Humulene,«- and

The similarity between humulene and caryophyllene had not escaped Chapman s notice at the time that he isolated humulene, but as he was nnable to prepare a hydrate, which is one of the easiest of the caryophyllene derivatives to obtain in a pure state, he concluded that the sesquiterpene was not identical with caryophyllene. Eecent work by fiemmler does not tend to establish the identity of the two sesquiterpenes, and unless and until further evidence to the contrary is forthcoming, humvdene may be regarded as a definite chemical individual. 

Plectranthus barbatus Andr. This species contains a wide range of mono-and sesquiterpenoids including humulene and P-caryophyllene, 5-selinene, bomeol, camphene, P -phellandrene, a-ionone and a-thujene (65). The leaves are used as a purgative and for stomachaches. Leaves are soaked in warm water and the water is used to bath babies with measles (35). 

Plectranthus barbatus Andr. humulene and P-caryophyllene, 5-selinene, borneol, camphene, p -phellandrene, a-ionone, a-thujene 65... 

Electrophilic Ring Contraction of Humulene and Related Epoxides... 

Recrystallization of humulene nitrosite from hot ethanol produces both humulene and isohumulene (336) (ca. 1 1) together with the dinitro-cbmpound (334) and the nitrosite (333). I. Bryson and J. S. Roberts, unpublished results. 

The volatile oil contains mainly myrcene, humulene and caryophyllene. Up to 0.15% of 2-methyl-3-buten-2-ol can be detected in... 

The relationship between these materials is clear from their biogenesis which is discussed in Chapter 2 (see Figure 2.11). Cyclisation of farnesyl pyrophosphate produces the 11-membered ring of the humulenes and this then can undergo ( -annular cyclisation to give the bicyclic structure of the caryophyllenes. 

The resins of a number of species in the subfamily Dipterocarpoideae were investigated and found to contain several sesquiterpenes and triterpenes. Thus, the resins from five species of the genus Doona Shored) were examined and reported to contain sesquiterpenes such as caryophyllene (17), copaene (18), -elemene, and humulene, and... 

Essential oil from the seeds of A. katsumadai, a Chinese drug "caodoukou", was analyzed by GLC and 22 components were detected [35]. Three main constituents were isolated and identified as 1,8-cineol, a-humulene and trans,trans- ameso. From the seed residue, after removal of the essential oil by steam, alpinetin and cardamonin were isolated [36]. Together with trans,trans-fameso, rrawj-cinnamaldehyde and three flavonoids, alpinetin, cardamonin and pinocembrin, six diarylheptanoids 34-39 were isolated from the seeds of A. katsumadai and identified on the basis of chemical and spectral evidence [37]. 

The intramolecular version of the allylation has been carried out by Corey. The 11-membered cyclic ketone 554 was obtained from the silyl enol ether 553 in 52% yield, and short syntheses of humulene and 5-araneosene have been achieved utilizing the reaction as a key step [203],... 

Croteau, R. and A. Gundy, Cyclization of famesyl pyrophosphate to the sesquiterpene olefins humulene and caryophyllene by an enzyme system from sage (Salvia officinalis). Arch. Biochem. Biophys., 233, 838-841 (1984). 

The oil obtained from Melaleuca cajuputi Powell is the natural variety. To adulterate this oil, other species like Eucalyptus ssp. or Cinnamomum camphora (1,8-cineole type) are used. Eucalyptus terpenes, a phellandrene, and a-terpineol were used for blending. Detection is done by GC/MS with the smaller components like a-selinene, a-humulene, and a-terpineol. 

Fernandes ES, Passes GF, Medeiros R, da Cunha FM, Ferreira J, Campos MM, Pianowski LF, Calixto JB (2007) Anti-inflammatory effects of compounds alpha-humulene and (—)-trans-oaryophyllene isolated from the essential oil of Cordia verbenacea. Eur J Pharmacol 569(3) 228-236... 

Roots of Echinacea purpurea contain up to 0.2% essential oil [4, 14,15, 21, 67, 69, 74]. According to Becker [75] and Martin [76] it is composed of 2.1% caryophyl-lene, 0.6% humulene and 1.3% caryophyllene epoxide. Heinzer et al. [14] have analyzed the essential oil by gas chromatography-mass spectrometry (GC-MS) and found compounds of the type dodeca-2,4- dien-l-yl-isovalerate, as well as palmitic and linolenic acid, vanillin, p-hydroxycinnamic acid methyl ester and germacrene D, which had already been reported by Bohlmann and Hoffmann [27] for the aerial parts of the plant. Nevertheless, . purpurea roots are not a typical essential oil drug, and therefore analysis of the essential oil has not been used often for standardization purposes of phytopreparations. However, gas chromatography of the essential oil can be used for the discrimination of the species (see Fig. 1) [14]. 

Nicotiana. The comprehensive study mentioned already above (see Sect. 7.2.1.1) demonstrated also the occurrence of Cj VOCs, i.e., sesquiterpenes e.g., p-caryophyllene (Fig. 7.4), a-cedrene, different famesenes (Fig. 7.4), a-humulene and oxygenated sesquiterpenes (e.g., different cis-trans isomers of nerolidol, far-nesal, and famesol, as well as caryophyllene oxide) (Raguso et al. 2003). Further constitutive sesquiterpenoids from Nicotiana will be discussed below in connection with phytoalexins of this genus. 

