Of flavonoidal alkaloids

Auzi, A.A., Hartley, T.G., and Waterman, P.G., Distribution of flavonoids, alkaloids, acetophenones and phloroglucinols in the genus Bosistoa (Rutaceae), Biochem. Syst. EcoL, 25, 611, 1997. 

An organic extract of the leaves of Buchenavia capitata (Vahl) Eichl. showed anti-HIV activity in the screening procedure carried out by the National Cancer Institue in the USA [14]. This activity was traced to the alkaloidal component of the extract. This species had previously been shown to contain a group of flavonoidal alkaloids known as the buchenavianines [15]. 

Some of the potential uses of the fats and oils found in plants have been reviewed and some uses of carbohydrate-based polymers briefly discussed. Plants contain a whole variety of other chemicals including amino acids, terpenes, flavonoids, alkaloids, etc. When the potential for these naturally occurring materials are combined with the secondary products that can be obtained by fermentation or other microbial processes or by traditional chemical transformations, the array of chemicals that can readily be created from renewable resources is huge. In this section a few of the more interesting examples are considered. 

Separation of flavonoid and alkaloid fractions of SyncUsia scabrida... 

There are three categories of constituents in passionflower flavonoids, maltol, and indole alkaloids. Among flavonoids are chrysin (5,7-dihydro flavone), vitexin, coumerin, and umbelliferone (figure 6.6). The greatest accumulation of flavonoids occurs in the leaves (Menghini and... 

Most recently a series of piperidinyl-flavonoid alkaloids have been isolated from two Buchenavia spp. (Combretaceae) (6). The leaves of B. macrophylla Eichl. yielded buchenavianine (8) and iV-demethylbuchenavianine (9). The fruits... 

The flavonoidal alkaloids have thus been found widely scattered throughout the higher plants. In view of the ubiquitous occurrence of flavonoids and the simplicity of the nitrogenous component in the compounds so far isolated, it is quite possible that they may occur in more species. The occurrence of the flavonoid alkaloids in Buchenavia but not Terminalia has been used to confirm the taxonomic distinction between these genera (6). 

The UV spectra of all flavonoidal alkaloids is related entirely to the flavonoid part of the molecule. Table I lists the data reported for each alkaloid. Flavones exhibit maxima in the region of 270-325 nm whereas the flavanones show maxima at about 250-320 nm. The flavan vochysine shows an absorbtion only at 275 nm since there is no conjugation system in ring C. 

The molecular ions of some of the alkaloids isolated more recently have been obtained and have been useful indicators of the substituents present on a common nucleus, particularly for the Buchenavia alkaloids (6). All spectra so far reported have been obtained using electron impact fragmentation. Table III lists the fragmentation patterns reported. Thus far no studies have been made on the breakdown mechanisms, but the cleavage of the flavonoid and nitrogenous rings is obviously an important process. 

No studies have been carried out on the biosynthesis of the flavonoidal alkaloids. It is assumed, however, that the flavonoid moiety is formed by the usual... 

Bennett, R.N. et al., Profiling glucosinolates, flavonoids, alkaloids, and other secondary metabolites in tissues of Azima tetracantha L. (Salvadoraceae), J. Agric. Food Chem., 52, 5856, 2004. 

Certain flavonoids are used by plants to protect them from invasion by parasites. For example, poplar (Populus spp.) cultivars produce a chemical barrier to parasitization by mistletoe (Viscum album).Resistant poplar cultivars were significantly higher in flavonols and flavones compared to susceptible cultivars. Likewise, in Streblus asper the bark and wood of trees that are resistant to the parasite Cuscuta reflexa hold higher levels of flavonoids, as well as steroids and alkaloids. 

The bioactive secondary metabolites reported from Broussonetia kazinoki can be classified into major two groups, alkaloids and flavonoids (Table 1), Fig. (1). The Kusano group at Osaka University of Pharmaceutical Sciences in Japan reported over 20 pyrrolidine alkaloids, broussonetines A-H, K-M, O-T, V-X, and Mi, and broussonetinines A and B, four pyrrolidinyl piperidine alkaloids, broussonetines I, J, Ji, and J2, two pyrroline alkaloids, broussonetines U and U, and one pyrrolizidine alkaloid, broussonetine N, from hot water extracts of B. kazinoki [16-24]. As shown in Table 1, some of these alkaloids exhibited strong... 

Bacteria and fungi play an essential role in the biosphere by breaking down the many aromatic products of plant metabolism.150 153 These include vast amounts of lignin, alkaloids, flavonoid compounds, and other biochemically "inert" substances. Lignin is a major constituent of wood and a plant product second only to cellulose in abundance. 

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