1988 Volume 37 Issue 5 Pages 269-276
We studied the tumor-localizing characteristics of alicyclic a-amino acid analogs (a-j) without α-hydrogen, because of the selective affinity of synthetic nonmetabolizing amino acids such as 1-aminocyclopentanecarboxylic acid (ACPC) and α-aminoisobutyric acid (α-AIB) to tumor tissues. Ten different alicyclic α-amino acids (a-j) were labeled with 14C using a modified Bucherer synthesis for amino acids. The tissue distributions and whole-body autoradiographic study of these 14C-labeled alicyclic α-amino acid analogs (a-j) were investigated in mice bearing Ehrlich tumor. These results showed that the tumor uptakes and tumor to tissue concentration ratios increased with decreasing ringsize in homologous series (8- through 4-membered ring systems) and alicyclic α-amino acid analogs containing 3- or 4-methyl group had the higher tumor to tissue concentration ratios. On the other hand, alicyclic α-amino acid analogs containing 2-methyl group and 4-phenyl group showed the lower tumor uptakes and the lower tumor to tissue concentration ratios. These results suggest that the small ringsize alicyclic α-amino acid analogs containing 3-methyl group such as 3-methyl-l-aminocyclopentanecarboxylic acid (3-McACPC) may be effective for the early detection of tumors.
