A microbial metabolite inhibitor of CD28–CD80 interactions

Abstract The organic extract of the fermentation broth of a Streptomycete microorganism was found to contain SCH 212394 ( 1 ), a condensed aromatic peptide. The structure was established by extensive NMR spectral data and derivatization. SCH 212394 ( 1 ), inhibited CD28–CD80 costimulation with an IC 50 of 1.25 μM.