Boronated unnatural cyclic amino acids as potential delivery agents for neutron capture therapy

Boron delivery characteristics of cis and trans isomers of a boronated unnatural amino acid, 1-amino-3-boronocyclopentanecarboxylic acid (ABCPC) were tested in the B16 mouse model for human melanoma. Both ABCPC isomers delivered comparable boron to B16 melanoma tumor cells as L-p-boronophenylalanine (BPA). Secondary ion mass spectrometry (SIMS) analysis revealed the presence of boron throughout the tumor from these compounds, and a near homogeneous distribution between the nucleus and cytoplasm of B16 cells grown in vitro. These encouraging observations support further studies of these new boron carriers in BNCT.