1
|
Rama A, Govindan I, Hebbar S, Chaturvedi A, Rani U, Naha A. Advancing posaconazole quantification analysis with a new reverse-phase HPLC method in its bulk and marketed dosage form. F1000Res 2023; 12:468. [PMID: 37396051 PMCID: PMC10314186 DOI: 10.12688/f1000research.132841.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/23/2023] [Indexed: 07/04/2023] Open
Abstract
Introduction: Posaconazole is a widely used antifungal drug, and its accurate quantification is essential for quality control and assessment of its pharmaceutical products. This study aimed to develop and validate a reverse-phase high-performance liquid chromatography (HPLC) analytical method for quantifying Posaconazole in bulk and dosage form. Methods: The HPLC method was developed and validated based on International Conference on Harmonisation (ICH) guidelines. The developed method was then applied to quantify Posaconazole in a marketed tablet formulation. The method's specificity, linearity, precision, accuracy, robustness, and stability were evaluated. Results: The developed HPLC method showed good linearity over a 2-20 μg/mL concentration range. The percentage recovery of Posaconazole from the bulk and marketed formulations was found to be 99.01% and 99.05%, respectively. The intra-day and inter-day precisions were less than 1%, and the method was stable under different conditions. The HPLC method was successfully applied to quantify Posaconazole in the marketed formulation. Conclusion: The developed and validated HPLC method is reliable and efficient for analyzing Posaconazole in bulk and dosage forms. The method's accuracy, precision, specificity, linearity, robustness, and stability demonstrate its effectiveness. The method can be used for the quality control and assessment of Posaconazole-containing pharmaceutical products.
Collapse
Affiliation(s)
- Annamalai Rama
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Induja Govindan
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Srinivas Hebbar
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Abhishek Chaturvedi
- Division of Biochemistry, Department of Basic Medical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Usha Rani
- Department of Social Health and Innovation, Prasanna School of Public Health, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Anup Naha
- Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| |
Collapse
|
2
|
Garcia CV, Bitencourt AS, Oliveira SS, Gobetti C, Mendez ASL. Analytical Study of the Antifungal Posaconazole in Raw Material: Quantitative Bioassay, Decomposition Chemical Kinetics, and Degradation Impurities by LC-QTOF-MS. J AOAC Int 2021; 104:1055-1064. [PMID: 33470411 DOI: 10.1093/jaoacint/qsab009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/21/2020] [Accepted: 01/10/2021] [Indexed: 11/14/2022]
Abstract
BACKGROUND Posaconazole is a triazole antifungal drug that was approved by the U.S. Food and Drug Administration in 2006. No bioassay of it is available in the literature nor official codes for potency determination in bulk. OBJECTIVE To conduct an analytical study focused on posaconazole in bulk. METHODS An alternative microbiological assay was validated for drug quantitation, applying agar diffusion technics (3 × 3 design), using Saccharomyces cerevisiae ATCC MYA 1942 as a test microorganism (2% inoculum). An isocratic HPLC-DAD method, with C8 Shim-pack column (250 × 4.6 mm, 5 μm) and methanol-water (75:25 v/v) mobile phase was used for stress stability by photolysis and oxidation, indicating the formation of degradation products, which were investigated by ultra-performance liquid chromatography to quadrupole time-of-flight mass spectrometry. RESULTS The established conditions for the bioassay were satisfactory. It was linear in the range evaluated (2.5-10.0 µg/mL), as well as precise, accurate, and robust. Stress tests showed drug susceptibility to the factors evaluated (60% of degradation after 120 min). Kinetics curves for photolytic decomposition followed first-order kinetics. From a photolytic and oxidative degraded matrix, three major degradation products were identified as being derivatives with modifications in the piperazine central ring and in the triazole and triazolone side chains, whose mass spectra results were m/z 683 (DP1), m/z 411 (DP2), and m/z 465 (DP3). CONCLUSIONS The microbiological method was adequately validated and demonstrated to be equivalent to physico-chemical ones. The impurities found are described for the first time in studies with posaconazole raw material. HIGHLIGHTS A microbiological bioassay was developed for posaconazole, first-order kinetics was determined for photolytic degradation, and structures for new degradation products were suggested.
