title: Synthesis of sulfonamide- and sulfonyl-phenylboronic acid-modified silica phases for boronate affinity chromatography at physiological pH.
abstract: Two new types of boronate affinity solid phases were synthesized and characterized. The materials were prepared by silylation of porous silica gel with monochlorosilane derivatives containing synthetic sulfonyl- and sulfonamide-substituted phenylboronic acids. The new solid phases were evaluated for boronate affinity chromatography with aryl and alkyl cis-diol compounds and were found to be suitable for the retention of cis-diols under acidic conditions. Significant correlations between the retention factor (K) and the pH of the mobile phase demonstrate that the binding of cis-diols to the solid phases is best rationalized by chelation. Based on the lower pKa, caused by the electron-withdrawing effects of the sulfonyl and sulfonamide groups, these media display an enhanced affinity for cis-diols as compared with unsubstituted phenylboronic acid. Using isocratic elution, a mixture of various biologically relevant l-tyrosines, l-DOPA, and several catecholamines were resolved with a mobile phase composed of 0.05M phosphate buffer (pH 5.5). Mono-, di-, and triphosphates of adenosine were also separated at pH 6.0. Hence, the new boronate solid phase offers efficient affinity separation and purification of cis-diol-containing molecules under rather mild pH conditions.
authors.affiliation: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66047, USA.
authors.forename: Xiaobao
authors.initials: X
authors.lastname: Li
authors.forename: Justin
authors.initials: J
authors.lastname: Pennington
authors.forename: John F
authors.initials: JF
authors.lastname: Stobaugh
authors.forename: Christian
authors.initials: C
authors.lastname: Schöneich
mesh_terms: D001897:Boronic Acids / Q000494:pharmacology; D002395:Catecholamines / Q000302:isolation & purification*; D002846:Chromatography, Affinity / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid / Q000379:methods; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007980:Levodopa / Q000302:isolation & purification*; D012822:Silicon Dioxide; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D001897:Boronic Acids; D002395:Catecholamines; D013449:Sulfonamides; D007980:Levodopa; D012822:Silicon Dioxide; C010686:benzeneboronic acid