Balicalin, the Predominant Flavone Glucuronide of Scutellariae Radix, is Absorbed from the Rat Gastrointestinal Tract as the Aglycone and Restored to its Original Form

作者：Teruaki Akao, Kiyoshi Kawabata, Erika Yanagisawa, Kazuhisa Ishihara, Yasuharu Mizuhara, Yoko Wakui, Yoko Sakashita, Kyoichi Kobashi · 发表于：Journal of Pharmacy and Pharmacology · 年份：2000 · DOI：10.1211/0022357001777621 · 被引用次数：254 · 研究领域：Flavonoids in Medical Research、Natural product bioactivities and synthesis、Phytochemistry and Biological Activities

When baicalin was orally administered to conventional rats, it was detected in their plasma for 24 h after administration, but baicalein, the aglycone of baicalin, was not detected. However, when baicalin was given to germ-free rats, only a small amount of baicalin was detected in their plasma within 2 h after the administration, its AUC0-lim (the area under the concentration-time curve from 0 to last determination time) being 12.0% of that in conventional rats. Subsequently, a considerable amount (55.1 +/- 6.2%) of baicalin was recovered from the gastrointestinal tract even 4 h after administration. When baicalein was orally administered to conventional rats, however, baicalin appeared rapidly in their plasma at an AUC0-lim value similar to that obtained after oral administration of baicalin, despite the absence of baicalein in plasma. When intestinal absorption was evaluated by the rat jejunal loop method, baicalein was absorbed readily, but only traces of baicalin were absorbed. Moreover, in conventional rats a small amount (13.4 +/- 3.1%) of baicalin and an appreciable amount (21.9 +/- 3.4%) of baicalein were recovered from the gastrointestinal tract even 4 h after oral administration of baicalin, but only a small amount (3.93 +/- 1.43%) of baicalein was detected in the intestinal tract 1 h after administration of baicalein. Baicalin was transformed to baicalein readily by the rat gastric and caecal contents. When baicalin was administered orally to conventional rats, an ...