Biotransformation of Total Saponins in Siraitia Fructus by Human Intestinal Microbiota of Normal and Type 2 Diabetic Patients: Comprehensive Metabolite Identification and Metabolic Profile Elucidation Using LC-Q-TOF/MS

Siraitia fructus, known as Luo-Han-Guo (LHG) in Chinese, shows good antidiabetic activity. Gut microbiota have emerged as parameter of the pathophysiology of type 2 diabetes (t2D) mellitus. In this study, in vitro biotransformation of LHG extract by t2D and normal human intestinal microbiota was analyzed using ultraperformance liquid chromatography with time-of-flight mass spectrometry. A total of 19 and 12 metabolites were characterized in t2D and normal human intestinal microbiota, respectively. These metabolites were formed by a series of metabolic reactions including deglycosylation, oxidation, isomerization, and/or deoxidation. The metabolite classes of LHG extract in normal and t2D human intestinal microbiota were nearly the same, but oxidation and isomerization reactions were usually present in t2D human intestinal bacteria. This might be due to metabolic activation by pathological human intestinal bacteria. Our study indicates that there are differences in the biotransformation of LHG extract in normal and t2D human intestinal bacteria.