Silicon Fluoride Acceptors (SiFAs) for Peptide and Protein Labeling with<sup>18</sup>F

Schirrmacher, Ralf; Kostikov, Alexey; Wängler, Carmen; Jurkschat, Klaus; Bernard‐Gauthier, Vadim; Schirrmacher, Esther; Wängler, Björn

doi:10.1002/9781118834114.ch16

Cited by 3 publications

(2 citation statements)

References 44 publications

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“…The high polarization of Si-F bond results in the kinetic instability of Si-F-bond [124] and allows an exchange under mild conditions. Due to the low energy of vacant d-orbitals tetravalent silicon as weak Lewis acid reacts with Lewis bases [125], which allows a nucleophilic attack by hydroxyl-groups in the case of aqueous conditions.…”

Section: Deuteration On Other Parts Of the Molecule To Avoid Degramentioning

confidence: 99%

Methods to Increase the Metabolic Stability of 18F-Radiotracers

2015

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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

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Section: Deuteration On Other Parts Of the Molecule To Avoid Degramentioning

confidence: 99%

Methods to Increase the Metabolic Stability of 18F-Radiotracers

2015

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“…In Schirrmacher's opinion 109 , "the muezzin, in making a verbal confession of faith, compels other people to participate in the exercise of another religion five times a day. As a result, this .…”

Section: An Analysis Of Competing Constitutional Rights To Religious Freedom and Property In The Context Of The Ellaurie Casementioning

confidence: 99%

How Loud Is Too Loud? Competing Rights to Religious Freedom and Property and the Muslim Call to Prayer (Adhan or Azan) in South Africa

Moosa

2021

Religions

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This article approaches the position of the call to prayer (adhan or azan) in South Africa from the perspective of both legislation and case law. Although only an unamplified adhan has religious status in Islam, Muslim religious authorities (ulama) have since the twentieth century also approved of, and permitted, an amplified adhan. The adhan has been rendered in both forms from South African mosques (masjids) for some 223 years. However, the unamplified adhan has recently come under the legal and judicial spotlight when the volume of its rendering by human voice was restricted. In August 2020, after prior attempts at municipal level and mediation had been unsuccessful, a high court in KwaZulu-Natal, South Africa, ruled that the sound of the unamplified adhan emanating from a mosque located on the premises of an Islamic institution (madrassa) in the city of Durban should not be audible within the house situated on nearby property belonging to a Hindu neighbor. Wide media coverage reported that the ruling was publicly decried and met with criticism. The Madrassa lodged an appeal in September 2020 and the matter is ongoing. The High Court’s decision is binding in KwaZulu-Natal, a province where Hindus, as a religious minority, are concentrated. The article highlights that although the decision is not binding on similar courts in other provinces, its outcome may yet have far-reaching consequences for the adhan as a religious and cultural heritage symbol, and for religious symbols generally, because similar complaints have been lodged, albeit against amplified adhans, against several mosques located in major cities (Cape Town and Tshwane) of two other provinces where Muslims, as a religious minority, are largely concentrated. The article examines the adhan in the context of competing constitutional rights to religious freedom and property (neighbor law) in South Africa. The article proffers some recommendations for the way forward in South Africa based in some instances on the position of the adhan in several countries. It concludes that, ultimately, unamplified, unduly amplified and duly amplified adhans may all yet be found to constitute a noise nuisance in South Africa, if challenged and found to be unreasonable.

