Impact of anthocyanin component and metabolite of Saskatoon berry on gut microbiome and relationship with fecal short chain fatty acids in diet-induced insulin resistant mice

Previous studies demonstrated that oral administration of Saskatoon berry powder (SBp) reduced fasting plasma glucose (FPG), insulin resistance, lipids, and inflammatory markers in diet-induced insulin resistant rodents. Mechanism for the beneficial effects of SB remains unclear. The present study examined the effects of high fat-high sucrose (HFHS) diet supplemented with or without 5% SBp, cyanidin-3-glucoside (C3G, an anthocyanin rich in SBp) at a dosage of C3G in 5% SBp, or equimolar concentration of protocatechuic acid (PCA, a relatively stable metabolite of C3G) for 11 weeks on FPG, cholesterol, triglycerides, insulin, homeostatic model assessment of insulin resistance (HOMA-IR), circulatory inflammatory markers, fecal microbiota, and short chain fatty acids in mice. HFHS diet significantly enhanced FPG, insulin, HOMA-IR, lipids and inflammatory markers, but reduced the abundance of fecal Bacteroidetes, Muribaculaceae and propionate compared to low fat diet. Supplementation of SBp, C3G or PCA significantly attenuated HFHS diet induced metabolic and inflammatory markers, and increased the abundances of fecal Muribaculaceae and propionate compared to HFHS diet alone. The abundances of fecal Muribaculaceae negatively correlated with FPG, lipids, HOMA-IR and inflammatory markers in the mice. The abundances of fecal propionate positively correlated with fecal Muribaculaceae and negatively correlated with the metabolic and inflammatory markers. The findings suggest that C3G in SBp and PCA contribute to the metabolic and anti-inflammatory effect of SBp in mice. The increases in fecal Muribaculaceae and propionate may play important regulatory roles in the anti-diabetic and anti-inflammatory benefits of SBp, C3G, and PCA in mice.