Piriprost (potassium salt)

Piriprost (U 60257) is a leukotriene synthesis inhibitor [1].

Leukotrienes belong to a family of eicosanoid inflammatory mediators produced in leukocytes. Leukotrienes mainly act on a subfamily of G protein-coupled receptors. The production of leukotrienes is implicated in triggerring contractions in the smooth muscles lining the bronchioles and is a major cause of inflammation in asthma and allergic rhinitis [2].

Piriprost inhibited the formation of 5-hydroxyeicosatetraenoic acid (5-HETE), LTB4, and the sulfidopeptide leukotrienes with the IC50 values ranged from 9 to 14 μM for the mouse mast cells and 15-50 μM for the basophil leukemia cells. Piriprost weakly inhibited the solubilized LTC synthase of rat basophil leukemia cells with the IC50 of 1.5 mM [1]. Piriprost increased alkaline phosphatase (ALP) activity in cultured endometrial stromal cells. Piriprost (100 μM) inhibited 5-lipoxygenase activity and decreased 5-hydroxy-eicosatetraenoic acid (a 5-lipoxygenase product) by 53% [3].

In smoke-exposed rabbits, pretreatment with piriprost attenuated the smoke-induced increase in alveolar-capillary barrier permeability and decrease in plasminogen activator activity and causes a swelling of type I alveolar epithelium [4].

References:
[1] Bach M K, Brashler J R, White G J, et al.  Experiments on the mode of action of piriprost (U-60,257), an inhibitor of leukotriene formation in cloned mouse mast cells and in rat basophil leukemia cells[J]. Biochemical pharmacology, 1987, 36(9): 1461-1466.
[2] Smith M J H, Ford‐Hutchinson A W, Bray M A.  Leukotriene B: a potential mediator of inflammation[J]. Journal of Pharmacy and Pharmacology, 1980, 32(1): 517-518.
[3] Cejic S S, Kennedy T G.  Examination of the effects of piriprost (U-60,257 B) on alkaline phosphatase activity of rat endometrial stromal cells in vitro[J]. Prostaglandins, 1991, 42(2): 179-189.
[4] itten M L, Grad R, Quan S F, et al.  Piriprost pretreatment attenuates the smoke-induced increase in 99mTcDTPA lung clearance[J]. Experimental lung research, 1990, 16(4): 339-353.