In Vitro Biotransformation of Ziziphi Spinosae Semen Saponins by Gut Microbiota from Healthy and Insomniac Groups

Ziziphi Spinosae Semen saponins (ZSSS) show sedative-hypnotic activity but have very low bioavailability, potentially due to their conversion into bioactive metabolites by gut microbiota. In this study, the biotransformation of ZSSS by gut microbiota from healthy humans and patients with insomnia in vitro was analyzed. A total of 21 prototype compounds and 49 metabolites were identified using UHPLC-Q-Orbitrap-MS. Deglycosylation, deoxygenation, dehydration, and deacylation were detected in both healthy individuals and insomniacs. However, oxidation and hydrogenation were uniquely observed in insomniacs. ZSSS can enhance beneficial bacteria, such as <i>Veillonella</i>, <i>Dialister</i>, and <i>Bacteroides.</i> ZSSS can promote the synthesis of short-chain fatty acids (SCFAs), especially acetic acid, propionic acid, and butyric acid. Furthermore, it was found that the sedative-hypnotic activity of ZSSS was enhanced after biotransformation, as determined by a sodium pentobarbital-induced sleeping test (SPST), open-field behavior test (OFBT), and molecular docking experiment (MDE). These results collectively offer valuable insight into the mechanism of action of ZSSS.