Dietary supplementation with watermelon pomace juice enhances arginine availability and ameliorates the metabolic syndrome in Zucker diabetic fatty rats.
Watermelon is rich in L-citrulline, an effective precursor of L-arginine. This study was conducted to determine whether dietary supplementation with watermelon pomace juice could ameliorate the metabolic syndrome in the Zucker diabetic fatty (ZDF) rat, an animal model of noninsulin-dependent diabetes mellitus. Nine-week-old ZDF rats were assigned randomly to receive drinking water containing 0% (control) or 0.2% L-arginine (as 0.24% L-arginine-HCl), 63% watermelon pomace juice, 0.01% lycopene, or 0.05% citrus pectin (n = 6 per treatment). At the end of the 4-wk supplementation period, blood samples, aortic rings, and hearts were obtained for biochemical and physiological analyses. Feed or energy intakes did not differ among the 5 groups of rats. However, dietary supplementation with watermelon pomace juice or L-arginine increased serum concentrations of arginine; reduced fat accretion; lowered serum concentrations of glucose, free fatty acids, homocysteine, and dimethylarginines; enhanced GTP cyclohydrolase-I activity and tetrahydrobiopterin concentrations in the heart; and improved acetylcholine-induced vascular relaxation. Compared with the control, dietary supplementation with lycopene or citrus pectin did not affect any measured parameter. These results provide the first evidence to our knowledge for a beneficial effect of watermelon pomace juice as a functional food for increasing arginine availability, reducing serum concentrations of cardiovascular risk factors, improving glycemic control, and ameliorating vascular dysfunction in obese animals with type-II diabetes.
Wu
Guoyao
G
Faculty of Nutrition and Department of Animal Science, Texas A&M University, College Station, TX 77843, USA. g-wu@tamu.edu
Collins
Julie K
JK
Perkins-Veazie
Penelope
P
Siddiq
Muhammad
M
Dolan
Kirk D
KD
Kelly
Katherine A
KA
Heaps
Cristine L
CL
Meininger
Cynthia J
CJ
D000818:Animals; D001011:Aorta / Q000187:drug effects; D001120:Arginine / Q000097:blood; D001628:Beverages; D001786:Blood Glucose; D002956:Citrulline / Q000097:blood; D029773:Citrullus; D048909:Diabetes Complications / Q000188:drug therapy* / Q000378:metabolism*; D019587:Dietary Supplements; D004326:Drinking; D004435:Eating; D004734:Energy Metabolism; D006136:GTP Cyclohydrolase / Q000378:metabolism; D008055:Lipids / Q000097:blood; D024821:Metabolic Syndrome / Q000150:complications* / Q000188:drug therapy* / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology; D009569:Nitric Oxide / Q000097:blood; D019001:Nitric Oxide Synthase / Q000378:metabolism; D051381:Rats; D011924:Rats, Zucker; D014867:Water
D001786:Blood Glucose; D008055:Lipids; D014867:Water; D002956:Citrulline; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D006136:GTP Cyclohydrolase