The acid sphingomyelinase is an emerging drug target, especially for inflammatory lung diseases. Presently, there are no directly-acting potent inhibitors available for cell-based studies. The potent inhibitor phosphatidylinositol-3, 5-bisphosphate (PtdIns3, 5P2) is not only unsuited for cell culture studies, but also does not provide hints for further structural improvements. In the SAR study described here, we replaced the inositolphosphate ...