Discovery of Isatin‐Based Carbohydrazones as Potential Dual Inhibitors of Fatty Acid Amide Hydrolase and Monoacylglycerol Lipase

Abstract

Using ligand-based design strategy, a set of isatin-3-carbohydrazones was designed, synthesized and evaluated for dual fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) inhibition properties. Compound 5-chloro-N'-(5-chloro-2-oxoindolin-3-ylidene)-2-hydroxybenzohydrazide (13 b) emerged as a potent MAGL inhibitor with nanomolar activity (IC 50 = 3.33 nM), while compound 5-chloro-N'-(1-(4-fluorobenzyl)-2-oxoindolin-3-ylidene)-2-hydroxybenzohydrazide (13 j) was the most potent selective FAAH inhibitor (IC 50 = 37 nM). Compound 5-chloro-N'-(6-chloro-2-oxoindolin-3-ylidene)-2-hydroxybenzohydrazide (13 c) showed dual FAAH-MAGL inhibitory activity with an IC 50 of 31 and 29 nM respectively. Enzyme kinetics studies revealed that the isatin-based carbohydrazones are reversible inhibitors for both FAAH and MAGL. Further, blood-brain permeability assay confirmed that the lead compounds (13 b, 13 c, 13 g, 13 m and 13 q) are suitable as CNS candidates. Molecular dynamics simulation studies revealed the putative binding modes and key interactions of lead inhibitors within the enzyme active sites. The lead dual FAAH-MAGL inhibitor 13 c showed significant antioxidant activity and neuroprotection in the cell-based cytotoxicity assay. In summary, the study yielded three potent FAAH/MAGL inhibitor compounds (13 b, 13 c and 13 j) with acceptable pharmacokinetic profile and thus can be considered as promising candidates for treating neurological and mood disorders.

Synthesis and evaluation of carbamate derivatives as fatty acid amide hydrolase and monoacylglycerol lipase inhibitors

“…All final compounds were tested for in vitro FAAH/MAGL inhibition using our earlier reported protocol. [ 52 ] The results are expressed in IC 50 and presented in Table 1. All the synthesized compounds displayed a good inhibition profile against FAAH and MAGL enzymes.…”

“…The FAAH and MAGL in vitro assay has been carried out by our earlier reported protocols, [ 10,52 ] summarized in Supporting Information Sections and .…”

“…Hence, selective and dual FAAH and MAGL inhibitors (compounds 2e, 2i, and 3h) were assessed for their BBB permeability by using a parallel artificial membrane permeation assay of the BBB (PAMPA-BBB), reported by Di et al [54] Validation of the PAMPA model was performed by using our earlier reported protocol. [52] As shown in Table 2 the P e values of compounds 2e, 2i, and 3h were 8.15 × 10 −6 , 5.47 × 10 −6 , and 8.47 × 10 −6 cm/s respectively, which were more than the threshold value (P e = 3.44 × 10 −6 cm/s), reported by Di et al Thus, these findings suggest that the tested carbamates possess acceptable CNS penetration properties.…”

“Magic Chloro”: Profound Effects of the Chlorine Atom in Drug Discovery

“…80 When studying MAGL inhibition, a notable chloro effect was observed with an isatin-derived hydrazone scaffold (Figure 3F). 81 Compared to the parent isatin compound 21A, the 5-chloro analog 21B was the most active against MAGL, with a 1003 × improvement in activity. Compound 21C, with a Cl in position C6 of the isatin core, was found to be 114 × more active than compound 21A as a MAGL inhibitor.…”

“…The lead molecules 21B and 21C showed an acceptable pharmacokinetic profile and were deemed promising candidates for treating neurological and mood disorders. 81 Another remarkable example of the magic chloro effect is demonstrated by compound 22B, which is a potent and competitive antagonist of the human dopamine-3 (D3) receptor (Figure 3G). 82 The D3 receptor, one of the five subtypes of dopamine receptors, belonging to the subfamily of D2-like receptors, is an important target for the treatment of a variety of neurological diseases, including schizophrenia, Parkinson's disease, depression and substance use disorders.…”