Background:

FIPI is a derivative of halopemide which potently inhibits both PLD1 and PLD2 with IC50s of 25 nM and 20 nM, respectively.
Despite the high clearance of greater than 2 L/h/kg, FIPI shows a half-life of greater than 5 h, a Cmax of greater than 10-fold the 50 versus PLD2, and moderate bioavailability of 18%[1]. FIPI inhibits both PLD1 and PLD2 in a dose-dependent manner, with 50% loss of activity observed at approximately 25 nM. FIPI is not an irreversible suicide inhibitor but neither is it rapidly and completely reverses upon removal of the drug. IPI does not alter PLD subcellular localization, access to PIP2, actin stress fibers, or upstream signaling events. FIPI rescues PLD2-suppressed membrane ruffling and cell spreading[2]. FIPI attenuats the thimerosal-induced PLD activation, and the Hg-induced PLD activation in MAECs in a dose-dependent manner, and the agonist- and oxidant-induced PLD activation in a dose-dependent manner in MAECs[3].
Reference:
[1]. Monovich L, et al. Optimization of halopemide for phospholipase D2 inhibition. Bioorg Med Chem Lett. 2007 Apr 15;17(8):2310-1.
[2]. Su W, et al. 5-Fluoro-2-indolyl des-chlorohalopemide (FIPI), a phospholipase D pharmacological inhibitor that alters cell spreading and inhibits chemotaxis. Mol Pharmacol. 2009 Mar;75(3):437-46.
[3]. Secor JD, et al. Novel lipid-soluble thiol-redox antioxidant and heavy metal chelator, N,N'-bis(2-mercaptoethyl)isophthalamide (NBMI) and phospholipase D-specific inhibitor, 5-fluoro-2-indolyl des-chlorohalopemide (FIPI) attenuate mercury-induced lipid si