Abstract

Anthocyanins (ACNs) and dehydrozingerone (DHZ) are purple and yellow natural pigment substances found in purple sweet potato and ginger, respectively. The mechanisms of intestinal absorption of these substances are ambiguous or have not been studied. The purpose of this study was to clarify the absorption of these substances using Caco-2 and T84 cell lines as in vitro models of intestinal absorption. For the intracellular uptake experiment, cells were cultivated on plastic dishes. For bidirectional permeability experiment, Transwell method was used. The uptake of ANCs by Caco-2 and T84 reached a maximum at 0.5 to 1 min in both pH 6.5 and 7.4, and decreased until 20 min. The uptake amounts were slightly higher in pH 6.5 than pH 7.4 in Caco-2, while no difference was observed in T84. The uptake of DHZ increased rapidly from 1 to 2 min, and then gradually increased thereafter with no pH dependency. Transepithelial transport of ANCs across Caco-2 and T84 were bidirectional, with similar rates of absorptive and secretory transports, suggesting no active transporter involvement in the ANCs transport. The transepithelial transport of DHZ in Caco-2 exhibited secretory-directed, with a secretory rate of approximately 7 at the lowest concentration (1.0 μg/mL). However, secretory-directed transport was not observed at higher concentrations. In T84, secretory-directed transport with secretory rate of approximately 3 at 10.0 μg/mL, but not at higher concentration. Both intracellular uptake and transcellular transport of ANCs were minimal, while DHZ exhibited significantly greater abundance. It can be inferred that no transporters mediating both absorptive and secretory directions participate in the intestinal absorptive process for ANCs. For DHZ, a secretory transporter may be involved in the absorptive process at lower concentrations; however, the contribution of the secretory transporter is minimal, and a considerable amount of DHZ is suggested to be absorbed from intestine.