Synthesis and biological evaluation of methylene spacer incorporated 4-methylsulfonyl phenyl semicarbazones as dual FAAH-MAGL inhibitors

Building upon our previous work, we investigated the impact of a methylene spacer on the dual fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) inhibition activity of 4-methylsulfonylphenyl semicarbazones by designing and synthesizing a set of extended semicarbazone analogs. The inhibition data demonstrated that several compounds had a good inhibitory activity against both FAAH and MAGL. Compound 15h, [1-(4-hydroxyphenyl)ethylidene]-2-{[4-(methylsulfonyl)phenyl]amino}acetohydrazide, exhibited a well-balanced FAAH and MAGL inhibition activity with IC₅₀ values of 48 nM and 40 nM, respectively. The enzyme kinetics studies demonstrated that compound 15h inhibits FAAH and MAGL reversibly with noncompetitive and mixed inhibition mode, respectively. Moreover, these experimental results were also supported by molecular modeling and simulation studies. The dual FAAH-MAGL inhibitor 15h, exhibited no cytotoxicity on human neuronal SH-SY5Y cell lines and showed significant neuroprotection in LPS-induced toxicity. Further, compound 15h showed potent analgesic activity and relieved oxidative stress in rats induced by chronic constriction injury (CCI) surgery. Furthermore, compound 15h was non-hepatotoxic up to 2000 mg/kg (po). Overall, the present study identified compound 15h as a promising dual FAAH-MAGL inhibitor and anti-nociceptive agent that merits further investigation.