Studies on Structure-Activity Relationships of FK-156,an Immunostimulating Peptide, and Related Compounds. I. Synthesis of Stereoisomeric Analogues of FK-156

Five stereoisomeric analogues, 2-6, of FK-156 (1), an immunostimulating microbial metabolite, have been synthesized and screened for immunostimulating activity. The results indicate that the D-configuration of glutamic acid and L-configuration of diaminopimelic acid at the site combining with other amino acids are essential, while the configurations of lactic acid and alanine are of little importance for the biological activity of the FK-156 series.