Gut microbiota mediates the pharmacokinetics of Zhi-zi-chi decoction for the personalized treatment of depression

Ethnopharmacological relevance: Zhi-zi-chi decoction (ZZCD), from "Treatise on Febrile Diseases", is a typical traditional Chinese medicine herb pair, which consists of Gardeniae Fructus (GF) and Semen Sojae Praeparatu (SSP). In clinical research, ZZCD was widely used to fight depression, remove annoyance. Many studies have reported that gut microbiota is critical target for the influence of depress through gut-brain axis, and our pre-viously studies have found that ZZCD exhibiting antidepressant effect was through the gut-brain axis. However, the specific mechanism by which gut microbiota mediates the pharmacokinetics parameters of active compounds from ZZCD during the process of depression treatment has not yet been studied.Aim of the study: To explore the differences in pharmacokinetics characters of bioactive iridoids from ZZCD and study the changes of gut microbiota at different stages of depression with the personalized medicine of ZZCD.Materials and methods: A new strategy exploring the relationship among disease phenotypes (D), intestinal microbiota (I), enzymes (E) and traits of metabolism (T) named as "DIET" was established. Firstly, a fast, se-lective and sensitive ultra-performance liquid chromatography coupled with tandem mass spectrometer (UPLC-MS/MS) was established and validated to quality the main bioactive compounds from ZZCD and compare the pharmacokinetics and bioavailability of different iridoids prototypes and metabolites from ZZCD between normal and chronic unpredictable mild stress rats. Subsequently, the activity of corresponding metabolic enzymes of anti-depressive compounds, B-glucosidases and sulfotransferases, were analyzed by p-nitrophenyl-B -D-gluco-pyranoside and sulfotransferases ELISA kits, respectively. Finally, 16S rRNA gene sequencing was adopt to analyze intestinal bacteria composition for the treatment of depression by ZZCD.Results: The antidepressant effect of ZZCD was promoted due to the increased exposures and reduced elimina-tions of anti-depressive compounds, especially geniposide and genipin 1-gentiobioside, under the depression state. With the ZZCD treatment, the depression was improved, but the exposures of anti-depressive compounds from ZZCD gradually decreased. Meanwhile, there were the corresponding decreased trends on the activity of B-glucosidases and sulfotransferases. With the consumption of ZZDC and the improvement of depression, the exposures of anti-depressive iridoid glycosides decreased and the activity of metabolism enzymes restored. Meanwhile, the dysbiosis of pathogenic bacteria (Bacteroidota) induced by depression was ameliorated and the probiotics (Firmicutes) at the phylum and genus level raised, the two phyla are closely related to the production of B-glucosidase and sulfotransferases.Conclusions: It is the first proposed that ZZCD could personalized to treat depression at different stages targeting gut microbiota and gut microbiome could emerged as a potential diagnostic and therapeutic biomarker in depression.