[Absorption of triterpenoid compounds from Indian bread (Poria cocos) across human intestinal epithelial (Caco-2) cells in vitro]

Objective: To study the absorption of 3-epidehydrotumulosic acid (EDHTA), polyporenic acid C (PPAC) and 6alpha-hydroxypolyporenic acid C (HPPA) isolated from the sclerotium of Poria cocos. In human intestinal epithelial.

Method: By using Caco-2 (the human colonic adenocarcinoma cell lines) cells monolayer as an intestinal epithelial cell model, the permeability of EDHTA, PPAC and HPPA were studied from apical side (AP side) to basolateral side (BL side) or from BL side to AP side. The three compounds were measured by reversed-phase high performance liquid chromatography (HPLC) coupled with UV detector. Transport parameters and apparent permeability coefficients (P(app)) were then calculated and compared with those of propranolol and atenolol, which are the transcellular transport marker and as a control substance for high and poor permeability, respectively.

Result: The P(app) values of EDHTA, PPAC and HPPA were (9.99 +/- 1.08) x 10(-6), (10.06 +/- 0.53) x 10(-6) and (3.32 +/- 0.66) x 10(-6) cm x s(-1) from AP side to BL side, and (17.76 +/- 0.91) x 10(-6), (19.23 +/- 1.16) x 10(-6) and (8.19 +/- 0.57) x 10(-6) cm x s(-1) from BL side to AP side,respectively. Under the condition of this experiment, the P(app) value was 1.45 x 10(-5) cm x s(-1) for propranolol and 4.22 x 0(-7) cm x s(-1) for atenolol. The P(app) values of EDHTA and PPAC were at a nearly same magnitude with those of propranolol, and HPPA lied between those of propranolol and atenolol. On the other hand, the efflux transport of EDHTA, PPAC and HPPA were higher 1.78, 1.91 and 2. 47 times more than its influx transport with 0.56, 0.52 and 0.41 rate of P(app A --> B)/P(app (B --> A).

Conclusion: EDHTA, PPAC and HPPA can be absorbed across intestinal epithelial cells, among EDHTA and PPAC will be completely. HPPA will be moderately absorbed compounds. EDHTA, PPAC and HPPA may have been involved in efflux mechanism in Caco-2 cells monolayers model from the basolateral-to-apical direction.