Abstract
Flavonoids exhibit a broad range of biological activities. However, poor absorption of some flavonoids is a major limitation for use of flavonoids as nutraceuticals. To investigate the structure requirements for flavonoids intestinal absorption, transepithelial transport and cellular accumulation (CA) of 30 flavonoids were determined using the Caco-2 cell monolayer. The bilateral permeation of five types of flavonoids followed the order: flavanones ≥ isoflavones > flavones ≥ chalcones > flavonols. The concentration of flavonoids accumulated in cells did not correlate with cell penetration since the correlation coefficient between the apparent permeability coefficient (Papp) and their corresponding CA was poor (R2 < 0.3). Most flavonoids exhibited a ratio of 0.8–1.5 for Papp A to B/Papp B to A, suggesting passive diffusion pathways. However, luteolin, morin and taxifolin may involve the efflux mechanisms. The quantitative structure-permeability relationship (QSPR) study demonstrated that the intestinal absorption of flavonoids can be related to atomic charges on carbon 3′ (QC3′), molecule surface area (SlogP_V3), balance between the center of mass and position of hydrophobic region (vsurf_ID1) and solvation energy of flavonoids (E_sol). These results provide useful information for initially screening of flavonoids with high intestinal absorption.
Highlights
Flavonoids which are produced by plants as secondary plant metabolites are one of the most widely distributed polyphenols
Cell viability was evaluated in Caco-2 cells treated with 40 μM flavonoid
There is no significant difference (p < 0.05) between the Caco-2 cell viability of the control and each flavonoid. These results indicated that the flavonoids at the tested concentration showed no cytotoxicity to Caco-2 cells
Summary
Flavonoids which are produced by plants as secondary plant metabolites are one of the most widely distributed polyphenols. Flavonoids exhibit health benefits due to their various biological activities including antioxidant, anti-cancer [2], antimicrobial [3], anti-inflammation [4] and others. Low bioavailability has been associated with flavonoid interactions at various stages of the digestion, absorption and distribution process, which are strongly affected by their molecular structures. An increase in absorption of flavonoids is one way to improve their oral bioavailability. Previous studies have shown that the molecular structures play an important role on the absorption of flavonoids, including the degree or position of substitution of hydroxyl and alkyl group [5], methoxyl group [6], prenyl group [7], and glycosidic group [8]
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