The Analysis of Boron in Dextran-Sulfhydrylborane Conjugates

Abstract

In the present study the sodium salt of sulfhydrylborane (BSH) was covalently linked to dextran derivatives. This reaction was accomplished in two ways, activation of dextran with 1-cyano-4-dimethylaminopyridine (1) with subsequent reaction with 2-aminoethylpyridyldisulphide which underwent a disulphide exchange reaction with BSH. In the second way, dextran was allylated to a multiallyl derivative which in good yield reacted with BSH in a free radical initiated addition reaction (2). For the assessment of boron content of the derivatives elemental analysis of sulphur (3) was compared with Inductive Coupled Plasma Mass Spectrometry, ICP-MS of boron (4), the reference method in the analysis of the boron dextran derivatives. This was done under the assumption that the ratio of sulphur to boron would be constant during all the synthesis steps. The study was carried out to investigate a possibility to simplify the analysis of boron and for other clinical purposes. Our immediate interest in boronated dextran is its practical use for the treatment of arteriovenous malformations by BNCT in line with the ideas of Larsson (5) and Hatanaka (6).