Guaiane sesquiterpenes

Interestingly, a few species of the section Dapetes growing in different parts of the world seem to contain different metabolites. For instance, aldehyde 4.5 has been isolated from Indian (27) but not from European specimens of L. deterrimus, while lactarofulvene (4.2) was isolated from Californian 28) but not from European specimens of L. deliciosus (5). An explanation of these apparent differences between specimens grown in different continents may be the existence of subspecies (5) or a change in the metabolism related to different habitats, or it may be due to the formation of artifacts during the extraction. A 

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Drimane, farnesane, glutinopallane, protoilludane, isolactarane, and guaiane sesquiterpenes have been isolated so far in a few Lactarius species therefore, they may be considered chemotaxonomic markers. By contrast, large quantities of marasmane, lactarane and secolactarane metabolites occur in almost all Sections, as reported in Table 24. 

Guaiane sesquiterpenes (Table 4) have been isolated so far only from Lactarius species of the Section Dapetes (Lactarius deliciosus, L. sanguifluus, etc.) which are characterized by the secretion of a strong coloured milky juice. Usually these mushrooms are edible and of pleasant taste. 

Three guaiane sesquiterpenes, the ester (4.13), lactaroviolin (4.3), and deterrol (4.7) showed a weak mutagenic activity in the Ames Salmonella assay (137). In addition, deterrol (4.7) exhibited moderate cytotoxicity towards Ehrlich ascitic tumor cells (EGA cells) and weak toxicity towards L1210 cells (lymphocytic leukaemia mouse) (137). Lactaroviolin (4.3) showed a weak inhibitory effect towards EGA cells, while the ester 4.13 did not impair either cell line at 50 Xg/ml (137). The Swedish authors pointed out that the greater toxicity of deterrol than of lactaroviolin was rather... 

Examples of other antimicrobial sesquiterpenes from the Anthemideae tribe also included new sesquiterpenes from the hexane extract of aerial parts of Santolina rosmarinifolia subsp. canescens (Lagasca) Nyman [175], and the guaiane sesquiterpenes rupicolin A, Fig. (13) and B, 1-deoxy-la-peroxy-rupicolin A and B isolated from Achillea clavennae [25]. 

From the dried rhizomes of C. aeruginosa, two novel guaiane sesquiterpene lactones, zedoalactone A (222) and zedoalactone B (223) were isolated together with zedoarondiol (194) and isozedoarondiol (195)... 

Guaiane sesquiterpenes, which are not formed by the same biosynthetic pathway as the types of sesquiterpenes found in the pungent Lactarius species (Scheme 1), can be considered chemotaxonomic markers of species belonging to Section Dapetes. The latter mushrooms are characterized by the secretion of a strongly colored milky juice and are usually edible and of pleasant taste (2). 

Sterner, O., O. Bergendorff, and F. Bocchio The Isolation of a Guaiane Sesquiterpene from Fruit Bodies of Lactarius sanguifluus. Phytochemistry, 28, 2501 (1989). 

De Rosa, S., and S. De Stefano Guaiane Sesquiterpenes from Lactarius sanguifluus. Phytochemistry, 26, 2007 (1987). 

A very interesting free-radical-initiated double cyclization permits access to guaiane sesquiterpenes, as shown in Scheme 4 [39]. 

The englerin guaiane sesquiterpenes have attracted much recent attention, and Scheme 21 delineates an approach utilizing an RCM [56]. 

The guaiane sesquiterpene atismol was synthesized by a cyclopentene + cyclopentenone [2 + 2], and a radical-induced fragmentation as shown in Scheme 57 [94]. 

Recently, it has been found that five-membered cyclic carbonate exists in nature. Rosselli and co-workers have presented the first example of natural origin cyclic carbonate terpenoid. They isolated a new guaiane sesquiterpene (Scheme 2), carrying a carbonate ring, from the aerial parts of the Centaurea hololeuca (Boiss) plant. 

Kobayashi, M., B.W. Son, M. Kido, Y. Kyogoku, and I. Kitagawa Clavukerin A, a New Triwor-guaiane Sesquiterpene from the Okinawan Soft Coral Clavularia koellikeri. Chem. Pharm. Bull. (Japan) 31, 2160 (1983). 

Chakraborty, K, Lipton, A.P., Paulraj, R., and Chakraborty, R.D. (2010) Guaiane sesquiterpenes from seaweed Ulva fasdata Delile and their antibacterial properties. Eur. J. Med. Chem., 45, 2237-2244. 

Kobayashi, M., Son, B.W., Kyogoku, Y, and Kitagawa, I. (1984c) Clavukerin C, a new trinor-guaiane sesquiterpene having a hydroperoxy function, from the Okinawan soft coral Clavularia koellikeri. Chem. Pharm. Bull, 32,1667-1670. 

The biogenesis of the germacrane, eudesmane, and guaiane sesquiterpenes is initiated by a cyclization between the terminal double bond... 

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