Fungal Carotenoids

Whereas the isoprene units of the higher plant carotenoids that are biosynthesized within the chloroplasts are formed via the 1-deoxyxylulose pathway, the fungal carotenoids are biosynthesized from acetate via mevalonic add. The C40 carbon skeleton of the carotenoids is formed by the head-to-head coupling of two C20 geranylgeranyl diphosphate units by phytoene synthase. 

---

Surveys of the early literature on fungal carotenoids are given in the reviews by Haxo (355) and Goodwin (298, 300, 301) and in the introduction to the paper by Fiasson, Lebreton and Arpin (239). The citation of many review articles dealing with carotenoids, including fungal carotenoids, may be found in the compendium compiled by Straub (633). 

Essays in the older hterature (42, 43) deahng with the purification and characterisation of carotenoids have been superseded by recent accounts of the application of HPLC to carotenoid analysis and separation (551) and of modern techniques of high field n.m.r. spectroscopy to elucidation of their structures (216). The mass spectra of several of the fungal carotenoids discussed above have been studied in detail by Liaaen-Jensen (217). 

Aasen, A.J., and S. Liaaen-Jensen Fungal Carotenoids II. The Structure of the Carotenoid Acid Neurosporaxanthin. Acta Chem. Scand. 19, 1843 (1965). 

Arpin, N., and S. Liaaen-Jensen Recherches Chimiotaxinomiques sur les Champignons. Fungal Carotenoids IV. Les Carotenoides de Phillipsia carminea (Pat.) Le Gal Isolement et Identification d une Xanthophylle Naturelle Nouvelle. Bull. soc. chim. biol. (Paris) 49, 527 (1967). 

Some Biochemical Aspects of Fungal Carotenoids. Fortschr. Chem. organ. Natur-stoffe 12, 169 (1955). 

Liaaen-Jensen, S. On Fungal Carotenoids and the Natural Distribution of Spirillo-xanthin. Phytochem. 4, 925 (1965). 

Mapari, S. A.S. et al., Exploring fungal biodiversity for the production of water-soluble pigments as potential natural food colorants, Curr. Opin. BiotechnoL, 16, 231, 2005. Dufosse, L., Mabon, R, and Binet, A., Assessment of the coloring strength of Brevi-bacterium linens strains spectrocolorimetry versus total carotenoid extraction/quan-tification, J. Dairy ScL, 84, 354, 2001. 

Other Degraded Carotenoids. A new synthesis of the fungal sex hormone ( )-(7 , 9 )-trisporic acid B methyl ester (114) utilized as the key step a Michael-aldol sequence on the /3-keto-ester (115) to yield the highly functionalized cyclo-hexenone (116). The latter underwent Wittig reaction with the phosphonium salt (117) to give (114). After basic alumina-catalysed hydrogen exchange in tritiated... 

Scheme 23.16 Microbial pathways from triterpene and tetraterpene (carotenoid) precursors to valuable flavour and fragrance compounds. 1 Carotenoid-cleaving peroxidase-containing supernatant of certain fungal cultures, e.g. Lepista irina 2 Serratia liquefaciens, Botrytis sp.

Identification and quantitative analyses of 25 compounds in steam distillates of burley tobacco stalk were accomplished. Compounds included twelve C,-C. compounds that were probable fatty acid oxidation products and 13 compounds >C that varied in origin. The latter included oxidation products of fatty acids, a C. prenyl pyrophosphate metabolite, and biodegradation products of carotenoids and chlorophyll. About 1/3 of the distillate mass was accounted for. Burley tobacco stalk headspace volatiles were also studied. When compared to the steam distillate, the headspace contained greater concentrations of sesquiterpenoids but lower concentrations of C, and C aldehydes and alcohols. Volatiles in steam distillates of tobacco stalk were not quantitatively different in a fungal resistant and a fungal sensitive variety of tobacco. Yield comparisons were made of headspace volatiles from tobacco and wheat. 

The carotenoids which are tetraterpenoids, are discussed in the chapter on fungal pigments (Chapter 7). 

Apart from the carotenoids relatively few terpenoids have sufficient conjugated unsaturation to contribute to fungal pigments. Exceptions are the sesquiterpe-noid lactarazulenes, e.g. lactaroviolin (7.42), which are obtained from several Lactarius species of milk cap. These are discussed in Chapter 5. 

The fungal hormones trisporic acids B and C were shown to have a carotenoid origin. The absolute stereochemistry of trisporic acid C (82) was established by ozonolysis and c.d. measurements. In addition to the all-trons isomers, 9-cis trisporic acids are also present." ... 

Carotenoids in Photosynthesis Photoresponses in Plants Carotenoids and Vision Development in animals Pigmentation in Animals Pigmentation of Flowers and Fruits Uses of Carotenoids Metabolites of Carotenoids Plant Growth-Regulating Compounds Carotenoids Metabolites as Fungal Pheromones References... 

Aspects of the early and later stages of carotenoid biosynthesis have been reviewed (136, 181) and a comprehensive account of the stereochemistry of naturally occurring carotenoids, including fungal pigments, has been pubhshed (458). 

---