Flavonoids prenylation

Botta B et al (2005) Novel prenylttansferase enzymes as a tool for flavonoid prenylation. Trends Pharmacol Sci 26(12) 606-608... 

In addition to the bitter acids and essential oils, the flowers of hops offer a rich array of polyphenolic compounds, primarily chalcones and their accompanying flavanones, many of which are prenylated derivatives (Stevens et al., 1997,1999a, b). The most prominent flavonoid in all plants studied was xanthohumol [342] (3 -prenyl-6 -0-methylchalconaringenin chalconaringenin is 2, 4, 6, 4-tetrahydroxychalcone) (see Fig. 4.11 for structures 342-346). Several additional chalcones—variously adorned with 0-methyl and/or C-prenyl functions—were also encountered, along with their respective flavanones. Three new compounds were described in the Stevens et al. 

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. - ... 

Chalcones Chalcones and dihydrochalcones can be considered as flavonoids with an open structure (see Fig. 5.1). Although dihydrochalcones such as phloretin glycosides and 3-hydroxyphloretin glycosides have been found in many fruits and vegetables (Tsao and others 2003 Arabbi and others 2004), the occurrence in general is rare (Tomas-Barberan and Clifford 2000). Prenylated chalcones such as xanthohumol are found in hops (Zhao and others 2005) (see Fig. 5.2). 

El-Bassouny A, Abouzid S. (2010) Anew prenylated flavonoid with antibacterial activity from propolis collected in Egypt. Nat Prod Commun 5 43 5. 

Recent developments in delayed extraction TOF allow higher resolving power and mass accuracy, and this method in the reflector mode has been used for accurate measurement of the mass of several compounds including two prenylated flavonoids. However, the performance of the MALDI-TOF instrument was not better than those of the FAB and FT-ICR MS instruments, and insufficient to give acceptable accuracy for literature reporting. 

Abegaz, B.M. et al., Prenylated flavonoids, monoterpenoid furanocoumarins and other constituents from the twigs of Dorstenia elliptica (Moraceae), Phytochemistry, 65, 221, 2004. 

Magalhaes, A.F. et al., Prenylated flavonoids from Deguelia hatschbachii and their systematic significance in Deguelia, Phytochemistry, 57, 77, 2001. 

The formation of phytoalexins such as glyceollins and phaseollins requires C-prenylation by a range of pterocarpan prenyltransferase (PTP) activities, with dimethylallyl pyrophosphate (DMAPP) as the prenyl donor. For glyceollins and phaseollins, prenylation occurs at position C-2 or C-4 of glycinol or C-10 of 3,9-dihydroxypterocarpan. ° ° However, there are differing activities in other species. For example, in Lupinus albus (white lupin) a prenyltransferase acting at the C-6, -8, and -3 positions of isoflavones has been identified.PTPs have also been characterized in detail for the formation of prenylated flavanones in Sophora flavescens (see, e.g., Ref. 207). However, no cDNA clones for flavonoid-related prenyltransferases have been published to date. 

Quercetin and a selection of naturally occurring prenylated flavonoids used as antiinflammatory agents in Chinese medicine were also tested for their ability to inhibit the... 

Chi, Y.S. et al., Effects of naturally occurring prenylated flavonoids on enzymes metabolizing arachidonic acid cyclooxygenases and lipoxygenases, Biochem. Pharmacol., 62, 1185, 2001. 

OH-, OMe-groups C-methyl methylenedioxy groups C-prenylation (9-prenylation (dihydro)furanosubstitution pyranosubstitution complex cyclosubstitution aromatic substitution esterification chlorination. These residues may also occur combined in one flavonoid structure. 

Linear substituted prenyl flavones exhibit a tendency towards prenylation at positions 3,6- and 8- of the flavonoid molecule. 3 -Prenylation of ring B occurs occasionally. The prenyl residue is mostly of the 3,3-dimethylallyl structure or the OH-equivalent of it. The prenyl residue T,l-dimethylallyl is rare. Geranylated flavones are also not very... 

Species of the genus Vellozia have been extensively studied for their flavonoid complement in relation to chemosystematics. In addition to a series of C-methylflavonols and two C-prenylated flavonols, derivatives of vellokaempferol and velloquercetin are accumulated in whole plants, leaves, and leaf exudates. The basic structure of these compounds is characterized by 7,6-isopropenylfurano substitution, based upon kaempferol, quercetin, and their 0-methyl ethers. In addition, 8-C-methyl derivatives of these compounds were also identified from leaves of V. stipitata " So far, species of this genus are the only reported sources of these compounds, which in parts have been proved to be accumulated externally. ° Structures are exemplified by Figure 12.10. 

Aspects on substitution patterns of prenylated flavonoids and their derivatives including the frequency of occurrence have been discussed in detail. Thus, these aspects will not be... 

Mitscher, L.A. et al. Antimicrobial agents from higher plants prenylated flavonoids and other phenols from Glycyrrhiza lepidota. Phytochemistry, 22, 573, 1983. 

Ahsan, M. et al., Novel O-prenylated flavonoids from two varieties of Boronia coerulescens, Phytochemistry, 37, 259, 1994. 

Chang, C.H. et al., Flavonoids and a prenylated xanthone from Cudrania cochinchinensis var. gerontogea. Phytochemistry, 40, 945, 1995. 

Ngadjui, B.T. et al., Dorsilurins C, D and E, three prenylated flavonoids from the roots of Dorstenia psilurus. Phytochemistry, 52, 731, 1999. 

Fukai, T. et al.. Structures of five new prenylated flavonoids, gancaonins L, M, N, O and P from aerial parts of Glycyrrhiza uralmsis. Heterocycles, 31, 373, 1990. 

Garcez, F.R. et al., Prenylated flavonoids as evolutionary indicators in the genus Dahlstedtia, Phytochemistry, 27, 1079, 1988. 

Kijjoa, A. et al.. Further prenylated flavonoids from Artocarpus elasticus. Phytochemistry, 47, 875, 1998. 

Seo, E.-K. et ak. Bioactive prenylated flavonoids from the stem bark of Artocarpus kemando. Arch. Pharm. Res., 26, 124, 2003. 

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