Procyanidins, also known as condensed tannins, have recently attracted a great deal of attention because of their promising health-promoting effects. However, their oral bioavailability and subsequent bio-efficacy are hindered by their poor gastrointestinal stability and low intestinal absorption. In this study, polymer-based delivery systems were developed to encapsulate procyanidin dimer A₂ (PAC A₂) and B₂ (PAC B₂) with the encapsulation efficiency reaching 84.9% and 88.2%, respectively. The in vitro dissolution study and ex vivo permeation study (Franz cells) were performed, and it was found that the encapsulation significantly improved the transmembrane rates of PAC A₂ and B₂ by 1.4-fold and 1.47-fold, respectively. Moreover, the cellular uptake study indicated that both encapsulated gliadin-carboxymethyl dextran (G-CMD) nanoparticles and whey protein-cellobiose Maillard conjugates (WPI-CE) could enter Caco-2 cells within 2 hours and were observed surrounding the cell nuclei. Furthermore, G-CMD nanoparticles slightly increased the anti-lipogenic activity of PAC A₂, which reduced lipid accumulation in differentiated 3T3-L1 cells in a dose-dependent manner. It was determined that PAC B₂ loaded in WPI-CE conjugates exhibited a higher antioxidant ability than the free PAC B₂ at all concentrations (0-50 µM) on the Hep-G2 cell line. In vitro microbial fermentation was conducted to investigate the metabolic pathways of the encapsulated and the free procyanidin dimers, and a high-throughput UHPLC-QqQ-MS/MS method combining QuEChERS and (EMR)-lipid technology was successfully developed for sample preparation and analysis. It was found that PAC A₂ and B₂ have different metabolism pathways and encapsulated dimers showed a slower metabolism rate and better retention during fermentation. In conclusion, polymer-based delivery systems were successfully developed for two procyanidin dimers, and the encapsulated procyanidin dimers showed improved bioaccessibility and bio-efficacy compared to their free forms.

Qingrong Huang

Rutgers Univ

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