Plipastatin A1, a lipopeptide isolated from B. cereus, demonstrates enzyme inhibitory and immunosuppressant properties. It effectively inhibits enzymes phospholipase A2 (PLA2), phospholipase C (PLC), and phospholipase D (PLD) with half-maximal inhibitory concentrations (IC50s) of 2.9, 1.3, and 1.4 µM, respectively. Additionally, at a concentration of 100 µg/ml, plipastatin A1 inhibits lipopolysaccharide (LPS)-induced B cell blastogenesis and T cell blastogenesis triggered by concanavalin A. In vivo studies reveal that a dose of 0.1 mg/animal effectively suppresses delayed-type hypersensitivity in mice.