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

5-Demethylnobiletin (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 (...

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Main Authors: Yanping Xin, Ting Zheng, Man Zhang, Ruiqiang Zhang, Siyue Zhu, Dongli Li, Denggao Zhao, Yanyan Ma, Chi-Tang Ho, Qingrong Huang
Format: Article
Language:English
Published: Tsinghua University Press 2022-09-01
Series:Food Science and Human Wellness
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Online Access:http://www.sciencedirect.com/science/article/pii/S2213453022000568
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Summary:5-Demethylnobiletin (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) and 5,3',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 1H 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 and 5,3',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.
ISSN:2213-4530