Profile analysis and in vitro absorption study of citrus peel polymethoxyflavones

摘要

Polymethoxyflavones (PMFs) are a group of flavonoids found exclusively in citrus genus that have been identified with many potent biological activities, including anti-inflammation, anti-cancer, anti-atherosclerosis, and antioxidant. However, the bioavailability of PMFs is seldom studied. As far as we know, PMFs have poor aqueous solubility, and may potentially have high permeability due to their lipophilic structure. Biological studies rely on efficient separation method to obtain pure compounds. Silica gel column chromatography was utilized in this study to separate individual PMFs from aged orange peel extracts, and the yielded products had more than 95% purity. With this established method, purified PMF derivatives from chemical modification were also obtained.;In this research, we systemically investigated permeability and solubility of totally six PMFs and their derivatives, namely, sinensetin (SIN), 5-hydroxy-sinensetin (5-OH-SIN), 5-acetyl-sinensetin (5-Ac-SIN), 3,5,6,7,8,3',4 '-Heptamethoxyflavone (HeptaMF), 5-hydroxy-3,6,7,8,3 ',4'-hexamethoxyflavone (5-OH-HeptaMF), and 5-acetyl- 3,6,7,8,3',4'-hexamethoxyflavone (5-Ac-HeptaMF). Among them, 5-OH-SIN, 5-Ac-SIN, and 5-Ac-HeptaMF were prepared via chemical modification. From the octanol/water solubility test, it was found that PMFs and their derivatives had very low aqueous solubility. Permeability experiment via Caco-2 cell monolayer transport model was conducted indicating high permeability of all the tested compounds. Furthermore, PMFs had the greatest permeability, followed by 5-acetyl PMFs and 5-hydroxy PMFs. Moreover, metabolism especially deacetylation was observed during the transport of 5-acetyl PMFs. Considering permeability and solubility together, PMFs and their derivatives are expected having good absorption. This study gives indicative information on the bioavailability of PMFs and their derivatives, which provides clues on the application of PMFs in functional food or nutraceutical products.