Flavonoids catechins

Morel, I., Lescoat, G., Cogrel, P., Sergent, O., Pasdeloup, N., Brissot, P., Cillard, P. and Cillard, J. (1993). Antioxidant and iron chelating activities of the flavonoids catechin, quercetin and diosmetin on iron-loaded rat hepatocyte cultures. Biochem. Pharmacol. 45, 13-19. 

The leaves of K. dasyrachis gave kopsirachine (54), which is constituted from union of the flavonoid, catechine and two units of skytanthine. The gross structure was deduced from spectral and chemical evidence but the stereochemistry of the skytanthine units in 54 remains to be firmly established [57]. 

A number of heterogeneous natural products have been isolated from American species including aromatic and phenolic compounds, flavonoids, catechins etc. 

Afanas ev et al. demonstrated the ability of rutin to form a stable complex with Fe2+ at physiological pH [142]. The absorption spectrum of the Fe2+-rutin complex did not change during 8 hours [142]. Morel et al. investigated radiochemically the capacity of three flavonoids (catechin, quercetin and diosmetin) and desferrioxamine - a powerful chelator of Fe3+ - to remove Fe3+ from iron-loaded hepatocytes [18, 143]. Nitrilotriacetic acid - a low affinity iron-chelator - was used to maintain Fe3+ in a soluble state. The iron-chelating ability decreased in the following order desferrioxamine > catechin > quercetin > diosmetin (which had a very low activity) [18, 143]. 

MSA is derivatized with a diazonium salt to produce a diazosulfone, which is quantified by HPLC [157]. The flavonoids catechin, epicatechin, 7,8-dihydroxyflavone, and rutin showed a OH scavenging activity 100 to 300 times higher than mannitol, whereas baicalein (5,6,7-trihydroxyflavone), quercetin, myricetin, and morin enhanced the OH production [16]. The pro-oxidant activity of morin increased with an increasing concentration of morin, whereas an increasing concentration of the other three flavonoids did not enhance their pro-oxidant activity. Hanasaki et al. suggested that these pro-oxidant flavonoids produce H2O2 during their auto-oxidation, which then stimulates the Fenton reaction [16]. 

SpdcSil et al. [96] compared HPLC and UHPLC for the analysis of 34 phenolic compounds belonging to several families, such as phenolic acids, flavonoids, catechins, and coumarins. Retention time, peak area, asymmetry factor, resolution, and peak capacity were calculated for all components with both techniques. In the case of phenolic acids, all studied parameters were significantly better for UHPLC. Figure 16.1 shows that UHPLC analyses were performed 4.6 times faster than those by HPLC. Furthermore, it can be observed that UHPLC peak shape is better than HPLC peaks, and UHPLC provides better resolution in shorter running time than HPLC. 

Phenolic acids, flavonoids, catechins, coumarins Acquity UPLC BEHC18 (100 X 2.1 mm, 1.7 pm) Gradient elution A 0.1% formic acid in water B methanol Flow rate 0.45 mL/min UV Tea, wine / filtration 14... 

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