Picornavirus Inhibitors: Trifluoromethyl Substitution Provides a Global Protective Effect against Hepatic Metabolism

Article abstract of DOI:10.1021/jm00008a014

Several modifications of the oxazoline ring of WIN 54954, a broad spectrum antipicornavirus compound, have been prepared in order to address the acid lability and metabolic instability of this compound.We have previously shown that the oxadiazole analogue 3 displayed comparable activity against a variety of rhinoviruses and appeared to be stable to acid.A monkey liver microsomal assay was developed to examine the metabolic stability in vitro of both compounds, and it was determined that WIN 54954 displayed 18 metabolic products while 3 was converted to 8 products.Two major products of 3 were determined by LC-MS/MS to be monohydroxylated at each of the terminal methyl groups.Replacement of the methyl on the isoxazole ring with a trifluoromethyl group, while preventing hydroxylation at this position, did not reduce the sensitivity of the molecule to microsomal metabolism at other sites.However, the (trifluoromethyl)oxadiazole 9 not only prevented hydroxylation at this position but also provided protection at the isoxazole end of the molecule, resulting in only two minor products to the extent of 4percent.The major product was identified as the monohydroxylated compound 23.The global metabolic protective effect of trifluoromethyl group on the oxadiazole ring was further demonstrated by examining a variety of analogues including heterocyclic replacements of the isoxazole ring.In each case, the trifluoromethyl analogue displayed a protective effect when compared to the corresponding methyl analogue.