Polysaccharides from Callerya speciosa alleviate metabolic disorders and gut microbiota dysbiosis in diet-induced obese C57BL/6 mice.

Callerya speciosa ("Niu Dali" in Chinese) is a well-known edible plant in Southeast China. C. speciosa roots contain a high level of polysaccharides, which have been reported to show multiple health-promoting effects. In the current study, the anti-obesity effects of a crude extract of C. speciosa polysaccharides (NP) and its underlying mechanisms of action are investigated. C57BL/6 mice were divided into three groups and fed either a standard diet or a high-fat diet (HFD). The HFD + NP group mice received oral administration of NP (100 mg per kg per day) every other day for 10 weeks. NP supplementation alleviated HFD-induced diabetic biomarkers including body weight gain, hyperlipidemia, liver steatosis, and adipocyte hypertrophy. Western blot and RT-PCR analyses revealed that NP inhibited hepatic de novo lipogenesis and adipogenesis ( i.e. decreased expression of Srebp1c, Fas, Cebpα, and Pparγ), stimulated adipocyte lipolysis (enhanced mRNA expression of Hsl and Mgl ), and attenuated HFD-induced hepatic inflammation (decreased expression of TNF-α and NF-κB p65). Furthermore, 16S rDNA and GC-MS analyses showed that NP supplementation restored the Firmicutes/Bacteroidetes proportion, elevated colon-derived SCFAs, especially acetic acid content, and increased the relative abundance of genera associated with SCFA production in HFD-fed mice. Findings from this study suggest that NP alleviated HFD-induced obesity in a mouse model, which was possibly due to its ameliorative effects on diet-induced gut dysbiosis. Polysaccharides from C. speciosa are promising prebiotics and they may be further developed as functional foods for the management of obesity.