Studies on structure-activity relationships of FK-156, an immunostimulating peptide, and related compounds. II. Synthesis of N2-(gamma-D-glutamyl)-2(L), 2'(D)-diaminopimelic acid as the minimal essential structure of FK-156.

Abstract

Five partial structures, 3-7, of FK-156 (1), an immunostimulating acyl peptide, have been prepared. The compounds were evaluated for biological activities, and it was found that N2-(γ-D-glutamyl)-2 (L), 2' (D)-diaminopimelic acid (3) represents the minimal active structure unit essential for the immunostimulating property of FK-156 (1). Its caprylyl derivative 8 and stearoyl derivative 9 were found to be capable of increasing resistance to bacterial infection as efficiently as 1. Moreover, compound 9 showed a potent tumor-suppressive activity lacking in 1.