1
|
Jin B, Liu H, Che S, Gao J, Yu Y, Liu J, Men Y. Substantial defluorination of polychlorofluorocarboxylic acids triggered by anaerobic microbial hydrolytic dechlorination. NATURE WATER 2023; 1:451-461. [PMID: 38405335 PMCID: PMC10888525 DOI: 10.1038/s44221-023-00077-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 04/04/2023] [Indexed: 02/27/2024]
Abstract
Chlorinated polyfluorocarboxylic acids (Cl-PFCAs) derived from the widely used chlorotrifluoroethylene (CTFE) polymers and oligomers may enter and influence the aquatic environment. Here, we report significant defluorination of Cl-PFCAs by an anaerobic microbial community via novel pathways triggered by anaerobic microbial dechlorination. Cl-PFCAs first underwent microbial reductive, hydrolytic, and eliminative dechlorination, and it was the hydrolytic dechlorination that led to significant spontaneous defluorination. Hydrolytic dechlorination was favored with increased Cl-substitutions. An isolated, highly enriched anaerobic defluorinating culture was dominated by two genomes closest to Desulfovibrio aminophilus and Sporomusa sphaeroides, both of which exhibited active defluorination of CTFE tetramer acid. It implies the critical role played by anaerobic non-respiratory hydrolytic dechlorination in the fate of chlorinated polyfluoro-chemicals in natural and engineered water environments. The greatly enhanced biodegradability by Cl-substitutions also sheds light on the design of cost-effective treatment biotechnologies, as well as alternative PFAS that are readily biodegradable and less toxic.
Collapse
Affiliation(s)
- Bosen Jin
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
| | - Huaqing Liu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
| | - Shun Che
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, United States
| | - Jinyu Gao
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
| | - Yaochun Yu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, United States
| | - Jinyong Liu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
| | - Yujie Men
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, United States
| |
Collapse
|
2
|
Lemm S, Köhler S, Wodtke R, Jung F, Küpper JH, Pietzsch J, Laube M. Investigation of Radiotracer Metabolic Stability In Vitro with CYP-Overexpressing Hepatoma Cell Lines. Cells 2022; 11:cells11152447. [PMID: 35954291 PMCID: PMC9368227 DOI: 10.3390/cells11152447] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/22/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
The characterization of novel radiotracers toward their metabolic stability is an essential part of their development. While in vitro methods such as liver microsome assays or ex vivo blood or tissue samples provide information on overall stability, little or no information is obtained on cytochrome P450 (CYP) enzyme and isoform-specific contribution to the metabolic fate of individual radiotracers. Herein, we investigated recently established CYP-overexpressing hepatoblastoma cell lines (HepG2) for their suitability to study the metabolic stability of radiotracers in general and to gain insight into CYP isoform specificity. Wildtype HepG2 and CYP1A2-, CYP2C19-, and CYP3A4-overexpressing HepG2 cells were incubated with radiotracers, and metabolic turnover was analyzed. The optimized protocol, covering cell seeding in 96-well plates and analysis of supernatant by radio thin-layer-chromatography for higher throughput, was transferred to the evaluation of three 18F-labeled celecoxib-derived cyclooxygenase-2 inhibitors (coxibs). These investigations revealed time-dependent degradation of the intact radiotracers, as well as CYP isoform- and substrate-specific differences in their metabolic profiles. HepG2 CYP2C19 proved to be the cell line showing the highest metabolic turnover for each radiotracer studied here. Comparison with human and murine liver microsome assays showed good agreement with the human metabolite profile obtained by the HepG2 cell lines. Therefore, CYP-overexpressing HepG2 cells provide a good complement for assessing the metabolic stability of radiotracers and allow the analysis of the CYP isoform-specific contribution to the overall radiotracer metabolism.
