Quercetin 7-O-glucoside suppresses nitrite-induced formation of dinitrosocatechins and their quinones in catechin/nitrite systems under stomach simulating conditions.
Foods of plant origin contain flavonoids. In the adzuki bean, (+)-catechin, quercetin 3-O-rutinoside (rutin), and quercetin 7-O-β-D-glucopyranoside (Q7G) are the major flavonoids. During mastication of foods prepared from the adzuki bean, the flavonoids are mixed with saliva and swallowed into the stomach. Here we investigated the interactions between Q7G and (+)-catechin at pH 2, which may proceed in the stomach after the ingestion of foods prepared from the adzuki bean. Q7G reacted with nitrous acid producing nitric oxide (˙NO) and a glucoside of 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone. (+)-Catechin reacted with nitrous acid producing ˙NO and 6,8-dinitrosocatechin. The production of the dinitrosocatechin was partly suppressed by Q7G, and the suppression resulted in the enhancement of Q7G oxidation. 6,8-Dinitrosocatechin reacted further with nitrous acid generating the o-quinone, and the quinone formation was effectively suppressed by Q7G. In the flavonoids investigated, the suppressive effect decreased in the order Q7G≈quercetin>kaempferol>quercetin 4'-O-glucoside>rutin. Essentially the same results were obtained when (-)-epicatechin was used instead of (+)-catechin. The results indicate that nitrous acid-induced formation of 6,8-dinitrosocatechins and the o-quinones can be suppressed by flavonols in the stomach, and that both a hydroxyl group at C3 and ortho-hydroxyl groups in the B-ring are required for efficient suppression.
Institute for Multidisciplinary Research, University of Belgrade, Belgrade 11030, Republic of Serbia.
Filis
F
Morina
Umeo
U
Takahama
Ryo
R
Yamauchi
Sachiko
S
Hirota
Sonja
S
Veljovic-Jovanovic
D000818:Animals; D016588:Anticarcinogenic Agents / Q000737:chemistry / Q000378:metabolism*; D001572:Benzofurans / Q000737:chemistry / Q000378:metabolism; D016227:Benzoquinones / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D002273:Carcinogens / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D019587:Dietary Supplements; D004063:Digestion; D007887:Fabaceae / Q000737:chemistry; D055951:Functional Food / Q000032:analysis; D005750:Gastric Juice / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D005960:Glucosides / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D009603:Nitroso Compounds / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D009608:Nitrous Acid / Q000737:chemistry / Q000378:metabolism; D011794:Quercetin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D011809:Quinones / Q000737:chemistry / Q000378:metabolism; D012463:Saliva / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D012639:Seeds / Q000737:chemistry; D013237:Stereoisomerism
C000601184:2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone; C000601185:6,8-dinitrosocatechin; D016588:Anticarcinogenic Agents; D001572:Benzofurans; D016227:Benzoquinones; D002273:Carcinogens; D005960:Glucosides; D009603:Nitroso Compounds; D011809:Quinones; D009569:Nitric Oxide; C004532:quinone; C089996:quercimeritrin; D002392:Catechin; D011794:Quercetin; D009608:Nitrous Acid