In the search for new anticancer drugs. XXIV: Synthesis and anticancer activity of amino acids and dipeptides containing the 2-chloroethyl- and [N'-(2-chloroethyl)-N'-nitroso]-aminocarbonyl groups.

A series of L,L- (42, 44, 46, and 60) and D,D- (43, 45, 47, and 61) dipeptide derivatives composed of phenylglycine, phenylalanine, homophenylalanine, and valine and containing a 2-chloroethylamino group at the C-terminus and an N'-(2-chloroethyl)-N'-nitroso-aminocarbonyl group at the N-terminus of the dipeptides were prepared. The dipeptide derivatives (42-47, 60, and 61) were first evaluated in vivo for their anticancer activities against the murine lymphocytic leukemia P388. Compounds 42, 44, 46, and 60 possessed activities ranging from 46 to 111 percent increase in life span (%ILS), whereas 43 was marginal (%ILS = 31) and 45, 47, and 61 were inactive. In general, the L,L-series exhibited low to good activity (%ILS = 46-111), whereas the corresponding D, D-series, except for 43 (%ILS = 31), was devoid of activity. The analogously structured monoamino acid derivatives of L-alanine (74), L-phenylalanine (75), and L-aspartic acid (76) exhibited higher activity against P388 than the dipeptide derivatives (i.e., 481, 297, and 481 %ILS, respectively). The more active representatives of dipeptides (i.e., 42, 44, and 60) and the amino acids derivatives 74-76 were then tested in vivo against the murine lymphoid leukemia L1210. Compounds 42, 44, and 60 exhibited either low or marginal activity (i.e., the %ILS values were 46, 31, and 26, respectively). Compounds 74, 75, and 76 possessed low to moderate activity, as evidenced by the %ILS values of 56, 48, and 64, respectively. The %ILS parameters obtained against the P388 and L1210 tumor lines were correlated with the corresponding lipophilicities, and there is a trend towards higher activity with concomitant decrease in hydrophobicity.