茯苓三萜类化合物在人源Caco-2细胞单层模型中的吸收研究

目的：研究中药茯苓中3-表去氢土莫酸(3-epidehydrotumulosic acid，EDHTA)、猪苓酸C(polyporenic acid C,PPAC)和6α-羟基猪苓酸C(6α-hydroxypolyporenic acid C,HPPA)在人肠的吸收。方法：采用人源结肠腺癌细胞系Caco-2细胞单层模型研究EDHTA,PPAC和HPPA由绒毛面(AP侧)到基底面(BL侧)、BL侧到AP侧2个方向的转运过程。应用高效液相色谱法分离、紫外检测法对上述3个化合物进行定量分析，计算转运参数和表观渗透系数，并与阳性对照药普萘洛尔和阿替洛尔进行比较。结果：EDHTA，PPAC和HPPA由AP侧到BL侧的表观渗透系数(P_app) 值分别为(9.99±1.08)×10^-6、(10.06±0.53)×10^-6和(3.32±0.66)× 10^-6 cm·s^-1；由BL侧到AP侧的P_app值分别为(17.76±0.91)×10^-6、(19.23±1.16)×10^-6和(8.19±0.57)×10^-6 cm·s^-1。与本实验中在Caco-2细胞单层模型上呈良好吸收的阳性对照药普萘洛尔的P_app值(1.45×10^-5 cm·s^-1)和呈难于吸收的阳性对照药阿替洛尔的P_app值(4.22×10^-7 cm·s^-1)比较，EDHTA和PPAC与普萘洛尔在同一数量级；HPPA介于普萘洛尔和阿替洛尔之间。EDHTA、PPAC和HPPA的P_{app A→B}/P_{app B→A}比值分别为0.56,0.52和0.41；EDHTA,PPAC和HPPA外流分别是摄取的1.78，1.91，2.47倍。结论：EDHTA，PPAC和HPPA可以通过小肠上皮细胞被动吸收进入体内，EDHTA和PPAC属于良好吸收的化合物；HPPA属于中等吸收的化合物。EDHTA、PPAC和HPPA在Caco-2细胞单层模型中的转运可能存在外流机制。

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.