Abstract: 【Objective】 The purpose of this study was to observe the effect of Platycodon grandiflorum ultrafine powder on the diversity of intestinal flora in mice,and provide evidence for clinical application and safety of Platycodon grandiflorum ultrafine powder. 【Method】 Twenty-four male Kunming mice were randomly divided into control group and high (3.0 g/kg),medium (1.5 g/kg) and low (0.3 g/kg) dose groups of Platycodon grandiflorum ultrafine powder，6 mice in each group.Mice in each dose groups of Platycodon grandiflorum ultrafine powder were gavaged with the corresponding dose of Platycodon grandiflorum ultrafine powder dissolved in water,and mice in control group were gavaged with equal volume of purified water,the medication was administered continuously for 14 days.The body weight and feed consumption of mice in each group were recorded daily.On the 15th day of the experiment,mice in each group were sacrificed for autopsy and histopathological observation.Meanwhile,the feces of mice were aseptically collected to amplify the V3-V4 regions of the 16S rRNA gene of the fecal microbiota.High-throughput sequencing was used to analyze Alpha and Beta diversity of the microbiota and the species composition at phylum and genus levels.And microbial function prediction and analysis were conducted. 【Result】 ①The body weight gain of mice in medium and high dose groups were significantly lower than those in control group (P＜0.05).The average feed consumption of mice in medium dose group of Platycodon grandiflorum superfine powder was lower than that in control group.②Compared with control group,no pathological abnormalities were found in stomach,duodenum,jejunum and ileum of mice in each dose group of Platycodon grandiflorum superfine powder.③The Alpha diversity index in intestinal flora of mice in each dose group of Platycodon grandiflorum superfine powder was higher than that in control group(P＞0.05),and increased with the increase of the dosage.Beta diversity analysis of intestinal flora showed that low and high doses of Platycodon grandiflorum superfine powder had no significant effect on the structure of intestinal flora in mice,while medium doses of Platycodon grandiflorum superfine powder could significantly change the structure of intestinal flora in mice (P＜0.05).④Compared with control group,at phylum level,the contents of Firmicutes and Cyanobacteria in the intestinal tract of mice in medium dose group of Platycodon grandiflorum ultrafine powder were significantly increased (P＜0.05),while the abundance of Bacteroidetes,Proteobacteria and Planctomycetes was significantly decreased (P＜0.05).At genus level,the abundance of Prevotella,Parabacteroides and rc4_4 in the intestinal tract of mice in medium dose group was significantly increased (P＜0.05),while the abundance of Kaistobacter and Pseudomonas etc.was significantly decreased (P＜0.05).⑤Microbial function prediction analysis found that the intestinal microbial genome functions of mice in medium dose group of Platycodon grandiflorum superfine powder were mainly enriched in amino acid biosynthesis and cofactors,prosthetic groups,electronic carriers and vitamin biosynthesis and nucleotide biosynthesis.Compared with control group,there were 11 significantly downregulated differential metabolic pathways in medium dose group of Platycodon grandiflorum superfine powder,mainly involving the degradation of fluorobenzoates,polycyclic aromatic hydrocarbons and yeast meiosis. 【Conclusion】 Platycodon grandiflorum ultrafine powder was able to increase the diversity of intestinal flora in mice,and 1.5 g/kg Platycodon grandiflorum ultrafine powder could significantly change the structure of intestinal flora.The results of this experiment provided data support for the scientific dosage and safety of Platycodon grandiflorum ultrafine powder’s clinical use,and also support for future pharmacodynamic studies related to Platycodon grandiflorum ultrafine powder and intestinal flora.

Key words: Platycodon grandiflorum ultrafine powder; 16S rRNA; mice; intestinal flora; microbial diversity