The chemical investigation of the crude extract obtained from the growth media of the marine-derived actinomycete Streptomyces acrimycini isolated from marine sediments led to the isolation of two new dipeptide derivatives: 8-amino-[ 1,4] diazonane-2,5-dione (1) and leucyl-4-hydroxyproline (3). The dipeptides were isolated from the growth media by a series of chromatographic steps, and identified by analysis of spectroscopic data. The macrocyclic carbon backbone of 8-amino-[ 1,4] diazonane-2,5-dione has been previously reported only once in marinobactins, siderophores isolated from the marine bacterium Marinobacter sp.