The Antidiabetic Effect of Dietary Persimmon (Diospyros kaki L. cv. Sangjudungsi) Peel in Streptozotocin-induced Diabetic Rats

ABSTRACT: The phytochemical composition of persimmon ( Diospyros kaki L. cv. Sangjudungsi) peel (PP), a waste by product of dried persimmon, and its possible antidiabetic influence in streptozotocin-induced diabetic rats were examined. Dietary fiber was found to be the major component of PP, with a high content of 40.35% (w/w). PP also contains high levels of antioxidants including total carotenoids, vitamin C, and total phenolics. A 2-wk dietary supplementation of PP at both 5% and 10% (w/w) significantly lowered food intake, blood glucose, plasma triglyceride, and total cholesterol levels in diabetic rats. Dietary PP also restored the reduced plasma high-density lipoprotein (HDL) -cholesterol levels in diabetic rats. Although regression of the hypertrophies of liver and kidney was not observed in diabetic rats, dietary PP showed the partial or complete restoration of plasma aspartate amino transferase (AST), and creatinine levels, which serve as indicators of liver and renal dysfunctions, respectively. Therefore, PP containing high levels of dietary fiber and antioxidants with antidiabetic properties represents a potential dietary supplement for improving hyperglycemia and diabetic complications.     

Plant Alkaloid Tetrandrine Is a Nuclear Receptor 4A1 Antagonist and Inhibits Panc-1 Cell Growth In Vitro and In Vivo

The orphan nuclear receptor 4A1 (NR4A1) is highly expressed in human pancreatic cancer cells and exerts pro-oncogenic activity. In a previous study, we demonstrated that fangchinoline (FCN), a natural inhibitor of nuclear NR4A1, induces NR4A1-dependent apoptosis in human pancreatic cancer cells. In this study, we evaluated FCN and its structural analogs (berbamine, isotetrandrine, tetrandrine, and tubocurarine) for their inhibitory effects on NR4A1 transactivity, and confirmed that tetrandrine (TTD) showed the highest inhibitory effect in pancreatic cancer cells. Moreover, in a tryptophan fluorescence quenching assay, TTD directly bound to the ligand binding domain (LBD) of NR4A1 with a K_D value of 10.60 μM. Treatment with TTD decreased proliferation and induced apoptosis in Panc-1 human pancreatic cancer cells in part through the reduced expression of the Sp1-dependent anti-apoptotic gene survivin and induction of ROS-mediated endoplasmic reticulum stress, which are the well-known NR4A1-dependent proapoptotic pathways. Furthermore, at a dose of 25 mg/kg/day, TTD reduced tumor growth in an athymic nude mouse xenograft model bearing Panc-1 cells. These data show that TTD is an NR4A1 antagonist and that modulation of the NR4A1-mediated pro-survival pathways is involved in the antitumor effects of TTD.     

Nrf2-mediated protective effect of protein hydrolysates from Protaetia brevitarsis larvae against oxidative stress-induced hepatotoxicity

Food Science and Biotechnology - In this study, we hypothesized that Protaetia brevitarsis larvae (PBL) protein hydrolysates, which have been previously reported to exhibit strong antioxidant...