Several forms of aging of SOA vapors have been observed. One clear form is oxidation of multiply unsaturated alkenes. Many terpenes have multiple unsaturations, and in some cases different double bonds have very different rate constants for reaction with ozone. Examples include terpinolene, myrcene, hmo-nene, a-humulene, and p-caryophyllene [149, 150]. In these systems, ozone will react with one double bond in the terpene and produce some SOA. However, after the precursor is completely removed, SOA levels can continue to rise as the first-generation semi-volatile products continue to react with ozone to produce less volatile second-generation products [149]. 

Lists of occurrence of sesquiterpenoids in higher plants are available (155, 207, 275 Vol. Ill b, c, 296, 305, 396). Thble 8.1.3 gives a list of plant families known for accumulating sesquiterpenoids. Of these, Cupressaceae, Compositae, Dipterocarpaceae and Myrtaceae are specially prolific in producing these compounds. Humulene and caryophyllene are the most extensively distributed sesquiterpenes. 

The primary aromatic substances in beer are derived from raw materials (barley or hops) that confer the beer s typical odour and taste. Bitter acids of hops have a bitter taste (see Section 8.3.5.1.3), but hop cones also contain 0.3-1% m/m of terpenoids (60-80% of hop essential oil), which have a considerable influence on the smell of beer. The main components of aromatic hop oils are sesquiterpenic hydrocarbons in which a-humulene, P-caryophyllene and famesene dominate. The major monoter-penic hydrocarbon is myrcene. For example, the essential oil content of fine aromatic varieties, such as Saaz, is 0.8% m/m, of which 23% is myrcene, 20.5% a-humulene, 14% famesene 6% and P-caryophyUene. Significant components of the hop aroma in beer are mainly isomeric terpenoid monoepoxides resulting from autoxidation and diepoxides of a-humulene and fS-caryophyUene, but also other terpenoids. Important components of hops odour are also various alcohols (such as geraniol and hnalool), esters (ethyl 2-methylpropanoate, methyl 2-methylbutanoate, propyl 2-methylbutanoate and esters of terpenic alcohols, such as geranyl isobutanoate), hydrocarbons, aldehydes and ketones formed by oxidation of fatty acids, such as (3E,5Z)-undeca-l,3,5-triene, (Z)-hex-3-enal, nonanal, (Z)-octa-l,5-dien-3-one, their epoxides, such as ( )-4,5-epoxydec-2-enal and sulfur compounds. Other important components of hops are so-called polyphenols (condensed tannins) that influence the beer s taste and have antioxidant effects. Less important compounds are waxes and other hpids. Hop products, such as powder, pellets and extracts (by extraction with carbon... 

On distilling one of these oils he again obtained the olefenic terpene above referred to, which is probably myrcene, and linalol, tc ether with an acid GgH gOo (probably isononylic acid) in the form of esters. Dipentene was also detected and probably esters of geraniol. The sesquiterpene humulene and the olefenic terpene make up more than 80 per cent, of the oil. Schimmel Co. have detected gurfun oil as an adulterant of this oil. 

C. verum cinnamon bark oil contains as its major component cinnamic aldehyde (usually 60-80%) other major constituents include sesquiterpenoids (4-5%) (e.g., a-humulene and P-caryophyllene that make up 3-4% of the total, limonene, and others), eugenol, eu-genol acetate, cinnamyl acetate, cinnamyl alcohol, methyl eugenol, benzaldehyde, cu-minaldehyde, benzyl benzoate, monoterpenes (e.g., linalool, pinene, phellandrene, and cym-ene), carophyllene, safrole, and others (list AND horhammer MASADA RAVINDRAN). °... 

Regardless of their apparent structural differences, all terpenoids are related. According to a formalism called the isoprene rule, they can be thought of as arising from head-to-tail joining of 5-carbon isoprene units (2-methyl-1,3-butadiene). Carbon 1 is the head of the isoprene unit, and carbon 4 is the tail. For example, myrcene contains two isoprene units joined head to tail, forming an 8-carbon chain with two 1-carbon branches. a-Pinene similarly contains two isoprene units assembled into a more complex cyclic structure, and humulene contains three isoprene units. See if you can identify the isoprene units in a-pinene, humulene, and /3-santalene. 

CHAlUHGtl Humulene and a-caryophyllene alcohol are terpene constituents of carnation extracts. The former is converted into the latter hy acid-catalyzed hydration in one step. Write a mechanism. (Hint The mechanism includes cation-induced double-bond isomerization, cyclizations, and rearrangements that may involve hydrogen and alkyl-group migrations. Two of the intermediates in the mechanistic sequence are shown five carbon atoms are identified by starts to help you track their positions through the process.)... 

Chamber (Caltech Indoor Chamber Facility) experiments have also been carried out by Lee et al. to monitor the time evolution and yields of gas-phase VOCs produced by the ozonolysis of ten different terpenes [197] six monoterpenes (a-pinene, (3-pinene, 3-carene, terpinolene, a-terpinene and myrcene), two sesquiterpenes (a-humulene and p-caryophyllene) and two oxygenated terpenes (methyl chavicol and linalool). Several gas-phase oxidation products were identified including formaldehyde, acetaldehyde, formic acid, acetone, acetic acid, nopinone and pinonaldehyde. 

The carbon skeleton of africanane can be formally deduced from that of farnesyl pyrophosphate and the cation leading to humulene and related derivatives (Figure 20.21) (Tursch et al, 1974). A hybrid alcyonarian formed from Sinularia maxima and Sinularia polydactyla contains polymaxenolide, which is a chemical hybrid... 

---