PREPARATION OF SULFHYDRYLBORANE-DEXTRAN CONJUGATES FOR BORON NEUTRON-CAPTURE THERAPY

This study presents a carrier system for boron, potentially useful in boron neutron capture therapy (BNCT). Na2B12H11SH (BSH) was covalently coupled to dextran derivatives. This was accomplished in two ways. Th e first method comprises activation of dextran with 1-cyano-4-(dimethy lamino)pyridine (CDAP) with subsequent coupling of 2-aminoethyl pyridy l disulfide (method A). The thiolated dextran could then couple BSH in a disulfide exchange reaction. In the second procedure, dextran was d erivatized to a multiallyl derivative (method B) which reacted with BS H in a free-radical-initiated addition reaction. The assessment of bor on content of the conjugates was done by elemental analysis of sulfur and atomic spectroscopy of boron (ICP-AES). With method A, only limite d numbers of boron cages could be coupled (10-20 cages per dextran cha in). With method B, 100-125 boron cages per dextran chain was obtained , corresponding to 1200-1500 boron atoms per dextran chain. This resul t makes this derivative a promising template for use in the developmen t of BNCT agents.