Ultrasonic assisted extraction, characterization and gut microbiota-dependent anti-obesity effect of polysaccharide from Pericarpium Citri Reticulatae 'Chachiensis'

Pericarpium Citri Reticulatae 'Chachiensis' (PCRC), the premium aged pericarps of Pericarpium Citri Reticulatae, is widely used in traditional Chinese medicines with a diversity of promising bioactivity. Herein we report the extraction, characterization and underlying mechanism of anti-metabolic syndrome of an arabinan-rich polysaccharide from PCRC (PCRCP). This polysaccharide was obtained in a 7.0% yield by using ultrasound-assisted extraction under the optimized conditions of 30 mL/g liquid-to-solid ratio, 250 W ultrasound power for 20 min at 90 °C with pH 4.5. The PCRCP with an average molecular weight of 122.0 kDa, is mainly composed of D-galacturonic acid, arabinose and galactose, which may link via 1,4-linked Gal(p)-UA, 1,4-linked Ara(f) and 1,4-linked Gal(p). Supplementation with PCRCP not only effectively alleviated the weight gain, adiposity and hyperglycemia, but also regulated the key metabolic pathways involved in the de novo synthesis and β-oxidation of fatty acid in high-fat diet (HFD)-fed mice. Furthermore, PCRCP treatment caused a significant normalization in the intestinal barrier and composition of gut microbiota in mice fed by HFD. Notably, PCRCP selectively enriched Lactobacillus johnsonii at the family-genus-species levels, a known commensal bacterium, the level of which was decreased in mice fed by HFD. The depletion of microbiome induced by antibiotics, significantly compromised the effects of anti-metabolic syndrome of PCRCP in mice fed by HFD, demonstrating that the protective phenotype of PCRCP against anti-obesity is dependent on gut microbiota. PCRCP is exploitable as a potential prebiotic for the intervention of obesity and its complications.