Sesquiterpenes structure

The calcified green alga Neomeris annulata manufactures a range of brominated sesquiterpenes (Structures 2.44-2.46), which are concentrated in the fleshy tips of this alga91 and which are individually deterrent to parrotfishes and the sea urchin. However, a mixture of the three metabolites did not increase deterrence, implying that other ecological roles may apply to these metabolites.92... 

Figure 3.8 Artemisinin and related endoperoxide-containing sesquiterpenes structures of artemisinin and related congeners (dihydroartemisinin and arte-mether), the fluorescent artemisinin probe used to identify the targeting of SERCA, and two putative radical intermediates that are formed upon reaction with haem and a haem adduct.

Semiochemicals are usually compounds with structures much simpler than that of brevenal. But even with simple compounds, there are possibilities of misassigning their absolute configuration. Male-produced pheromone components of the flea beetle Aphthona flava were isolated and identified in 2001 by Bartelt etal6 They proposed himachalene-type sesquiterpene structures 2—5 (Figure 2) to the components. In 2004, Mori and coworkers synthesized 2-5 and their enantiomers ent-2—mt-S from enantiomers of citronellal, and the... 

Members of the Celastraceae family produce a wide variety of macrocyclic sesquiterpene pyridine alkaloids, which will be discussed below. In addition, various nicotinoyl esters of the base sesquiterpene structure p-dihydroagarofuran are produced, such as in the cangorins [160], wilforcidine [161], triptofordinines [162], and related compounds [163]. 

Zerumbone, from Zingiber zerumbet, was shown to effectively suppress free radical generation, pro-inflammatory protein production, and cancer cell proliferation while additionally inducing the apoptosis of these same cells. An analysis of the relationship between the compound s structure and its activity indicated that the a, (5-unsaturated carbonyl group in the sesquiterpene structure is a requisite for the compound s... 

The composition of vetiver essential oil is extremely complex. According to recent studies, more than 170 constituents have been reported. Most of them possess a sesquiterpenic structure. (17) The ISO standard for oil of vetiver provides good criteria for assessing vetiver oil quality. (18)... 

Daniewski, W.M., A. Wawrzun, M. De Bernardi, G. Vidari, P. Vita-Finzi, G. Fronza, and G. Gatti Structural Studies on Lactarius Sesquiterpenes Structure Elucidation of Lactarorufins D and E and Conformational Analysis of Lactaran-5-olides. Tetrahedron, 40, 2757 (1984). 

There are more than 170 known trichothecenes which can be classified in four categories (A, B, C, and D) according to their chemical structure (Krska et al., 2001). All trichothecene mycotoxins have a basic tetracydic sesquiterpene structure with a six-membered oxygen containing ring, an epoxide group on the 12,13 position, and an olefinic bond on the 9,10... 

The great structural complexity encountered among sesquiterpenes implies that multiple cyclizations, shifts, and rearrangements of the parent cyclic intermediates may occur before stabilization to the final product, and in many instances several routes to the same sesquiterpene are feasible. Whether such reactions are concerted, take place sequentially on the enzyme surface, or involve discrete free intermediates is not yet generally known, and all three mechanistic alternatives, as well as multiple pathways, have been invoked to rationalize the same sesquiterpene structures. Because very few cell-free systems are available to examine these questions directly, and because of the difficulties associated with obtaining direct evidence of biosynthetic routes via in vivo tracer studies, hypothetic il pathways based mainly on chemical reasoning have been the rule (Roberts, 1972 Rucker, 1973 Anderson ef al., 1978). 

Ipomoeamarone a Phytoalexin (see) with a sesquiterpene structure. I. is formed when sweet potatoes are infected by phytopathogenk microorganisms. For synthesis, see Rg. 

In all living organisms, famesyl synthases convert isopentenyl pyrophosphate (IPP) into famesyl pyrophosphate (FPP) (77), the precursor of all sesquiterpene structures. The enzyme generating FPP, FPP synthase, has been extensively studied, and it was shown that the E,E conformation of FPP is the predominant product of famesyl synthases and generally is the substrate for sesquiterpene synthases in eukaryotes [22]. 

The enzyme, farnesyl pyrophosphate synthetase (prenyl transferase), is responsible for the condensation of (4.14) with (4.15) to give geranyl pyrophosphate (4.41). The same enzyme mediates addition of a further molecule of (4.14) to (4.41) yielding 2- ran5-farnesyl pyrophosphate (4.19). This is the basic unit for the elaboration of the structurally diverse sesquiterpenes. The results obtained on biosynthesis are as interesting as the sesquiterpene structures. The 2 cis... 

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