Quercetin, derive 7-glucoside

Because of the advantageous dietary effects of flavonoids they have been vigorously investigated in food and food products. The objectives of these measurements were the separation and quantitation of well-known flavonoids in foods and the identification of new flavonoids. An HPLC-ESI MS method has been developed for the isolation and identification of new quercetin derivatives in the leaves of Eruca sativa (Mill). Fresh leaves (500g) were homogenized with 1 200 ml of methanol-water (7 3, v/v), the suspension was macerated for 24h at ambient temperature, then it was filtered, concentrated to 50 ml and diluted with water to 500 ml. The extract was applied to an Amberlite XAD-2 column (75 X 8cm i.d.) and was washed subsequently with 11 of water and 11 of diethyl ether. The glucoside fraction was eluted with 1.51 of methanol and the eluate was concentrated in vacuum and liophilized. 

Catechin is the main flavan-3-ol detected (54 mg/kg), although epicatechin (5 mg/kg), gallocatechin (4 mg/kg) and epigallocatechin (3 mg/kg) have also been found [19]. Quercetin and kaempferol derivatives (kaempferol and quercetin 3-glucoside, 3-rutinoside and 3-galactoside) were present in the fruit skin, at levels of 10 mg/kg fresh weight [21]. 

Fig. 2.50. Profiles of calendula (a), milk-thistle (b) and passion flower (c) tinctures (each 60 per cent v/v, ethanol) with the HPLC-MS attributions of the components detected, lc = quercetin-3-O-ruti-nosylrhamnoside 2c = rutin 3c = isorhamnetin-3-O-ruti-nosylrhamnoside 4c = isoquercitrin 5c = isorhamnetin-3-O-gluco-sylglucoside 6c = narcissin 7c = isorhamnetin-3-O-glucoside lm = taxifolin 2m = siliydianin 3m = silychristin 4m = oxy derivative of silybin/isosilybin isomers 5m and 6m = 2,3-dehydro derivatives of silybin/isosilybin isomers 7m = silybin 8m = isosilybin lp = 6,8-diC-glucosylapigenin 2p = isoschaftoside 3p = shaftoside 4p = homoorientin 5p = isovetexin-2"-0-glucoside 6p = vitexin. Reprinted with permission from A. R. Biha et al. [150].

B With the NP/PEG reagent, the methanolic Viscum album (2) extract develops a series of blue fluorescent zones from the start till up to Rf 0.55, due to various plant acids. The blue-green zones in the higher R, range might derive from quercetin ethers and chalcon glucosides. 

The species Chamomilla recutita (chamomile) is rich in phenolic compounds, cumarines, phenolic acids and, especially, flavonoids such as p-D-glycosyl-7-apigenine and their acetylated derivatives, luteolin glucosides, quercetin heterosides and their methylated genines [90]. Apart from its known antispasmolytic activity, it also protects against ulceration mediated by indomethacin, stress and absolute alcohol. 

The external part of the fruit contains several quercetin and kaempferol derivatives, mainly quercetin and kaempferol 3-glucosides and glucuronides. However, other less frequent glycosidic combinations have been reported in specific cultivars [32 33]. 

The 3-glucuronide and 3-glucoside derivatives of kaempferol and quercetin are the main flavonoid constituents. They particularly accumulate in the external tissues of the fruit [36]. In a study of 20 cultivars the content varied from 21 to 174 mg/kg f.w. 

Thirteen kaempferol and quercetin ihamnodiglucosides (flavinol glucosides) in tea were separated as their benzoyl derivatives using a silica column (2 = 260 nm and 354 nm) and a 150/90/30 iso-octane/etfayl ether/acetonitrile mobile phase... 

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