Decoction is one of the most commonly used dosage forms of traditional Chinese medicine. The stability of chemical constituents in decoction is closely related to the clinical efficacy and safety. There were few reports about the influence of metal ions in the stability of chemical constituents in traditional Chinese medicine. However, there is no evidence that metal ions in decoction water need to be controlled. In this study, 2,3,5,4'-tetrahydroxy stilbene-2-O-β-D-glucoside (THSG), one of the main constituents in Polygoni Multiflori Radix was studied. Ordinary tap water, deionized water, and water containing different metal ions were used to investigate and compare the influence on THSG. The results showed that after storage in a dark place at the room temperature for 10 days, the degradation of THSG was 7% in deionized water, while undetectable in tap water. The content of THSG could be decreased by different kinds of metal ions, and the effect was concentration-dependent. Moreover, Fe3+ and Fe2+ showed the greatest influence at the same concentration; and our study has shown that THSG decreased more than 98% in Fe and Fe2+ solutions at 500 ppm concentration. In the same time we found out p-hydroxybenzaldehyde (molecular weight: 122.036 7) and 2,3,5-trihydroxybenzaldehyde-2-O-glycoside (molecular weight: 316.079 4) were the main degradation products of THSG in tap water and water containing Cu2+, Ca2+, Zn2+, Mg2+ and Al3+. The product of THSG dimer with a water molecule was found in water containing Fe3+ and Fe2+. The above results showed that the metal ions in water could significantly influence the stability of THSG in water, indicating that the clinical efficacy and safety of decoction would be affected if the metal ions in water were not under control. It's suggested that deionized water should be used in the preparation of decoction containing Polygoni Multiflori Radix in the clinic to avoid degradation of THSG. Meanwhile, decoction prepared by tap water should be taken by patients in a short time. Our investigation provides important information and reference about the influence of metal ions on the stability of decoctions in other traditional Chinese medicine that have unstable groups such as hydroxyls and unsaturated bonds, etc.

Berberine(BBR),an isoquinoline alkaloid,has been found in many plants,such as Coptis chinensis Franch and Phellodendron chinense Schneid.Although BBR has a wide spectrum of pharmacological effects,its oral bioavailability is extremely low.In recent years,gut microbiota has emerged as a cynosure to un-derstand the mechanisms of action of herbal compounds.Numerous studies have demonstrated that due to its low bioavailability,BBR can interact with the gut microbiota,thereby exhibiting altered pharma-cological effects.However,no systematic and comprehensive review has summarized these interactions and their corresponding influences on pharmacological effects.Here,we describe the direct interactive relationships between BBR and gut microbiota,including regulation of gut microbiota composition and metabolism by BBR and metabolization of BBR by gut microbiota.In addition,the complex interactions between gut microbiota and BBR as well as the side effects and personalized use of BBR are discussed.Furthermore,we provide our viewpoint on future research directions regarding BBR and gut microbiota.This review not only helps to explain the mechanisms underlying BBR activity but also provides support for the rational use of BBR in clinical practice.