(P03-043-23) Scytosiphon lomentaria Extract Modulates Gut Microbiota and Prevents Obesity in High-Fat Diet-Fed Mice

Objectives: Obesity is a chronic disease characterized by energy expenditure abnormalities and inflammation of adipose tissue. The brown seaweed Scytosiphon lomentaria (SL) contains several bioactive compounds with antioxidant and anti-inflammatory properties; however, its anti-obesity effects and effects on the gut microbiota profile are unclear. The aim of this study was to examine the anti-obesity properties of SL in in vitro and in vivo models, as well as the underlying mechanisms.

Methods: Experiments were conducted in vitro with 3T3-L1 adipocytes to investigate the effect of SL extract on lipids and the potential mechanism for suppressing lipid formation using Oil Red O Staining, RT-PCR, and Western Blotting. In animal experiments, mice were fed a multigrain diet or a high-fat diet (HF) and were orally administered SL extract or PBS daily. The lipogenic and thermogenic pathways and the composition of intestinal flora were investigated using H&E staining, blood analysis, RT-PCR, Western Blot, and 16S rRNA gene sequencing.

Results: Sinapinic acid, catechins, quercetin, hydroxycresylphenol A, acacetin, and caffeic acid were identified in SL extract by LC-MS. In cell experiments, SL extract inhibited lipid formation in 3T3-L1 adipocytes without cytotoxicity, regulated mRNA (Acc1, C/ebpa, Pparg, Ucp1) and protein expression (p-ACC1/ACC1, p-AMPK/AMPK, UCP1). In animal experiments, SL extract reduced body fat and weight, and regulated mRNA (Acc1, Fas, C/ebpa, Srebp1, Ampk, Pgc1a, Ppara, Prdm16, Ucp1) and protein expression (p-ACC1/ACC1, p-AMPK/AMPK, UCP1). SL extract decreased the HF-induced Firmicutes/Bacteroidetes ratio and reversed the HF-induced reduction in the abundance of Bacteroides, Bacteroides vulgaris, and Fusobacterium prausnitzii.

Conclusions: These findings suggested that SL extract can aid in weight loss in mice fed a high-fat diet and can be used as an anti-obesity preventative by altering adipogenic and thermogenic pathways as well as the composition of the gut microbiota.

Funding Sources: National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT)