Site-selective radiolabeling of peptides by 18F-fluorobenzoylation with [18F]SFB in solution and on solid phase: a comparative study (original) (raw)
Related papers
2000
First and foremost I would like to express my sincere gratitude to my supervisor during the project Dr. Ole Kristian Hjelstuen for giving me the opportunity to explore the exiting field of PET, and for his support and critical review of my work. I am also very thankful to all scientists and staff at Discovery Research, GE Healthcare, Oslo for all help and assistance and nice lunches during these years. In particular, thanks to Joseph M. Arukwe, my organic chemistry mentor, for his good advice, positive attitude and his numerous contributions and always having his office door open for me and my never ending questions.
Nature Protocols, 2012
Here we present a procedure to label peptides with the positron-emitting radioisotope fluorine-18 ( 18 F) using the silicon-fluoride acceptor (siFa) labeling methodology. positron emission tomography (pet) has gained high importance in noninvasive imaging of various diseases over the past decades, and thus new specific imaging probes for pet imaging, especially those labeled with 18 F, because of the advantageous properties of this nuclide, are highly sought after. N-terminally siFa-modified peptides can be labeled with 18 F − in one step at room temperature (20-25 °c) or below without forming side products, thereby producing satisfactory radiochemical yields of 46 ± 1.5% (n = 10). the degree of chemoselectivity of the 18 F-introduction, which is based on simple isotopic exchange, allows for a facile cartridge-based purification fully devoid of Hplc implementation, thereby yielding peptides with specific activities between 44.4 and 62.9 GBq mmol − 1 (1,200-1,700 ci mmol − 1 ) within 25 min.
Using 5-deoxy-5-[18F]fluororibose to glycosylate peptides for positron emission tomography
Nature Protocols, 2013
so far seven peptide-based 18 F-radiopharmaceuticals for diagnostic applications with positron emission tomography (pet) have entered into clinical trials. three candidates out of these seven are glycosylated peptides, which may be explained by the beneficial influence of glycosylation on in vivo pharmacokinetics of peptide tracers. this protocol describes the method for labeling peptides with 5-deoxy-5-[ 18 F]fluororibose ([ 18 F]FDr) as a prosthetic group. the synthesis of [ 18 F]FDr is effected by a nucleophilic fluorination step by using dried Kryptofix 2.2.2-K 2 co 3 -K 18 F complex and a subsequent Hcl-catalyzed hydrolysis. the conjugation of [ 18 F]FDr to the n-terminus aminooxy (-onH 2 )-functionalized peptides is carried out in anilinium buffer at pH 4.6 and at room temperature (rt, 21-23 °c), with the concentration of peptide precursors being 0.3 mM. the procedure takes about 120 min and includes two cartridge isolation steps and two reversed-phase (rp) Hplc purification steps. the quaternary methyl amine (QMa) anion exchange cartridge and the hydrophilic-lipophilic balanced (HlB) cartridge are used for the isolation of 18 F-fluoride and [ 18 F]FDr-conjugated peptides, respectively. the first Hplc purification provides the 18 F-fluorinated precursor of [ 18 F]FDr and the second Hplc purification is to separate labeled peptides from their unlabeled precursors. the final product is formulated in pBs ready for injection, with a radiochemical purity of >98% and a radiochemical yield (rcY) of 27-37% starting from the end of bombardment (eoB). the carbohydrate nature of [ 18 F]FDr and the operational convenience of this protocol should facilitate its general use. protocol nature protocols | VOL.9 NO.1 | 2014 | 139 protocol nature protocols | VOL.9 NO.1 | 2014 | 141
Bioconjugate Chemistry, 2004
18 F]Fluorothiols are a new generation of peptide labeling reagents. This article describes the preparation of suitable methanesulfonyl precursors and their use in no-carrier-added radiosyntheses of 18 F-fluorothiols. The preparations of (3-[ 18 F]fluoropropylsulfanyl)triphenylmethane, (2-{2-[2-(2-[ 18 F]fluoroethoxy)ethoxy]ethoxy}ethylsulfanyl)triphenylmethane, and 4-[ 18 F]fluoromethyl-N-[2-triphenylmethanesulfanyl)ethyl]benzamide starting from the corresponding methanesulfonyl precursors were investigated. Following the removal of the triphenylmethane protecting group, the 18 F-fluorothiols were reacted with the N-terminal chloroacetylated model peptide ClCH 2 C(O)-LysGlyPheGlyLys. The corresponding radiochemical yields of 18 F-labeled isolated model peptide, decay-corrected to 18 F fluoride, were 10%, 32%, and 1%, respectively. These results indicate a considerable potential of 18 F-fluorothiols for the chemoselective labeling of peptides as tracers for positron emission tomography (PET).
Rapid solid phase synthesis and biodistribution of 18F-labelled linear peptides
European Journal of Nuclear Medicine and Molecular Imaging, 2002
A rapid method for radiolabelling short peptides with 18 F (t 1/2 =109.7 min) for use in positron emission tomography (PET) was developed. Linear peptides (13mers) were synthesised using solid phase peptide synthesis and 9-fluorenylmethoxycarbonyl (Fmoc) chemistry. The peptides were assembled on a solid-phase polyethylene glycol-polystyrene support using the "hyper acid labile" linker xanthen-2-oxyvaleric acid and were labelled in situ with 4-[ 19 F]-or 4-[ 18 F]fluorobenzoic acid. Optimum coupling of 4-[ 19 F]fluorobenzoic acid to the peptidyl resin was achieved within 2 min using N-[(dimethylamino)-1H-1,2,3-triazolo[4,5-b]pyridin-1-ylmethylene]-Nmethylmethanaminium hexafluorophosphate N-oxide (HATU/DIPEA), and optimum cleavage was achieved within 7 min using trifluoroacetic acid/phenol/water/Triisopropylsilane at 37°C. The linear peptides were rapidly labelled with 4-[ 18 F]fluorobenzoic acid with an overall radiochemical yield of 80%-90% (decay corrected), a radiochemical purity of >95% without HPLC purification and an overall synthesis time of 20 min. This novel method was used to label peptides containing the arginine-glycine-aspartic acid (RGD) motif, the binding site of many integrins. In vitro studies showed that the fluorobenzoyl prosthetic group had no deleterious effect on the ability of these peptides to inhibit the binding of human cells via integrins. Biodistribution studies in tumour-bearing mice showed that although the linear peptides were rapidly removed from the circulation by the liver and kidneys, there was a transient and non-RGD-dependent accumulation in the tumour of both the test and the control peptides. The use of more selective peptides with a longer half-life in the circulation combined with this rapid labelling technique will significantly enhance the application of peptides in PET.