Sesquiterpene lactone structure

Ivle, G. W. Wltzel, D. A. "Sesquiterpene Lactones Structure, Biological Action, and Toxicological Significance", In press. 

Schmidt, T. J. 1999. Toxic activities of sesquiterpene lactones structural and biochemical aspects. Curr. Org. Chem. 3, 577-608... 

Schmidt TJ (1999) Toxic Activities of Sesquiterpene Lactones. Structural and Biochemical Aspects. Curr Org Chem 3 577, especially pp. 599-600... 

Artemisinin (Fig. 1), isolated in 1972 from Chinese medicinal plant Artemisia annua L, is a novel antimalarial drug with a sesquiterpene lactone structure containing an internal endoperoxide linkage which is essential for the drug s activity. Artemisinin and its derivatitives form a series of antimalarial compounds with activity against chloroquine-resistant malaria parasites. In contrast to chloroquine, artemisinin penetrates the blood brain barrier, which makes it especially valuable for the treatment of cerebral malaria. ... 

Effects of Sesquiterpene Lactones on Seed Germination. Sesquiterpene lactones are common constituents of the Asteraceae but are also found in other angiosperm families and in certain liverworts (31,32). These highly bitter substances exhibit a wide spectrum of biological activities (J 3) which include cytotoxicity, anti-tumor, anti-microbial, insecticidal (34) and molluscicidal (35) properties. Furthermore, they are known causes for livestock poisoning and contact dermatitis in humans (33). Structure-activity relationship studies on sesquiterpene lactones have demonstrated that biological activity frequently depend on the presence of the cr... 

Some allelochemicals such as sesquiterpene lactones or alkaloids penetrate into a cell, binding with various cellular compartments, and changing the cellular fluorescence excited by ultra-violet or violet light. This makes clear cellular mechanisms of actions for the allelochemicals. Sesquiterpene lactones azulene and proazulenes binds DNA-containing structures such as nuclei and chloroplasts, which fluoresce in blue (Roshchina, 2004). 

Besides sesquiterpene lactones, an alkaloid analyzed as CgH14N203 (45), was isolated from the leaves of Arnica montana L. (80). Distinction between the two possible structures 45 (amide-urethane) and 46 (ester + urea) was accomplished by a selective synthesis from prolinamide. 

In 1959-61, a Czech group [8,9] reported the isolation of a new sesquiterpene lactone from Chrysanthemum (Tanacetum) parthenium as part of a study of the sesquiterpene lactones of the Compositae family. They named it parthenolide. The initial structure for parthenolide was later revised [10,11] and the accepted structure for parthenolide today is represented by structure (1). Parthenolide is a germacranolide-type sesquiterpene lactone. The crystal structure for parthenolide has also been reported [12]. Extractions of C. (T.) parthenium grown in Mexico, known locally as santamaria, did not yield parthenolide [13], but a closely related compound was isolated and named santamarine (3). This suggests that regional variations in the chemical constituents may occur. 

Parthenolide was only the first of many sesquiterpene lactones to be isolated from feverfew. Two further compounds were isolated and named chrysartemin A (4) and B (5) [14]. The structure of chrysartemin B was later revised [15], Recently, several studies have shown that chrysartemin A and B are not present in feverfew as the structures shown in (4) and (5) but are in fact the isomeric canin (19) and artecanin (20), respectively (see... 

A (4) and B (5) structures originally presented [15] were wrong and that these compounds do not occur in feverfew. Canin (19) is an example of a guainolide-type sesquiterpene lactone. 

A number of sesquiterpenes have been demonstrated to have pronounced biological activity ( ) among the non-volatile compounds the sesquiterpene lactones are best known (M) but other oxygenated sesquiterpenes are also known to be active. For example, the role of gossypol, a dimeric sesquiterpene and structurally related compounds has been investigated (21,22). The oxygenated sesquiterpenes, shiromodiol monoacetate and diacetate, from Parabenzoin trilobum (=Lindera triloba Blume) possess potent anti feeding activity toward Spodoptera litura larvae (85). 

Bilobalide (40) was isolated from the leaves by Wsinges ef al. [41], and is a sesquiterpene lactone, which has a Cert-butyl group and two hydroxyl groups in its chemical structure [42]. The ginkgo terpenes described above (bilobalide and ginkgolides) seem to be unique constituents to Ginkgo biloba because they have never been found in any other plants. 

Examination of the Montenegro Achillea clavennae reveals the presence of three new chlorine-containing guaianolides 277-279 in addition to several known analogues (524). The first investigation of the Chinese medicinal plant Vernonia chinensis has uncovered the new chlorinated sesquiterpene lactones vemchinilides A (280), B (281), C (282) and E (283) (525). Vemchinilides B and E exhibit potent cytotoxic activity against the P-388 and A-549 cell lines. The structurally similar vemolide C (284) was found in the Cambodian traditional medicinal plant Vernonia cinera (fever, colic, malaria) (526). Indeed, vemolide C could be identical with vemchinilide A. 

Osawa T, Suzuki A, Tamura S, Ohashi Y, Sasada Y (1973) Structure of Chlorochrymorin, a Novel Sesquiterpene Lactone from Chrysanthemum morifolium. Tetrahedron Lett 14 5135... 

Fischer, N.H., Weidenhamer, J.D., Riopel, J.L., Quijano, L., Menelaou, M.A. Stimulation of witchweed germination by sesquiterpene lactones a structure-activity study. Phytochemistry 1990 29 2479-2483. 

Often used in concert with mass spectrometry, NMR spectroscopy remains an invaluable structural diagnostic tool of particular importance to tricyclic natural products chemistry. For example, the tricyclic phenolic compound moracin P (3) was one of eight previously known compounds identified together with two new isoprenoid-substituted flavanones in isolates of the root bark of mulberry trees <89H(29)807>. In a series of studies of 6-7-5 tricyclic natural products, ID and 2D H and l3C NMR spectroscopy were employed extensively in the structure determination of sesquiterpene lactones (4)—(8) found among the aerial natural products of toxic plants (85P1378,90P551, 90P3875). 

Encelin from Montanoa speciosa is inhibitory to growth and development of fungal cells of Mucor rouxii. Other cytotoxic sesquiterpene lactones from Montanoa tomentosa ssp. microcephala have been reported.45,46 A number of kaurane diterpenes and e/tf-kauranoids have been reported that are potentially useful because of their cytotoxicity against human tumor cells, anti-HIV activity, and trypanosomicidal activity.47 56 New structures are frequently discovered, and probably we will learn new effects in humans and animals in the future.57,58 Paradoxically, these plant natural products probably have specific and important effects in the plants, but we are still ignorant of these roles. 

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