Taxifolin

Tautomerism Tax gallon Taxifolin Taxilan Tax incentives Taxol [330d9-d2-4]... 

The chemical formulae for a variety of plant phenols are given in Fig. 16.2, including examples of simpler phenols, such as cinnamic acid derivative, and of tocopherols, flavonoids, flavonoid glycosides and anthocyanidins. The flavonoids include the following subclasses flavanones (taxifolin), flavones (luteolin), flavonols (quercetin) and flavanols (catechin/epicatechin). The... 

Flavanonols Flavanonols can be considered as flavanones with a hydroxyl group on position 3. They are sometimes referred to as dihydroflavonols. Similar to the situation of flavanones, flavanonols are no longer a minor subgroup of flavonoids, and they are a structurally highly diverse and multisubstituted subgroup (Grayer and Veitch 2006). A well-known flavanonol is taxifolin from citrus fruits (Kawaii and others 1999) (see Table 5.1 and Fig. 5.2). 

The above findings are supported in the other studies of the inhibitory effects of flavonoids on iron-stimulated lipid peroxidation. Quercetin was found to be an inhibitor of iron-stimulated hepatic microsomal lipid peroxidation (/50 = 200 pmol I ) [134]. Flavonoids eriodictyol, luteolin, quercetin, and taxifolin inhibited ascorbate and ferrous ion-stimulated MDA formation and oxidative stress (measured by fluorescence of 2,7,-dichlorodihydro-fluorescein) in cultured retinal cells [135]. It should be mentioned that in recent work Heijnen et al. [136] revised the structure activity relationship for the protective effects of flavonoids against lipid peroxidation. 

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].

Cinnamic acid OH derivatives H J> H Caffeic acid / -Coumaric acid o-Coumaric acid CH Ferulic acid Cinnamic acid Sinapinic acid COOH Flavonoids Flavones Apigenin q JT 11 Luteolin R2 Flavanonol 1 i IJ R3 V >r (+)-Taxifolin OH 0... 

Ishimaru, K. et al., Taxifolin 3-arabinoside from Fragaria x ananassa. Phytochemistry, 40, 345, 1995. 

R,3R) 3,7,3, 4 -PentaOP[-Flavanone (taxifolin) 3-a-Arabinopyranoside C20H20O11 436 Rhododendron ferrugineum Ericaceae Leaf, flower 271... 

Silymarin is considered the active constituent of the milk thistle seed, but it is not a single compound but a descriptive term for several flavonoli-gnans. Constituent analysis of five milk thistle products identified six constituents (representative amount) taxifolin (3.3%), silichristin (23.6 /o), silidianin (5.3 /o), silybin A (20%i), silybin B (30.7%i), and isosilybin (17.3 /o). The total amounts of silybin A and B in the five different products analyzed ranged from 45.7 /o to 61%i. The biological effect of each constituent is not known hence, spectrophotometric analysis would not provide sufficient information for a critical comparison of these products. 

Taxifolin Coumarins Bergamottin C. paradisi, C. aurantium, C. sinensis. hm (50),... 

Pistacia lentiscus L. Ru Xiang (resin) Masticinic acid, masticonic acid, masticoresene, fisetin, fustin, gallic acid, quercetin, taxifolin.49-50 Antitumor, antitussive, analgesic, sedative in gastralgia, cardiodynia, mastitis, peptic ulcer. 

---