scholarly journals Isomerization of antimalarial drug WR99210 explains its inactivity in a commercial stock

2020 ◽  
Author(s):  
T. Parks Remcho ◽  
Sravanthi D. Guggilapu ◽  
Phillip Cruz ◽  
Glenn A. Nardone ◽  
Gavin Heffernan ◽  
...  
Keyword(s):  
Active Site ◽  
Antimalarial Drug ◽  
High Performance ◽  
Mass Spectra ◽  
Drug Candidate ◽  
Resonance Spectroscopy ◽  
Computational Docking ◽  
Layer Chromatography ◽  
Commercial Stock ◽  
Selection Of

ABSTRACTWR99210, a former antimalarial drug candidate now widely used for the selection of Plasmodium transfectants, selectively targets the parasite dihydrofolate reductase thymidine synthase bifunctional enzyme (DHFR-TS) but not human DHFR, which is not fused with TS. Accordingly, WR99210 and plasmids expressing human dhfr have become valued tools for the genetic modification of parasites in the laboratory. Concerns over the ineffectiveness of WR99210 from some sources encouraged us to investigate the biological and chemical differences of supplies from two different companies (compounds 1 and 2). Compound 1 proved effective at low nanomolar concentrations against Plasmodium falciparum parasites, whereas compound 2 was ineffective even at micromolar concentrations. Intact and fragmented mass spectra indicated identical molecular formulae of the unprotonated (free base) structures of 1 and 2; however, the compounds displayed differences by thin layer chromatography, reverse phase high performance liquid chromatography, and ultraviolet-visible spectroscopy, indicating important isomeric differences. Structural evaluations by 1H, 13C, and 15N nuclear magnetic resonance spectroscopy confirmed 1 as WR99210 and 2 as an isomeric dihydrotriazine. Induced fit, computational docking models showed that 1 binds tightly and specifically in the P. falciparum DHFR active site whereas 2 fits poorly to the active site in loose and varied orientations. Stocks and concentrates of WR99210 should be monitored for the presence of isomer 2, particularly when they are not supplied as the hydrochloride salt or are exposed to basic conditions that can promote isomerization. Absorption spectroscopy may serve for assays of the unrearranged and rearranged triazines.

scholarly journals Regioisomerization of Antimalarial Drug WR99210 Explains the Inactivity of a Commercial Stock

2020 ◽  
Vol 65 (1) ◽  
pp. e01385-20
Author(s):  
T. Parks Remcho ◽  
Sravanthi D. Guggilapu ◽  
Phillip Cruz ◽  
Glenn A. Nardone ◽  
Gavin Heffernan ◽  
...  
Keyword(s):  
Active Site ◽  
Antimalarial Drug ◽  
High Performance ◽  
Drug Candidate ◽  
Resonance Spectroscopy ◽  
Content Type ◽  
Computational Docking ◽  
Layer Chromatography ◽  
Commercial Stock ◽  
Selection Of

ABSTRACTWR99210, a former antimalarial drug candidate now widely used for the selection of Plasmodium transfectants, selectively targets the parasite’s dihydrofolate reductase thymidine synthase bifunctional enzyme (DHFR-TS) but not human DHFR, which is not fused with TS. Accordingly, WR99210 and plasmids expressing the human dhfr gene have become valued tools for the genetic modification of parasites in the laboratory. Concerns over the ineffectiveness of WR99210 from some sources encouraged us to investigate the biological and chemical differences of supplies from two different companies (compounds 1 and 2). Compound 1 proved effective at low nanomolar concentrations against Plasmodium falciparum parasites, whereas compound 2 was ineffective, even at micromolar concentrations. Intact and fragmented mass spectra indicated identical molecular formulae of the unprotonated (free base) structures of compounds 1 and 2; however, the compounds displayed differences by thin-layer chromatography, reverse-phase high-performance liquid chromatography, and UV-visible spectroscopy, indicating important isomeric differences. Structural evaluations by 1H, 13C, and 15N nuclear magnetic resonance spectroscopy confirmed compound 1 as WR99210 and compound 2 as a dihydrotriazine regioisomer. Induced fit computational docking models showed that compound 1 binds tightly and specifically in the P. falciparum DHFR active site, whereas compound 2 fits poorly to the active site in loose and varied orientations. Stocks and concentrates of WR99210 should be monitored for the presence of regioisomer 2, particularly when they are not supplied as the hydrochloride salt or are exposed to basic conditions that may promote rearrangement. Absorption spectroscopy can serve for assays of the unrearranged and rearranged triazines.

