ABSTRACT
OBJECTIVE: To study the disposition of geniposide and genipin via intestinal absorption barrier. METHODS: The biotransformation of geniposide was studied by incubating it with intestinal flora or intestinal enzymes. The intestinal absorption of genipin at duodenum, jejunum, ileum and colon was investigated using single-pass intestinal perfusion model. RESULTS: The metabolism activity of intestinal flora for geniposide was (1098.3±519.2) μmol · h-1 · g-1. The concentration of geniposide reduced from 20.00 to 9.60 μmol · L-1 after 4 h of incubation with intestinal enzymes, while the concentration of the metabolite of geniposide, genipin, increased to 3.52 μmol · L-1. The effective permeability coefficients(Peff*) of ginipin at duodenum, jejunum, ileum, and colon were 3.77±0.38, 3.00±0.20, 2.79±0.16, and 2.11 ±0.62, respectively, and the absorption percentages at different intestinal segments of 10 cm long(10 cm% ABS) were (70.24±7.88)%, (56.94 ±4.34)%, (53.44±3.73)%, and (48.52 ±9.59)%, respectively. There were significant differences between duodenum and the other regions of intestine of rats (P < 0.05). The phase II metabolite of genipin was found in rat bile, and its UV absorption spectrum was in accordance with that of genipin hydrolyzed by β-glu-curonidase. CONCLUSION: Geniposide can be transformed to genipin in rat intestine. Genipin can be well absorbed in general intestinal tract without specific absorption site. The phase II metabolite of genipin can be excreted to small intestine through bile.