Sesquiterpenes oxygenated

The aldehyde rubrocinctal A (7.4), the 12-carboxymethyl ester rubrocinctal B (7.16), and the corresponding 6-oxostearoyl esters 7.27 and 7.31 were isolated from Lactarius rubrocinctus Section Ichorati (2), (69). They are of special interest because they are, along with glutinopallal esters 8.2 and 8.3, the only examples of 12-oxygenated sesquiterpenes isolated from Lactarius species. 

Amyris Oil. Obtained by steam distillation of the wood of y m hakamijera L., the so-called West Indian sandalwood which is indigenous to northern South America, Central America, and the West Indies, amyris oil [8015-65-4] is a pale yellow to brownish yellow viscous oil with a slightly oily-sweet and occasionally peppery balsamic woody note. It finds use as a blender and fixative for soap fragrances. The volatile constituents, which are primarily hydrocarbon and oxygenated sesquiterpenes, are shown in Table 22 and Figure 5 (63). 

Eight olibanum samples of unknown botanical origin have been analysed [26]. The chemical compositions are summarized in Table 10.3 for three of them. Both the olibanum coming from Somalia and that from a market in Ta izz (Yemen) have been attributed to Boswellia carteri or sacra on the basis of the occurrence of the characteristic diterpenes isoincensole and isoincensole acetate (128) together with diterpene 126. The absence of methylchavicol (38), oxygenated sesquiterpene 91 and diterpene 124 and the presence in relatively large amount of (3-caryophyllene (73), ot-humulene (78) and caryophyllene oxide (95) excluded the hypothesis of a B. serrata sample. 

Figure 10.8 Total ion current chromatograms obtained after headspace SPME for (a) Kyphi and (b) B. sacra olibanum. Peak labels correspond to compound identification given in Table 10.3. The occurrence of isoincensole acetate (128) as well as the occur rence of the oxygenated sesquiterpene 98 and of dimer 2 (111) in Kyphi are clear fingerprints of the botanical origin of the olibanum used. Peaks labelled by letters correspond to the following compounds a, cinnamaldehyde b, vanilline c, curzerene d, furanoeudesma 1,3 diene e, a santalol f, 2 methoxyfuranodiene. Reproduced from S. Hamm, j. Bleton, j. Connan, A. Tchapla, Phytochemistry, 66, 1499 1514. Copyright 2005 Elsevier Limited...

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). 

Fruit maturity has a major impact on peel oil composition. Terpenes are almost exclusively present in the oil from unripe fruit. As fruit mature, concentrations of aliphatic aldehydes and oxygen-containing terpenes and sesquiterpenes increase [30]. For example, nootkatone and a-selinenone were not detected in the peel oils from fully developed immature fruit, but the oil from ripe fruits contained up to 0.15% of these oxygenated sesquiterpenes. 

In the last few years, sesquiterpene synthase from different plants has raised attention. In 2004, Schalk and Clark [88] described a process (patented by Fir-menich, Switzerland) that makes it possible to obtain sesquiterpene synthase and to produce various aliphatic and oxygenated sesquiterpenes from farnesyl diphosphate. For instance, valencene can be obtained in this way. 

With Tartrate-Derived Chiral 1,4-Diol/Ti Complexes A catalytic asymmetric Diels-Alder reaction is promoted by the use of a chiral titanium catalyst prepared in situ from (Pr O TiC and a tartrate-derived (2.R,3.R)-l,l>4,4-tetraphenyl-2,3-0-(l-phenylethylidene)-l,2,3,4-butanetetrol. This chiral titanium catalyst, developed by Narasaka, has been successfully executed with oxazolidinone derivatives of 3-borylpropenoic acids as P-hydroxy acrylic acid equivalents [40] (Eq. 8A.21). The resulting chiral adduct can be utilized for the first asymmetric total synthesis of a highly oxygenated sesquiterpene, (-i-)-Paniculide. 

About 20 oxygenated sesquiterpenes have been identified from pepper oil. They are 5,10(15)-cadinen-4-ol,caryophylla-3(12), 7(15)-dien-4-P-ol, caryophylla-2,7(15)-dien-4- 3-ol, caryophylla-2,7(15)-dien-4-ol, P-caryophellene alcohol, caryophyllene ketone, caryophellene oxide, epoxy-dihydrocaryophellene, cis-nero-lidol, 4,10,10-trimethyl-7-methylene bicycle-(6.2.0) decane-4-carboxaldehyde, cubenol, epi-cubenol, viridiflorol, a- and P-bisabolols, cubebol, elemol and y-eudesmol. 

