C8 L-threo Ceramide is a bioactive sphingolipid and cell-permeable analog of naturally occurring ceramides. It is cytotoxic to U937 cells (IC50 = 10 μM) and, like C8 D-threo ceramide , induces nuclear DNA fragmentation 5- to 6-fold more potently than C8 L-erythro ceramide . C8 D-threo Ceramide also enhances V. cholerae cytolysin pore formation in liposome lipid membranes, as measured by calcein release, with a 50% release dose (RD50) value of ~30 μg/ml.