain of interest for the last 10 ye... more Supercritical Fluid Chromatography (SFC) has known a strong regain of interest for the last 10 years, especially in the field of pharmaceutical analysis. Besides the development and validation of the SFC method in one individual laboratory, it is also important to demonstrate its applicability and transferability to various laboratories around the world. Therefore, an inter-laboratory study was conducted and published for the first time in SFC, to assess method reproducibility, and evaluate whether this chromatographic technique could become a reference method for quality control (QC) laboratories. This study involved 19 participating laboratories from 4 continents and 9 different countries. It included 5 academic groups, 3 demonstration laboratories at analytical instrument companies, 10 pharmaceutical companies and 1 food company. In the initial analysis of the study results, consistencies within- and between-laboratories were deeply examined. In the subsequent analysis, the metho...

Research paper thumbnail of Comparison of ultra-high performance methods in liquid and supercritical fluid chromatography coupled to electrospray ionization - mass spectrometry for impurity profiling of drug candidates

Journal of chromatography. A, Jan 11, 2016

Impurity profiling of organic products synthesized as possible drug candidates represents a major... more Impurity profiling of organic products synthesized as possible drug candidates represents a major analytical challenge. Complementary analytical methods are required to ensure that all impurities are detected. Both high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) can be used for this purpose. In this study, we compared ultra-high performance HPLC (UHPLC) and ultra-high performance SFC (UHPSFC) using a large dataset of 140 pharmaceutical compounds. Four previously optimized methods (two on each technique) were selected to ensure fast high-resolution separations. The four methods were evaluated based on response rate, peak capacity, peak shape and capability to detect impurities (UV). The orthogonality between all methods was also assessed. The best UHPLC method and UHPSFC methods provided comparable quality for the 140 compounds included in this study. Moreover, they were found to be highly orthogonal. At last, the potential of the combined u...

Research paper thumbnail of An improved classification of stationary phases for ultra-high performance supercritical fluid chromatography

Journal of Chromatography A, 2016

An improved solvation parameter model is useful to measure ionic interactions 30 columns based on... more An improved solvation parameter model is useful to measure ionic interactions 30 columns based on sub-2 µm fully porous or sub-3 µm superficially porous particles Evaluation is based on neutral and ionizable probe molecules A revised classification map is proposed to be used in UHPSFC Applicability of this system to real-life samples is demonstrated with drug candidates

Research paper thumbnail of Development of an achiral supercritical fluid chromatography method with ultraviolet absorbance and mass spectrometric detection for impurity profiling of drug candidates. Part II. Selection of an orthogonal set of stationary phases

Journal of chromatography. A, Jan 21, 2015

Impurity profiling of organic products that are synthesized as possible drug candidates requires ... more Impurity profiling of organic products that are synthesized as possible drug candidates requires complementary analytical methods to ensure that all impurities are identified. Supercritical fluid chromatography (SFC) is a very useful tool to achieve this objective, as an adequate selection of stationary phases can provide orthogonal separations so as to maximize the chances to see all impurities. In this series of papers, we have developed a method for achiral SFC-MS profiling of drug candidates, based on a selection of 160 analytes issued from Servier Research Laboratories. In the first part of this study, focusing on mobile phase selection, a gradient elution with carbon dioxide and methanol comprising 2% water and 20mM ammonium acetate proved to be the best in terms of chromatographic performance, while also providing good MS response [1]. The objective of this second part was the selection of an orthogonal set of ultra-high performance stationary phases, that was carried out in ...

Research paper thumbnail of A reinvestigation of the intramolecular Buchner reaction of 1-diazo-4-phenylbutan-2-ones leading to 2-tetralones

Journal of the Chemical Society, 1993

Research paper thumbnail of 19F nuclear magnetic resonance screening of glucokinase activators

Analytical Biochemistry, 2015

Research paper thumbnail of ChemInform Abstract: A Reinvestigation of the Intramolecular Buchner Reaction of 1‐Diazo‐4‐ phenylbutan‐2‐ones Leading to 2‐Tetralones

ChemInform, 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Research paper thumbnail of New substrate analogues of human serotonin N‐acetyltransferase produce in situ specific and potent inhibitors

