Ketones flavonoid

Phytochemistry Aboveground parts contain essential oil, phenols, ketones, flavonoids, alkaloids, and coumarins (Plant Resources of the USSR 1993). 

The retention behaviour of flavonoids has also been extensively studied on silica stationary phases using heptane, benzene or dichloromethane as weaker components of the binary mobile phase and ethyl acetate and methyl ethyl ketone as modifier. Flavones (3-hydroxy, 5-hydroxy and 7-hydroxyflavone, tectochrysin, chrysin, apigenin, genkwanin, baicalein), flavonols (galangin, pilloin, kaempferol, rhamnetin, quercetin, robinetin,... 

One of the simplest natural flavonoids is the flavanone liquiritigenin, a material that contributes to the bright yellow colour of liquorice root. Liquiritigenin may be synthesized readily, as shown, by a two-stage process starting from the phenolic ketone and aldehyde. 

In 2003, Bernini and coworkers established a method for converting some flavonoid ketones into the corresponding lactones with hydrogen peroxide as oxidant catalyzed by MTO supported on poly(4-vinylpyridine) polymers (equation 82) °. Conversions and... 

Brevifolin carboxylic acid (phenolic ketone) Capillarisin (flavonoid) 2-Carbethoxy-5,7-dihydroxy-4 -methoxy-isoflavone (isoflavone) (+)-Catechin (= Catechinic acid Catechuic acid (+)-Cyanidanol (27 ,3i)-5,7,3, 4 -Tetrahydroxyflavan-3-ol) (flavan-3-ol)... 

Raspberries accumulate a variety of flavonoid and aroma compounds that derive from PKS type III reactions (Borejsza-Wysocki and Hrazdina, 1996, Zheng et al., 2001). CHS produces precursors for flavonol, flavandiol and anthocyanin synthesis. Benzalacetone synthase (BAS) carries out a single condensation step in the synthesis of p-hydroxybenzalacetone, the precursor of raspberry ketone, that is responsible for the characteristic aroma of raspberries. To understand the role of the type III PKS during the ripening of fruits, we cloned and characterized five type III PKS genes/gene products and discuss then-properties below. 

Figure 5.8 Chemical structures of alkaloids, flavonoids and ketones isolated from the P. methysticum plant.

Silica gel Alcohols, aldehydes, alkaloids, amines, amino acids, amphetamines, antibiotics, antioxidants, barbiturates, carbohydrates, flavonoids, herbicides, heterocyclic compounds, hydrocarbons, indoles, insecticides, ketones, lipids, nitro compounds, organic acids, peroxides, pesticides, phenols, plasticizers, polypeptides, steroids, terpenes, unsaturated compounds, vitamins. 

Aldot condensations between a ketone acting as methylene compound and an aldehyde are termed C laiscn-Schmidt condensations [9]. Therefore. Claisen-Schmidt condensations between acetophenone and bcn/aldchyde derivatives allow u.p-unsaturated ketones called chalconcs (Figure 14) 1110, 182, 256-258]. Chalcones are flavonoids of numerous applications as pesticides, phoioproiector in plastics, solar creams, food additives and many biological activities [Pg.98]

Differences between flavonoid subclasses flavonols have a 2-3 double bond, 3-hydroxyl and 4-ketone group flavones have a 2-3 double bond and 4-ketone group flavanones have a 4-ketone group isoflavones have a 4-ketone group and have the B ring attached at the 3-position flavan-3-ols are hydroxylated or gaUoylated at the 3-position. 

Ketones derived from the pyrans, C5H4O2, Mr 96.09. 2//-pyran-2-one (a-P., cumalin) colorless liquid with an odor of hay and woodruff, mp. 5 °C, bp. 206 °C. 4W-Pyran-4-one (y-P.) hygroscopic cryst., mp. 32 °C, bp. 217 °C. Substituted P. such as maltol are formed, e. g., on heating carbohydrates, coffee, cocoa, coffee substitutes they are also involved in the odor and taste of bread and bakery products some of them act as taste intensifiers. Other derivatives of 2- or 4-P. such as kawain (see styrylpyrones), chelidonic acid, meconic acid, and kojic acid, etc. are found as metabolic products in plants and microorganisms in particular, the condensed ring systems of the chromones and coumarins are present in numerous natural products examples flavonoids, furocoumarins, "aflatoxins, and other mycotoxins. 

It is instructive to concentrate on the flavonoids, as these are of primary importance in qualitative assays of several HDs. Silica gel as stationary phase and ethyl acetate-ethyl methyl ketone-formic acid-water (50 30 10 10 by volume) as mobile phase is used in the analysis of flavonoids with C-glycosides (hawthorn, passion flower), and a mobile phase of ethyl acetate-formic acid-acetic acid-water (100 11 11 27 by volume) is used as the basic solvent for 0-glycosides (arnica, calendula, chamomille). Following spraying of the plates with 2-aminoethyldiphenyl-borinate (NTS, 1% in methanol) and subsequent treatment with poly(ethylene glycol) 4000 (PEG, 5% in ethanol), flavonoids display yellow to green fluorescence under UV irradiation at 365 nm. The frequently observed blue spots represent phenol... 

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