Flavonoids major

We are concerned here with systems that have been studied using secondary products—flavonoids and terpenoids in particular— but other information, including micro- and macrofossils, and occasionally chromosome numbers, will be included in the discussions when snch information is available. The majority of current research on postglacial reestablishment of plant distribution patterns is based on DNA seqnence information. In a few instances below, reference will be made to such information, but this in not the place for a detailed review of that literature. 

Perhaps the most useful contribution made by flavonoids in this group of plants, however, was the assistance they provided in studies of natural hybridization between Dubautia scabra and D. ciliolata (Crins et al., 1988a). Dubautia scabra is a pioneer plant that colonizes new lava moderately D. ciliolata occurs on somewhat older lava. Where newer flows overlap older ones, one can often find plants with features intermediate between the two species. This phenomenon is readily observed in the vicinity of Kilauea Volcano on the island of Hawaii, where one finds D. scabra subsp. scabra on newer substrate and D. ciliolata subsp. glutinosa on the older substrate. Since the two taxa exhibit different flavonoid profiles, and we know that flavonoid profiles are inherited in an additive fashion, hybrids would be expected to exhibit flavonoid markers inherited from each parent. A major advantage in this study was the availability of known Fj hybrids that had been produced from controlled crosses at the University of Hawaii (by G. D. Carr). Analysis of the... 

A detailed study of the flavonoid chemistry of the island endemics, the closely related G. tinctoria, and live additional species from the mainland provided additional evidence pointing toward G. tinctoria as the ancestral species (Pacheco et al., 1993). The flavonoid profiles of all species consisted of flavonol glycosides as major components with an unidentified flavone glycoside and several unidentified phenolic compounds (presumably not flavonoids). The pattern of distribution of the flavonol glycosides and unidentified flavones within the set of nine species proved to be extremely informative. (The phenols were ubiquitous and are not considered further.) Kaempferol glycosides were seen in neither the island species nor G. tinctoria, but were present, in several combinations, in the rest of the mainland taxa. The isorhamnetin glycosides showed the reverse pattern, with one exception the island endemics and G. tinctoria exhibited these compounds, whereas four of the other mainland species did not. The sole exception is G. boliviari, which exhibited one of the isorhamnetin derivatives. 

Major exudate flavonoids of Dubautia arborea (Asteraceae). Biochem. Syst. Ecol. 

EWALD C, FJELKNER MODIG S, JOHANSSON K, SJOHOLM I and AKESSON B (1999) Effect of processing on major flavonoids in processed onions, green beans, and peas . Food Chem, 64 (2) 231-5. 

The shikimate pathway is the major route in the biosynthesis of ubiquinone, menaquinone, phyloquinone, plastoquinone, and various colored naphthoquinones. The early steps of this process are common with the steps involved in the biosynthesis of phenols, flavonoids, and aromatic amino acids. Shikimic acid is formed in several steps from precursors of carbohydrate metabolism. The key intermediate in quinone biosynthesis via the shikimate pathway is the chorismate. In the case of ubiquinones, the chorismate is converted to para-hydoxybenzoate and then, depending on the organism, the process continues with prenylation, decarboxylation, three hydroxy-lations, and three methylation steps. - ... 

Curcumin possesses strong antioxidant capacities, which may explain its effects against degenerative diseases in which oxidative stress plays a major role. As previously described for flavonoids, it is unlikely that curcumin acts as a direct antioxidant outside the digestive tract since its concentration in peripheral blood and organs is very low (near or below 1 pM, even after acute or long-term supplementation). Indeed, it has been shown that the intestinal epithelium limits its entry into the body, as reflected by absorption studies in various models (portal blood perfusion, everted bags). ... 

Each plant tissue tends to have an obviously distinctive profile of flavonoids. The flavonoid content can reach about 0.5% in pollen, 10% in propolis, and about 6 mg/kg in honey. Havonoid aglycones appear to be present only in propolis and honey, while pollen contains flavanols in herosidic forms. The flavonoids in honey and propolis have been identified as flavanones and flavanones/flavanols (Campos et ah, 1990). The antimi-crobially active flavanone pinocembrine was foimd to be a major flavonoid in honey (Bogdanov, 1989). Amiot et ah (1989) studied two blossom and two honeydew Swiss honey samples and foimd that pinocembrine was the main flavonoid. Pinocembrine concentration varied between 2 and 3 mg/kg (Bogdanov, 1989). Berahia et ah (1993) analyzed sunflower honey samples and detected six flavone/flavols, four flavanone/ flavols, and pinocembrin, of which pinocembrin is the main flavonoid. The flavonoids in sunflower honey and propolis were characterized and assessed for their effects on hepatic drug-metabolizing enzymes and benzo [fl]pyrene-DNA adduct formation (Sabatier et ah, 1992 Siess et ah, 1996). 

This evidence taken together lends considerable support to the view that sedative Asteraceae owe their activity to the GABAergic property of their flavonoids. One major difficulty seems to be explaining the mechanism by which these polar substances would cross the hemato-encephalic barrier to reach GABA receptors in the brain. 

Heerden FR. van, Viljoen AM, van Wyk BE. The major flavonoid of Dodonaea angus-tifolia. Fitoterapia 2000 71 602-604. 

Wolfender, J. L., Waridel, P., Ndjoko, K., Hobby, K. R., Major, H. J. and Hostettmann, K. (2000). Evaluation of Q-TOF-MS/MS and multiple stage IT-MSn for the dereplication of flavonoids and related compounds in crude plant extracts. Analysis 28 895-906A. 

Waridel P, Wolfender J-L, Ndjoko K, Hobby KR, Major HJ and Hostettmann K. 2001. Evaluation of quadrupole time-of-flight tandem mass spectrometry and ion-trap multiple-stage mass spectrometry for the differentiation of C-glycosidic flavonoid isomers. J Chromatogr A 926(1) 29-41. 

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