Antidiabetic Activity of Lessonia nigrescens Extract in Type 2 Diabetic Mice

Lessonia nigrescens inhabits rocky intertidal and shallow subtidal zone, being a crucial brown algae to ecology and economy. L. nigrescens contains a broad range of bioactive compounds, such as fucans and phlorotannins. In this study, the antidiabetic activity of Lessonia nigrescens ethanolic extract was investigated in streptozotocin (SZT)-induced type 2 diabetic mice fed with a high-sucrose/high-fat diet. The components of the intestinal microflora in diabetic mice were analyzed by high-throughput next-generation 16S rRNA gene sequencing. Fasting blood glucose levels in type 2 diabetic mice were significantly decreased after administration of the extract. The histology revealed that the extract could protect the cellular architecture of liver and kidney. The extract significantly increased Bacteroidetes bacteria and decreased Firmicutes populations in intestinal microflora. Specifically, the extract can increase Barnesiella and reduce Clostridium and Alistipes. The increased gene and protein expression levels of PI3K in liver were observed in the extract groups, while the expressions of JNK1 were significantly downregulated by the extract.