Fermented Psidium guajava leaves regulate the gut microbiota and improve metabolic alterations in diabetic mice

The phenolic extract from fermented Psidium guajava leaves (PFGL) helps to improve diabetes; however, its hypoglycemic and hypolipidemic mechanisms remain unclear. In this study, gut microbiota modulation and glucose-lipid metabolism was investigated. The results showed that dietary supplement of PFGL enriched in quercetin glucosides significantly improved serum glucose-lipid profiles as well as insulin resistance in diabetic mice. The gut microbiota of diabetic mice was modulated by PFGL (200 mg/kg), causing an abundance of Bacteroidetes, Prevotellaceae, and Alistipes and a reduced the presence of Firmicutes and Streptococcus. Increased levels of short-chain fatty acids (SCFA) activated G protein-coupled receptor signaling that induced peptide YY release to promote insulin secretion. Diabetes-induced serum metabolite disorders that are involved in glycer-ophospholipid metabolism and tryptophan metabolism were restored by PFGL. The protein expression of metabolic enzymes including phospho-adenosine 5'-monophosphate-activated protein kinase, fatty acid syn-thase, acyl-coenzyme A oxidase, and diacylglycerol aeyltransferase 2 were also regulated to promote glucose -lipid metabolism. In particular, gut microbiota enriched with Alistipes genera and SCFA metabolic regulation were closely correlated with diabetes-related indicators. These findings provide a theoretical support for the development and application of PFGL for the treatment of diabetes.

Automated summary

The phenolic extract from fermented Psidium guajava leaves (PFGL) improves diabetes by modulating gut microbiota and glucose-lipid metabolism.