Sch 53823 and Sch 53825, novel fungal metabolites with phospholipase D inhibitory activity

Two novel phospholipase D (PLD) inhibitors, Sch 53823 (1) and Sch 53825 (2), were isolated from a fungal culture. The acetylated derivatives, Sch 53827 (3) and Sch 53829 (4), were prepared for the purpose of structure determination. The extensive NMR studies of 3 and 4 including DEPT, COSY, NOESY, HETCOR, and selective INEPT experiments permitted the establishment of their structures, as well as relative stereochemistries. Among these compounds, 3 exhibited the most potent inhibitory activity in the phospholipase D assay with the IC50 = 17 μM.