미강 페놀산 농축물과 Hydroxycinnamic Acids의 세포내 항당뇨 및 항산화 활성 = Anti-hyperglycemic and Antioxidative Activities of Phenolic Acid Concentrates of Rice Bran and Hydroxycinnamic Acids in Cell Assays

다국어 초록 (Multilingual Abstract)

Phenolic acid concentrates of rice bran(RB-ex) and hydroxycinnamic acids were investigated for their anti-hyperglycemic activities through glucose uptake and glucokinase activity using HepG2 cells and stimulatory effects on insulin secretion using HIT-T15 cells. RB-ex was prepared as an ethylacetate extract after alkaline hydrolysis and hydroxycinnamic acids, found as major compositions of RB-ex, such as ferulic acid(FA), sinapic acid(SA) and p-coumaric acid(p-CA) were investigated to compare with the properties of RB-ex. The properties of glucose uptake in HepG2 cells were examined in the absence of insulin and two different glucose concentrations(5.5 mM and 25 mM). RB-ex and FA showed anti-hyperglycemic activities through the increase of glucose uptake and the stimulation of glucokinase activity in HepG2 cells. RB-ex exhibited higher glucose uptakes with higher glucose concentrations, whereas FA exhibited the same increasing effects on both concentrations of glucose. RB-ex and FA exhibited doubled glucokinase activities relative to control. In the presence of insulin in the 25 mM glucose-containing medium, the levels of glucose uptake were increased in all treatments compared with control.
As stimulatory effects of samples on insulin secretion were estimated, RB-ex and FA stimulated insulin secretion at a concentration of 25 ㎍/㎖and in particular, FA showed the highest amount of insulin-release in HIT-T15 cells. Antioxidative effects on HIT-T15 cells, RB-ex and hydroxycinnamic acids, excluding p-CA, showed inhibitory activities of 78% to 80%at a concentration of 100 ㎍/㎖. On the basis of these results, we conclude that RB-ex and FA could help decrease blood glucose levels and prevent the cell damages via antioxidant activity.

참고문헌 (Reference)

1 Simin L, "Whole-grain consumption and risk of coronary heart disease : Result from the nurses health study" 70 : 412-419, 1999

2 Faulds CB, "The role of hydroxycinnamates in the plant cell wall, review" 79 : 393-395, 1999

3 Nomura E, "Synthesis of amide compounds of ferulic acid, and their stimulatory effects on insulin secretion in vitro" 11 : 3807-3813, 2003

4 Baynes JW, "Role of oxidative stress in development of complications in diabetes" 40 : 405-412, 1991

5 Tiedge M, "Relation between antioxidant enzyme gene expression and antioxidative defense status of insulin-producing cells" 46 : 1733-1742, 1997

6 Lowry OH, "Protein measurement with the Folin phenol reagent" 193 : 265-272, 1951

7 Balasubashini MS, "Protective effects of ferulic acid on hyperlipidemic diabetic rats" 40 : 118-122, 2003

8 Baek SH, "Prevention of type 2 diabetes" 3 : 128-131, 2007

9 Cheruvanky R, "Phytochemical Functional Foods. Phytochemical Products: Rice Bran" CRC press 347-376, 2000

10 Pratipanawatr T, "Normalization of plasma glucose concentration by insulin therapy improves insulin-stimulated glycogen synthesis in type 2 diabetes" 51 : 462-468, 2002

11 Eng J, "Isolation and characterization of exendin-4, an exendin-3 analogue, from Heloderma suspectum venom. Further evidence for an exendin receptor on dispersed from guinea pig pancreas" 15 : 7402-7405, 1992

12 Zhang H, "Insulin secretion and cAMP metabolism in HIT cells" 38 : 44-48, 1989

13 Jung EH, "Hypoglycemic effect of a phenolic acid fraction of rice bran and ferulic acid in C57BL/KsJ-db/db mice" 55 : 9800-9804, 2007

14 Kushi LH, "Grains, legumes, and chronic disease risk reduction. Evidence epidemiological studies" 70 : 451s-458s, 1999

15 Zimmet P, "Global and societal implications of the diabetes epidemic" 414 : 782-787, 2001

16 Rukkumani R, "Ferulic acid, a natural phenolic antioxidant modulates altered lipid profiles during alcohol and thermally oxidized sunflower oil induced toxicity" 4 : 119-132, 2004

17 Davidson AL, "Factors underlying significant underestimations of glucokinase activity in crude liver extracts: Physiological implications of higher cellular activity" 253 : 156-167, 1987

18 Waltner-Law ME, "Epigallate, a constituent of green tea, represses hepatic glucose production" 38 : 34933-34940, 2002

19 Chang YS, "Effects of vitamin E supplementation on the lipid peroxides and activities of antioxidative enzymes in the pancreas of diabetic KK mice" 31 : 153-158, 1998

20 Yin J, "Effects of berberine on glucose metabolism in vitro" 51 : 1439-1443, 2002

21 Hiramatsu K, "Effect of r-oryzanol on atheroma formation in hypercholesterolemic rabbits" 15 : 299-306, 1990

22 Wolff SP, "Diabetes mellitus and free radicals" 49 : 642-652, 1993

23 Tura F, "Correction of diabetic alteration by glucokinase" 93 : 7225-7230, 1996

24 Singleton VL, "Colorimetry of total phenolics with phosphomolybdic-phosphotungstic acid reagents" 16 : 144-158, 1965

25 Baltolome B, "Barley spent grain: release of hydroxycinnamic acid (ferulic and p-coumaric acids) by commercial enzyme preparation" 79 : 435-439, 1999

26 Ohnishi M, "Antioxidant activity and hypoglycemic effect of ferulic acid in STZ-induced diabetic mice and KK-Ay mice" 21 : 315-319, 2004

27 Abel, ED, "Adiposeselective targeting of the GLUT4 gene impairs insulin action in muscle and liver" 409 : 729-733, 2001

28 Peungvicha P, "4-Hydroxybenzoic acid: A hypoglycemic constituent of aqueous extract of pandanus odorus root" 62 : 79-84, 1998