The Hypoglycemic Activities and Underlying Mechanisms of Two Saponins-Rich Components from Fried Ziziphus jujuba...

Dried Ziziphus jujuba Mill. kernel is a potential natural source of nutraceutical and therapeutic agents in China. Recent researches have shown that the saponins of dried Z. jujuba Mill. kernel (SZJs: SZJ-1 and SZJ-2) have various biological effects. However, the hypoglycemic activities and underlying mechanisms of SZJs remain obscure.

In the current study, two saponins SZJ-1 and SZJ-2 mainly composed of betulinic acid, spinosin, jujuboside A, and jujuboside B are extracted and is olated from dried Z. jujuba Mill. kernel. The SZJ-1 and SZJ-2 could significantly inhibit the activities of digestion enzymes α-glucosidase and α-amylases. The hypoglycemic ability of SZJ-1 and SZJ-2 is further investigated and the results show that SZJ-1 and SZJ-2 can improve the hyperglycemic by increasing the glucose consumption, improving the superoxide dismutase (SOD), hexokinase (HK), pyruvate kinase (PK) activities, and decrease the MDA content of insulin resistant HepG2 cells. Furthermore, SZJ-1 and SZJ-2 can activate the phosphorated adenosine 5'-monophosphate (AMP)-activated protein kinase α (p-AMPK), phosphoinositide 3-kinase p110α (PI3K-p110α), and phosphorated glycogen synthase kinase-3β (Ser9) (p-GSK3β).

These results indicating that the SZJ-1 and SZJ-2 might improve the insulin resistant symptoms by improving the energy metabolic level and increasing the glycogen synthase activity of HepG2 cells.