Collapse
Affiliation(s)
- Sandy Lemm
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstrasse 4, 01062 Dresden, Germany
| | - Susanne Köhler
- Institute of Biotechnology, Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz 1, 01968 Senftenberg, Germany
| | - Robert Wodtke
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - Friedrich Jung
- Institute of Biotechnology, Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz 1, 01968 Senftenberg, Germany
| | - Jan-Heiner Küpper
- Institute of Biotechnology, Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz 1, 01968 Senftenberg, Germany
| | - Jens Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstrasse 4, 01062 Dresden, Germany
| | - Markus Laube
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Correspondence:
| |
Collapse
|
3
|
Otaru S, Niemikoski H, Sarparanta M, Airaksinen AJ. Metabolism of a Bioorthogonal PET Tracer Candidate [ 19F/ 18F]SiFA-Tetrazine in Mouse Liver Microsomes: Biotransformation Pathways and Defluorination Investigated by UHPLC-HRMS. Mol Pharm 2020; 17:3106-3115. [PMID: 32539414 PMCID: PMC7497667 DOI: 10.1021/acs.molpharmaceut.0c00523] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Organofluorosilicon based 18F-radiolabeling is an efficient
method for incorporating fluorine-18 into 18F-radiopharmaceuticals
for positron emission tomography (PET) by 19F/18F isotopic exchange (IE). The first PET radiopharmaceutical, 18F-SiFAlin-TATE, radiolabeled with a silicon-based
[18F]fluoride acceptor (SiFA), namely, a para-substituted
di-tert-butyl[18F]fluorosilylbenzene,
has entered clinical trials, and is paving the way for other potential
[18F]SiFA-labeled radiopharmaceuticals for diagnostic use.
In this study, we report the in vitro metabolism
of an oxime-linked SiFA tetrazine (SiFA–Tz), a new PET-radiotracer
candidate, recently evaluated for pretargeted PET imaging and macromolecule
labeling. Metabolism of SiFA–Tz was studied in mouse liver
microsomes (MLM) for elucidating its major biotransformation pathways.
Nontargeted screening by ultrahigh performance liquid chromatography
high-resolution mass spectrometry (UHPLC-HRMS) was utilized for detection
of unknown metabolites. The oxime bond between the SiFA and Tz groups
forms two geometric (E/Z) isomers,
which underwent the same biotransformations, but unexpectedly with
different kinetics. In total, nine proposed metabolites of SiFA–Tz
from phase I and II reactions were detected, five of which were defluorinated
in MLMs, elucidating the metabolic pathway leading to previously reported
defluorination of [18F]SiFA–Tz in vivo. Based on the HRMS studies a biotransformation pathway is proposed:
hydroxylation (+O) to tert-butyl group adjacent to
the silicon, followed by oxidative defluorination (+OH/-F) cleaving
the fluorine off the silicon. Interestingly, eight proposed metabolites
of a reduced dihydrotetrazine analogue, SiFA–H2Tz,
from phase I and II reactions were additionally detected. To the best
of our knowledge, this is the first reported comprehensive investigation
of enzyme mediated metabolic pathway of tetrazines and para-substituted
di-tert-butylfluorosilylbenzene fluoride acceptors,
providing novel structural information on the biotransformation and
fragmentation patterns of radiotracers bearing these structural motifs.
By investigating the metabolism preceding defluorination, structurally
optimized new SiFA compounds can be designed for expanding the portfolio
of efficient 19F/18F isotopic exchange labeling
probes for PET imaging.
