Flavonols analysis

Table 3.2 Methodological Overview of Flavonol Analysis from Foods and Biological Samples...

Relative emission Intensity measurements were made at 475 nm for tin analysis, the emission maximum for the tln-flavonol complexes examined In this work. Emission spectra are uncorrected. 

Tin Analysis. Figures 2, 3 and 4 Illustrate typical emission spectra obtained In the characterization of Sn /flavonol Interactions. As seen In Figure 2, the free ligand (5.0 x 10" M)... 

DE PASCUAL-TERESA S, TREUTTER D, RIVAS-GONZALO J 0 and SATOS-BUELGA C (1998) Analysis of flavonols in beverages by high-performance liquid chromatography with chemical reaction detection , J Agric Food Chem, 46, 4209-13. 

JUSTESEN u, KNUTHSEN p and LETH T (1998) Quantitative analysis of flavonols, flavones, and flavanones in fruits, vegetables and beverages by high-performance liquid chromatography with photo-diode array and mass specfrometric detection, /C/u matogr A, 799, 101-10. 

CZE is particularly useful for separating anthocyanin dimers or polymeric anthocyanins. Calvo et al. (2004)" separated 13 anthocyanins by CZE including acylated and non-acylated anthocyanins, pyranoanthocyanins, and flavonol derivatives in wine. Saenz-Lopez et al. (2004)" applied CZE to analyze wine aging (1 to 14 yr) as related to monomeric anthocyanins, anthocyanin derivatives, tannins, and fla-vonols. Bicard et al. (1999)" reported the improved detection sensitivity of anthocyanin chemical degradation analysis by CZE. 

Wang J and Sporns P. 2000a. MALDI-TOF MS analysis of food flavonol glycosides. J Agric Food Chem... 

Owens DK, Alerding AB, Crosby KC, Bandara AB, Westwood JH and Winkel BSJ. 2008. Functional analysis of a predicted flavonol synthase gene family in Arabidopsis. Plant Physiol 147 1046-1061. 

It was stated that this combined technique (HPLC-DAD, HPLC-ESI-MS, GC-MS) allows the safe identification of flavonol aglycones and glycosides and can be used for the analysis of these compounds in berries [161]. 

Another isocratic elution method was applied for the determination of flavonols in green and black tea leaves and green tea infusions by RP-HPLC. The chemical structures of the flavonols studied are shown in Fig. 2.66. Infusions of teas were prepared by mixing lg of tea leaves with 100 ml of boiling water for 5min, then they have filtered and used for HPLC analysis. The infusion step was repeated three times. Flavonoids were hydrolysed by mixing lg of tea leaves with 40 ml of 60 per cent aqueous ethanol and 5 ml of 6 M HC1. The suspension was heated at 95°C for 2 h, then filtered and the volume was adjusted to 50 ml with 60 per cent aqueous ethanol. Separation was performed in an ODS column (150 X 4.6mm i.d.) operated at 30°C. The isocratic mobile phase consisted of 30 per cent aqueous ACN in 0.025 M KH2P04, and the pH was adjusted to 2.5 with 6 M HC1. The... 

It has been stated that the extraction, hydrolysis, and RP-HPLC separation method is specific and sensitive for the analysis of flavonols, flavones and flavanons. The data can be used for the estimation of the daily intake of these compounds [187]. 

Direct injection API-Electrospray MS is capable of analyzing much larger and less volatile substances than either EI/MS or CI/MS. As a result, this method is often used to provide structural information on peptides, proteins, and polymers derived from both natural and synthetic processes it is also useful in the analysis of many natural compounds including molecules such as saponins and flavonol glycosides, derived from plants. When using direct injection API-electrospray, partial purification and EC preparation are performed elsewhere and a collected fraction is dissolved in an appropriate solvent and injected as a bolus into the mass spectrometer (flow or direct injection or syringe infusion). This has an advantage, as the mass... 

WeUmann F, Lukacin R, Moriguchi T, Britsch L, SchUtz E, Matern U (2002) Eunctional expression and mutational analysis of flavonol synthase from Citrus unshiu. Eur 1 Biochem 269(16) 4134-4142... 

Among the numerous applications of SPE are separations of phenolic acids and flavonoids from wines and fruit juices. Sep-Pak Cig cartridges have been used for the fractionation of flavonol glycosides and phenolic compounds from cranberry juice into neutral and acidic parts before HPLC analysis. Antimutagenic flavonoids were identified in aqueous extracts of dry spinach after removal of lipophilic compounds by SPE. ... 

Ducrey, B. et al.. Analysis of flavonol glycosides of thirteen Epilobium species (Onagraceae) by LC-UV and thermospray LC-MS, Phytochemistry, 38, 129, 1995. 

Nymphaea caerulea, for seven natural anthocyanins stabilizing a DNA triplex, etc. Sequential analysis of the oligosaccharide structures of the flavonol tamarixetin-7-O-rutino-side has been performed by ID multistep-relayed COSY-ROESY experiments. Selective excitation was performed by Gaussian-shaped soft pulses. 

The APCI source (Table 2.8) has been used for the analysis of various flavonoids, especially flavonols, flavones, flavanones, and chalcones (Table 2.11). APCI is based on gaseous-phase ionization, and is most suitable for compounds that are partially volatile and have a medium polarity. Thus, the application of APCI with respect to analysis of condensed tannins and anthocyanins is more limited. Compared with ESI, APCI produces more fragment ions in the spectrum due to the harsher vaporization and ionization processes. More information about ESI and APCI can be found in Section 1.4.5. 

UV-Vis linear dichroism and (mid-)IR ATR IR analysis have been used to explain the possible association between DNA and the flavonols quercetin, rutin (quercetin-3-rutino-side), and morin (3,5,7,2, 4 -pentahydroxyflavone) in solution.These nucleophilic flavonoids were shown to bind DNA by intercalation with an interaction having similar nature and geometry however, under comparable conditions, quercetin exhibited a greater number... 

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