Collapse
Affiliation(s)
- Cássia V Garcia
- Laboratório de Controle de Qualidade Farmacêutico, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil.,Programa de Pós-graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil
| | - Andressa S Bitencourt
- Laboratório de Controle de Qualidade Farmacêutico, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil
| | - Sendy S Oliveira
- Laboratório de Controle de Qualidade Farmacêutico, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil
| | - Caren Gobetti
- Laboratório de Controle de Qualidade Farmacêutico, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil.,Programa de Pós-graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil
| | - Andreas S L Mendez
- Laboratório de Controle de Qualidade Farmacêutico, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil.,Programa de Pós-graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil
| |
Collapse
|
3
|
|
4
|
Ni QZ, Yang F, Can TV, Sergeyev IV, D’Addio SM, Jawla SK, Li Y, Lipert MP, Xu W, Williamson RT, Leone A, Griffin RG, Su Y. In Situ Characterization of Pharmaceutical Formulations by Dynamic Nuclear Polarization Enhanced MAS NMR. J Phys Chem B 2017; 121:8132-8141. [PMID: 28762740 PMCID: PMC5592962 DOI: 10.1021/acs.jpcb.7b07213] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A principal advantage of magic angle spinning (MAS) NMR spectroscopy lies in its ability to determine molecular structure in a noninvasive and quantitative manner. Accordingly, MAS should be widely applicable to studies of the structure of active pharmaceutical ingredients (API) and formulations. However, the low sensitivity encountered in spectroscopy of natural abundance APIs present at low concentration has limited the success of MAS experiments. Dynamic nuclear polarization (DNP) enhances NMR sensitivity and can be used to circumvent this problem provided that suitable paramagnetic polarizing agent can be incorporated into the system without altering the integrity of solid dosages. Here, we demonstrate that DNP polarizing agents can be added in situ during the preparation of amorphous solid dispersions (ASDs) via spray drying and hot-melt extrusion so that ASDs can be examined during drug development. Specifically, the dependence of DNP enhancement on sample composition, radical concentration, relaxation properties of the API and excipients, types of polarizing agents and proton density, has been thoroughly investigated. Optimal enhancement values are obtained from ASDs containing 1% w/w radical concentration. Both polarizing agents TOTAPOL and AMUPol provided reasonable enhancements. Partial deuteration of the excipient produced 3× higher enhancement values. With these parameters, an ASD containing posaconazole and vinyl acetate yields a 32-fold enhancement which presumably results in a reduction of NMR measurement time by ∼1000. This boost in signal intensity enables the full assignment of the natural abundance pharmaceutical formulation through multidimensional correlation experiments.
