Tetraterpenes carotenoids

Tetraterpenes. Carotenoids make up the most important group of C q terpenes and terpenoids, although not all carotenoids contain 40 carbon atoms. They are widely distributed in plant, marine, and animal life. It has been estimated that nature produces about 100 million t/yr of carotenoids synthetic production amounts to several hundred tons per year (207,208). 

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.

There are two important classes of allelochemicals synthesized by oxidative cleavages of tetraterpene carotenoids. One is the plant hormone abscisic acid (ABA, 31) that plays important roles in growth and development of plants, especially in seed development and dormancy.17 Dry dormant seeds contain relatively large amounts of ABA, particularly in the seed coats. ABA and phenolic allelochemicals in the seed coats are easily released into the environment when the seeds are imbibed, resulting in inhibition of seed germination and seedling growth of plants in the vicinity. Both ABA and the phenolic compounds are rapidly broken down in the soil, and therefore the inhibition is short-lived. 

Isopentenyl pyrophosphate Hemiterpenes (isoprene). Monoterpenes (iridoid components of volatile oils). Sesquiterpenes (bitter principles, components of volatile oils). Diterpenes (components of resins, gibberellins, phytol). THterpenes (squalene, sterols, etc.). Tetraterpenes (carotenoids, xanthophylls). Polyterpenes (caoutchouc, gutta percha). 

Tetraterpenes Carotenoids, trisporic acids (D 6.5) Blakeslea trispora B... 

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