Collapse
Affiliation(s)
- Sofia Otaru
- Radiochemistry, Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland
| | - Hanna Niemikoski
- Finnish Institute for Verification of the Chemical Weapons Convention (VERIFIN), Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland
| | - Mirkka Sarparanta
- Radiochemistry, Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland
| | - Anu J Airaksinen
- Radiochemistry, Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland.,Turku PET Centre, Department of Chemistry, University of Turku, 20500 Turku, Finland
| |
Collapse
|
4
|
Synthesis and basic evaluation of 7α-(3-[ 18F]fluoropropyl)-testosterone and 7α-(3-[ 18F]fluoropropyl)-dihydrotestosterone. Ann Nucl Med 2016; 31:53-62. [PMID: 27680022 DOI: 10.1007/s12149-016-1130-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Accepted: 09/23/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVE 7α-Substituted androgen derivatives may have the potential to visualize androgen receptors with positron emission tomography. In the present study, we synthesized fluoropropyl derivatives of 7α-(3-[18F]fluoropropyl)-testosterone ([18F]7) and 7α-(3-[18F]fluoropropyl)-dihydrotestosterone ([18F]15), and characterized their in vitro binding, in vivo biodistribution, and performed blocking studies in mature androgen deprived male rats. METHODS We synthesized [18F]7 and [18F]15. In vitro binding to recombinant rat AR ligand binding domain protein was determined using a competitive radiometric ligand-binding assay with the high-affinity synthetic androgen [17α-methyl-3H]-methyltrienolone ([3H]R1881). In vivo biodistribution was performed in mature male rats treated with diethylstilbestrol (chemical castration). A blocking study was performed by co-administration of dihydrotestosterone (36 µg/animal). RESULTS 7α-(3-Fluoropropyl)-testosterone (7) and 7α-(3-fluoropropyl)-dihydrotestosterone (15) showed competitive binding to recombinant rat AR ligand binding domain protein. The IC50 value of 15 (13.0 ± 3.3 nM) was higher than 7 (47.8 ± 10.0 nM). In contrast to the AR binding affinity, the ventral prostate uptake of [18F]7 and [18F]15 at 2 h post-injection was similar (0.07 % injected dose/g of tissue). A blocking study indicated that specific binding of [18F]15 is observed in the ventral prostate. [18F]7 and [18F]15 showed moderate levels of bone uptake, which indicates moderate metabolic de-fluorination in rodents. CONCLUSION [18F]15 is better than [18F]7 in terms of radiochemical yield, in vitro binding affinity, prostate specific binding and stability against in vivo metabolic de-fluorination. However, the net uptake level of [18F]15 in prostate might be insufficient for in vivo visualization. Although [18F]7 and [18F]15 improved in vivo stability against de-fluorination, other basic characterization data in rodents were not superior to the current standard tracer 16β-[18F]fluoro-5α-dihydrotestosterone. It is also revealed that the shorter side chain length of 7α-[18F]fluoromethyl-dihydrotestosterone is superior to the longer three carbon chain in [18F]15, in terms of net prostate uptake and in vivo metabolic stability.
Collapse
|
5
|
Methods to Increase the Metabolic Stability of (18)F-Radiotracers. Molecules 2015; 20:16186-220. [PMID: 26404227 PMCID: PMC6332123 DOI: 10.3390/molecules200916186] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/20/2015] [Accepted: 08/26/2015] [Indexed: 11/17/2022] Open
Abstract
The majority of pharmaceuticals and other organic compounds incorporating radiotracers that are considered foreign to the body undergo metabolic changes in vivo. Metabolic degradation of these drugs is commonly caused by a system of enzymes of low substrate specificity requirement, which is present mainly in the liver, but drug metabolism may also take place in the kidneys or other organs. Thus, radiotracers and all other pharmaceuticals are faced with enormous challenges to maintain their stability in vivo highlighting the importance of their structure. Often in practice, such biologically active molecules exhibit these properties in vitro, but fail during in vivo studies due to obtaining an increased metabolism within minutes. Many pharmacologically and biologically interesting compounds never see application due to their lack of stability. One of the most important issues of radiotracers development based on fluorine-18 is the stability in vitro and in vivo. Sometimes, the metabolism of 18F-radiotracers goes along with the cleavage of the C-F bond and with the rejection of [18F]fluoride mostly combined with high background and accumulation in the skeleton. This review deals with the impact of radiodefluorination and with approaches to stabilize the C-F bond to avoid the cleavage between fluorine and carbon.
Collapse
|
6
|
Rydberg P. Reactivity‐Based Approaches and Machine Learning Methods for Predicting the Sites of Cytochrome P450‐Mediated Metabolism. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/9783527673261.ch11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
7
|
Yamazoe Y, Ito K, Yoshinari K. Construction of a CYP2E1-template system for prediction of the metabolism on both site and preference order. Drug Metab Rev 2012; 43:409-39. [PMID: 22017508 DOI: 10.3109/03602532.2011.624103] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We have constructed an in silico system for the prediction of CYP2E1-mediated reaction using a two-dimensional template derived from substrate structures. Although CYP2E1 prefers small-size molecules for the substrates, the enzyme mediates oxidations of large-size molecules, such as benzo[a]pyrene. Overlays of these substrates, to assemble their sites of oxidation into a specific area, suggested a range of regions frequently occupied. The region, having a benzo[a]pyrene-like shape, was thus used as a CYP2E1 template. In this system, atoms in substrates, except for hydrogen atoms, were placed on corners of honeycomb structures of the template after having expanded the structures. Using published data for the metabolism on more than 80 substrates of CYP2E1, the core template was further refined to verify the adjacent area and to define the relative contribution of template positions for the catalysis. The positions on the template were classified into four different point (0-3) groups, depending on relative usage. In addition, we set independent points (-5 to 3) for specific positions to incorporate three-dimensional or functional information. Total scores from both position-occupancy and -function points were calculated for all the orientations of possible conformers of test substrates, and the scores were found to predict the relative abundance (i.e., order) as well as the regioselectivity of human CYP2E1 reactions with high fidelities.
