Synthesis and Structure−Activity Relationships of Chiral Allosteric Modifiers of Hemoglobin

Abstract

A series of allosteric effectors of hemoglobin, 2-(aryloxy)-2-alkanoic acids, was prepared to investigate the effect of the stereocenter on allosteric activity. The chiral analogues were based on the lead compound, RSR13 (3b), with different alkyl/alkanoic and cycloalkyl/cycloalkanoic groups positioned at the acidic chiral center. Of the 23 racemic molecules synthesized, 5 were selected for resolution based on structure-activity relationships. One chiral analogue, (-)-(1R,2R)-1-[4-[[(3, 5-dimethylanilino)carbonyl]methyl]phenoxy]-2-methylcyclopentane carbox ylic acid (11), exhibited greater in vitro activity in hemoglobin solutions than its antipode, racemate, and RSR13. Compound (-)-(1R, 2R)-11 was equipotent with RSR13 in whole blood, is a candidate for in vivo animal studies, and if efficacious and safe has a potential for use in humans. In general, it was found that chirality affects allosteric effector activity with measurable differences observed between enantiomers and the racemates.

Design, Synthesis, and Investigation of Novel Nitric Oxide (NO)-Releasing Prodrugs as Drug Candidates for the Treatment of Ischemic Disorders: Insights into NO-Releasing Prodrug Biotransformation and Hemoglobin–NO Biochemistry

“…This observation is in contrast to our previous structural study of deoxyHb in complex with RSR13 (1:5 molar ratio) that showed very strong RSR13 electron density 5 . Notably, other analogs of RSR13 that have amino acid substitution at the carboxylate are also characterized by weak density and/or significantly less allosteric potency than RSR13 65,66 . As will be discussed later, UPLC-MS analysis of the crystallization solution showed DD-1 to predominate the mixture, which is at least 3-fold excess over RSR13 and RSR13-CH 2 CH 2 OH combined, suggesting that the binding site may have a weaker affinity for DD-1, and thus explaining the weak presence of the effector in the structure.…”

Mass spectrometric characterization of efaproxiral (RSR13) and its implementation into doping controls using liquid chromatography–atmospheric pressure ionization‐tandem mass spectrometry

“…Purity was greater 90% as measured by means of LC–MS, and overall yields ranged from 31 to 42% of the theoretical values. Owing to detailed studies on the principal synthesis and series of products resulting from the employed approach,6, 8 structure confirmations using conventional strategies such as NMR or IR were not performed, and the determination of elemental compositions using high‐resolution/high‐accurate mass analyses was considered sufficient.…”

“…The synthesis of efaproxiral and structural analogs was accomplished according to established procedures described elsewhere 6, 8. Briefly, 4‐hydroxyphenylacetic acid (2.6 g, 17 mmol) was converted into the corresponding acetyl chloride by reflux in 10 ml of thionyl chloride for 30 min.…”

“…in case of myocardial ischemia or treatment of tumors, and may be accomplished by an artificial reduction of the oxygen affinity of hemoglobin 4, 5. For these purposes, numerous synthetic analogs of 2,3‐DPG have been developed in the past 6–8. The drug efaproxiral (2‐[4‐[[(3,5‐dimethylanilino)carbonyl]methyl]phenoxyl]‐2‐methylpropionic acid, formerly referred to as RSR13, Scheme , 1 ) is a typical representative of the class of synthetic allosteric modifiers of Hb and has demonstrated promising results in clinical trials 4…”

RSR13 e modificação alostérica da afinidade hemoglobina-oxigênio: abuso entre atletas

“…xi]-2-metilpropiônico, cujo nome genérico é efaproxiral ou simplesmente RSR13, é um composto sintético (Allos Therapeutics, Denver, CO, EUA), análogo da droga clofibrato e modificador alostético da Hb, com a qual se liga de forma não-covalente através de pontes de hidrogênio e interações hidrofóbicas com três das quatro subunidades, diminuindo sua afinidade pelo O 2 [3][4][5] . Assim sendo, o RSR13 não altera a massa de hemácias, mas interfere na função da Hb, desviando para a direita a curva de dissociação da oxi-hemoglobina (HbO 2 ) de forma dose-dependente 6,7 .…”