Identification of cytochrome P450 isoforms involved in the metabolism of Syl930, a selective S1PR1 agonist acting as a potential therapeutic agent for autoimmune encephalitis

Syl930 is a novel sphingosine-1-phosphate receptor subtype 1 (S1PR1) agonist for the treatment of autoimmune encephalitis with promising receptor selectivity and little risk of bradycardia. Syl930 could be reversibly converted to its phosphorylated metabolite, acting as the active form to provide therapeutic effects, but eliminated principally in the form of oxidative metabolites. The aim of the present study was to identify the cytochrome P450 isoforms (CYPs) responsible for the oxidative metabolism of Syl930. Considerable production of hydroxylated metabolite (Syl930-M1) was found in both rat blood and tissue homogenates in vivo and in vitro. Moreover, another hydroxylated metabolite, Syl930-M2, was detected in human, beagle dog and cynomolgus monkey liver microsomes with significant differences in the Km, Vmax and CLint of the metabolites among species. CYP1A1, CYP2J2, CYP4F2 and CYP3A4 were identified to be the major CYPs mediated in the hydroxylation of Syl930 by using 14 recombinant human CYPs, selective chemical inhibitors and monoclonal antibodies against CYPs. The multiple CYPs mediated oxidation was believed to be one of the reasons for the relatively short elimination half-life of Syl930.