BACE-1/Mpro-IN-1 is a compound capable of penetrating the blood-brain barrier, acting as a dual inhibitor for BACE-1 (IC50 = 0.26 μM) and SARS-CoV-2 Mpro (IC50 = 0.91 μM). It functions as a mixed inhibitor by binding to aspartic and cysteine proteases and demonstrates optimal docking scores alongside robust interaction characteristics. BACE-1/Mpro-IN-1 is applicable in research focusing on COVID-19-related neuroinflammation and Alzheimer’s disease.

BACE-1/Mpro-IN-1 (Compound 6c) interacts specifically with the active site and allosteric pocket of BACE1, reducing Vmax and increasing Km, thereby lowering substrate affinity. It exhibits π-sulfur binding affinity at Asp228 and Arg235, hydrophilic hydrogen bonding with amino acid residues like Thr72, Asn233, and Lys224, and hydrophobic π-π interactions at Tyr71 and Tyr198. The quinoline portion of BACE-1/Mpro-IN-1 engages in a π-sulfur interaction with Cys145 near the S1 sub-pocket. In the S1’ region, Met49 and Cys145 display π-sulfur interactions with the phenyl ether and quinoline parts. His41 in the S2 region is involved in π-π stacking with the phenyl portion, while Gln189 forms both hydrogen bonds and π-alkyl interactions. In the S3 region, Met165, Ala191, and Arg188 participate in π-alkyl and π-π stacking interactions. The compound shows a binding energy of −7.6 kcal/mol at 0-100μM, indicating significant inhibition potential towards Mpro. Its high blood-brain barrier permeability is confirmed through parallel artificial membrane permeability assay, with a permeability (PAMPA-BBB) P e(tested) (10 −6 cm/s) of 12.74.

BACE-1/Mpro-IN-1 (50-750 mg/kg) demonstrates good safety at low to moderate doses (≤ 150 mg/kg BW) but exhibits significant toxicity in Swiss albino mice at higher doses (≥ 350 mg/kg BW).