Measurement of optical purity of p-BPA-Tyrosine dipeptide

Melanin biosynthesis is very active in melanoma cells, and tyrosine is one of the substrates of the melanin biosynthesis. Tyrosine is oxidized to dopa by tyrosinase at the beginning of melanin biosynthesis process. Therefore, p-boronophenylalanine (BPA)-tyrosine dipeptide is expected to be a substrate of melanin biosynthesis process, and the peptide will be incorporated in melanoma cells, and then tumor boron concentration lasts in their cells for long time. Since p-BPA tyrosine are amino acids, they have D, L isomers. Therefore, we have tried to synthesize four isomers (L-L, L-D, D-L, D-D) of p-BPA-Tyrosine dipeptide, and have measured their optical purity with HPLC. (author)