Drug discovery approaches targeting 5-lipoxygenase-activating protein (FLAP) for inhibition of cellular leukotriene biosynthesis.

Leukotrienes are proinflammatory lipid mediators associated with diverse chronic inflammatory diseases such as asthma, COPD, IBD, arthritis, atherosclerosis, dermatitis and cancer. Cellular leukotrienes are produced from arachidonic acid via the 5-lipoxygenase pathway in which the 5-lipoxygenase activating protein, also named as FLAP, plays a critical role by operating as a regulatory protein for efficient transfer of arachidonic acid to 5-lipoxygenase. By blocking leukotriene production, FLAP inhibitors may behave as broad-spectrum leukotriene modulators, which might be of therapeutic use for chronic inflammatory diseases requiring anti-leukotriene therapy. The early development of FLAP inhibitors (i.e. MK-886, MK-591, BAY-X-1005) mostly concentrated on asthma cure, and resulted in promising readouts in preclinical and clinical studies with asthma patients. Following the recent elucidation of the 3D-structure of FLAP, development of new inhibitor chemotypes is highly accelerated, eventually leading to the evolution of many un-drug-like structures into more drug-like entities such as AZD6642 and BI665915 as development candidates. The most clinically advanced FLAP inhibitor to date is GSK2190918 (formerly AM803) that has successfully completed phase II clinical trials in asthmatics. Concluding, although there are no FLAP inhibitors reached to the drug approval phase yet, due to the rising number of indications for anti-LT therapy such as atherosclerosis, FLAP inhibitor development remains a significant research field. FLAP inhibitors reviewed herein are classified into four sub-classes as the first-generation FLAP inhibitors (indole and quinoline derivatives), the second-generation FLAP inhibitors (diaryl-alkanes and biaryl amino-heteroarenes), the benzimidazole-containing FLAP inhibitors and other FLAP inhibitors with polypharmacology for easiness of the reader. Hence, we meticulously summarize how FLAP inhibitors historically developed from scratch to their current advanced state, and leave the reader with a positive view that a FLAP inhibitor might soon reach to the need of patients who may require anti-LT therapy.

Crystal structure and Hirshfeld surface analysis of 1-(2,4-di-chloro-benz-yl)-5-methyl-N-(thio-phene-2-sulfon-yl)-1H-pyrazole-3-carboxamide.

In the title compound, C16H13Cl2N3O3S2, the thio-phene ring is disordered in a 0.762 (3):0.238 (3) ratio by an approximate 180° rotation of the ring around the S-C bond linking the ring to the sulfonyl unit. The di-chloro-benzene group is also disordered over two sets of sites with the same occupancy ratio. The mol-ecular conformation is stabilized by intra-molecular C-H⋯Cl and C-H⋯N hydrogen bonds, forming rings with graph-set notation S(5). In the crystal, pairs of mol-ecules are linked by N-H⋯O and C-H⋯O hydrogen bonds, forming inversion dimers with graph-set notation R22(8) and R12(11), which are connected by C-H⋯O hydrogen-bonding inter-actions into ribbons parallel to (100). The ribbons are further connected into a three-dimensional network by C-H⋯π inter-actions and π-π stacking inter-actions between benzene and thio-phene rings, with centroid-to-centroid distances of 3.865 (2), 3.867 (7) and 3.853 (2) Å. Hirshfeld surface analysis has been used to confirm and qu-antify the supra-molecular inter-actions.

Identification of multi-target inhibitors of leukotriene and prostaglandin E2 biosynthesis by structural tuning of the FLAP inhibitor BRP-7.

Leukotrienes (LTs) and prostaglandin (PG)E2 are enzymatically produced from arachidonic acid and represent highly bioactive lipid mediators with pro-inflammatory functions. Here, we report on novel multi-target inhibitors that potently and dually interfere with 5-lipoxygenase-activating protein (FLAP) and microsomal prostaglandin E2 synthase (mPGES)-1 in LT and PGE2 biosynthesis, based on the previously identified selective FLAP inhibitor BRP-7 (8, IC50 = 0.31 µM). C (5)-substitution of the benzimidazole ring of BRP-7 by carboxylic acid and its bioisosteres provided compounds, exemplified by 57 that potently suppress LT formation (IC50 = 0.05 µM) by targeting FLAP along with inhibition of mPGES-1 (IC50 = 0.42 µM). Besides FLAP, also 5-lipoxygenase (5-LO) and LTC4 synthase activities were inhibited by 57, albeit with lower potency (IC50 = 0.6 and 6.2 µM) than FLAP. Docking studies and molecular dynamic simulations with FLAP, mPGES-1 and 5-LO provide valuable insights into potential binding interactions of the inhibitors with their targets. Together, these novel benzimidazole derivatives may possess potential as leads for development of effective anti-inflammatory drugs with multi-target properties for dually inhibiting LT and PGE2 production.