Preparation and mass spectral behaviour of some 5β-cholenoic acids

1979 ◽  
Vol 57 (3) ◽  
pp. 216-225 ◽  
Author(s):  
P. Child ◽  
A. Kuksis ◽  
L. Marai
Keyword(s):  
Mass Spectrometry ◽  
Thin Layer ◽  
Bile Acids ◽  
Spectral Properties ◽  
Mass Spectra ◽  
Resonance Spectroscopy ◽  
Mass Spectral ◽  
Spectral Behaviour ◽  
Simple Chemical ◽  
Layer Chromatography

Monounsaturated 5β-cholanoic acids with double bonds in rings A, B, and C were prepared by POCl3 and ZnCl2 dehydration from natural bile acids with selectively blocked hydroxyl functions. The yields ranged from 15 to 100%. The products were purified by thin-layer and AgNO3 thin-layer chromatography and the structures were confirmed by nuclear magnetic resonance spectroscopy and mass spectrometry. The methyl ester acetates of the unsaturated 5β-cholanoic acids possessed chromatographic properties closely similar to those of the corresponding saturated bile acids. Several characteristic fragments were seen in the mass spectra which, in conjunction with the chromatographic properties, permitted an unambiguous distinction between different monounsaturated acids, and between saturated and unsaturated bile acids of the same number and configuration of functional groups. The 20 5β-cholenoic acids examined represent all of the simple chemical and enzymatic dehydration products of natural bile acids and can be completely identified by their combined chromatographic and mass spectral properties.

scholarly journals Metabolic Profiling of Saponin-Rich Ophiopogon japonicus Roots Based on 1H NMR and HPTLC Platforms

Planta Medica ◽  
2019 ◽  
Vol 85 (11/12) ◽  
pp. 917-924 ◽  
Author(s):  
Yanhui Ge ◽  
Xiaojia Chen ◽  
Dejan Gođevac ◽  
Paula C. P. Bueno ◽  
Luis F. Salomé Abarca ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
High Performance ◽  
Resonance Spectroscopy ◽  
Layer Chromatography ◽  
Nuclear Magnetic

AbstractIdeally, metabolomics should deal with all the metabolites that are found within cells and biological systems. The most common technologies for metabolomics include mass spectrometry, and in most cases, hyphenated to chromatographic separations (liquid chromatography- or gas chromatography-mass spectrometry) and nuclear magnetic resonance spectroscopy. However, limitations such as low sensitivity and highly congested spectra in nuclear magnetic resonance spectroscopy and relatively low signal reproducibility in mass spectrometry impede the progression of these techniques from being universal metabolomics tools. These disadvantages are more notorious in studies of certain plant secondary metabolites, such as saponins, which are difficult to analyse, but have a great biological importance in organisms. In this study, high-performance thin-layer chromatography was used as a supplementary tool for metabolomics. A method consisting of coupling 1H nuclear magnetic resonance spectroscopy and high-performance thin-layer chromatography was applied to distinguish between Ophiopogon japonicus roots that were collected from two growth locations and were of different ages. The results allowed the root samples from the two growth locations to be clearly distinguished. The difficulties encountered in the identification of the marker compounds by 1H nuclear magnetic resonance spectroscopy was overcome using high-performance thin-layer chromatography to separate and isolate the compounds. The saponins, ophiojaponin C or ophiopogonin D, were found to be marker metabolites in the root samples and proved to be greatly influenced by plant growth location, but barely by age variation. The procedure used in this study is fully described with the purpose of making a valuable contribution to the quality control of saponin-rich herbal drugs using high-performance thin-layer chromatography as a supplementary analytical tool for metabolomics research.

