Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, 1441 Moursund Street, Houston, Texas 77030, USA.
J Agric Food Chem. 2010 Jun 9;58(11):6650-9. doi: 10.1021/jf904459u.
The purposes of this study were to determine content uniformity of phenolics in the St. John's wort (SJW) supplements and to demonstrate how variations in the product matrices affect their absorption and efflux. LC and LC-MS/MS methods were used to determine the phenolic contents of 12 different products purchased locally or from the Internet. Three representative extracts were further submitted to Caco-2 cell transport experiment, and transport of rutin, hyperoside, and isoquercitrin was evaluated. The results indicated that the 12 different products displayed 12 different HPLC fingerprints, but all products contained the following major compounds: rutin, hyperoside, isoquercitrin, quercitrin, quercetin, and amentoflavone. The content uniformity of these major compounds was poor across products, with the smallest difference in the amounts of amentoflavone (3.6-fold) and largest difference in that of isoquercitrin (28.8-fold). The Caco-2 experiments indicated transport of rutin in products was vectorial, with the permeabilities varied about 3.6-fold in both directions of transport. The vectorial permeabilities of hyperoside and isoquercitrin were similarly different. Use of efflux transporter inhibitor studies suggested that MRP2 was involved in isoquercitrin's efflux and the product matrix affected the extent of its efflux. In conclusion, different SJW supplements had highly variable contents of phenolics, and the variability in product matrix and phytochemical compositions affected the permeabilities of key phenolics across the Caco-2 monolayers, which may further affect their bioavailabilities. Therefore, standardization will be necessary to ensure safe and efficacious using of supplements such as SJW.
本研究旨在确定圣约翰草（SJW）补充剂中酚类物质的含量均匀性，并展示产品基质的变化如何影响其吸收和外排。本研究采用 LC 和 LC-MS/MS 方法测定了从当地或互联网购买的 12 种不同产品的酚类含量。进一步将三种代表性提取物提交至 Caco-2 细胞转运实验，评估了芦丁、金丝桃苷和异槲皮苷的转运情况。结果表明，12 种不同的产品显示出 12 种不同的 HPLC 指纹图谱，但所有产品均含有以下主要化合物：芦丁、金丝桃苷、异槲皮苷、槲皮苷、槲皮素和山柰酚。这些主要化合物在不同产品之间的含量均匀性较差，其中山柰酚的差异最小（3.6 倍），而异槲皮苷的差异最大（28.8 倍）。Caco-2 实验表明，产品中芦丁的转运具有方向性，在双向转运中渗透率差异约为 3.6 倍。金丝桃苷和异槲皮苷的方向性渗透率也存在明显差异。使用外排转运体抑制剂研究表明，MRP2 参与异槲皮苷的外排，产品基质影响其外排程度。总之，不同的 SJW 补充剂中酚类物质的含量差异很大，产品基质和植物化学成分的变化影响了关键酚类物质通过 Caco-2 单层的通透性，这可能进一步影响其生物利用度。因此，为确保 SJW 等补充剂的安全有效使用，标准化将是必要的。