European Journal of Biochemistry, 2004

Melatonin is synthesized by an enzymatic pathway, in which arylalkylamine (serotonin) N‐acetyltra... more Melatonin is synthesized by an enzymatic pathway, in which arylalkylamine (serotonin) N‐acetyltransferase catalyzes the rate‐limiting step. A previous study [Khalil, E.M., De Angelis, J., Ishii, M. & Cole, P.A. (1999) Proc. Natl Acad. Sci. USA96, 12418–12423] reported the discovery of bromoacetyltryptamine (BAT), a new type of inhibitor of this enzyme. This compound is the precursor of a potent bifunctional inhibitor (analogue of the transition state), capable of interfering with both the substrate and the cosubstrate binding sites. This inhibitor is biosynthesized by the enzyme itself in the presence of free coenzyme A. In the present report, we describe the potency of new N‐halogenoacetyl derivatives leading to a strong in situ inhibition of serotonin N‐acetyltransferase. The new concept behind the mechanism of action of these precursors was studied by following the biosynthesis of the inhibitor from tritiated‐BAT in a living cell. The fate of tritiated‐phenylethylamine (PEA), a n...

Research paper thumbnail of Solution conformation by NMR and molecular modeling of three sulfide-free somatostatin octapeptide analogs compared to angiopeptin

Journal of Computer-Aided Molecular Design, 1996

The conformation in dimethylsulfoxide of the somatostatin derivative angiopeptin and of three dis... more The conformation in dimethylsulfoxide of the somatostatin derivative angiopeptin and of three disulfide-free analogs was estimated by two-dimensional nuclear magnetic resonance spectroscopy at room temperature. The resulting 3D molecular graphics were compared and shown to reflect the observed differences in the inhibition of restenosis after rat aorta balloon injury by these octapeptide inhibitors. Angiopeptin and its active analog 2 displayed a relatively rigid conformation of the cyclic hexapeptide backbone due to the presence of two well-defined hydrogen bonds, further stabilized by a third hydrogen bond outside the ring. No such constraints were detected for the two biologically inactive analogs, which, compared to 2, had a two-atom longer or shorter hexapeptide ring. The well-defined structure of compound 2 may serve as an improved pharmacophore for this new class of drugs.

Research paper thumbnail of A zinc chelator inhibiting gelatinases exerts potent in vitro anti-invasive effects

European Journal of Pharmacology, 1998

Matrix metalloproteinases are zinc metalloenzymes involved in remodelling of the extracellular ma... more Matrix metalloproteinases are zinc metalloenzymes involved in remodelling of the extracellular matrix. We compared the anti-invasive properties of a zinc ejector matrix metalloproteinase inhibitor with those of reference compounds (hydroxamic acid-based BB-94 and Ro-31-9790) which form inactive ternary complexes with the enzymes and the catalytic zinc. We show that the compound undecadenedioic acid bis-[[2-(3 H-imidazol-4-yl)-ethyl]-amide] (S 30372) is active against gelatinases, chelates zinc and exhibits enzymatic features compatible with the potential to extract zinc from gelatinases. We then used five invasive cell lines in the Matrigel invasion chamber assay (NIH-3T3 fibroblasts, Lewis lung carcinoma cells, EJ138 and J82 bladder carcinoma and HT1080 fibrosarcoma cells). With the exception of J82 cells which were unaffected by the three inhibitors, all remaining cells were substantially more sensitive to S 30372 in terms of maximal inhibition of invasion attained. This suggests that matrix metalloproteinase inhibitors with zinc chelating/ejecting properties may be more efficient in preventing tumor progression.

Research paper thumbnail of Identification and characterisation of the isomers of cyclothiazide responsible for potentiating ampa current

Bioorganic & Medicinal Chemistry Letters, 1994

ABSTRACT

Research paper thumbnail of Combinatorial Peptide Libraries: Robotic Synthesis and Analysis by Nuclear Magnetic Resonance, Mass Spectrometry, Tandem Mass Spectrometry, and High-Performance Capillary Electrophoresis Techniques

Analytical Biochemistry, 1996

Research paper thumbnail of Isolation, sequence, and conformation of seven trichorzianines from Trichoderma harzianum

