Sesquiterpene quinones

The sesquiterpene quinones and hydroquinones display a wide range of biological activities.4 Some of the compounds are cytu-toxic, whereas others show antimicrobial characteristics. Avarol (2) has been the subject of investigation as a consequence of its ability to inhibit reverse transcriptase, but no clinical value (as an anti-AIDS agent, for example) has yet been established.3... 

Finally, Thiele acetoxylation of quinones, by treatment with acetic anhydride and sulfuric acid, is another excellent method of introducing functionality at an alkene carbon atom, for further synthetic elaboration (equation 50)196. This reaction was recently used as a key synthetic step in the total synthesis of metachromin-A, a useful sesquiterpene quinone moiety197. 

Urban S, Capon RJ (1996) Deoxyspongiaquinones New Sesquiterpene Quinones and Hydroquinones from a Southern Australian Marine Sponge Euryspongia sp. Aust J Chem 49 611... 

ABSTRACT Marine invertebrates such as ascidians, sponges and others are a prolific source of bioactive secondary metabolites. We have isolated a variety of marine natural products from the Okinawan marine invertebrates by using the sea urchin egg assay. Our recent work, the isolation, structure determination and activities of chlorinated macrolides, sesterterpenic acids, a bromotyrosine derivative, acetogenin derived endoperoxides, diterpene alkaloids, sesquiterpene quinones and spiro-sesquiterpenes, is presented in this article. The syntheses of these metabolites are also described. 

Ilimaquinone (29) is a marine sesquiterpene quinone first isolated in 1979 from the sponge Hippospongia metachromia90 It has been reported to have mild antibacterial, antiviral, antifungal, and anti-inflammatory activities, but more interestingly, ilimaquinone has been found to break down the Golgi apparatus into small vesicles, thereby blocking cellular secretion.91 92... 

Ceratocystis ulmi. These sesquiterpenes quinones possess antifungal properties. None of the mansonones was detected by TLC in extracts from healthy U. Americana. Accumulation of mansonones A, C, D and G in... 

Every effort has been made to include all known naturally occurring marine sesquiterpene/quinones as of September 1992. While compounds 9 0 to 93 appear not to satisfy the criteria of the survey, they are in fact aromatic ring contracted analogues. Likewise, although compounds 97 to 108 have received recognition in the literature as polyketides, in the absence of any definitive biosynthetic evidence to the contrary it is the contention of this author that they be considered as... 

As reviewed in an earlier volume in this series (110) the absolute stereochemistry attributed to ilimaquinone [75] on the basis of circular dichroism measurements was incorrect. The correct absolute stereochemistry for ilimaquinone was ultimately established by degradative correlation to aureol [49]. The absolute stereochemistry of aureol had been determined via X-ray analysis of a monobromo derivative. This stereochemical reassignment to ilimaquinone was important for reasons other than simply establishing the correct stereostructure for this particular marine metabolite. Ilimaquinone is a common co-metabolite in sponges that in turn have been the source of a variety of new sesquiterpene/quinones. Frequently these new compounds have been attributed the same "absolute stereochemistry" as ilimaquinone [75], principally on the basis of biosynthetic considerations. 

Careful examination of these stereochemical assignments revealed that in many instances a simple chemical transformation could have provided a more secure correlation. Over the last few years we have pursued several chemical correlations between marine sesquiterpene/quinones with interesting and useful consequences. Some of these results are highlighted below. 

More recently we completed a re-examination of the marine sesquiterpene/quinone spongiaquinone (33). This investigation was prompted by our discovery from a southern Australian marine sponge of the... 

Additional opportunities exist to chemically inter-relate naturally occurring marine sesquiterpene/quinones, and in doing so to both resolve their absolute stereostructures and to explore their chemical reactivity. 

Sesquiterpene quinones of the cuparane type from cultures of the inky caps Coprinus lagopus, C. cinereus, and C. macrorhizus (Basidiomycetes). The wild forms of these mushrooms do not form lagopodins. L A CijHigOj, Mr 246.31, yellow cryst., (ali, -10 (CHClj), L. B (C,5H,g04, Mr 262.31), and hydroxy-L B (CijHigOj, Mr 278.30, orange red cryst., mp. 184-186 C) have been described. Both L. A and L. B are unstable in aqueous solution and ex-... 

Bohlmann, F., C. Zdero, H. Robinson, and R.M. King Naturally Occurring Terpene Derivatives. 357. A Diterpene, a Sesquiterpene Quinone and Flavanones from Wyethia helenioides. Phytochem., 20, 2245 (1981). 

McNamara, C.E., Larsen, L., Perry, N.B., Harper, J.L., Berridge, M.V., Chia, E.W., Kelly, M., Webb, V.L., 2005. Anti-inflammatory sesquiterpene-quinones from the New Zealand sponge Dysidea cf. cristagalli. J. Nat. Prod. 68, 1431-1433. 

Bourguet-Kondracki, M.L., Longeon, A., Morel, E., and Guyot, M. (1991) Sesquiterpene quinones as immunomodulating agents. Int. J. Immunol. Pharmacol., 13, 393-399. 

Schroder, J., Magg, C., and Seifert, K. (2000) Total synthesis of the marine sesquiterpene hydroquinones zonarol and isozonarol and the sesquiterpene quinones zonarone and isozonarone. Tetrahedron Lett., 41, 5469-5473. 

Capon, R.J. (1995) Marine sesquiterpene quinones, in Studies in Natural Producs Chemistry, vol. 15 (ed. Atta-iu-Rahman), Elsevier Science, pp. 289-326. 

Capon, R.J., Groves, D.R., Urban, S., and Watson, R.G. (1993) Spongiaquinone revisited structural and stereochemical studies on marine sesquiterpene quinones from a Southern Australian marine sponge, Spongia sp. Aust.J. Chem., 46,1245-1253. 

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