A Review article on Analytical Method Development for the combination of Azelnidipine and Telmisartan

2021 ◽  
pp. 227-234
Author(s):  
Nirma Chavda ◽  
Suresh Kumar
Keyword(s):  
Liquid Chromatography ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
High Performance ◽  
Method Development ◽  
Ultra Performance Liquid Chromatography ◽  
Resonance Spectroscopy ◽  
Stability Indicating ◽  
Stability Indicating Method ◽  
Layer Chromatography

The literature survey explains that there is not any stability indicating method reportedly for combination of Azelnidipine and Telmisartan till date. Validation and development of stability indicating analytical methods is possible as per ICH Guidelines. There are several of Spectroscopic methods such as Ultraviolet Spectroscopy, Mass spectroscopy, infrared spectroscopy, Nuclear magnetic resonance spectroscopy and Chromatographic methods such as High performance liquid chromatography, Thin layer Chromatography, High Performance thin layer chromatography, Gas chromatography and Ultra performance liquid chromatography etc. used for stability indicating method development and validation.

Separation and Identification of Phencyclidine and Some of Its Analogs

1983 ◽  
Vol 66 (5) ◽  
pp. 1186-1195
Author(s):  
K Gurudath Rao ◽  
Shiv K Soni
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Mass Spectra ◽  
Major Ions ◽  
Gas Chromatography Mass Spectrometry ◽  
Structural Variations ◽  
Layer Chromatography

Abstract l-(l-Phenylcyclohexyl)piperidine (PCP) and 9 of its analogs have been separated and identified by using thin layer chromatography, high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), and infrared spectroscopy (IR). Spectral and chromatographic characteristics are discussed in terms of the structural variations observed in these compounds. Some compounds decomposed on the GC column; the HPLC procedure is a helpful substitute. A tentative scheme is proposed for the fragmentation of the major ions observed in the mass spectra. The effect of substitution on the IR spectra of the analogs was investigated.

scholarly journals 2′-Hydroxylated 3-Deoxyanthocyanin from the Flowers of Cosmos sulphureus Cultivars

2019 ◽  
Vol 14 (9) ◽  
pp. 1934578X1987621
Author(s):  
Tsukasa Iwashina ◽  
Kotarou Amamiya ◽  
Tsunashi Kamo ◽  
Junichi Kitajima ◽  
Takayuki Mizuno ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Magnetic Resonance ◽  
High Performance ◽  
Mass Spectra ◽  
Chemical Structure ◽  
Resonance Spectroscopy ◽  
Spectroscopic Methods ◽  
Liquid Chromatograph

A new 3-deoxyanthocyanin was isolated from the orange flowers of Cosmos sulphureus cultivar “Diabolo,” together with known aurone, chalcone, flavone, flavonol, and flavanone. The chemical structure of 3-deoxyanthocyanin was established as 5,7,2′,4′-tetrahydroxyflavylium 4′- O-β-d-glucopyranoside by chemical and spectroscopic methods including UV, FAB MS, and 1H and 13C nuclear magnetic resonance spectroscopy (NMR), and named as cosmonidin 4′- O-glucoside (1a). Other known flavonoids were characterized as sulfuretin 6- O-glucoside (2), butein 4′- O-glucoside (3), quercetin 3- O-glucoside (4), luteolin 7- O-glucuronide (5), and eriodictyol 7- O-glucuronide (6) by UV, liquid chromatograph - mass spectra (LC-MS), NMR, and high performance liquid chromatography comparisons with authentic samples. Anthocyanin, which 2′-position is hydroxylated, has not been reported until now. Compound (1a) was also found in other 10 C. sulphureus cultivars “Lamala Lemon,” “Sunrise,” “Dwarf Yellow,” “Cosmic Yellow,” “Carpet Gold,” “Mandarin,” “Cosmic Orange,” “Orange Flare,” “Cosmic Red,” and “Sunset.”

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