Fig. 4.

Pelargonidin, the active component of strawberry, enables oral delivery of functional proteins in mice. (A) Kinetic experiments of pelargonidin permeation enhancement in mice showed that intestinal permeability to 4-kDa FITC-dextran (FITC-DX4) peaks 1 h after treatment and returns to baseline within another hour. (B) Pelargonidin treatment improved uptake of 40-kDa dextran but increased permeability tapered off for larger dextrans. (C) The efficacy of intestinally injected insulin at a dose of 1 U/kg was dependent on the dose of oral pelargonidin pretreatment, with (D) higher pelargonidin doses leading to higher bioactivity of the insulin. (E) Oral insulin doses of 1 U/kg (maroon) and 5 U/kg (red) reduced blood sugar in healthy mice when administered with pelargonidin in capsules. (F) Pelargonidin–insulin capsules resulted in double the bioactivity of subcutaneously injected insulin for 1 U/kg oral insulin. Error bars represent SEM (n = 8 to 10 mice for B, n = 5 or 6 for all other experiments). *P < 0.050 with respect to control, unless otherwise denoted, by two-tailed t test with Welch’s correction.