Novel 3-arylamino- and 3-cycloalkylamino-5, 6-diphenyl-pyridazines active as ACAT inhibitors

Discovery of novel acyl coenzyme a: cholesterol acyltransferase inhibitors: pharmacophore-based virtual screening, synthesis and pharmacology

The present study describes ligand-based pharmacophore modeling of a series of structurally diverse acyl coenzyme A cholesterol acyltransferase inhibitors. Quantitative pharmacophore models were generated using HypoGen module of Discovery Studio 2.1, whereby the best pharmacophore model possessing two hydrophobic, one ring aromatic, and one hydrogen bond acceptor feature for inhibition of acyl coenzyme A cholesterol acyltransferase showed a very good correlation coefficient (r = 0.942) along with satisfactory cost analysis. Hypo1 was also validated by test set and cross-validation methods. Developed models were found to be predictive as indicated by low error values for test set molecules. Virtual screening against Maybridge database using Hypo1 was performed. The two most potent compounds (47 and 48; predicted IC₅₀ = 1 nM) of the retrieved hits were synthesized and biologically evaluated. These compounds showed 86% and 88% inhibition of acyl coenzyme A cholesterol acyltransferase (at 10 μg/mL) with IC₅₀ value of 3.6 and 2.5 nM, respectively. As evident from the close proximity of biological data to the predicted values, it can be concluded that the generated model (Hypo1) is a reliable and useful tool for lead optimization of novel acyl coenzyme A cholesterol acyltransferase inhibitors.

Biphenyl versus phenylpyridazine derivatives: the role of the heterocycle in a series of acyl-CoA:cholesterol acyl transferase inhibitors

A series of alkylamido- ( 1) and alkylaminobiphenyl ( 2) derivatives were synthesized as possible bioisosters of the reported ACAT inhibitors phenylpyridazine analogues ( I). Both 1 and 2 were tested on the human ACAT-1 and ACAT-2 isoforms. The amino derivatives 2 were found to be inactive, contrary to the related pyridazine derivatives. By contrast, the ortho -substituted amides 1a and 1d showed an interesting activity. These results support the essential role of the pyridazine nucleus. Modeling studies were also performed.

3-Heptylamino-5-Phenylpyridazine Derivatives as Analogues of Acyl-CoA: Cholesterol Acyltransferase Inhibitors Containing theN-Heptyl-N′-Arylureidic Moiety

A series of novel Acyl-CoA: cholesterol acyltransferase (ACAT) inhibitors 8a-f was synthesized; the substances were characterized by the presence of a 2,5-dimethylpyrazin-3-yl moiety at one end and a 3-heptylamino-5-phenylpyridazine system at the other one, linked through linear alkyl spacers of different length. The new derivatives were designed based on the hypothesis that the 3-amino-5-phenylpyridazine moiety could mimic the aryl substituted urea, which was present in a number of ACAT inhibitors previously described. The choice of the 2,5-dimethylpyrazin-3-yl substituent was supported by a preliminary investigation, which indicated that this moiety is the most powerful in conferring ACAT inhibitory properties to the new series. The pharmacological results proved the idea to be sound. Finally, compounds 9a-c, lacking the phenylpyridazine moiety were prepared and tested to further strengthen our hypothesis.