Evaluation of the intestinal permeability of rosemary (<i>Rosmarinus officinalis</i> L.) extract polyphenols and terpenoids in Caco-2 cell monolayers

Rosemary (Rosmarinus officinalis) is grown throughout the world and is widely used as a medicinal herb and to season and preserve food. Rosemary polyphenols and terpenoids have attracted great interest due to their potential health benefits. However, complete information regarding their absorption and bioavailability in Caco-2 cell model is scarce. The permeation properties of the bioactive compounds (flavonoids, diterpenes, triterpenes and phenylpropanoids) of a rosemary extract (RE), obtained by supercritical fluid extraction, was studied in Caco-2 cell monolayer model, both in a free form or liposomed. Compounds were identified and quantitated by liquid chromatography coupled to quadrupole time-of-flight with electrospray ionization mass spectrometry analysis (HPLC-ESI-QTOF-MS), and the apparent permeability values (Papp) were determined, for the first time in the extract, for 24 compounds in both directions across cell monolayer. For some compounds, such as triterpenoids and some flavonoids, Papp values found were reported for the first time in Caco-2 cells.Our results indicate that most compounds are scarcely absorbed, and passive diffusion is suggested to be the primary mechanism of absorption. The use of liposomes to vehiculize the extract resulted in reduced permeability for most compounds. Finally, the biopharmaceutical classification (BCS) of all the compounds was achieved according to their permeability and solubility data for bioequivalence purposes. BCS study reveal that most of the RE compounds could be classified as classes III and IV (low permeability); therefore, RE itself should also be classified into this category.迷迭香（Rosmarinus officinalis）在全球范围内广泛栽培，作为药用草本植物被广泛应用于食品调味与防腐保鲜。迷迭香多酚与萜类化合物因其潜在的健康获益而受到广泛关注。然而，目前关于其在Caco-2细胞模型中的吸收行为与生物利用度的完整研究数据仍较为匮乏。本研究以超临界流体萃取得到的迷迭香提取物（RE）为对象，针对其所含的生物活性成分——黄酮类、二萜类、三萜类及苯丙素类化合物，分别以游离态与脂质体包载形式，在Caco-2细胞单层模型中探究其渗透特性。研究采用电喷雾电离四极杆飞行时间液相色谱-质谱联用法（HPLC-ESI-QTOF-MS）对各化合物进行定性与定量分析，并首次针对该提取物中的24种化合物，测定了其跨细胞单层双向的表观渗透系数（Papp）。其中，三萜类与部分黄酮类化合物的Papp值为首次在Caco-2细胞中报道。本研究结果显示，大部分化合物难以被吸收，提示被动扩散为其主要吸收机制。将提取物以脂质体包载后，多数化合物的渗透能力均有所下降。最后，本研究基于各化合物的渗透与溶解度数据，针对生物等效性评价需求完成了所有化合物的生物药剂学分类（BCS）。生物药剂学分类研究结果显示，迷迭香提取物中的多数化合物可归为III类与IV类（低渗透型），因此迷迭香提取物本身也应归入该类别。