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BackgroundKurozu concentrated liquid (KCL) is used as a health-promoting supplement for the treatment of disorders such as cancer, hyperlipidemia, and hypertension in Japan. We investigated the possible anti-obesity effects of KCL in rats.MethodsMale Sprague Dawley rats were fed American Institute of Nutrition 76 formula diet and were orally administrated KCL or acetic acid at a dose of 100 mg/kg body weight or deionized water for 4 weeks. Adipocyte size, DNA content in subcutaneous adipose tissue, lipid levels in the serum and liver, and the rate of fatty acid excretion were determined. Effects of KCL on pancreatic lipase activity and 3T3-L1 preadipocyte differentiation were investigated in vitro.ResultsIn the KCL group, the average adipocyte size in subcutaneous and perirenal adipose tissues was significantly reduced. The KCL-administered rats displayed greater numbers of small adipocytes in the subcutaneous, perirenal and mesenteric adipose tissues than did rats from the other groups. In the KCL group, the DNA content in subcutaneous adipose tissue was significantly increased. The rate of fatty acid excretion was significantly increased in the KCL group. Furthermore, KCL significantly inhibited pancreatic lipase activity in vitro, and also significantly inhibited fat accumulation and mRNA expression of fatty acid binding protein 2 (aP2) and peroxisome proliferator-activated γ (PPARγ) in 3T3-L1 preadipocyte. The levels of serum and liver lipids, the concentration of serum glucose, and the levels of adiponectin were similar among the 3 groups.ConclusionOral administration of KCL decreases the adipocyte size via inhibition of dietary fat absorption and reductions of PPARγ and aP2 mRNA expression levels in adipocytes.

BackgroundExogenously hypercholesterolemic (ExHC) rats develop hypercholesterolemia and low hepatic triacylglycerol (TAG) levels when dietary cholesterol is loaded. The responsible gene Smek2 was identified via linkage analysis using the original strain Sprague–Dawley (SD) rats. In this study, we compared SD and ExHC rats to investigate a relationship between hypercholesterolemia and the low hepatic TAG levels observed in ExHC rats.MethodsMale 4-weeks-old ExHC and SD rats were fed a 1% cholesterol diet for 1 week. Serum and liver parameters were analyzed. Gene expression and enzyme activities related to TAG metabolism were also assessed.ResultsWe reproducibly observed higher serum cholesterol and lower hepatic TAG levels in ExHC rats than in SD rats. Golgi apparatus in the livers of ExHC rats secreted β-very-low-density lipoprotein (β-VLDL) that had higher cholesterol ester (CE) and lower TAG content than those in the β-VLDL secreted by SD rats. Gene expression related to fatty acid and TAG synthesis in ExHC rats was lower than that in SD rats. Enzymatic activities for fatty acid synthesis were also relatively lower in ExHC rats. Moreover, the fatty acid composition of hepatic and serum CE in ExHC rats showed that these CEs were not modified after secretion from the liver despite the similar activities of serum lecithin-cholesterol acyltransferase (LCAT) in ExHC rats to those in SD rats.ConclusionsLow production of liver TAG and secretion of CE-rich, TAG-poor β-VLDL without modification by LCAT in the circulation contributed to hypercholesterolemia induced by dietary cholesterol in ExHC rats.

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Soyasaponins are triterpenoid glycosides found in soybean. We investigated whether soyasaponin ameliorates lipid metabolism and its possible mechanisms. In C57BL/6J mice fed a high‐fat diet (HFD), soyasaponin (SAP) was orally administered for 9 weeks. Additionally, we evaluated the effect of soyasapogenols on 3T3‐L1 adipocytes. In HFD‐fed mice, the SAP significantly reduced body weight by 7% and relative adipose tissue weight by 35%. X‐ray computed tomography demonstrated that the SAP reduced visceral and subcutaneous adipose tissue weights during week 3 of feeding. The SAP reduced sterol regulatory element‐binding protein‐1c (SREBP‐1c) mRNA levels by 32% in the epididymal adipose tissue, significantly decreasing the triacylglycerol (TAG) content by 37% and SREBP‐1c and fatty acid synthase mRNA levels by 52% and 61%, respectively, in the liver. In 3T3‐L1 adipocytes, soyasapogenol B significantly decreased lipid droplets. The SAP containing soyasaponin A and B as conjugates demonstrate anti‐obesity effects by suppressing adipocyte differentiation and lipogenesis, with a preventive effect on hepatic TAG accumulation by suppressing lipogenesis. Practical Application Soyasaponin is one of the oleanane triterpenoids in soybeans. We have demonstrated that soyasaponin potently reduces body weight and white adipose tissue weight, and hepatic triacylglycerol accumulation in high‐fat diet‐fed mice. Thus, soyasaponin is a beneficial compound to prevent obesity and fatty liver.