Uptake and washout of borocaptate sodium and borono-phenylalanine in cultured melanoma cells: A multi-nuclear NMR study

The cellular uptake and washout of the two principal boron neutron capture therapy (BNCT) agents, borocaptate sodium (BSH) and borono-phenylalanine (B PA), were monitored online, noninvasively, using nuclear magnetic resonance (NMR) spectroscopy. The uptake and washout of inorganic berate (B-i) was a lso followed for comparison. M2R mouse melanoma cells grown on polystyrene microspheres were perfused inside the NMR sample tube. B-11 NMR was used to detect the presence of B-i, BSH and BPA, and F-19 NMR was applied to detec t fluorinated BPA (F-19-BPA). The results revealed chemical modifications o f BSH due to spontaneous formation of the borocaptate dimer, BSSB, in the c ulture medium. BPA readily formed a complex with glucose contained in the c ulture medium but was also converted in the cells to a yet unidentified com pound in a reaction that probably involves the hydrolysis of BPA and the re lease of Bi. The cellular accumulation ratio for BPA was significantly high er than 1 and was also significantly higher than that for BSH. On the other hand, the cellular retention time observed for BSH was much longer than fo r BPA, indicating a strong trapping of BSH in cells. (C) 2000 by Radiation Research Society.