International Journal of Peptide and Protein Research, 2009

From the antagonistic fungus Triclroderma harzianum, a group of acidic new peptides, trichorziani... more From the antagonistic fungus Triclroderma harzianum, a group of acidic new peptides, trichorzianines B (TB), was isolated in addition to neutral trichorzianines A (TA) previously studied. TA and TB exhibit various biological activities related to their membrane properties and a different behaviour of the two groups was noticed. As observed for other peptaibols, TB consist in a microheterogeneous mixture which was resolved into pure peptides by reversed‐phase C18 HPLC. The sequence of the seven main isolated TB, namely TB IIa, TB IIIc, TB IVb. TB Vb. TB VIa. TB VIb, TB VII, was determined by the combined use of positive ion FAB mass spectrometry and 2D 1H n.m.r. spectroscopy, including COSY and NOESY experiments. TB differ from the corresponding TA only by the replacement of Gln 18 in the TA sequence by a glutamic acid. The 1H n.m.r. data suggested that the TB are mainly organized in an α helix.

Research paper thumbnail of Effect of dilution solvent and injection volume on the analysis of basic hydrophilic therapeutic polypeptide salts with pressurized carbon dioxide mobile phases

Journal of Chromatography B

Research paper thumbnail of Analysis of short-chain bioactive peptides by unified chromatography-electrospray ionization mass spectrometry. Part I. Method development

Journal of Chromatography A, 2021

A method to analyse short-chain bioactive peptides (MW < 800 Da) and their impurities was deve... more A method to analyse short-chain bioactive peptides (MW < 800 Da) and their impurities was developed with a unified chromatography (UC) analysis, including a wide mobile phase gradient ranging from supercritical fluid to near-liquid conditions, with UV and electrospray ionization mass spectrometry detection (ESI-MS). Four stationary phases and three mobile phase compositions were examined. Ten model peptides were first selected to identify the best operating conditions, including five linear tripeptides and five cyclic pentapeptides, with log P values ranging from -5.9 to 3.6, and including isomeric species. Derringer desirability functions were designed to identify optimal operating conditions based on 7 criteria, namely the number of peaks detected (including all impurities resolved), the proportion of the chromatogram occupied by target peaks, the least favourable resolution observed between the main peptide and impurities, peak shape features (asymmetry and peak width at half height), and finally the signal-to-noise ratio observed both with UV (210 nm) and ESI-MS in positive ionization mode. The optimum conditions were obtained on Ascentis Express OH5 stationary phase, with a mobile phase composed of carbon dioxide and methanol, comprising 2% water and 20 mM ammonium hydroxide. The final gradient program ranged from 5 to 80% co-solvent in CO2, with a reversed flow rate gradient ranging from 3.0 to 1.5 mL/min. Back-pressure was set at 120 bar and the column oven temperature at 60°C. Optimal conditions were applied to a large set of 76 peptides (34 linear tripeptides and 42 cyclic pentapeptides) and provided adequate scattering of the peaks in the retention space, together with some separation of isomeric species, particularly for the cyclic peptides.

Research paper thumbnail of Purification of drug degradation products supported by analytical and preparative supercritical fluid chromatography

Journal of Pharmaceutical and Biomedical Analysis, 2019

A stressed degradation (oxidation) was employed to produce metabolites from an active pharmaceuti... more A stressed degradation (oxidation) was employed to produce metabolites from an active pharmaceutical ingredient (API) with large molecular weight (about 900 g/mol). An analytical chromatographic method was desired to compare the products generated by different degradation methods while a multi-gram-scale preparative chromatographic method was necessary to purify the produced metabolites. Supercritical fluid chromatography (SFC) was selected for both tasks as no other chromatographic method had achieved the resolution of the API and metabolites (two isomeric mono-oxide species and one dioxide). First, an analytical-scale method was developed with ultra-high performance supercritical fluid chromatography (UHPSFC). Achiral stationary phases containing sub-2 μm fully porous particles or sub-3 μm superficially porous particles, and chiral phases containing 3 and 5 µm fully porous particles were selected for a first screening with gradient elution (carbon dioxidemethanol containing additives). The stationary phase providing the most promising results was ACQUITY Torus 2-PIC (100 x 3 mm, 1.7 μm, Waters). A central composite design (CCD) was conducted to optimize the gradient program and oven temperature. Final gradient conditions were as follows: 50 to 70 % methanol in 3.8 min with oven temperature set at 36°C, back-pressure set at 11 MPa and flow-rate at 0.8 mL/min. The optimized method was employed to analyze samples obtained with different degradation conditions. Then the method was adapted and transferred to preparativescale SFC on a 5 μm-particles Torus 2-PIC stationary phase (150 x 30 mm). The method was modified to comprise an isocratic step followed by a gradient, favoring peak shape of the last eluting compound and minimal volume of collected fractions. Batch injections in gradient mode were carried out to purify six grams of crude product.

