A-cubebene

The third component of the elm bark beetle pheromone (p T 4) is a-cubebene (34) which the beetle takes from the tree. Simple disconnections lead to ketone (35). What disconnection would you suggest next ... 

Sampling time 60 min extraction temperature 80°C. Monoterpenes a-pinene, p-myrcene, a-phellandreneand limonene sesquiterpenes a-cubebene, a-copaene, p-elemene, p-caryophyllene, a-humulene, y-muurolene, p-eudesmene and caryophyllene oxide diterpenes cembrene A and isoincensole acetate. 

Figure 12.3 GC/MS (a) and THM GC/MS (b) curves of aged dammar. Peak assignments 2, a cubebene 3, copaene 4, ft bourbonene 8,10 12, cadinane type pyrolysis fragments 14 16, cadinene type pyrolysis fragments 17, calamanene type pyrolysis fragments 18 21, unidentified sesquiterpenoids 22, dammaradienone 23, dammaradienol 24, nor a amyrone 25, 28 nor olean 17 en 3 one 26, dammarenolic acid methyl ester 27, oleanonic acid 28, hydroxydammarenone 29, oleanonic aldehyde 30, ursonic acid methyl ester 31, ursonic aldehyde 32, nor (3 amyrone 34, 20,24 epoxy 25 hydroxy 3,4 seco 4(28) dammaren 3 oic acid methyl ester 35, 20,24 epoxy 25 hydroxy dammaren 3 one 36, dammaradienol...

The elm bark beetle pheromone contains three compounds multistriatin, the alcohol 12 and a-cubebene 13. At first we shall consider simple molecules like 12 but by the end of the book we shall have thought about molecules at least as complex as multistriatin and cubebene. 

The terpenoid-exocrine theme emphasized by scolytid beetles was again evident when the chemical constitution of the secondary attractant for the smaller European elm bark beetle, Scolytus multistriatus, was elucidated. The aggregation pheromone was identified as a mixture of (-)-4-methyl-3-heptanol, 2,4-dimethyl-5-ethyl-6,8-dioxabicyclo [3.2.1]octane (multistriatin) (XXII), and (-)-a-cubebene (XXIII), a host-derived synergist (70). All three compounds are required for the maximum attraction of beetles. The inactive diastereomers of 4-methyl-3-heptanol and multistriatin did not inhibit the responses of airborne beetles. 

Composition 75-85% eugenol, 8-15% eugenyl acetate and 2-7% caryophyllene (ISO [66]). Further constituents are humulene, a-copaene and a-cubebene. Heptanol-2, nonanol-2 and the corresponding ketones are trace components which are responsible for the fruity note (especially strong in oleoresins). The content of eugenyl acetate is responsible for the quality of the oil when compared to leaf and stem oil. Its content in oleoresins is even higher and these, therefore, represent the sensory qualities of the drug better than the oil [67], For further constituents see [68, 69, 70]. 

Methyl-3-heptanol is only part of the elm bark beetle pheromone. It is released together with a-multistriatin and a-cubebene. The latter compound is to be regarded as a kairomone released from the tree. The three substances work synergistically (see Silverstein, 1981 and references therein for further details). 

The elm bark beetle releases three compounds in its pheromone mixture multistriatin (14), the alcohol (15), and a-cubebene (16). At first we shall be looking at simple molecules such as (15). We shall progress to natural multistriatin, and finally, by the end of the book, to molecules as complex as a-cubebene. 

Cubebol (91), a-cubebene (92), and p-cubebene (93) are isolated Irom the berries of Piper cubeba [79]. Due to its pronounced cooling effects, cubebol was patented in 2001 as a refieshing agent for applications in various products ranging... 

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