hMAO-B-IN-2 (compound 6j) is an orally active, potent, selective, BBB-penetrating, and competitively reversible inhibitor of hMAO-B (IC50 = 4 nM) used in Alzheimer's disease research. hMAO-B-IN-2 exhibits good neuroprotective effects and low toxicity in SH-SY5Y cells [1].

MAO-B:4 nM

hMAO-B-IN-2 (compound 6j) exhibits significant inhibitory activity across concentrations (0-100 μM), with IC50 values of 4 nM for hMAO-B and 6.04 nM for hMAO-A. As a reversible inhibitor of MAO-B, enzyme activity is largely recoverable after dilution to 0.1 × IC50 and 1 × IC50, showing approximately 82% and 45% activity restoration, respectively. At 25 μM over 48 hours, hMAO-B-IN-2 significantly inhibits MAO-B and reduces Aβ self-induced aggregation by 40.78 ± 6.27%. Furthermore, in SH-SY5Y neuroblastoma cells, it promotes cell survival in a dose-dependent manner without toxicity at concentrations up to 25 μM over 24 hours, highlighting its potential against neurodegenerative diseases.

Compound hMAO-B-IN-2 (6j), administered to male Sprague-Dawley rats at doses of 3 mg/kg intravenously (IV) and 10 mg/kg orally (PO), exhibits satisfactory pharmacokinetic properties, including a high peak concentration (Cmax), a suitable half-life (T 1/2), and favorable oral bioavailability (F%). Specifically, the intravenous administration resulted in a peak concentration of 639.29 ± 89.06 μg/L, a half-life of approximately 1.02 ± 0.17 hours, and a clearance rate of 3.33 ± 0.15 L/h/kg. Oral administration showed a peak concentration of 142.17 ± 72.21 μg/L, a half-life of 1.33 ± 0.16 hours, and an oral bioavailability of 36.10%. These findings underscore the compound's efficacy and its potential for further pharmacological development.