Quercetin, derive glycosyl derivs

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. 

Several strains of the fungus Aspergillus can grow on flavonols like quercetin or rutin (a 3-0-glycosylated derivative of quercetin). It was demonstrated in the 1960s that whole-cell cultures of Aspergillusflavus convert quercetin into an insoluble depside according to Equation (14). " ... 

However, each constituent in the flower extracts of Hypericum patulum such as an antidepressant and antiviral agent hypericin (15)(Figure 4) which is a naphthodianthrone of a red-coloured anthraquinone derivative in the extract of St John s wort, the flavones quercetin (16) and luteolin (17), the glycosylated flavonoide rutin (18), hyperoside (19) and quercitrin (20) and the biflavone 13, 118-biapigenin (21) (Figure 4) did not inhibit the binding up to their concentrations of 1 j,M. 

Koenigs-Knorr reactions or the orthoester procedure with disaccharide derivatives have been used in syntheses of 7-0-P-laminaribiosyl-formononetin and 3-0-(6-0-a-L-rhamnopyranosyl-P-D-galactopyranosyl)quercetin and in the glycosylation of cholest-5-en-3-ol with the disaccharide 1,2-orthoester (50). A... 

The main flavonols in onions are glycosylated derivatives, principally quercetin-4 -0-glucoside and quercetin-3,4 -O-diglucoside with smaller amounts of isorhamnetin-4 -0-glucoside (Figure 7.10) and other quercetin conjugates (Mullen et al. 2004). Yellow onions form one of the main sources of flavonols in the Northern European diet, the edible... 

---