Portulaca oleracea L. Extract Alleviated Type 2 Diabetes Via Modulating the Gut Microbiota and Serum Branched-Chain Amino Acid Metabolism

Abstract

Scope: Portulaca oleracea L. extracts (PE) show hypoglycemic function, but the precise mechanism remains obscure. This study is designed to investigate the association of the antidiabetes effect of PE with the gut microbiota modulation and BCAAs metabolism. Methods and Results: The Orbitrap LC-MS to Orbitrap Fusion Lumos Tribrid mass spectrometer is employed to analyze the major compounds in PE. The components of the intestinal microflora in diet-induced/STZ-treated diabetic mice are analyzed by high-throughput 16S rRNA genes sequencing. The results show that PE improves blood glucose and insulin level, increases anti-inflammatory cytokine level, lowers serum branched-chain amino acids (BCAAs), and increases serum glutamine level. PE also protects the mucosal epithelium of the colon and cecum from damage. On the impact of gut microbial composition, PE reduces the Firmicutes to Bacteroidetes ratio and the abundance of the Lachnospiraceae_NK4A136_group, Blautia, Ruminiclostridium_9, Dubosiella, and increases the abundance of the Bacteroides, Akkermansia, and Mucisprillum genera. Bacterial functionality prediction indicates PE potentially inhibits bacterial BCAAs biosynthesis, and promotes the tissue-specific expression of BCAAs catabolic enzyme for reducing BCAAs supplementation. Conclusion: These results reveal that PE improving T2D-related biochemical abnormalities is associated not only with gut microbiota modification but also with the tissue-specific expression of BCAAs catabolic enzyme.