Synthesis and Characterization of a Diazirine-Based Photolabel of the Nonanesthetic Fropofol

Abstract

The mechanisms of general anesthetics have been debated in the literature for many years and continue to be of great interest. As anesthetic molecules are notoriously difficult to study due to their low binding affinities and multitude of binding partners, it is advantageous to have additional tools to study these interactions. Fropofol is a hydroxyl to fluorine-substituted propofol analogue that is able to antagonize the actions of propofol. Understanding fropofol’s ability to antagonize propofol would facilitate further characterization of the binding interactions of propofol that may contribute to its anesthetic actions. However, the study of fropofol’s molecular interactions has many of the same difficulties as its parent compound. Here, we present the synthesis and characterization of ortho-azi-fropofol (AziFo) as a suitable photoaffinity label (PAL) of fropofol that can be used to covalently label proteins of interest to characterize fropofol’s binding interactions and their contribution to general anesthetic antagonism.

Emerging Applications of Aryl Trifluoromethyl Diazoalkanes and Diazirines in Synthetic Transformations

“…The photochemical properties of diazirines made them particularly useful as photoaffinity labeling reagents in chemical biology. , Indeed, most trifluoromethyl diazirines are decomposed under a 360 nm light irradiation, where a vast range of bioactive molecules do not absorb. ,,,, The elucidation of protein functions from their structure/activity and the understanding of molecular mechanisms involved in protein–ligand binding is a major challenge in chemical and molecular biology and drug design. ,,,,,− An outstanding example highlighting the use of trifluoromethyl diazirines in chemical biology was disclosed by Fadeyi, Oslund, and MacMillan et al in microenvironment mapping on immune cells for a better understanding of their role and mode of action (Scheme ). Their method uses a biotinylated trifluoromethyl diazirine that will be further conjugated to the studied protein.…”

Time to Wake Up! The Ongoing Search for General Anesthetic Reversal Agents

“…Fropofol (also called propofluor; table 2) has substituted a fluorine for the hydroxyl group. 90 Unlike propofol, fropofol does not directly activate, modulate, or inhibit the GABA A receptor. Furthermore, fropofol antagonizes propofol-induced sedation (or “hypnosis”) in Xenopus laevis tadpoles 99 and zebrafish.…”

“…Furthermore, fropofol antagonizes propofol-induced sedation (or “hypnosis”) in Xenopus laevis tadpoles 99 and zebrafish. 90 While these behavioral results seem to make fropofol a promising reversal agent, other behavioral endpoints such as responsiveness to stimuli have not been investigated. Additionally, while fropofol lacks propofol’s anesthetic properties, it causes similar side effects such as depressing myocardial contractions 99 and at high doses appears to induce seizure-like behaviors in tadpoles (after 40 min of exposure with greater than 30 μM concentration) and in mice (delivered in bolus vein injection at a dose greater than 180 mg/kg).…”

Antagonism of propofol anesthesia by alkyl-fluorobenzene derivatives

“…For example, the molecule Fropofol (fluorinated propofol) 15 , (renamed propo fluor for improved phonological clarity), is one such molecule. Although propofluor is inactive as an anesthetic, it was found to antagonize propofol in tadpoles 15 and zebrafish 16 . This study examines alkyl variations of propofluor for anesthetic and antagonistic properties using a previously validated zebrafish behavioral model of anesthesia 17 , 18 .…”