Research paper thumbnail of Characterization of Retention Mechanisms in Mixed-Mode HPLC with a Bimodal Reversed-Phase/Cation-Exchange Stationary Phase

Chromatographia, 2018

Mixed-mode HPLC (MM-HPLC), combining different interactions or retention modes in a single column... more Mixed-mode HPLC (MM-HPLC), combining different interactions or retention modes in a single column, can be an interesting alternative to reversed-phase HPLC, notably to achieve the combined retention of polar and non-polar species. In the present fundamental study, we have selected one bimodal stationary phase allowing for both reversed-phase and weak cationexchange retention modes (Acclaim mixed-mode WCX-1 LC). First, the mobile phase buffer composition (buffer pH ranging from 5 to 7 and concentration ranging from 20 to 100 mM) was explored with a small set of probe compounds (15 acids, bases and neutrals) to ensure adequate retention and peak shapes for the target compounds, and to evaluate the relative contributions of reversed-phase and ion-exchange mechanisms. Second, retention values measured for 63 probe compounds with various proportions of acetonitrile (ranging from 30 to 80%) served to establish linear solvation energy relationships based on (a) the usual and (b) a modified version of the solvation parameter model comprising additional descriptors to take account of interactions with ionizable species to bring some insights into the retention mechanisms. Finally, temperature effects at the low (30%) and high (60%) proportions of acetonitrile were observed between 20 and 40 °C (with 5 °C increments) and Van't Hoff plots were drawn to measure the changes in interactions energies when the mobile phase composition changed.

Research paper thumbnail of Impurity profiling of drug candidates: Analytical strategies using reversed-phase and mixed-mode high-performance liquid chromatography methods

Journal of Chromatography A, 2018

Please cite this article in press as: E. Lemasson, et al., Impurity profiling of drug candidates:... more Please cite this article in press as: E. Lemasson, et al., Impurity profiling of drug candidates: Analytical strategies using reversed-phase and mixed-mode high-performance liquid chromatography methods,

Research paper thumbnail of Interest of achiral-achiral tandem columns for impurity profiling of synthetic drugs with supercritical fluid chromatography

Journal of Chromatography A, 2018

To achieve the most complete impurity profiling of synthetic drugs with a single chromatographic ... more To achieve the most complete impurity profiling of synthetic drugs with a single chromatographic technique, high resolution is required, which may be gained with a combination of high efficiency and versatile selectivity, allowing to separate most similar analytes. Compared to a single-column chromatographic method, coupling complementary stationary phases promises both an increase in efficiency and an increase in selectivity possibilities. With supercritical fluid chromatography (SFC), the use of long columns is facilitated by the low viscosity of the mobile phase. In this paper, we investigate the interest of coupling two achiral stationary phases (Acquity UPC 2 HSS C18 SB and Nucleoshell HILIC) that were previously observed to have excellent complementarity in SFC to carry out impurity profiling on 25 individual drug substances containing varied numbers and amounts of impurities. The single-column gradient methods are compared to tandem-column gradient methods with the two possible ordering of columns (C18 phase in first or second position) based on selectivity, peak capacity, sensitivity, UV-estimated purity of the active pharmaceutical ingredient and number of impurities detected with UV-estimated concentration >0.04 %. It appears that it could be more beneficial to have two

Research paper thumbnail of Characterization of Novel Polymer-Based Pyridine Stationary Phases for Supercritical Fluid Chromatography

Chromatographia, 2018

2-Ethylpyridine-bonded silica is one of the most famous stationary phases employed in supercritic... more 2-Ethylpyridine-bonded silica is one of the most famous stationary phases employed in supercritical fluid chromatography, especially for the analysis of basic compounds and even without an additive in the mobile phase. In the present paper, we present the synthesis and characterization of three original stationary phases based on poly(vinylpyridine) polymers supported on silica. The position of nitrogen atom relative to the polymer chain was varied to be in the 2, 3, or 4 position. All these phases were prototypes, while the poly(4-vinylpyridine) phase was subsequently commercialized (DCPak P4VP from Daicel Corporation). The stationary phases obtained are characterized in supercritical fluid chromatography with carbon dioxide-methanol mobile phase, with a modified version of the solvation parameter model, to take account of ionic interactions. The three phases are also compared to a 2-ethylpyridine-bonded silica phase and a 2-picolylamine-bonded silica phase. It appears that the polymer-based pyridine phases are significantly more retentive than brush-type pyridine phases and adequately shield residual silanol groups to prevent unwanted interactions with basic compounds. The different selectivities and chromatographic performances are also evidenced with sample applications on pharmaceutical compounds, notably with a selection of 140 drug candidates.