Collapse
Affiliation(s)
- Yasushi Yamazoe
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University , Sendai , Japan
| | | | | |
Collapse
|
8
|
Jones JP, Joswig-Jones CA, Hebner M, Chu Y, Koop DR. The effects of nitrogen-heme-iron coordination on substrate affinities for cytochrome P450 2E1. Chem Biol Interact 2011; 193:50-6. [PMID: 21600194 DOI: 10.1016/j.cbi.2011.05.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 05/02/2011] [Accepted: 05/03/2011] [Indexed: 11/29/2022]
Abstract
A descriptor based computational model was developed for cytochrome P450 2E1 (CYP2E1) based on inhibition constants determined for inhibition of chlorzoxazone, or 4-nitrophenol, metabolism. An empirical descriptor for type II binding was developed and tested for a series of CYP2E1 inhibitors. Inhibition constants where measured for 51 different compounds. A fast 2-dimensional predictive model was developed based on 40 compounds, and tested on 8 compounds of diverse structure. The trained model (n=40) had an r(2) value of 0.76 and an RMSE of 0.48. The correlation between the predicted and actual pK(i) values of the test set of compounds not included in the model gives an r(2) value of 0.78. The features that described binding include heme coordination (type II binding), molecular volume, octanol/water partition coefficient, solvent accessible surface area, and the sum of the atomic polarizabilities. The heme coordination parameter assigns an integer between 0 and 6 depending on structure, and is a new descriptor, based on simple quantum chemical calculations with correction for steric effects. The type II binding parameter was found to be important in obtaining a good correlation between predicted and experimental inhibition constants increasing the r(2) value from 0.38 to 0.77.
Collapse
Affiliation(s)
- Jeffrey P Jones
- Department of Chemistry, Washington State University, Pullman, WA 99164-4630, USA.
| | | | | | | | | |
Collapse
|
9
|
White IN, Razvi N, Gibbs AH, Davies AM, Manno M, Zaccaro C, De Matteis F, Pähler A, Dekant W. Neoantigen formation and clastogenic action of HCFC-123 and perchloroethylene in human MCL-5 cells. Toxicol Lett 2001; 124:129-38. [PMID: 11684365 DOI: 10.1016/s0378-4274(00)00281-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, the metabolic activation of 2,2-dichloro-1,1,1-trifluoroethane (hydrochlorofluorocarbons-123, HCFC-123), halothane or 1,1-dichloro-1-fluoroethane (HCFC-141b) was compared to that of perchloroethylene, using lymphoblastoma derived cell lines expressing human CYP1A1, CYP1A2, CYP2E1, CYP2A6 and CYP3A4 (MCL-5 cells). A dose dependent increase in micronucleus formation was detected over a nominal concentration range of 0.05-2 mM for HCFC-123 and halothane, but this was not seen with HCFC-141b. No dose response for HCFC-123 was seen in a control cHo1 cell line not expressing this cytochrome P450's. Cell lines expressing individual human cytochrome P-450 (CYP) forms were also used to define the enzymes responsible for the clastogenic events and to investigate the formation of immunoreactive protein by microsomal fractions. It was shown that CYP2E1 or CYP2B6 catalysed the clastogenic response, but CYP2D6, CYP3A4, CYP1A2 or CYP1A1 all appeared to be inactive. The formation of neoantigenic trifluoroacetylated protein adducts by microsomal mixtures incubated with HCFC-123 and NADPH was catalysed primarily by CYP2E1 and to a lesser extent by CYP2C19, whereas, only trace levels of immunoreactive protein were seen with microsomes expressing CYP2B6 or CYP2C8. With perchloroethylene as a substrate, the extent of activation was low in comparison with HCFC-123, as judged by the absence of micronuclei formation in the MCL-5 cell line and the weak immunoreactivity of proteins following Western blotting. CYP1A2, CYP2B6 and CYP2C8 appeared to be responsible for perchloroethylene immunoreactivity and in contrast to the findings with the HCFC's, no activation of perchloroethylene by CYP2E1 could be detected. These results show that even though both saturated and unsaturated halocarbons can result in neoantigen formation, there is a marked difference in the specificity of the CYP enzymes involved in their metabolic activation.
