Quercetin onion

Flavonols Quercetin Onions 21.4 US Department of Agriculture 2007a... 

Flavonols Quercetin, kaempferol, myricetin, isorhamnetin, Apples, berries, broccoli, cabbages, chives, cranberries, grapes, kale, onions, peppers, spinach, Swiss chard, tomatoes, watercress... 

Aziz AA, Edwards CA, Lean ME and Crozier A. 1998. Absorption and excretion of conjugated flavonols, including quercetin-4 -0-(3-glucoside and isorhamnetin-4 -O-(i-gIu coside by human volunteers after the consumption of onions. Free Radic Res 29 257-269. 

In preclinical models of carcinogenesis, which include colorectal, breast, and prostate cancer, a remarkable efficacy of some phytochemicals has been found. Some of these are epigallocatechin from tea quercetin and genistein from onion and soy,... 

A new poly(7-oxobomene-5,6-dicarboxylic acid-Wod -norbomene)-coa(cd silica has been synthesized and applied for the separation of flavonoids in model systems and in the extracts of onion, elder flower blossom, lime blossom, St. John s Wort and red wine. Separation was performed in a (150 X 4 mm i.d. particle size 7 /rm) column at room temperature. Flavonoids (quercitrin, myricetin, quercetin, kaempferol and acacetin) were separated with gradient elution water-ACN (20 mmol TFA) from 78 22 to 70 30 v/v in 3min. The flow rate was 2 ml/min. The separation of the standard mixture is shown in Fig. 2.51. It has been stated that the method is rapid, accurate and the MS detection makes possible the reliable identification of flavonoids [153],... 

Fig. 2.55. Gradient reversed-phase HPLC analysis of flavonoids in white onions (a) and celery (b). ODS column of 150 X 3.9mm i.d particle size 5pm. Mobile phase 20min gradient of 15-35 per cent acetonitrile in water adjusted to pH 2.5 with TFA. Fowrate lml/min. Upper and lower traces represent samples before and after hydrolysis, respectively. Detection wavelength 365 nm. IS = internal standard Qc = quercetin Ap = apigenin Lt = luteolin. Reprinted with permission from A. Crozier et al. [159],...

Fig. 2.88. Chromatograms obtained from standard, onion, wine and plasma samples, (a) standard polyhydro xyflavones (5.00/ig/ml of each), (b) onion skin etract, (c) wine, and (d) plasma spiked with quercetin (5.00/ig/ml). Detection at 370 nm. Peaks 1 = rutin 2 = myricetin 3 = fisetin (internal standard) 4 = morin 5 = quercetin 6 = kaempferol. Reprinted with permission from H. Tsuchiya [210].

The flavonoid database described in this chapter was applied to 4-day weighed food records obtained from healthy Scottish men n = 41) and women ( = 52) to provide a provisional estimate of flavonoid intake in Scotland. All subjects consumed foods containing flavonols, procyanidins, and catechins, dietary intakes of which are given in Table 4.15. The main flavonol consumed was quercetin, accounting for 66 and 63% of the total flavonol intake of 18.8 mg/day. Primary sources of flavonols were from black tea (42.7%), onions (14.3%), apples (10.2%i), and lager (7.2%i) (Table 4.16). 

The absorption of intact quercetin glycosides has been demonstrated by some authors [64,65,76]. Hollmann demonstrated in ileostomy subjects (who lack colon with the bacterial flora, thus circumventing the problem of microbial degradation), that the quercetin glycosides from regular foods (onions, tea) were far better absorbed than pure aglycone (52% vs 24%). 

Glycosides of flavonols from onions, such as quercetin-4 -0-glucoside and quercetin-3 -0-methyl-4 -0-glucoside, have been found in the plasma of volunteers with a peak of absorption of 0.5 - 4 h [64]. 

The bioavailibility of quercetin-glycosides from onions, containing mainly quercetin-p-glucosides, was superior to that of various quercetin glycosides from apples (containing a mixture of quercetin-(3-galactosides and P-xylosides) and of pure quercetin-3-mtinoside (major species in tea). The possible matrix effect of the foods remains unclear. 

An HPLC separation method with diode array detector and mass spectrometric (MS) detection equipped with atmospheric pressure ionization (API) was developed to determine flavone, flavonol, and flavanone in various vegetables, including green bean, broccoli, brussels sprouts, celery, kale, leek, onion, parsley, pepper (green, yellow, and red), and tomato (118). The flavonoids were analyzed as aglycones after acid hydrolysis. The extraction and acid hydrolysis conditions are based on previous work by Hertog et al. (119). Quercetin is the overall major flavonol, followed by kaempferol. The flavones, apigenin and luteolin, were found only in limited foods,... 

Development of suitable sample handling, extraction, and HPLC/diode array detector (DAD) based methods for the analysis of flavonoids and their conjugates in four varieties of onions were described (125). The predominant flavonoids in onions (white, brown, red, and pink varieties) were quercetin mono- and diglucosides, which accounted for approximately 80% of the total flavonol fraction. 

Flavonoid Yellows Structures containing Phenols, names depending OH or OCH position Quercetin Black oak (Quercus velutina Lam.) Onions (Allium sp.) Red grapes (Vitis sp.) Requires mordant. Metal ions in a mordant fbrm insoluble lake with OH and OCH groups. 

Flavonols that accumulate in plant tissues are almost always in the form of glycosylated conjugates. The main flavonols in onions are quercetin- 4 -O-glucoside and quercetin-3,4 -0-,diglucoside with smaller amounts of isorham-netin-4 -0-glucoside (Fig. 1.3) [Mullen et al., 2004]. 

Mullen W, Edwards CA, Crozier A. 2006. Absorption, excretion and metabolic profiling of methyl-, glucuronyl-, glucosyl and sulpho-conjugates of quercetin in human plasma and urine after ingestion of onions. Brit J Nutr 96 107-116. 

McAnlis GT, McEneny J, Pearce J, Young IS. Absorption and antioxidant effects of quercetin from onions in man. 1999. Eur J Clin Nutr 53 92-96. 

Moon J-H, Nakata R, Oshima S, Inakuma T, Terao J. 2000. Accumulation of quercetin conjugates in blood plasma after the short-term ingestion of onion by women. Am J Physiol 279 R461-R467. 

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