Collapse
Affiliation(s)
- Qing Zhe Ni
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Fengyuan Yang
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Thach V. Can
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ivan V. Sergeyev
- Bruker BioSpin Corporation, Billerica, Massachusetts 01821, United States
| | - Suzanne M. D’Addio
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Sudheer K. Jawla
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yongjun Li
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Maya P. Lipert
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Wei Xu
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - R. Thomas Williamson
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Anthony Leone
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Robert G. Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yongchao Su
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| |
Collapse
|
5
|
Li R, Xie X, Ma F, Wang D, Wang L, Zhang J, Xu Y, Wang X, Zhang C, Wang Y. Resveratrol accumulation and its involvement in stilbene synthetic pathway of Chinese wild grapes during berry development using quantitative proteome analysis. Sci Rep 2017; 7:9295. [PMID: 28839259 PMCID: PMC5571159 DOI: 10.1038/s41598-017-10171-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 08/03/2017] [Indexed: 12/18/2022] Open
Abstract
Attention has become focused on resveratrol not only because of its role in grapevine fungal resistance but also because of its benefits in human health. This report describes the Chinese wild grapevine Vitis quinquangularis accession Danfeng-2 in relation to the high resveratrol content of its ripe berries. In this study, we used isobaric tags for relative and absolute quantification (iTRAQ) tandem mass spectrometry strategy to quantify and identify proteome changes, resulting in the detection of a total of 3,751 proteins produced under natural conditions. Among the proteins quantified, a total of 578 differentially expressed proteins were detected between Danfeng-2 and Cabernet Sauvignon during berry development. Differentially expressed proteins are involved in secondary metabolism, biotic stress, abiotic stress and transport activity and indicate novel biological processes in Chinese wild grapevine. Eleven proteins involved in phenylpropanoid metabolism and stilbene synthesis were differently expressed between Danfeng-2 and Cabernet Sauvignon at the veraison stage of berry development. These findings suggest that Chinese wild V. quinquangularis accession Danfeng-2 is an extremely important genetic resource for grape breeding and especially for increasing the resveratrol content of European grape cultivars for disease resistance and for improved human nutritional benefits.
Collapse
Affiliation(s)
- Ruimin Li
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
| | - Xiaoqing Xie
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
| | - Fuli Ma
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
| | - Dan Wang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
| | - Lan Wang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
| | - Jianxia Zhang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
| | - Yan Xu
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
| | - Xiping Wang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China
| | - Chaohong Zhang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China.
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China.
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China.
| | - Yuejin Wang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China.
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, The People's Republic of China.
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, The People's Republic of China.
| |
Collapse
|
6
|
Stability-indicating HPLC method development and structural elucidation of novel degradation products in posaconazole injection by LC–TOF/MS, LC–MS/MS and NMR. J Pharm Biomed Anal 2016; 125:165-77. [DOI: 10.1016/j.jpba.2016.03.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 03/11/2016] [Accepted: 03/14/2016] [Indexed: 11/23/2022]
|
7
|
Buevich AV, Williamson RT, Martin GE. NMR Structure Elucidation of Small Organic Molecules and Natural Products: Choosing ADEQUATE vs HMBC. JOURNAL OF NATURAL PRODUCTS 2014; 77:1942-1947. [PMID: 25098228 DOI: 10.1021/np500445s] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Long-range heteronuclear shift correlation methods have served as the cornerstone of modern structure elucidation protocols for several decades. The (1)H-(13)C HMBC experiment provides a versatile and relatively sensitive means of establishing predominantly (3)J(CH) connectivity with the occasional (2)J(CH) or (4)J(CH) correlation being observed. The two-bond and four-bond outliers must be identified specifically to avoid spectral and/or structural misassignment. Despite the versatility and extensive applications of the HMBC experiment, it can still fail to elucidate structures of molecules that are highly proton-deficient, e.g., those that fall under the so-called "Crews rule". In such cases, recourse to the ADEQUATE experiments should be considered. Thus, a study was undertaken to facilitate better investigator understanding of situations where it might be beneficial to apply 1,1- or 1,n-ADEQUATE to proton-rich or proton-deficient molecules. Equipped with a better understanding of when a given experiment might be more likely to provide the necessary correlation data, investigators can make better decisions on when it might be advisible to employ one experiment over the other. Strychnine (1) and cervinomycin A2 (2) were employed as model compounds to represent proton-rich and proton-deficient classes of molecules, respectively. DFT methods were employed to calculate the relevant (n)J(CH) heteronuclear proton-carbon and (n)J(CC) homonuclear carbon-carbon coupling constants for this study.
