We evaluated the biological activities of water and ethanolic extracts of G. procumbens, M. charantia, C. longa, and H. tuberosus (Jerusalem artichoke) concentrate. The biological activities of five kinds of Jerusalem artichoke composites with addition of G. procumbens, M. charantia and C. longa extracts to H. tuberosus concentrate at different ratio were investigated. The best optimal composite was selected, and its hypoglycemic, antidiabetic and hypolipidemic effects were evaluated in streptozotocin(STZ)-induced diabetic rats in vivo.
Water and 70% ethanol extracts of G. procumbens, M. charantia and C. longa were prepared, and hot water extract of H. tuberosus was concentrated to 60 brix. Solids content was higher in ethanolic than water extract. The pH levels of extracts was slightly acidic except for ethanolic extract of C. longa. Contents of total phenolic and flavonoids showed no significant differences between water and ethanolic extracts, and contents were the highest in ethanolic extract of C. longa. Cholesterol adsorption activity was over 50% in M. charantia extract. DPPH and ABTS radical scavenging activities and reducing power were higher in ethanolic extract than water extract. Especially, the antioxidant activities of water extract of G. procumbens and ethanolic extract of C. longa were highest.
The in vitro, the antioxidant, α-glucosidase inhibitory, and hypoglycemic activities of the five type of Jerusalem artichoke composites in Chang cells were evaluated. DPPH and ABTS radical scavenging activities and reducing power were slightly higher in Comp-2 and Comp-3, was higher in composites with ethanolic extracts compared to water extracts. Especially, Comp-3 had significantly higher α-glucosidase inhibitory activity. Cell viability decreased in a dose-dependent manner in response to ethanol extracts of G. procumbens and C. longa whereas M. charantia, Jerusalem artichoke concentrate, and the five types of composites had no effect on cytotoxicity. AMPK protein activity increased in Comp-1, 2, 3, and 4. Especially, Comp-1 had the highest AMPK protein and glucose uptake activities. However, Comp-3 was selected as the most proper composite considering flavor, taste and contents of H. tuberosus, in the sensory evaluation.
The effects of Jerusalem artichoke composite (Comp-3) were investigated on the hypoglycemic, antidiabetic and lipid improvement status in streptozotocin (STZ)-induced diabetic rats. Rats were divided into seven groups: normal, diabetic control, group fed G. procumbens extract (500 mg/kg bw, D-PGE), group fed Jerusalem artichoke composites (0.5 g/kg bw, D-JAP1; 1.5 g/kg bw, D-JAP2), group fed Jerusalem artichoke concentrate (1.5 g/kg bw, D-JA) and group fed metformin(200 mg/kg bw, D-MET). Blood glucose level decreased in all experimental groups according to time period. Reduction of glucose level in the D-JAP2 and D-MET groups was higher compared to other groups. In the oral glucose tolerance test (OGTT), glucose level of the D-PGE group was highest at 60 min after administration of glucose but significantly decreased after 180 min. Total lipid and triglyceride contents in serum decreased in the group fed composites compared to the diabetic control group. Especially, total lipid content was lower in the D-PGE, D-JAP1, and D-MET groups, and triglyceride content was lower in the D-PGE and D-JAP2 groups compared to the other groups. HDL-C contents of the D-PGE, D-JAP1 and D-JAP2 groups were significantly increased compared to the diabetic control group. Total lipid, triglyceride and cholesterol contents in liver tissue were significantly lower compared to the diabetic control group. AST, ALT, ALP and γ-GTP activities in serum significantly decreased in groups fed experimental diet compared to the diabetic control group. Especially, the D-JAP2 group had activities among the experimental groups. Hepatic TBARS content was significantly decreased in the D-JAP1 and D-JAP2 groups compared to the diabetic control group. Hepatic antioxidative enzyme SOD, catalase and GSH-Px activities were significantly elevated in groups fed experimental diet compared to the diabetic control group.
The selected optimal composite had hypoglycemic, antidiabetic, and lipid improvement effects compared to H. tuberosus concentrate in diabetes. Therefore, Jerusalem artichoke composite may be useful due to its antioxidant and antidiabetic activities in the human body.