title: Enzymatically modified isoquercitrin, alpha-oligoglucosyl quercetin 3-O-glucoside, is absorbed more easily than other quercetin glycosides or aglycone after oral administration in rats.
abstract: Quercetin, a flavonol contained in various vegetables and herbal medicines, has various biological activities including anti-cancer, anti-allergic and anti-oxidative activities. However, low oral bioavailability of quercetin due to insolubility in water has limited its use as a food additive or dietary supplement. Since the water solubility is enhanced by glycosyl conjugation, in the present study, we evaluated the bioavailability of several quercetin glycosides with different sugar moieties in rats. Quercetin, quercetin-3-O-rutinoside (rutin), and quercetin-3-O-glucoside (isoquercitrin, IQC) in suspension, and quercetin-3-O-maltoside (Q3M), quercetin-3-O-gentiobioside (Q3G), alpha-monoglucosyl rutin (alphaMR), alpha-oligoglucosyl rutin (alphaOR), and enzymatically modified isoquercitrin (alpha-oligoglucosyl isoquercitrin, EMIQ) dissolved in water, were orally administered to rats under anesthesia. Bioavailability (F value) was calculated from the concentrations of total quercetin in plasma from 0 to 12 h after the administration. F value of quercetin was 2.0%, and those of IQC, Q3M and EMIQ were 12%, 30%, and 35%, respectively. Although Q3G, alphaMR and alphaOR have high water solubility, their F values were low (3.0%, 4.1%, 1.8%, respectively). In the in vitro study, the homogenate of rat intestinal epithelium rapidly hydrolyzed IQC, Q3M and EMIQ to quercetin, and alphaMR and alphaOR to rutin. However, it could not hydrolyze Q3G or rutin to quercetin. Elongation of alpha-linkage of glucose moiety in IQC enhances the bioavailability of quercetin, and intestinal epithelial enzymes such as lactase-phrolizin hydrolase or mucosal maltase-glucoamylase would play important roles in the hydrolysis and absorption of these flavonol glycosides.
authors: Department of Pharmacognosy, Graduate School of Pharmaceutical Science, Nagoya City University, Japan. makino@phar.nagoya-cu.ac.jp
authors: Toshiaki
authors: T
authors: Makino
authors: Ryosuke
authors: R
authors: Shimizu
authors: Misaki
authors: M
authors: Kanemaru
authors: Yukio
authors: Y
authors: Suzuki
authors: Masamitsu
authors: M
authors: Moriwaki
authors: Hajime
authors: H
authors: Mizukami
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D005960:Glucosides / Q000737:chemistry / Q000493:pharmacokinetics*; D006027:Glycosides / Q000378:metabolism / Q000493:pharmacokinetics*; D006868:Hydrolysis; D007413:Intestinal Mucosa / Q000201:enzymology*; D008297:Male; D010936:Plant Extracts / Q000378:metabolism / Q000493:pharmacokinetics*; D011794:Quercetin / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D051381:Rats; D017208:Rats, Wistar; D012431:Rutin / Q000378:metabolism; D012995:Solubility
chemical_list: D005960:Glucosides; D006027:Glycosides; D010936:Plant Extracts; C548359:oligoglucosyl quercetin 3-O-glucoside; D012431:Rutin; D011794:Quercetin