Oleoyl serinol is a gut microbe-derived agonist of GPR119.1 It stimulates secretion of GLP-1 in vitro (IC50 = 12 µM).² Oleoyl serinol has a variety of meal-related effects in mice, including a reduction of plasma insulin, but not leptin, levels in ad libitum-fed mice and an increase in both plasma insulin and leptin levels in mice fasted for 12 hours, then refed.¹ It alters the circadian oscillations of mouse plasma phosphatidylcholine and ceramide levels in a molecular species-specific manner. Oleoyl serinol (100 µM) also reduces cell viability of F-11 neuroblastoma cells and induces apoptosis in U87 astrocytoma cells.³ At 80 µM, it induces formation of a complex including PAR-4 and PKCζ in embryoid body-derived cells, decreases the levels of the pluripotency marker Oct-4 and prostate apoptosis response-4 (PAR-4), which mediates ceramide-induced apoptosis in embryonic stem cells.⁴