Determination of Soyasapogenols Absorption Characteristics in Rat Gut Using in Situ Single-pass Intestinal Perfusion Model

Objective: To investigate the absorption characteristics of soyasapogenol A and B. Methods: The effects of absorption sites (duodenum, jejunum, ileum, and colon), concentration and bile on the intestinal absorption of soyasapogenol were determined using HPLC analysis and in situ single-pass intestinal perfusion model. Results: The order of apparent absorption coefficient (P_app) and absorption rate constant (K_a) of soyasapogenol absorption sites were as followed: Jejunum>duodenum>ileum>colon. The P_app and K_a of soyasapogenol A at a concentration of 50 mg/L were 15.34×10⁻⁵ cm/s and 3.06×10⁻⁵ s⁻¹ at jejunum, while soyasapogenol B were 11.36×10⁻⁵ cm/s and 2.74×10⁻⁵ s⁻¹. The absorption capacity of soyasapogenol A was significantly concentration-dependent (P<0.05) while soyasapogenol B was not significant (P>0.05). The P_app of soyasapogenol A and B with bile were 16.56×10⁻⁵ and 12.01×10⁻⁵ cm/s, and the K_a were 3.06×10⁻⁵ and 2.97×10⁻⁵ s⁻¹, which was higher than those without bile significantly (P<0.05). The presence of bile improved the absorption capability at upper part of the intestine to some extent. Conclusion: The absorption site of soyasapogenol was mainly at jejunum. The absorption mechanism of soyasapogenol A was passive diffusion, and the bile tended to have a positive impact on its intestinal absorption.