Flavonoid aglycones and glycosides

Gil, M.I. et al., Distribution of flavonoid aglycones and glycosides in Sideritis species from the Canary Islands and Madeira, Phytochemistry, 34, 227, 1993. 

TABLE 5. Flavonoids, Aglycones and Glycosides, from Astragalus spp. 

Given the various biological effects ascribed to flavonoids, questions arise on bioavailabihty. Therefore, there is a need for analytical methods for the analysis of flavonoid aglycones and glycosides in human biofluids. In addition, the useMness of flavonoid as a biomarker for the intake of fruit and vegetables must be evaluated. MS methods for the determination of flavonoids in biological samples were reviewed by Prasain et al. [68]. 

TLC is a technique which is applicable to all classes of flavonoids, and is especially useful for rapid analysis of partly purified mixtures derived from paper or column chromatography. Various TLC systems for the separation of flavonoid aglycones and glycosides have been described in the literature (Table 1, Refs. 11,12), and for further general information on the TLC of flavonoids, the reader is... 

HPLC is the most powerful and frequently used technique for the separation of natural compounds such as flavonoids. It has also been used extensively to determine both flavonoid aglycones and glycosides. 

A convenient and frequently used procedure is sequential solvent extraction. A first step, with dichloromethane, for example, will extract flavonoid aglycones and less polar material. A subsequent step with an alcohol will extract flavonoid glycosides and polar constituents. 

For quantitative analyses, scanning of the TLC plate with a densitometer provides good results. The flavonoids, both aglycones and glycosides, in Vaccinium myrtillus and V. vitis-idaea (Ericaceae) were determined after TLC and densitometry at 254 nm. " With suitable spray reagents, detection limits of 20 ng can be achieved by densitometry. ... 

A considerable amount of information has been accumulated during the review period with respect to fragmentation studies of flavonoid aglycones and their glycosides using ionization techniques such as El and CID (Figure 2.17). Tandem mass spectrometry with soft ionization methods such as FAB, ESI, and APCI have been used for the structural characterization of a variety of flavonoids, and both deprotonation ° ° and... 

Methylation has been reported at all available hydroxyls of flavones and flavonols (the C-5, -6, -7, -8, -2, -3, -4, and -5 positions), and it can occur on both aglycone and glycoside substrates. Many of the corresponding enzyme activities have been described in detail, and typically show strong preferences with regard to substrate type and the position methylated. Recently, cDNA sequences have been identified for several flavonoid OMTs, allowing sequence-based analysis and examination of recombinant protein activities. All are members of the SAM-MT family described in Section 3.4.9.2. 

Wollenweber, E., Stiiber, A., and Kraut, L., Flavonoid aglycones and flavonol glycosides in lipophilic leaf exudate of Nothofagus antarctica. Phytochemistry, 44, 1399, 1997. 

LC-MS plays a significant role in the analysis, dereplication, identification, and structural characterization of flavonoids. The MS analysis of flavonoid aglycones and flavonoid glycosides was reviewed by Cuyckens and Claeys [3],... 

Fig. 2A Meliloti herba (1,1a) and Asperulae herba (2,2a). show prominent quenching zones of flavonoid glycosides and caffeic acid derivatives in different patterns and amounts. The coumarins (T1-T3), flavonoid aglycones and caffeic add migrate almost up to the solvent front, Flavonoid glycosides and chlorogenic acid arc found from R, — 0.05 to 0.5. Extracts of Meliloti herba (1,1a) show mainly one prominent zone at R, -- 0.5, while Asperulae herba (2,2a) has four almost equally concentrated zones in the R, range 0.25-0.5.

Biosynthesis of C-Glycosyl Flavonoids Biosynthesis of Anthocyanins Systematic Studies with Flavone and Flavonol Glycosides Biological Activity of Flavone and Flavonol Aglycones and Glycosides... 

The presence of methylation, alkylation, or ester groups makes flavonoids more lipid-like in nature (Fig. 11.4). In many cases, aglycones and glycosides are additionally substituted and occur as esters (acetate, malonate, butyrate, cin-namate, p-coumarate, ferulate, etc.) or ethers. In contrast to water-soluble glycosides that are usually accumulated in the vacuole, flavonoid esters and ethers usually are associated with waxes or found in the cytoplasm. 

Soczewihski, E. Wojciak-Kosior, M. Matysik, G. Simultaneous separation of aglycones and glycosides of flavonoids by double-development TLC. J. Planar Chromatogr. 2004,17 (4), 261-263. 

Several complexes of [Bu2Sn(IV)] with flavonoid glycosides 3-[6-0-(6-deoxy-a-L-mannopyranosyl)-(jS-D-glucopyranosyl)oxy]-2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-H-l-benzopyran-4-one (rutin) and 2, 4, 3-trihydroxy-5, 4-dimetoxychalcone 4-rutinoside (hesperidin) and flavonoid aglycones (quercetin, morin, hesperitin, and other flavones) (Figure 5) were prepared. 

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