Human Gastrointestinal Metabolism of the Cistanches Herba Water Extract in Vitro: Elucidation of the Metabolic Profile Based on Comprehensive Metabolite Identification in Gastric Juice, Intestinal Juice, Human Intestinal Bacteria, and Intestinal Microsomes.

Cistanches Herba is taken orally as a health food supplement and medicinal plant in Asian countries. It consists of the stems of Cistanche deserticola (CD) and Cistanche tubulosa (CT). The gastrointestinal metabolism of the multiple components contained in Cistanches Herba is crucial for the discovery of bioactive constituents. This study aims to elucidate the comprehensive metabolic profile of the Cistanches Herba water extract by simulating human gastrointestinal metabolism in vitro independently and sequentially using four models: gastric juice, intestinal juice, human intestinal bacteria, and human intestinal microsomes. A total of 35 and 18 metabolites were characterized from CD and CT water extracts, respectively. These metabolites were formed through reduction, methylation, dimethylation, deglycosylation, decaffeoyl, derhamnose, dehydrogenation, and glucuronidation. The difference in metabolites of the Cistanches Herba water extract and single compounds and the difference in metabolites of CD and CT water extracts were caused by the oligosaccharides and polysaccharides in Cistanches Herba.