3-Substituted-4-hydroxy-7-chromanylacetic acid derivatives as antagonists of the leukotriene B4 (LTB4) receptor

Classification models and SAR analysis on CysLT1 receptor antagonists using machine learning algorithms

Cysteinyl leukotrienes 1 (CysLT1) receptor is a promising drug target for rhinitis or other allergic diseases. In our study, we built classification models to predict bioactivities of CysLT1 receptor antagonists. We built a dataset with 503 CysLT1 receptor antagonists which were divided into two groups: highly active molecules (IC₅₀ < 1000 nM) and weakly active molecules (IC₅₀ ≥ 1000 nM). The molecules were characterized by several descriptors including CORINA descriptors, MACCS fingerprints, Morgan fingerprint and molecular SMILES. For CORINA descriptors and two types of fingerprints, we used the random forests (RF) and deep neural networks (DNN) to build models. For molecular SMILES, we used recurrent neural networks (RNN) with the self-attention to build models. The accuracies of test sets for all models reached 85%, and the accuracy of the best model (Model 2C) was 93%. In addition, we made structure-activity relationship (SAR) analyses on CysLT1 receptor antagonists, which were based on the output from the random forest models and RNN model. It was found that highly active antagonists usually contained the common substructures such as tetrazoles, indoles and quinolines. These substructures may improve the bioactivity of the CysLT1 receptor antagonists.

Synthesis and structure-activity relationships of new 1, 3-disubstituted cyclohexanes as structurally rigid leukotriene B(4) receptor antagonists

A series of 1-hydroxy-3-¿3-hydroxy-7-phenyl-1-hepten-1-yl cyclohexane acetic acid derivatives was designed based on postulated active conformation of leukotriene B(4) (LTB(4)) and evaluated as human cell surface LTB(4) receptor (BLTR) antagonists. Binding was determined through ¿(3)HLTB(4) displacement from human neutrophils and receptor antagonistic assays by in vitro measurements of inhibition of leukocyte chemotaxis induced by LTB(4). On the basis of these assays, a structure-affinity relationship was investigated. Optimization of the acid chain length and omega-substitution of a phenyl group on the lipophilic tail were shown to be critical for binding activity. These modifications led to the discovery of compounds with submicromolar potency and selective BLTR antagonism. The most potent compound 3balpha (IC(50) = 250 nM) was found to significantly inhibit oedema formation in a topical model of phorbolester-induced inflammation. Substantial improvement of in vitro potency was achieved by modification of the carboxylic acid function leading to the identification of the N,N-dimethylamide series. Compound 5balpha, free of agonist activity, displayed higher potency in receptor binding with an IC(50) of 40 nM. These results support the hypothesis that the spatial relationship between the carboxylic acid and allylic hydroxyl functions is crucial for high binding affinity with BLTR.

trans-3-Benzyl-4-hydroxy-7-chromanylbenzoic acid derivatives as antagonists of the leukotriene B4 (LTB4) receptor

The SAR of a series of 2-(7-chromanyl)benzoic acids has been investigated with the aim of identifying potent and selective LTB4 receptor antagonists that maintain potency in complex biological fluids. We found optimal activity in derivatives with electron-withdrawing groups in the benzoic acid ring and with an unsubstituted C-3 benzyl group on the chromanol nucleus. While compounds containing a 3-(4-phenyl)benzyl chromanol substituent were potent LTB4 receptor antagonists, the increased lipophilicity imparted by the additional phenyl substituent led to decreased potency in the presence of plasma proteins. From among the potent compounds identified, CP-195543, the 5'-trifluoromethyl 3-benzyl chromanol, was selected for development.

Synthetic approaches to 2-(4-hydroxy-7-chromanyl)benzoic acids as antagonists of leukotriene B4

Structural modification of 1 led to a series of 2-(4-hydroxy-7-chromanyl)benzoic acid LTB4 antagonists exemplified by 2 and 3. The use of an organostannane biaryl coupling, a non steroselective reduction and a chromatographic resolution limited the utility of this synthetic route. To address these issues, a new synthetic route was developed utilizing a palladium catalyzed coupling of aryl oxazolines in tandem with a stereospecific enone reduction as key synthetic steps. Resolution was achieved by fractional crystallization of a (S)-(-)-alpha-methylbenzylamine salt.