Moutan Cortex and Paeoniae Radix Rubra reverse high-fat-diet-induced metabolic disorder and restore gut microbiota homeostasis / 中国天然药物

The present study was designed to investigate the therapeutic effcts of Moutan Cortex (CM, root bark of Paeonia suffruticosa Andr) and Paeoniae Radix Rubra (PR, root of Paeonia veitchii Lynch) on metabolic disorders, focusing on the infuence of CM and PR on the obesity-related gut microbiota homeostasis. The diet-induced obese (DIO) mouse model was used to test the therapeutic effects of CM and PR. The mice were orally administered with CM and PR for 6 weeks, and oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed to evaluate the insulin sensitivity of the mice. Sterol-regulatory element binding proteins (SREBPs) and their target genes were measured by quantitative RT-PCR. High-throughput 16S ribosomal RNA (16S rRNA) gene sequencing technology was used to determine the composition of gut microbiota, and the metabolites in serum were analyzed by GC-MS. Our results indicated that CM and PR combination alleviated obese and insulin resistance in the DIO mice, leading to increased glucose uptake and gene expression in muscle and liver, and down-regulated SREBPs and their target genes in liver. Interesting, neither the CM-PR extracts, nor the major components of CM and PR did not affect SREBPs activity in cultured cells. Meanwhile, CM and PR significantly modulated the gut microbiota of the high-fat diet (HFD) treated mice, similar to metformin, and CM-PR reversed the overall microbiota composition similar to the normal chow diet (NCD) treated mice. In conclusion, our results provide novel mechanisms of action for the effects of CM and PR in treating DIO-induced dysregulation of sugar and lipid metabolism.

Petroleum ether sub-fraction of rosemary extract improves hyperlipidemia and insulin resistance by inhibiting SREBPs / 中国天然药物

As a culinary and medicinal herb, rosemary is widely used. The present work aimed to investigate the effects of rosemary extracts on metabolic diseases and the underlying mechanisms of action. Liver cells stably expressing SREBP reporter were used to evaluate the inhibitory effects of different fractions of rosemary extracts on SREBP activity. The obese mice induced by Western-type diet were orally administered with rosemary extracts or vehicle for 7 weeks, the plasma and tissue lipids were analyzed. SREBPs and their target genes were measured by quantitative RT-PCR. We demonstrated that the petroleum ether sub-fraction of rosemary extracts (PER) exhibited the best activity in regulating lipid metabolism by inhibiting SREBPs, while water and n-BuOH sub-fraction showed the SREBPs agonist-effect. After PER treatment, there was a significant reduction of total SREBPs in liver cells. PER not only decreased SREBPs nuclear abundance, but also inhibited their activity, resulting in decreased expression of SREBP-1c and SREBP-2 target genes in vitro and in vivo. Inhibiting SREBPs by PER decreased the total triglycerides and cholesterol contents of the liver cells. In the mice fed with Western-type diet, PER treatment decreased TG, TC, ALT, glucose, and insulin in blood, and improved glucose tolerance and insulin sensitivity. Furthermore, PER treatment also decreased lipid contents in liver, brown adipose tissue, and white adipose tissue. Our results from the present study suggested that petroleum ether fraction of rosemary extracts exhibited the best potential of improving lipid metabolism by inhibiting SREBPs activity.