Gut microbiota-based pharmacokinetic-pharmacodynamic study and molecular mechanism of specnuezhenide in the treatment of colorectal cancer targeting carboxylesterase

Specnuezhenide(SNZ)is among the main components of Fructus Ligustri Lucidi,which has antiinflammation,anti-oxidation,and anti-tumor effect.The low bioavailability makes it difficult to explain the mechanism of pharmacological effect of SNZ.In this study,the role of the gut microbiota in the metabolism and pharmacokinetics characteristics of SNZ as well as the pharmacological meaning were explored.SNZ can be rapidly metabolized by the gut microbiome,and two intestinal bacterial metabolites of SNZ,salidroside and tyrosol,were discovered.In addition,carboxylesterase may be the main intestinal bacterial enzyme that mediates its metabolism.At the same time,no metabolism was found in the incubation system of SNZ with liver microsomes or liver homogenate,indicating that the gut microbiota is the main part involved in the metabolism of SNZ.In addition,pharmacokinetic studies showed that salidroside and tyrosol can be detected in plasma in the presence of gut microbiota.Interestingly,tumor development was inhibited in a colorectal tumor mice model administered orally with SNZ,which indicated that SNZ exhibited potential to inhibit tumor growth,and tissue distribution studies showed that salidroside and tyrosol could be distributed in tumor tissues.At the same time,SNZ modulated the structure of gut microbiota and fungal group,which may be the mechanism governing the antitumoral activity of SNZ.Furthermore,SNZ stimulates the secretion of short-chain fatty acids by intestinal flora in vitro and in vivo.In the future,targeting gut microbes and the interaction between natural products and gut microbes could lead to the discovery and development of new drugs.

Sources of varieties and quality of circular Fructus Ligustri Lucidi

This study aimed to trace sources and quantitatively analyze the specnuezhenide content of circular Fructus Ligustri Lucidi for clinical use. Different specifications of Fructus Ligustri Lucidi were identified using DNA barcoding technology and the specnuezhenide content was analyzed by High Performance Liquid Chromatography(HPLC). The ITS sequence of circular Fructus Ligustri Lucidi was identical to that of standard privet, which was determined through botanical identification. ITS sequence similarity between circular Fructus Ligustri Lucidi and Fructus Ligustri Lucidi which was registered in NCBI ranged from 99.5% to 100%. The sequences of circular and other Fructus Ligustri Lucidi were clustered in a Neighbor-Joining tree with bootstrap value of 95, and these sequences could be distinguished from adulterants. Conforming to pharmacopoeia standard, the average specnuezhenide content of circular Fructus Ligustri Lucidi was higher than that of chicken waist Fructus Ligustri Lucidi. Circular Fructus Ligustri Lucidi derived from Ligustrum lucidum Ait. and the specnuezhenide content was higher in circular Fructus Ligustri Lucidi than that in chicken waist Fructus Ligustri Lucidi.