Depsidones biosynthesis

Sala T, Sargent MV (1981) Depsidone Synthesis. Part 16. Benzophenone - Grisa-3 ,5 -diene-2 ,3-dione - Depsidone Interconversion A New Theory of Depsidone Biosynthesis. J Chem Soc Perkin Trans 1 855... 

Sala and Sargent 276) postulate that the benzophenone precursors to depsidones would arise by acylation of one orsellinic acid type by another. Thus j -depside and depsidone biosynthesis would diverge at the mononuclear stage. A decision between the Barton-Erdtman theory 12, 135) and that of Sala and Sargent would require the feeding of appropriate advanced precursors. This is probably the most challenging experiment yet to be carried out in the area of depsidone chemistry. 

Phenolic compounds are widespread products of secondary metabolism of lichen, and antioxidant activity is most frequently associated with their presence. Lichen phenolics are mainly depsides, depsidones and dibenzofurans, whereas vascular plant phenolics include tannins, lignins and flavonoids. Orsellinic acid is the basic unit in the biosynthesis of hchen phenolics. Lichen phenols are generally secreted by the fungal partner and deposited as crystals on the surface of the ceU wall of the fungal hyphae. Lichen phenols are primarily acetate-polymalonate derived with the exception of pulvinic acid derivates which are synthesised via... 

The biosynthesis of phenylalanine derivatives goes through shikimic acid and phenylalanine in contrast to the aromatic units of the anthraquinones, depsides, depsidones, depsones, dibenzofuranes, and xanthones, which are formed on a polyacetate pathway. This justifies a separate classification for the phenylalanine derivatives, which include polyporic acid, thelephoric acid, and pulvinic acid derivatives, all deeply pigmented (yellow, orange, red, or violet). 

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