Collapse
Affiliation(s)
- I N White
- MRC Toxicology Unit, Hodgkin Building, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK.
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Abstract
Cytochrome (CYP) P450 2E1 is clinically and toxicologically important and it is constitutively expressed in the liver and many other tissues. In contrast to many other CYP isoenzymes, indisputable evidence for a functionally important polymorphism of CYP2E1 in the human population is lacking. CYP2E1 metabolizes a wide variety of chemicals with different structures, in particular small and hydrophobic compounds, including potential cytotoxic and carcinogenic agents. In addition, chlorzoxazone and trimethadione metabolism are good CYP2E1 probes for liver disease in vivo and in vitro. In the future, methods for fully analysing the function of CYP2E1 using knockout mice will be established. This article reviews recent advances in our understanding of the role of human CYP2E1 in drug metabolism.
Collapse
Affiliation(s)
- E Tanaka
- Institute of Community Medicine, University of Tsukuba, Ibaraki-ken 305-8575, Japan.
| | | | | |
Collapse
|
11
|
Magata Y, Lang L, Kiesewetter DO, Jagoda EM, Channing MA, Eckelman WC. Biologically stable [(18)F]-labeled benzylfluoride derivatives. Nucl Med Biol 2000; 27:163-8. [PMID: 10773545 DOI: 10.1016/s0969-8051(99)00108-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Use of the [(18)F]-fluoromethyl phenyl group is an attractive alternative to direct fluorination of phenyl groups because the fluorination of the methyl group takes place under milder reaction conditions. However, we have found that 4-FMeBWAY showed femur uptake equal to that of fluoride up to 30 min in rat whereas 4-FMeQNB had a significantly lower percent injected dose per gram in femur up to 120 min. For these and other benzylfluoride derivatives, there was no clear in vivo structure-defluorination relationship. Because benzylchlorides (BzCls) are known alkylating agents, benzylfluorides may be alkylating agents as well, which may be the mechanism of defluorination. On this basis, the effects of substitution on chemical stability were evaluated by the 4-(4-nitro-benzyl)-pyridine (NBP) test, which is used to estimate alkylating activity with NBP. The effect of substitution on the alkylating activity was evaluated for nine BzCl derivatives: BzCl; 3- or 4-methoxy (electron donation) substituted BzCl; 2-, 3-, or 4-nitro (electron withdrawing) substituted BzCl; and 2-, 3-, or 4-chloro (electron withdrawing) substituted BzCl. Taken together, the alkylating reactivity of 3-chloro-BzCl was the weakest. This result was then applied to [(18)F]-benzylfluoride derivatives and in vivo and in vitro stability were evaluated. Consequently, 3-chloro-[(18)F]-benzylfluoride showed a 70-80% decrease of defluorination in both experiments in comparison with [(18)F]-benzylfluoride, as expected. Moreover, a good linear relationship between in vivo femur uptake and in vitro hepatocyte metabolism was observed with seven (18)F-labeled radiopharmaceuticals, which were benzylfluorides, alkylfluorides, and arylfluorides. Apparently, the [(18)F]-fluoride ion is released by metabolism in the liver in vivo. In conclusion, 3-chloro substituted BzCls are the most stable, which suggests that 3-chloro benzylfluorides will be the most chemically stable compound. This result should be important in future design of radioligands labeled with a benzylfluoride moiety.
Collapse
Affiliation(s)
- Y Magata
- PET Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland, USA.
| | | | | | | | | | | |
Collapse
|
12
|
Determination of Monochloroacetic Acid and Dichloroacetic Acid for Quality Control of Acetic Acid Chlorination Industry by Ion Chromatography. Microchem J 1999. [DOI: 10.1006/mchj.1999.1759] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|