The aroma and flavour of ginger are determined by the composition of its steam-volatile oil, which is comprised mainly of sesquiterpene hydrocarbons, monoterpene hydrocarbons and oxygenated monoter-penes. The monoterpene constituents are believed to be the most important contributors to the aroma of ginger and they tend to be relatively more abundant in the natural oil of the fresh ( green ) rhizome than in the essential oil distilled from dried ginger. Oxygenated sesquiterpenes are relatively minor constituents of the volatile oil but appear to be significant contributors to its flavour properties. 

Previous studies (Z) showed evidence for the presence of at least 20 sesquKerpene hydrocarbons in pineapple. These researchers identified 7 sesquiterpenes (1 tentative). We confirmed the presence of 3 of the sesquiterpenes and identified p-copaene, y-muurolene, a- and p-selinene in addition. Mass spectral data indicated the presence of other sesquiterpene hydrocarbons and oxygenated sesquiterpenes which we have been unable to characterize at present. 

The volatile constituents of Conyza dioscorides L. (Desf.) growing in Egypt showed promising antimicrobial activities against some tested microorganisms [153]. The volatile constituents consisted mainly of sesquiterpene hydrocarbons and oxygenated sesquiterpenes. The major sesquiterpene hydrocarbons are (3-maaliene and a-elemene, while the major oxygenated sesquiterpene compounds are a-cadinol, muurolol, caryophyllene oxide isomers and a sesquiterpene alcohol. 

The highly oxygenated sesquiterpene paniculide A was synthesized by N. Chida et al. starting from D-glucose. The key step to construct the substituted cyclohexane subunit of the natural product involved the Type II Ferrier rearrangement. 

Composition Main constituent is zingiberene (>30%) followed by P-sesquiphelland-rene. (-H)-ar-curcumene, (E,E)-a-famesene and (-)-P-bisabolene are further important sesquiterpene hydrocarbons. a-Terpineol and citral (up to 9% in Australian ginger) result in the citrus note, whereas nerolidol is responsible for the woody-soapy taste [115]. Further constituents are camphene, limonene, phellandrene, bomeol, 1,8-cine-ole, linalool, a-bisabolene, oxygenated sesquiterpene hydrocarbons, etc. For recent analytical data see [116, 117, 118]. 

The Amazon Indians Waiapi living in the West of Amapa State of Brazil, treat malaria with an inhalation of vapor obtained from leaves of Viola surinamensis. The antimalarial activity of the aromatic volatile plant extracts from leaves, showed that nerolidol (an acyclic oxygenated sesquiterpene) was identified as one of the active principles (36). Another recent study suggested the presence of an active isoprenoid pathway for biosynthesis of isoprenic chains of coenzyme Q in P. falciparum (37), parasites treated with nerolidol showed decreased ability to synthesize coenzyme Q in all intraerythrocytic stages. A challenge would be to now identify which African medicinal plants contain similar chemistry. 

The dramatic increase in terpene formation, accumulation, and emission in P. abies in response to methyl jasmonate is consistent with the effect of methyl jasmonate or jasmonic acid on many defense compounds in angiosperms. In conifers, jasmonates had been previously shown to promote the formation of heat shock and defense signaling proteins, to enhance resistance to pathogenic fimgi, and to promote colonization with ectomycorrhizae. In relation to terpenes, jasmonates had been shown to promote formation of an oxygenated sesquiterpene, todomatuic acid, and an oxygenated diterpene, paclitaxel (taxol), in cell cultures, but had never before been reported to enhance terpene accumulation in intact plants. 

Paniculide-A is structurally the least complicated of the paniculides, a family of highly oxygenated sesquiterpenes from Andrographis paniculata. Jacobi s synthesis of paniculide-A began with a four-step conversion of 3-methyl glutaric anhydride 175 to the oxazole acetylenic ketone 176 (Fig. 3.54). Cycloaddition of... 

Costunolide, treated with BF3-OEt2, produces the cyclocos-tunolide (2) and a C-4 oxygenated sesquiterpene lactone (3), 4Q -hydroxycyclocostunolide (eq 14). ... 

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