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[¹⁸F]Ethenesulfonyl Fluoride as a Practical Radiofluoride Relay Reagent

Zhang

Fraser

Klenner

et al. 2019

Chemistry A European J

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Fluorine-18 is the most utilized radioisotope in positrone mission tomography (PET), but the wide application of fluorine-18 radiopharmaceuticals is hinderedb y its challenging labellingc onditions. As such, many potentially importantr adiotracers remainu nderutilized. Herein, we describe the use of [ 18 F]ethenesulfonyl fluoride(ESF) as an ovel radiofluorider elay reagent that allowsr adiofluorination reactions to be performedi nm inimally equipped satelliten uclear medicine centres. [ 18 F]ESFh as as imple and reliable production route andc an be stored on inert cartridges. The cartridges can then be shipped remotely and the trapped [ 18 F]ESF can be liberated by simple solvent elution. We have tested 18 radiolabellingprecursors, inclusive of model and clinically used structures, and most precursors have demonstratedc omparable radiofluorination efficienciest ot hose obtained using ac onventionally dried [ 18 F]fluoride source.Development of novel and efficient methods for incorporating fluorine-18r adioisotope into pharmaceutically relevant structures is of paramount importance forg uaranteeing aw ide access to positron emission tomography( PET) tracers. [1,2] The traditional approach of nucleophilic substitution uses dried [ 18 F]fluoride and can only be performedi nf ew centresw ith the appropriate level of equipment and expertise (e.g.,c yclotron, synthesizersa nd bulky hot cells). [3] On the other hand, in most nuclear medicine departments where 99m Tc is used, "shake&b ake" labelling reactions are performed using minimal equipment, [4] thus providing access to aw ide array of 99m Tc radiotracers. [5] Similar protocols can also be applied to other radiometal labellingt echniques (e.g., 68 Ga, 64 Cu), but such simplicity has not yet been achievedf or C-18 Fl abelling. [6][7][8] To achieves uch an important target, we focusedo nf luoride relay reagents, [9] where reactive fluorides peciesc an be releasedf ollowing simple chemical or physical interaction. This interesting concept was reported recently by Pees, et al. [10] using [ 18 F]triflyl fluoride, and previously by DeGrado's group [11] using [ 18 F]acetyl fluoride. Both reagents were produced as gases and used immediately in their respective radiofluorination reactions. DeGrado's group also reportedt he feasibility of trapping [ 18 F]acetyl fluoride in ac artridge but limitedi nformation was given and the reactions cope was relatively narrow. While these approaches may potentially represent simpler ways to activate [ 18 F]fluoride (i.e.,i nstead of azeotropic drying), it is unclear whethers uch reagents could be shipped conveniently foroff-site use on aw ider range of precursors.Thereafter,[ 18 F]ethenesulfonyl fluoride( ESF)s tartedt oa ttract our attention. [ 18 F]ESF containings tructures were recently reported to release [ 18 F]fluoride and therefore were not useful as PET tracers. However,E SF is liquid at room temperature, and has facile synthesis, simple purification and the feasibility to be trapped in acartridge. [12] Therefore, [ 18 F]ESF migh...

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Silicon Fluoride Acceptors (SiFAs) for Peptide and Protein Labeling with¹⁸F

Cited by 3 publications

References 44 publications

Methods to Increase the Metabolic Stability of 18F-Radiotracers

Methods to Increase the Metabolic Stability of 18F-Radiotracers

How Loud Is Too Loud? Competing Rights to Religious Freedom and Property and the Muslim Call to Prayer (Adhan or Azan) in South Africa

[¹⁸F]Ethenesulfonyl Fluoride as a Practical Radiofluoride Relay Reagent

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Silicon Fluoride Acceptors (SiFAs) for Peptide and Protein Labeling with18F

Cited by 3 publications

References 44 publications

Methods to Increase the Metabolic Stability of 18F-Radiotracers

Methods to Increase the Metabolic Stability of 18F-Radiotracers

How Loud Is Too Loud? Competing Rights to Religious Freedom and Property and the Muslim Call to Prayer (Adhan or Azan) in South Africa

[18F]Ethenesulfonyl Fluoride as a Practical Radiofluoride Relay Reagent

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Silicon Fluoride Acceptors (SiFAs) for Peptide and Protein Labeling with¹⁸F

[¹⁸F]Ethenesulfonyl Fluoride as a Practical Radiofluoride Relay Reagent