Five sparsomycin analogs (9-13) were prepared and examined for their ability to inhibit deoxyribonucleic acid (DNA) synthesis in L5178Y lymphoma cells. All of the compounds showed significant activity in the DNA synthesis assay. The compounds having Rc configuration exhibited almost the same activities independently of the configuration at the sulfoxide sulfur atom. Among the Sc isomers, the Rs configuration was advantageous for the appearance of activity.