Flavonol glycosides extraction

Separate the flavonol glycoside extract from the insoluble plant material by filtering the slurry by gravity through a Whatman no. 1 filter paper into a 250-ml round-bottom flask. 

Aqueous flavonol glycoside extract (see Basic Protocol 1)... 

Load 5 ml aqueous flavonol glycoside extract onto the column. Load at a rate of 1 ml/min to ensure complete adsorption of flavonol glycosides. 

Store purified flavonol glycoside extract up to 1 to 2 weeks at 4°C. 

Matrix solution 2/,4/,6/-trihydroxyacetophenone monohydrate (THAP Aldrich) dissolved in acetone at 2 mg/100 pi, freshly prepared Purified aqueous flavonol glycoside extract (see Basic Protocol 2)... 

Load 0.5 pi purified aqueous flavonol glycoside extract on top of matrix and allow to air dry (requires 2 min with a fan). 

RETENTION TIMES AND TENTATIVE STRUCTURES OF FLAVONOL GLYCOSIDES IN THE UNHYDROLYSED BERRY EXTRACTS... 

Modifications of the method (dry-column chromatography, vacuum liquid chromatography, VLC, for example) are also of practical use for the rapid fractionation of plant extracts. VLC with a polyamide support has been reported for the separation of flavonol glycosides. ... 

The technique of CPC was also employed as a key step in the purification of 26 phenolic compounds from the needles of Norway spruce (Picea abies, Pinaceae). An aqueous extract of needles (5.45 g) was separated with the solvent system CHCl3-Me0H-i-Pr0H-H20 (5 6 1 4), initially with the lower phase as mobile phase and then subsequently switching to the upper phase as mobile phase. Final purification of the constituent flavonol glycosides, stilbenes, and catechins was by gel filtration and semipreparative HPLC. °... 

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. ... 

The recommended dosages of an oral standardized dry extract of ginkgo (24% ginkgo flavonol glycosides and 6% terpene lactones) are 120 to 240 mg daily for dementia and memory impairment, and 120 to 160 mg daily for intermittent claudication and tinnitus. Adverse effects include gastrointestinal disturbances, diarrhea, vomiting, allergic reactions, pruritus, headache, dizziness, and nose bleeds. 

In general, the biological evaluation of hypericin in various test models is limited by its poor water solubility. It was shown in in vitro as well as in vivo studies (18,78) that the water solubility of hypericin was remarkably enhanced in the presence of procyanidins or flavonol glycosides of SJW extract. In a recent pharmacokinetic study in rats, it was shown that procyanidin B2 as well as hyperoside increased the oral bioavailability of hypericin by approximately 58% (B2) and 34% (hyperoside) (Fig. 5) (19). Procyanidin B2 and hyperoside had a different influence on the plasma kinetics of hypericin median maximal plasma levels of hypericin were detected after 360 minutes (Cmav 8.6 ng/mL) for B2, and after 150 minutes... 

In the course of our phytochemical work we studied seven Licania species all belonging to Venezuelan flora, collected in Puerto Ayacucho, Estado Amazonas and in the Parque Nacional Henry Pittieri, Maracay, Estado Aragua. A number of new and known secondary metabolites, mainly flavonoids, especially flavonol glycosides, sterols, and triterpenes having the lupane, ursane, and oleanane skeleton were isolated and characterized. The last part of this chapter deals also with the isolation of clerodane diterpenes from the methanol extract of L. intrapetiolaris by Oberlies et al., 2001 [4]. All the Licania species investigated up to now are reported in Table 1. 

Basic Protocol 1 Extraction of Flavonol Glycosides from Plant Sources 11.5.1... 

EXTRACTION OF FLAVONOL GLYCOSIDES FROM PLANT SOURCES... 

The volume of extract applied to the cartridge depends on the sample concentration, flavonol glycoside concentration, and amount of sorbent packing in the column. 

Flavonol glycosides may be non-uniformly distributed throughout the plant. For example, the seedcoats of nuts may be much richer in flavonol glycosides than the flesh. It may be beneficial in such circumstances to extract and analyze the flavonol glycoside-rich components separately to increase the concentration in the extract. 

Flavonol glycosides were suggested as a suitable indicator of the adulteration of black currant products with red currants (74) and with blackberries (75). The black currant methanolic extract is purified using polyamide columns and analyzed for flavonoids by HPLC. Anthocyanins are removed by chromatography on Dowex 50W-X4, eluting with 70% methanol (74). Quercetin-3-0-gluccuronide was a suitable indicator to detect adulteration of blackcurrant products with blackberries (75). 

For phenolic acids in bilberry juice, a reversed-phase HPLC method (16) using a linear-gradient elution of (a) 2% aqueous acetic acid and (b) acidified, aqueous acetonitrile on two Cl8 columns was able to separate the 12 phenolic acids and flavonoids (three flavonol glycosides and three flavonols) in ethyl acetate extract. Phenolics in blueberries were extracted, isolated, and... 

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