Division of Applied Regulatory Toxicology, U.S. Food and Drug Administration, 8301 Muirkirk Road, Laurel, MD, 20708, USA.
Chem Biol Interact. 2018 Jun 25;290:37-43. doi: 10.1016/j.cbi.2018.05.006. Epub 2018 May 19.
Caco-2 cells are a commonly used model for estimating the intestinal bioavailability of single chemical entity pharmaceuticals. Caco-2 cells, when induced with calcitriol, also express other biological functions such as phase I (CYP) and phase II (glucuronosyltransferases) drug metabolizing enzymes which are relevant to drug-supplement interactions. Intestinal bioavailability is an important factor in the overall safety assessment of products consumed orally. Foods, including herbal dietary supplements, are complex substances with multiple chemical components. Because of potential interactions between components of complex mixtures, more reliable safety assessments can be obtained by studying the commercial products "as consumed" rather than by testing individual chemical components one at a time. The present study evaluated the apparent intestinal permeability (P) of a model herbal extract, Rauwolfia serpentina, using both whole plant extracts and the individual purified Rauwolfia alkaloids. All test compounds, endpoint substrates, and their metabolites were quantified using liquid chromatography and high-resolution mass spectrometry. The P values for individual Rauwolfia alkaloids were comparable whether measured individually or as components of the complete extract. Both Rauwolfia extract and all individual Rauwolfia alkaloids except yohimbine inhibited CYP3A4 activity (midazolam 1'-hydroxylation). Both Rauwolfia extract and all individual Rauwolfia alkaloids except corynanthine and reserpic acid significantly increased glucuronosyltransferase activity (glucuronidation of 4-methylumbelliferone). The positive control, ketoconazole, significantly inhibited both CYP3A4 and glucuronosyltransferase activities. These findings suggest that the Caco-2 assay is capable of simultaneously identifying both bioavailability and potentially hazardous intestinal drug-supplement interactions in complex mixtures.
Caco-2 细胞常用于估计单一化学实体药物的肠道生物利用度。用骨化三醇诱导的 Caco-2 细胞也表达其他生物学功能，如 I 相（CYP）和 II 相（葡萄糖醛酸转移酶）药物代谢酶，这些酶与药物-补充剂相互作用有关。肠道生物利用度是口服摄入产品总体安全性评估的一个重要因素。食物，包括草药膳食补充剂，是具有多种化学成分的复杂物质。由于复杂混合物中成分之间存在潜在相互作用，因此通过研究“实际食用”的商业产品而不是逐个测试单个化学成分，可以获得更可靠的安全性评估。本研究使用全植物提取物和单个纯化的罗芙木生物碱评估了一种模型草药提取物罗芙木的表观肠道通透性（P）。所有测试化合物、终点底物及其代谢物均使用液相色谱和高分辨率质谱进行定量。无论单独测量还是作为完整提取物的成分，单个罗芙木生物碱的 P 值都是可比的。罗芙木提取物和除育亨宾以外的所有单个罗芙木生物碱均抑制 CYP3A4 活性（咪达唑仑 1'-羟化）。罗芙木提取物和除考利那碱和利血平酸以外的所有单个罗芙木生物碱均显著增加葡萄糖醛酸转移酶活性（4-甲基伞形酮的葡萄糖醛酸化）。阳性对照酮康唑显著抑制 CYP3A4 和葡萄糖醛酸转移酶活性。这些发现表明 Caco-2 测定法能够同时识别复杂混合物中的生物利用度和潜在危险的肠道药物-补充剂相互作用。
