Flavonoids in plants

Bioactive sesquiterpenic y-lactones and flavonoids in plants of Inula L. genus 97MI20. 

Proanthocyanidins are an important group of di- to oligomeric flavonoids in plants. Four proanthocyanidins (procyanidin B3, prodelphinidin B4, ECG-(4 8)-ECG and GC-(4 8)-EGCG) were determined quantitatively in tea. The amounts in fresh tea leaves were between 1 and 2 g/kg per compound (Nakabayashi, 1991). The occurrence of proanthocyanidins may serve as a criterion for the differentiation between fermented and non-fermented teas (Kiehne et al, 1997). 

Flavonoids in plants usually occur glycosylated mainly with glucose or rhamnose, but they can also be linked with galactose, arabinose, xylose, glucuronic acid, or other sugars. The number of glycosyl moieties usually varies from one to three nevertheless, flavonoids have been identified with four and also five moieties (Vallejo and others 2004). 

C.W. Huck, M.R. Buchmeiser and G.K. Bonn, Fast analysis of flavonoids in plant extracts by liquid chromatography-ultraviolet absorbance detection on poly(carboxylic acid)coated silica and electrospray ionization tandem mass spectrometric detection. J. Chromatogr.A 943 (2002) 33-38. 

Significance of Flavonoid Accumulation in Cell Walls Whereas the accumulation of flavonoids in plant cell walls may be difficult to explain, however, it may be considered as a means of eliminating such cytotoxic agents from the cell symplast. Such site for flavonoid accumulation may also be considered as a means of protection against pathogens, predators and ultraviolet radiation (54), especially in the absence of ligni-fied tissues, as in the case of Chrysosplenium. 

The CE MS combination may provide valuable, structure-selective information about flavonoids in plant extracts however, this coupled technique has hitherto found only very... 

Mattila, P. Astola, J, and Kumpulainen, J., Determination of flavonoids in plant material by HPLC with diode-array and electro-array detections, J. Agric. Food Chem., 48, 5834, 2000. 

Harbome, J.B., Eunctions of flavonoids in plants, in Chemistry and Biochemistry of Plant Pigments, Goodwin, T.W., Ed., vol. 1, Academic Press, London, 1976, 736. 

Hedin, P.A. and Waage, S.K., Roles of flavonoids in plant resistance to insects, in Plant Flavonoids in Biology and Medicine Biochemical, Pharmacological and Structure Activity Relationship, Cody, V., Middleton, E., and Harbome, J.B., Eds., Alan Liss, New York, 1986, 87. 

Treutter D. 2006. Significance of flavonoids in plant resistance a review. Environ Chem Lett 4 147-157. 

Flavonols are the most common flavonoids in plant-derived food products, and they often occur as glycosidic combinations of myricetin, quercetin, and kaempferol and their methyl ethers (isorhamnetin and tamarixetin). Flavonols are relevant in onions, apples, green tea, grapes,... 

The biogenesis of flavonoids in plants is well documented and known to take place by chain extension of 4-hydroxycinnamoyl-CoA (126) with malonyl CoA through the acetate pathway involving enzymes like chalcone S3mthase (86). Here, the initially formed polyketide 127 may undergo a Claisen-type condensation to form a chalcone and subsequently other flavonoids, as shown in Fig. 25. It is pertinent to... 

There are several published information regarding the isolation and the identification of flavonoids in plant material using different methods, mainly chromatographic and spectroscopic. Today, high-performance liquid chromatography (HPLC) is established as the most convenient method which enables separation and identification of... 

Phenolic acids include the benzoic acids (Ce-Ci), e.g., gallic, vanillic, syringic, protocatechuic, p-hydroxy-benzoic acid, as well as cinnamic acids (C6-C3), e.g., caffeic, p-coumaric, ferulic, sinapic acids, and their dep-sides and derivates, e.g., rosmarinic acid and lithospermic acid (Fig. 1). Phenolic acids and flavonoids in plants may occur in the free form, but they are often glycosylated with various sugars, especially glucose. Phenolic acids may also be present in the esterified as well as bound forms. Free phenolic acids are found especially in herbs and spices and, very often, in compounds responsible for antioxidant activity (benzoic and cinnamic acids and some of their derivatives). The bound forms are more common for the fruits, vegetables, and other plant materials. Therefore, in some cases, it is necessary to combine the analysis of their free and bound forms. 

Other trisaccharides which, it has been suggested, occur in combination with flavonoids in plants are 0-/3-D-glucopyranosyl-(l— 2)-0-a-ii-rhamno-pyranosyl-(l- )-D-glucopyranose as a kaempferol derivative in potato flowers,and a galactosylsophoroside of kaempferol in Pisum arvense. -However, for both, a great deal more work is required before these structures can be fully accepted. 

Flavonoids, due to their ability to absorb ultraviolet (UV) radiation, can protect DNA (Deoxyribonucleic acid) from the damage caused by UV radiation. This effect is one of the physiological functions proposed for the flavonoids in plants [57], In studies performed with UV-B irradiated plasmids, both naringenin and rutin showed protecting activity against DNA damage, induced by UV radiation [58], Besides a direct protection,... 

Kaempferol (3,4, S,7-tetrahydroxyflavone). Formula see under flavones. CuHioOg, Mr 286.24, yellow needles (aqueous C2H5OH), mp. 276-278°C, uv 365 nm. K. is a flavonol which, besides quercetin, in the form of various glycosides represents the most frequently occurring flavonoid in plants. 0.3% aqueous ethanol solutions are used for the photometric determination of Ga, In, and Sn(iv) (uv, 430 nm, log e 4.6). 

In eukaryotes and prokaryotes, ACCase is a key enzyme in fatty acid biosynthesis [1]. The reaction product, malonyl-CoA, is both an intermediate in the de novo synthesis of primary fatty acids and also a substrate in the formation of long-chain fatty acids and flavonoids in plants [2, 3]. Aryloxyphenoxypropionates (APPs) and cyclohexandiones (CHDs) are two chemical classes of molecules that selectively inhibit homomeric, chloroplastic ACCase from grasses [4, 5], which makes them post emergent herbicides used worldwide to control grassy weeds. 

Nomura, T., T. Fukai, Y. Hano, S. Yoshizawa, M. Suganuma, and H. Fujiki Chemistry and Anti-tumor Promoting Activity of Morus Flavonoids In Plant Flavonoids in Biology and Medicine II. Biochemical, Cellular and Medicinal Properties. (V. Cody, E. Middleton, Jr. and J.B. Harborne, eds.). New York Alan R. Liss, Inc. 1988, in press. 

Duff SJB, Murray WD (1990) Non aqueous reaction systems for the oxidation of higher molecular weight alcohols by alcohol oxidase from Pichia pastoris. In Charalambous G (ed) Flavours and off-flavours 89. Developments in food science, vol 24. Elsevier, Amsterdam, pp 701-713 Esguerra EB, Kawada K, Kitagawa H (1992) Removal of astringency in Amas Banana (Musa AA group) with postharvest ethanol treatment. Acta Hortic 321 811-820 Eskin NAM (1979) Terpenoides and flavonoides. In Plant pigments, flavours and textures. Academic Press, New York, pp 65-93... 

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