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Aronia berries have many potential effects on health, including an antioxidant effect, effect for antimutagenesis, hepatoprotection and cardioprotection, an antidiabetic effect and inhibition of cancer cell proliferation. Previous human studies have shown that aronia juice may be useful for treatment of obesity disorders. In this study, we found that aronia juice has an inhibitory effect against dipeptidyl peptidase IV (DPP IV) (EC 3.4.14.5). DPP IV is a peptidase that cleaves the N-terminal region of incretins such as glucagon-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). Inactivation of incretins by DPP IV induces reduction of insulin secretion.Furthermore, we identified that cyanidin 3, 5-diglucoside as the DPP IV inhibitor in aronia juice. DPP IV was inhibited more strongly by cyanidin 3, 5-diglucoside than by cyanidin and cyanidin 3-glucoside. The results suggest that DPP IV is inhibited by cyanidin 3, 5-diglucoside present in aronia juice. The antidiabetic effect of aronia juice may be mediated through DPP IV inhibition by cyanidin 3, 5-diglucoside.

Legumain (EC 3.4.22.34) is an asparaginyl endopeptidase. Strong legumain activity was observed in the mouse kidney, and legumain was found to be highly expressed in tumors. We previously reported that bovine kidney annexin A2 was co-purified with legumain and that legumain cleaved the N-terminal region of annexin A2 at an Asn residue in vitro and in vivo. In this study, we found a p53-binding site in intron 1 of the human legumain gene using computational analysis. To determine whether transcription of the legumain gene is regulated by p53, HCT116 cells were transfected with p53 siRNA and the effect of knockdown of p53 expression on legumain expression was examined. The results showed that expression levels of both legumain mRNA and protein were decreased in the siRNA-treated cells. Furthermore, enzyme activity of legumain was also increased by doxorubicin and its activity was reduced by knockdown of p53 in HCT116 cells. These results suggest that legumain expression and its enzyme activity are regulated by p53.

of these enzyme activities and may be useful for prevention of metabolic diseases in adult healthy Japanese.

Background: Aronia berries contain many important effects on potential health, with previous studies suggesting that aronia juice is useful for the treatment of hypertension.Objective: To examine whether aronia berries have improvement effects on hypertension through the inhibition of angiotensin-converting enzyme (ACE) activity.Method: The normal diet containing 10% freeze-dried aronia berries was administered to five spontaneously hypertensive rats (SHRs) in each group for 28 days, with their body weight, food intake, and systolic blood pressure being measured. At 28 days after administration of aronia berry-containing diets, the serum, lungs, and kidneys were isolated and used for measurement of ACE activity.Results: In this study, we found that blood pressure in SHRs fed freeze-dried aronia berries-containing diet decreased compared with the blood pressure in SHRs fed normal diet. We also discovered that the catalytic activity of ACE was reduced in the kidney of SHRs fed freeze-dried aronia berries-containing diet but not in the lungs of aronia berries-administered rats.Conclusion: Aronia berries have beneficial effects on the amelioration of hypertension through inhibition of the kidney renin-angiotensin system.Key word: aronia, hypertension improvement, kidney renin-angiotensin system, ACE.