Sesquiterpenoid lactones

Synthesis of germacrane sesquiterpenoid lactones and related compounds 99T2115. 

The primary active chemical constituent in feverfew is parthenolide, a sesquiterpenoid lactone (figure 8.8) (Robbers et al. 1996). Levels of sesquiterpene lactones vary across different types of extracts ethanol extracts contain about 0.5%, whereas aqueous ones contain 0.3% (Gromek et al. 1991). The sesquiterpene lactones in feverfew inhibit the... 

A few individual terpenoids, as well as less expensive mixtures of these compounds, find practical applications. Some examples are the tli terpenoid Vitamin A, the sesquiterpenoid santonin (as an anthelmintic), and the pyrcthnns, pyrctholonc esters of the monoterpenoid chrysanthcmic acid (used as an insecticide). A number of sesquiterpenoid lactones of the germacranolide. guaianolide and elemanolide types have shown promise as rumor inhibitors. 

Chicory (Cichorium intybus) is cultivated in cool regions such as Northern Europe. Recently, this vegetable has arisen out of claims that it is able to promote good health since no pesticides are used to cultivate chicory in the field, while the plant remains noticeably free from herbivore and microbial attack. The bitter substances, lactupicrin, 8-deoxylactucin and some phenolics had previously been shown to possess insect antifeedant properties in chicory (Rees and Harbome, 1985). Specifically, sesquiterpenoid lactones from chicory leaves, such as 8-deoxylactucin and lactupicrin (Figure 1), were identified as insect antifeedants against desert locust, Schistocerca gregaria. Similarly, we found some biologically active secondary metabolites in the... 

Various studies have also been reported on sesquiterpenoid lactones in Xanthium strumarium and Vemonia species,452,453 diterpenoids of Isodon species,454 and triterpenoids in Lycopodium species.455 Analyses of the carotenoids of Medicago species and of berries from a range of sources reinforce previously held views that the distribution of carotenoids in these sources has no taxonomic significance.456,457 Although most higher plants that have been investigated do not retain the capacity to biosynthesize the normal pattern of terpenoids when in tissue culture, it has been reported that Ruta graveolens did retain this ability.458... 

A comprehensive review of the sesquiterpenoid lactones from various species of the genus Artemesia has been presented. 

As a result of a detailed n.m.r. analysis of no less than 290 sesquiterpenoid lactones Yoshioka et have reached the following conclusions with respect to the partial structure (486) a) in those compounds with 8a-OH, the geminal... 

The structural elucidation and total synthesis of sesquiterpenoid lactones such as the germacranolides [cf. (310)] and eudesmanolides [cf. (311)] continues to be a very... 

Interest in the cytotoxic properties of extracts of Helenium amarum (bitter-weed) has resulted in the isolation of a number of sesquiterpenoid lactones e.g. tenulin, helenalin, etc.). The structure of heleniamarin (587), a recently discovered member of this group, has been determined by X-ray crystallographic analysis. ... 

The occurrence of a,P-unsaturated carbonyl structures in comparison with other terpenoid classes, is rather high. A very high percentage, 63 % of all sesquiterpenes in the DNP and 81 % of all sesquiterpenoid lactones, contain at least one a,P-unsaturated carbonyl structure element, while these numbers are lower in case of the mono-, di- and triterpenes (10/75%, 14/59% and 7/51%, respectively (numbers based on DNP [4]). However, it becomes evident from these figures that lactone groups tend to be associated with a,P-unsaturated carbonyls throughout all classes of terpenoids. 

A very comprehensive review of all sesquiterpenoid lactones reported in the literature up until the early part of 1979 has been published. Recent additions... 

Daniewski, W.M., M. Gumulka, P. Skibicki, U. Jacobsson, and T. Norin Constituents of Higher Fungi. Part XIX. New Sesquiterpenoid Lactone of Marasmane Skeleton from Lactarius vellereus. Bull. Acad. Polon. Sci., Ser. Sci. Chim., 35, 251 (1987). 

Connolly JD, Thornton IMS (1973) Sesquiterpenoid lactones from the liverwort Frullania tamarisci. Phytochem 12 631-632 Culberson CF (1969) Chemical and botanical guide to lichen products. University of North Carolina Press, Chapel Hill Dahlquist I, Fregert S (1980) Contact allergy to atranorin in lichens and perfumes. Contact Dermatitis 6 111-119 Dahlquist I, Fregert S (1981) Atranorin and oak moss contact allergy. Contact Dermatitis 7 168-169 Fernandez de Corres L (1984) Contact dermatitis from frullania ... 

There have been several analyses of sesquiterpenes whose structures are based on the azulene skeleton. To define completely the stmeture and absolute stereochemistry of the cytotoxic sesquiterpenoid lactone gaillaidin... 

In 2013, Liao reported the first asymmetric total syntheses of the sesquiterpenoid lactones (+)-eudesmadiene-12,6-olide and (+)-fruUanolide, which were based oti an initial dearomatization of 4-bromo-2-methoxyphenol 240 into the corresprMidmg MOB 241 (Fig. 58) [129]. An asymmetric Diels-Alder reaction wifli the chiral furan R)-2A2 furnished the bicyclo[2.2.2]octenone 243 in good yield with high chemo-, regio-, and stereoselectivities. This compound was further transformed in a few steps to reach (+)-eudesmadiene-12,6-olide, whose m-decalin core was elaborated by a high-yielding anionic oxy-Cope rearrangement of the allylic alcohol 244 (Fig. 58) [129]. 

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