Terpene metabolism

The cases where terpene metabolism has been studied In Insects are very few Indeed. Certain Ips and Dendroctonus bark beetles convert monoterpenes such as a-plnene, 6-plnene and myr-cene to oxidation products, some of which have pheromonal activities ( 5, 3A, 35). A Dendroc tonus bark beetle s cytochrome... 

The brown algal genus Dictyopteris shows extraordinary chemical diversity and contains examples both of fatty-acid-derived hydrocarbons and of products from terpene metabolism. The... 

Tholl D. Terpene synthases and the regulation, diversity and biological roles of terpene metabolism. Curr. Opin. Plant Biol. 2006 9 297-304. 

Many aroma compounds in fruits and plant materials are derived from lipid metabolism. Fatty acid biosynthesis and degradation and their connections with glycolysis, gluconeogenesis, TCA cycle, glyoxylate cycle and terpene metabolism have been described by Lynen (2) and Stumpf ( ). During fatty acid biosynthesis in the cytoplasm acetyl-CoA is transformed into malonyl-CoA. The de novo synthesis of palmitic acid by palmitoyl-ACP synthetase involves the sequential addition of C2-units by a series of reactions which have been well characterized. Palmitoyl-ACP is transformed into stearoyl-ACP and oleoyl-CoA in chloroplasts and plastides. During B-oxi-dation in mitochondria and microsomes the fatty acids are bound to CoASH. The B-oxidation pathway shows a similar reaction sequence compared to that of de novo synthesis. B-Oxidation and de novo synthesis possess differences in activation, coenzymes, enzymes and the intermediates (SM+)-3-hydroxyacyl-S-CoA (B-oxidation) and (R)-(-)-3-hydroxyacyl-ACP (de novo synthesis). The key enzyme for de novo synthesis (acetyl-CoA carboxylase) is inhibited by palmitoyl-S-CoA and plays an important role in fatty acid metabolism. 

Dendrobium alkaloids. Alkaloids occurring in the orchid genus Dendrobium. Similar to the Nuphar alkaloids, these are pseudoalkaloids whose C-skeletons originate from terpene metabolism (sesquiterpenes). About 15 alkaloids are known, they were first isolated from Dendrobium nobile and later also from other species a typical representative is denr/w/nne C,6H25N02, Mr 263.38, mp. 134-136°C, [a]i -48.4° (CHjOH). ... 

C24H36O5, Mr 404.55, cryst., mp. 174°C, [a] +323° (CH3CN), a polyketide. M. is a potent inhibitor (K,= 1 nM) of HMG-CoA-reductase, the key enzyme in the biosynthesis of higher terpenes and steroids such as, e. g., cholesterol. It is produced by Aspergillus terreus and various Monascus species. Thus, e. g., the plasma cholesterol concentration (a major risk factor for the occurrence of arteriosclerosis) decreases by ca. 50% in patients under medication with M. In the terpene metabolism HMG-CoA-reductase reduces 3-hydroxy-3-methy Iglutary 1-CoA to mevalonate. M. mimics the substrate and thus leads to inhibition of the enzyme. M. is commercially available under the tradename Meva-cor . M. was the lead structure for numerous synthetic HMG-CoA-reductase inhibitors that are now available or are being developed (Atorvastatin, Cerivastatin, Fluvastatin, Pravastatin, Simvastatin). In these derivatives the hexahydronaphthalene structure is replaced by heterocylic ring systems, see also compactin. 

Skytanthus alkaloids. Alkaloids derived biogeneti-cally from the terpene metabolism (iridoid monoter-penes). 

Vitamin A and the carotenoids are products of the terpene metabolism. Industrial manufacturing processes are based on modular building blocks. Universal methods to couple these building blocks are the Wittig reaction, the Horner-Wadsworth-Emmons reaction, the sulfone coupling according to Julia, the Muller-Cunradi enol ether condensation and the Saucy-Marbet rearrangement. 

It has been a common assumption that secondary products are end products of sluggish metabolic pathways. As a result, tracer experiments have often involved incorporation periods from 24 h to several days. Results cited above indicate that terpene metabolism in plants is much more dynamic than this, and that synthesis and turnover may occur within minutes. 

This has led to an acceleration in the last decade in secondary metabolism research and generated a wealth of new knowledge related with terpene metabolism and other plant secondary pathways [5]. 

This chapter focuses on the terpenoid production from plant species, hairy root cultures, and Ri-plants the terpenoid increase by hairy root elicitation and recent strategies as T-DNA activation tagging/transcriptome analyses for isolating novel genes and hairy root engineering in order to improve terpene metabolism pathways. Lastly, therapeutic properties of some plant-derived terpenoids are reported. 

Olofsson L, Engstrom A, Lundgren A, Brodelius PE (2011) Relative expression of genes of terpene metabolism in different tissues of Artemisia annua L. BMC Plant Biol 11 45-57. doi 1186/147-2229-ll-45... 

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