The S-alkyl chain length as a determinant of the anti-leukemic activity of cysteine chloromethyl ketone compounds.

A series of cysteine chloromethyl ketone compounds with a systematic variation of the S-alkyl chain length have been synthesized in order to gauge the effect of the alkyl chain length on the cytotoxicity of these compounds against human acute lymphoblastic leukemia cells. Comparable activities were observed for compounds with S-alkyl chains ranging from pentyl to dodecyl, with the best being undecyl (IC50= 1.7 microM) and dodecyl (IC50=2.0 microM) against B-lineage leukemia cells and hexyl (IC50 = 0.7 microM) against T-lineage leukemia cells.