Figure 1. Compounds tested. (A) Structure and formula of NC009-1, AM404, VB-037 and LM-031. (B) Cytotoxicity of the tested compounds against HMC3 and SH-SY5Y cells using MTT viability assay. Cells were treated with 0.1−100 μM tested compounds and cell proliferation was measured after 28 h of treatment in HMC3 cells or 6 days of treatment in SH-SY5Y cells (n = 3). The IC50 of each compound was shown under the columns. To normalize, the relative viability in untreated cells is set as 100%. (C) Radical-scavenging activity of these compounds (10−160 μM) on DPPH (n = 3). (D) Molecular weight (MW), hydrogen bond donor (HBD), hydrogen bond acceptor (HBA), calculated octanol-water partition coefficient (cLogP), polar surface area (PSA), and predicted blood-brain barrier (BBB) score of these compounds.