Towards the synthesis of biotinylated boron compounds and 1, 3, 2 benzodiazaboroles derivatives and their application as potential BNCT delivery agents.
In this study, boron neutrons capture therapy (BNCT) principles which have been reported as the best treatment of glioblastoma multiforme tumors thus far were explored. The aim of this study was to synthesizing boron containing compounds which have a potential as boron delivery agents (BDA) with enhanced tumor selectivity. The tumor identification moiety chosen was biotin (a vitamin H) which is essential for every cell’s metabolism. The mechanism in which biotin accumulates in the tumor cell is through the receptors which are over-expressed in the tumor cells. Therefore the possibility that biotinylated boron compounds could be deposited more on tumor cells than to healthy cells is high. The synthetic approach involved the synthesis the boronic acids, 4-anilineboronic acid and 4-(hydromethyl) phenylboronic acid followed by their conjugation with D-biotin. These two boronic acids were chosen because their reactive grouping (OH, NH2) could bind to the carboxylic acid reactive part of D-biotin via the formation of an ester linkage. Of these two boronic acids, 4-(hydromethyl) phenylboronic acid was successfully synthesised and biotinylated at 62% yield to form a new boron compound. In this project it proposed that the addition of a fluorescent marker on this biotinylated compounds could potentially improve their imaging properties. The luminescence properties and stability of 1,3,2-benzodiazaboroles derivatives have been reported in literature. In this project, 1,3,2-benzodiazaboroles derivative of biotinylated boronic acid (already synthesised) was in 72% when reacted with o-phenylenediamine. It is anticipated that this compounds could have better tumor solubility, water solubility, less toxicity (brought about by the attached biotin) and enhanced luminescent properties (as reported for all 1,3,2-benzodiazaboroles derivatives). However, the biological testing on these compounds was not performed in this study.