The Novel <scp>l</scp>- and <scp>d</scp>-Amino Acid Derivatives of Hydroxyurea and Hydantoins:  Synthesis, X-ray Crystal Structure Study, and Cytostatic and Antiviral Activity Evaluations

The novel L- and D-amino acid derivatives of hydroxyurea 5a-o were prepared by aminolysis of N-(1-benzotriazolecarbonyl)amino acid amides 4a-o with hydroxylamine. The hydantoin derivatives 6a-e,m,p were synthesized by base-catalyzed cyclization of amides 4, common precursors for 5 and 6. X-ray crystal structure analysis shows that the C5 atom in 6e possesses the S configuration, which is consistent with the configuration of the starting reagent, l-leucine. Among L-amino acid derivatives of hydroxyurea, 5h and 5i inhibited specifically murine leukemia and human T-lymphocytes (IC(50) = 10-19 microM) and showed selectivity with respect to normal human fibroblasts (WI 38). d-Amino acid derivatives of hydroxyurea 5m and 5o inhibited the growth of all tumor cell lines (IC(50) = 4.8-83.9 microM), but not the growth of normal fibroblasts (WI 38; IC(50) > 100 microM). Results on antiviral evaluations showed that N-(1-benzotriazolecarbonyl)amino acid amide 4m and hydantoin 6m had marked activity against the Davis strain of CMV (4m, EC(50) = 3.2 microg/mL; 6m, EC(50) = 4.0 microg/mL). However, these compounds showed also rather expressed cytotoxicity (4m, CC(50) = 43.4 microg/mL; 6m, CC(50) = 12.5 microg/mL(-1)).