5-Demethylnobiletin and its major metabolites:efficient preparation and mechanism of their anti-proliferation activity in HepG2 cells

摘要

5-Demethylnobile tin(5-DMN),a hydroxylated polymethoxyflavone(OH-PMF)identified in aged citrus peels,has demonstrated health benefiting effects in previous studies.5-DMN undergoes biotransformation in vivo,yielding 5,3’-didemethylnobiletin(5,3’-DDMN),5,4’-didemethylnobiletin(5,4’-DDMN)and5,3’,4’-tridemethylnobiletin(5,3’,4’-TDMN).However,the anti-cancer effects of 5-DMN and its in vivo metabolites against HepG2 cells remain unclear.In this study,an efficient chemical synthetic method was developed to obtain 5-DMN and its 3 metabolites,and their molecular structures were confirmed by;H NMR and LC-MS.Cytotoxicity,cell cycle arrestment,apoptosis and caspase-3 expression were investigated to evaluate the anti-liver cancer effects of these OH-PMFs on HepG2 cells.The results showed that all 4 compounds inhibited the proliferation of HepG2 cells in a concentration-dependent manner.Their anti-proliferative activity was exerted through inducing G2/M phase arrestment,cell apoptosis and promoting expression of a key apoptotic protein called cleaved caspase-3.Our results indicated that 5,3’-DDMN and5,3’,4’-TDMN showed a stronger inhibitory activity on cell proliferation than 5-DMN,followed by 5,4’-DDMN.The expression of cleaved caspase-3 was the highest in cells treated with 5,4’-DDMN,implying that the apoptosis induced by other OH-PMFs might be mediated by other apoptotic execution proteins.Our research reveals the application potential and scientific evidence for the production and functionality of OH-PMFs.