Research paper thumbnail of First inter-laboratory study of a Supercritical Fluid Chromatography method for the determination of pharmaceutical impurities

Journal of pharmaceutical and biomedical analysis, Jan 23, 2018

Supercritical Fluid Chromatography (SFC) has known a strong regain of interest for the last 10 ye... more Supercritical Fluid Chromatography (SFC) has known a strong regain of interest for the last 10 years, especially in the field of pharmaceutical analysis. Besides the development and validation of the SFC method in one individual laboratory, it is also important to demonstrate its applicability and transferability to various laboratories around the world. Therefore, an inter-laboratory study was conducted and published for the first time in SFC, to assess method reproducibility, and evaluate whether this chromatographic technique could become a reference method for quality control (QC) laboratories. This study involved 19 participating laboratories from 4 continents and 9 different countries. It included 5 academic groups, 3 demonstration laboratories at analytical instrument companies, 10 pharmaceutical companies and 1 food company. In the initial analysis of the study results, consistencies within- and between-laboratories were deeply examined. In the subsequent analysis, the metho...

Research paper thumbnail of Comparison of ultra-high performance methods in liquid and supercritical fluid chromatography coupled to electrospray ionization - mass spectrometry for impurity profiling of drug candidates

Journal of chromatography. A, Jan 11, 2016

Impurity profiling of organic products synthesized as possible drug candidates represents a major... more Impurity profiling of organic products synthesized as possible drug candidates represents a major analytical challenge. Complementary analytical methods are required to ensure that all impurities are detected. Both high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) can be used for this purpose. In this study, we compared ultra-high performance HPLC (UHPLC) and ultra-high performance SFC (UHPSFC) using a large dataset of 140 pharmaceutical compounds. Four previously optimized methods (two on each technique) were selected to ensure fast high-resolution separations. The four methods were evaluated based on response rate, peak capacity, peak shape and capability to detect impurities (UV). The orthogonality between all methods was also assessed. The best UHPLC method and UHPSFC methods provided comparable quality for the 140 compounds included in this study. Moreover, they were found to be highly orthogonal. At last, the potential of the combined u...

Research paper thumbnail of An improved classification of stationary phases for ultra-high performance supercritical fluid chromatography

Journal of Chromatography A, 2016

An improved solvation parameter model is useful to measure ionic interactions 30 columns based on... more An improved solvation parameter model is useful to measure ionic interactions 30 columns based on sub-2 µm fully porous or sub-3 µm superficially porous particles Evaluation is based on neutral and ionizable probe molecules A revised classification map is proposed to be used in UHPSFC Applicability of this system to real-life samples is demonstrated with drug candidates

Research paper thumbnail of Development of an achiral supercritical fluid chromatography method with ultraviolet absorbance and mass spectrometric detection for impurity profiling of drug candidates. Part II. Selection of an orthogonal set of stationary phases

Journal of chromatography. A, Jan 21, 2015

Impurity profiling of organic products that are synthesized as possible drug candidates requires ... more Impurity profiling of organic products that are synthesized as possible drug candidates requires complementary analytical methods to ensure that all impurities are identified. Supercritical fluid chromatography (SFC) is a very useful tool to achieve this objective, as an adequate selection of stationary phases can provide orthogonal separations so as to maximize the chances to see all impurities. In this series of papers, we have developed a method for achiral SFC-MS profiling of drug candidates, based on a selection of 160 analytes issued from Servier Research Laboratories. In the first part of this study, focusing on mobile phase selection, a gradient elution with carbon dioxide and methanol comprising 2% water and 20mM ammonium acetate proved to be the best in terms of chromatographic performance, while also providing good MS response [1]. The objective of this second part was the selection of an orthogonal set of ultra-high performance stationary phases, that was carried out in ...