Collapse
Affiliation(s)
- Alexei V Buevich
- Discovery and Preclinical Sciences, Process and Analytical Chemistry, NMR Structure Elucidation, Merck Research Laboratories , Kenilworth, New Jersey 07033, United States
| | - R Thomas Williamson
- Discovery and Preclinical Sciences, Process and Analytical Chemistry, NMR Structure Elucidation, Merck Research Laboratories , Rahway, New Jersey 07065, United States
| | - Gary E Martin
- Discovery and Preclinical Sciences, Process and Analytical Chemistry, NMR Structure Elucidation, Merck Research Laboratories , Rahway, New Jersey 07065, United States
| |
Collapse
|
8
|
Martin GE, Blinov KA, Williamson RT. HMBC-1,n-ADEQUATE spectra calculated from HMBC and 1,n-ADEQUATE spectra. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:299-307. [PMID: 23483673 DOI: 10.1002/mrc.3946] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 01/30/2013] [Accepted: 02/06/2013] [Indexed: 06/01/2023]
Abstract
Unsymmetrical and generalized indirect covariance processing methods provide a means of mathematically combining pairs of 2D NMR spectra that share a common frequency domain to facilitate the extraction of correlation information. Previous reports have focused on the combination of HSQC spectra with 1,1-, 1,n-, and inverted (1)J(CC) 1,n-ADEQUATE spectra to afford carbon-carbon correlation spectra that allow the extraction of direct ((1)J(CC)), long-range ((n)J(CC), where n ≥ 2), and (1)J(CC)-edited long-range correlation data, respectively. Covariance processing of HMBC and 1,1-ADEQUATE spectra has also recently been reported, allowing convenient, high-sensitivity access to (n)J(CC) correlation data equivalent to the much lower sensitivity n,1-ADEQUATE experiment. Furthermore, HMBC-1,1-ADEQUATE correlations are observed in the F1 frequency domain at the intrinsic chemical shift of the (13)C resonance in question rather than at the double-quantum frequency of the pair of correlated carbons, as visualized by the n,1, and m,n-ADEQUATE experiments, greatly simplifying data interpretation. In an extension of previous work, the covariance processing of HMBC and 1,n-ADEQUATE spectra is now reported. The resulting HMBC-1,n-ADEQUATE spectrum affords long-range carbon-carbon correlation data equivalent to the very low sensitivity m,n-ADEQUATE experiment. In addition to the significantly higher sensitivity of the covariance calculated spectrum, correlations in the HMBC-1,n-ADEQUATE spectrum are again detected at the intrinsic (13)C chemical shifts of the correlated carbons rather than at the double-quantum frequency of the pair of correlated carbons. HMBC-1,n-ADEQUATE spectra can provide correlations ranging from diagonal ((0)J(CC) or diagonal correlations) to (4)J(CC) under normal circumstances to as much as (6)J(CC) in rare instances. The experiment affords the potential means of establishing the structures of severely proton-deficient molecules.
Collapse
Affiliation(s)
- Gary E Martin
- Discovery and Preclinical Sciences, Process and Analytical Chemistry, Structure Elucidation Group, Merck Research Laboratories, Summit, NJ 07901, USA.
| | | | | |
Collapse
|
9
|
Martin GE, Blinov KA, Reibarkh M, Williamson RT. 1J(CC)-edited HSQC-1,n-ADEQUATE: a new paradigm for simultaneous direct and long-range carbon-carbon correlation. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:722-728. [PMID: 22996413 DOI: 10.1002/mrc.3870] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/06/2012] [Accepted: 08/13/2012] [Indexed: 06/01/2023]
Abstract
Establishing the carbon skeleton of a molecule greatly facilitates the process of structure elucidation, leaving only heteroatoms to be inserted, heterocyclic rings to be closed, and stereochemical features to be defined. INADEQUATE, and more recently PANACEA, have been the only means of coming close to the goal of totally defining the carbon skeleton of a molecule. Unfortunately, the extremely low sensitivity and prodigious sample requirements of these experiments and the multiple receiver requirement for the latter experiment have severely restricted the usage of these experiments. Proton-detected ADEQUATE experiments, in contrast, have considerably higher sensitivity and more modest sample requirements. By combining experiments such as 1,1-ADEQUATE and 1,n-ADEQUATE with higher sensitivity experiments such as GHSQC through covariance processing, sample requirements can be further reduced with a commensurate improvement in the s/n ratio and F(1) resolution of the covariance processed spectrum. We now wish to report the covariance processing of an inverted (1)J(CC) 1,n-ADEQUATE experiment with a non-edited GHSQC spectrum to afford a spectrum that can trace the carbon skeleton of a molecule with the exception of correlations between quaternary carbons.
