Thiopyranol[2,3,4-c,d]indoles as inhibitors of 5-lipoxygenase, 5-lipoxygenase-activating protein, and leukotriene C4 synthase.
The attachment of an arylacetic or benzoic acid moiety to the thiopyrano[2,3,4-c,d]indole nucleus results in compounds which are highly potent and selective 5-lipoxygenase (5-LO) inhibitors. These compounds are structurally simpler than previous compounds of similar potency in that they contain a single chiral center. From the data presented, 2-[[1-(3-chlorobenzyl)-4-methyl-6-[(5-phenylpyridin-2-yl)methoxy]- 4, 5-dihydro-1H-thiopyrano[2,3,4-c,d]indol-2-yl]methoxy]-phenylacetic acid, 14b, was shown to inhibit 5-hydroperoxyeicosatetraenoic acid (5-HPETE) production by human 5-LO (IC50 of 18 nM). The acid 14b is highly selective as an inhibitor of 5-LO activity when compared to the inhibition of ram seminal vesicle cyclooxygenase (IC50 > 5 microM) or human leukocyte leukotriene A4 (LTA4) hydrolase (IC50 > 20 microM). In addition, 14b was inactive in a 5-lipoxygenase-activating protein (FLAP) binding assay at 10 microM. In vivo studies showed that 14b is bioavailable in rat and functionally active in the hyperreactive rat model of antigen-induced dyspnea (74% inhibition at 0.5 mk/kg po; 2 h pretreatment). In the conscious squirrel monkey model of asthma, 14b showed excellent functional activity at 0.1 mg/kg against antigen-induced bronchoconstriction (94% inhibition of the increase in RL and 100% inhibition in the decrease in Cdyn; n = 4). Resolution of this compound gave (-)-14b, the most potent enantiomer (IC50 = 10 nM in the human 5-LO assay), which was shown to possess the S configuration at the chiral center by X-ray crystallographic analysis of an intermediate. Subsequent studies on the aryl thiopyrano[2,3,4-c,d]indole series of inhibitors led to the discovery of potent dual inhibitors of both FLAP and 5-LO, the most potent of which is 2-[[1-(4-chlorobenzyl)-4-methyl-6-(quinolin-2-ylmethoxy)-4, 5-dihydro-1H-thiopyrano[2,3,4-c,d]indol-2-yl]methoxy]phenylacetic acid, 19. Acid 19 has an IC50 of 100 nM for the inhibition of 5-HPETE production by human 5-LO and is active in a FLAP binding assay with an IC50 of 32 nM. Furthermore, thiopyrano[2,3,4-c,d]indoles such as 1 and 14b are capable of inhibiting the LTC4 synthase reaction in a dose dependent manner (IC50s of 11 and 16 microM, respectively, compared to that of LTC2 at 1.2 microM) in contrast to other, structurally distinct 5-LO inhibitors. It has also been observed that the thiopyrano[2,3,4-c,d]indole class of compounds strongly promotes the translocation of 5-LO from the cytosol to a membrane fraction in the presence or absence of the ionophore A23187.(ABSTRACT TRUNCATED AT 400 WORDS)
D058927:5-Lipoxygenase-Activating Proteins; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D016084:Bronchoconstriction / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D018360:Crystallography, X-Ray; D004195:Disease Models, Animal; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors*; D000882:Haplorhini; D006801:Humans; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D016859:Lipoxygenase Inhibitors; D008297:Male; D008565:Membrane Proteins / Q000037:antagonists & inhibitors*; D008958:Models, Molecular; D051381:Rats; D012669:Seminal Vesicles / Q000201:enzymology; D012756:Sheep; D002722:Chlorobenzenes
D058927:5-Lipoxygenase-Activating Proteins; D016718:Arachidonic Acid; D000001:Calcimycin; D002352:Carrier Proteins; D005982:Glutathione Transferase; D007211:Indoles; D016859:Lipoxygenase Inhibitors; D008565:Membrane Proteins; C548592:ALOX5AP protein, human; C548594:Alox5ap protein, rat; C060893:MK-886; D002722:Chlorobenzenes; C041116:leukotriene-C4 synthase