Discovery, synthesis, and anti-cancer evaluation of 10-Pterostilbene methylamine hydrochloride derivatives as potential COX-2 and Topo I dual inhibitors

Abstract

A series of (E)-N-benzyl-1-(2, 4-dimethoxy-6-(4 methoxystyryl) phenyl) methanamine (DMPM) derivatives (D1-D25) were successfully synthesized in the form of hydrochloride, and characterized by spectroscopic techniques. The structure of D15 was further confirmed by X-ray single crystal diffraction, where D15 existed in the form of a dimer constructed by intermolecular hydrogen bonds between the active hydrogen of –NH2+− and Cl−, and the –CH=CH– in the molecule was identified as E configuration. Compounds were evaluated for their anti-cancer properties toward HepG2, Eac-109 and MDA-MB-231 cell lines in vitro. Meanwhile, bioactive compound's toxicity against L02 cell lines were also tested. Sixteen compounds (D2, D5-D8, D10, D13, D16-D23, and D25) exhibited significant cytotoxicity against tested cancer cells with IC50 values ranging from 4.13 to 36.77 μM/L. Their toxicity toward normal human liver cells was lower than that of Cisplatin. Among them, D10, D20 and D25 showed more potent anti-cancer abilities than others. Especially, D20 manifested anti-cancer effects comparable to Cisplatin on all tested cancer cell lines. SAR revealed that –OCH2CH(CH3)2 or –O(CH2)3CH3 substitution (R1) on the benzene ring of Pterostilbene is key factors in enhancing biological activities, while –OCH3, –Cl or –F substitution (R2) on another benzene ring is beneficial for improving anti-cancer abilities, and –OCH3 may be the most favorable modifying groups for enhancing skeleton's activities. Bioactive compounds displayed excellent inhibitory effects on COX-2 at nanomolar concentrations. D20 (IC50 (COX-2) = 69.92 nm/L) was identified as the most promising COX-2 inhibitor, meanwhile, it also exhibited significant Topo I inhibitory ability at 20 μM/L. In addition, D20 effectively docked to COX-2 (PDB: 5KIR) and Topo I protein (PDB: 1TBI) with affinity of -9.0 and -5.7 kcal/mol, respectively. As a potential COX-2 and Topo I dual inhibitor, D20 induced ROS-mediate mitochondria dysfunction and altered the expression of apoptosis related proteins such as Bcl-2, Bax, Caspase3/9, and P53, leading to significant apoptosis in HepG2 cells. Moreover, D20 markedly up-regulated P21, reduced the level of CDK4 or Cyclin D1, and caused G1 phase arrest on HepG2 cancer cell lines.