Collapse
Affiliation(s)
- Gary E Martin
- Discovery and Preclinical Sciences, Process & Analytical Chemistry - Structure Elucidation Group, Merck Research Laboratories, Summit, NJ 07901, USA.
| | | | | | | |
Collapse
|
10
|
Martin GE, Williamson RT, Blinov KA, Anklin CG, Bermel W. HMBC-1,1-ADEQUATE via generalized indirect covariance: a high sensitivity alternative to n,1-ADEQUATE. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:691-695. [PMID: 22930548 DOI: 10.1002/mrc.3863] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/03/2012] [Accepted: 07/23/2012] [Indexed: 06/01/2023]
Abstract
1,1-ADEQUATE and the related long-range 1,n- and n,1-ADEQUATE variants were developed to provide an unequivocal means of establishing (2)J(CH) and the equivalent of (n)J(CH) correlations where n = 3,4. Whereas the 1,1- and 1,n-ADEQUATE experiments have two simultaneous evolution periods that refocus the chemical shift and afford net single quantum evolution for the carbon spins, the n,1-variant has a single evolution period that leaves the carbon spin to be observed at the double quantum frequency. The n,1-ADEQUATE experiment begins with an HMBC-type (n)J(CH) magnetization transfer, which leads to inherently lower sensitivity than the 1,1- and 1,n-ADEQUATE experiments that begin with a (1)J(CH) transfer. These attributes, in tandem, serve to render the n,1-ADEQUATE experiment less generally applicable and more difficult to interpret than the 1,n-ADEQUATE experiment, which can in principle afford the same structural information. Unsymmetrical and generalized indirect covariance processing methods can complement and enhance the structural information encoded in combinations of experiments e.g. HSQC-1,1- or -1,n-ADEQUATE. Another benefit is that covariance processing methods offer the possibility of mathematically combining a higher sensitivity 2D NMR spectrum with for example 1,1- or 1,n-ADEQUATE to improve access to the information content of lower sensitivity congeners. The covariance spectrum also provides a significant enhancement in the F(1) digital resolution. The combination of HMBC and 1,1-ADEQUATE spectra is shown here using strychnine as a model compound to derive structural information inherent to an n,1-ADEQUATE spectrum with higher sensitivity and in a more convenient to interpret single quantum presentation.
Collapse
Affiliation(s)
- Gary E Martin
- Discovery and Preclinical Sciences-Process & Analytical Chemistry, Merck Research Laboratories, Summit, NJ 07901, USA.
| | | | | | | | | |
Collapse
|
11
|
Feng W, Hilton BD, Zhong W, Yang J, Yang X, Tong W, Martin GE. Characterization of an unusual ring-contraction degradant of the antifungal agent posaconazole. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:576-579. [PMID: 22715068 DOI: 10.1002/mrc.3835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/21/2012] [Accepted: 05/22/2012] [Indexed: 06/01/2023]
Abstract
Posaconazole, a clinically useful antifungal agent, has several known oxidative degradation products involving the piperazine ring near the center of the molecule. A novel degradant was recently isolated and characterized spectroscopically as a novel ring-contraction product incorporating a dihydroimidazolium moiety in lieu of the normally present piperazine ring.
Collapse
|