Fungal depsidones

SiERANKiEWicz and Gatenbeck (298) have studied the biosynthesis of tridechloro-O-nornidulin (449) using C-n.m.r. spectroscopy, and have shown that it is formed, as expected, from two polyketide moieties. The ring A orsellinic acid moiety is derived from one acetate unit and two malonate units. The ring B moiety is formed from one acetate unit and four malonate units, and in addition two one carbon units located as the methyl group at the 9-position and in the butenyl side chain adjacent to the ring. 

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Depsidone Synthesis. Part 11. Synthesis of Some Fungal Depsidones related to... 

Kawahara N, Nozawa K, Nakajima S, Kawai K-I (1988) Isolation and Structures of Novel Fungal Depsidones, Emeguisins A, B, and C, from Emericella unguis. J Chem Soc Perkin 1 2611... 

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... 

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