Phlobaphenes

The structure of phlobaphenes is poorly understood. These compounds are believed to be polymers of flavan-4-ols, notably apiferol (1.100) and luteoferol (1.101) (Shirley-Winkel, 2001). Both of these monomers are derived from naringenin (1.35). 

The polymerization is thought to be under chemical, rather than enzymatic control, and give rise to a polymer (1.102) in which the monomers are linked via a 4-8 linkage. The C-C bonds between the flavan-4-ol monomers would be difficult to break, which could help explain the difficulties with the structural elucidation of phlobaphenes. The reaction mechanism whereby the hydroxyl group on C-4 is eliminated and a C-C 

Svabek, C., Ibraheem, F., Jones, D., and Chopra, S., 2005, Characterization of a deletion allele of a sorghum Myb gene yellow seedl showing loss of 3-deoxyflavonoids, Plant Sci. 169 542-552. 

Boeijan, W., Ralph, J., and Baucher, M., 2003, Lignin biosynthesis. Ann. Rev. Plant Biol. 54 519-546. 

Brunow, G., Lundquist, K. and Gellerstedt, G., 1999, Lignin. In. Sjostrom, E. and Alen R., (eds.), Analytical Methods in Wood Chemistry, Pulping, and Papermaking, Springer-Verlag, Germany, pp. 77-124. 

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Rinden-. cortical, bark, -auszug, m. bark extract. -borke, /. outer bark, -farbstoffi m. phlobaphene. 

There are several materials that make up this category, including wood-derived tall oil rosins and pine stump extracts sold under the well known VinsoH trade mark. They consist of complicated mixtures containing greater or lesser amounts of abietic acid (Fig 3.2) together with pimaric acid, and phenolic compounds such as phlobaphenes. 

The PAs, or condensed tannins, are polymers synthesized from flavan-3-ol monomer units. The phlobaphenes are 3-deoxy-PAs formed from flavan-4-ol monomers. The biosynthesis of both types of PAs follows the biosynthetic route of anthocyanins from chalcones through to the branch points to flavan-3-ol and flavan-4-ol formation. In this section, the specific enzymes forming the monomers are discussed, along with a discussion on the polymerization process. Although the chemistry of tannins is described in detail elsewhere in this book, it is useful to briefly mention the nature of the monomer subunit types and the polymer forms. 

Zea mays cell lines Anthocyanins, phlobaphenes, and C-glycosylflavones increased 140, 405... 

Chopra, S. et al.. Excision of the Candystripel transposon from a hyper-mutable Yl-cs allele shows that the sorghum Y1 gene controls the biosynthesis of both 3-deoxyanthocyanidin phytoalexins and phlobaphene pigments. Physiol. Mol. Plant Pathol., 60, 321, 2002. 

Ulmus campestris L. U. macrocarpa Hance U. pumila L. Yu Bai Pi (Siberian elm, Chinese elm) (leaf) Butyric acid, capric acid, lipase, hexylenaldehyde, phlobaphene, phytosterol, sitosterol.50 For urinary calculi, diuretic, febrifuge. 

N.A. Aims crispus (Ait.) Pursh A. glutinosa (L.) Gaertn. Tannins, resins, phlobaphenes, flavone glycoside, alnulin, taraxerol, protoalnulin, beta-sitosterol.100-102 As an astringent, reduce inflammation and internal hemorrhage. 

Potentilla erecoa (L.) Rauschel. P. tormentilla (L.) Rauschel. Tannins, catechins, ellagitannins, phlobaphene." Gargle for throat infections, mouthwash for canker sores and infected gums. 

The maize P gene has been implicated in the regulation of phlobaphene synthesis. Phlobaphenes are red pigments that accumulate in the pericarp of the maize kernel, as well as various other parts of the plant, including the... 

Grotewold, E., Drummond, B. J., Boen, B., and Peterson, T., 1994, The myh -homologous P gene controls phlobaphene pigmentation in maize floral organs by directly activating a flavonoid biosynthetic gene subset, Cell 76 543-553. 

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