Abstract: In order to discover the metabolites of protopanaxatriol saponins from red ginseng in human intestinal flora via intestinal bacteria incubation model. The identification and quantification of protopanaxatriol saponins were determined by using rapid resolution liquid chromatography-quadrupole time-of-flight mass spectrometry (RRLC-Q-TOF MS) and ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-QQQ MS) , and applied 16S rDNA high-throughput sequencing technology to tinvestigate the effect of protopanaxatriol on intestinal microorganisms. The UPLC-Q-TOF MS analysis was performed on a Supelco Ascentis Express C₁₈ RRHD (50 mm×3.0 mm×2.7 μm) and a Thermo Syncronis-C₁₈RRHD(100 mm×2.1 mm×1.7 μm)was used to UPLC-QQQ MS. The gradient elution was column with acetonitrile and 0.1% formic acid water as mobile phase. The data was collected by electropray ionization in positive mode. The results show that the ginsenoside Re and Rg1 in the protopanaxatriol group, after incubated in the human intestinal flora, according to the contrast of the reference standards and accurate masses of molecules, the transformation products into Rg2, Rh1, F1 and PPT are identified by RRLC-Q-TOF MS. Through the quantitative analysis of the conversion rate of metabolites, at the period of 60 h incubation, the production rates of products Rg2, Rh1, F1 and PPT are about 6%, 12%, 11% and 56%, respectively. Illumina Hiseq 2500 platform was used to sequence intestinal flora of feces samples and compared with the feces of the blank group, the protopanaxatriol saponin group significantly increased the relative abundance of Firmicutes at the phylum level, significantly decreased Bacteroidetes, Proteobacteria, and significantly increased Prevotella_9, Faecalibacterium, Dialister at the genus level, and significantly decreased Escherichia-Shigella, Dorea, Lachnoclostridium. This study provides a basis for the determination of the pharmacodynamic material basis and pharmacodynamic targets of protopanaxatriol-type saponins based on the intestinal flora.

Key words: Protopanaxatriol, Human intestinal microflora, Metabolic transformation, Liquid chromatography-mass spectrometry, Micro-biodiversity