Humulene epoxides

A new labdane diterpene, ( )-labda-8(l 7), 12-diene-15-ol-16-al (84) was isolated from the rhizomes of A. formosana together with ( )-15,16-bisnorlabda-8(17),l l-diene-13-one, two known sesquiterpenes, furopelargone B and humulene epoxide, and three known phenolic compounds, methyl traws-cinnamate, dihydro-5,6-dehydrokawain and dihydroflavokawin B [62]. The chemotaxonomic significance of these compounds was discussed briefly [62]. 

Figure 1. Structures of hop oil components. Key I, humulene II, humulene epoxide I III, humulene epoxide II IV, humulol V, humulenol II VI, humula-dienone VII, a-eudesmol VIII, -eudesmol IX, hop ether X, karahana ether XI, p-ionone and XII, j3-damascenone.

In a later study, the aroma constituents of a Bavarian (Pilsener) beer brewed in Hallertau, near Munich, which possessed a desirable fine hop aroma, was examined [58]. Neither the terpenes and sesquiterpenes nor the methyl esters characterized in hop oil were detected but fraction IV (Table 13.6), which contained terpenoids and sesquiterpenoids, possessed an intensive pleasant hoppy odour. Noteworthy amongst the identified constituents are the cyclic ethers (80)-(86) first found in Japanese hops, the flowery notes of which contribute to hop aroma, and the sesquiterpenoids derived from humulene such as humulene epoxide I, humulene epoxide II, humulol, and humulenol II. Similar results were found with American beers [60, 86]. Humuladienone (79)... 

Gupta, A. S., and S. Dev Studies in Sesquiterpenes. XLVI. Sesquiterpenes from the Oleoresin of Dicterocarpus pilosus Humulene Epoxide-III, Caryophyllenol-I and Caryophyllenol-II. Tetrahedron 27, 635 (1971). 

Homosecodaphniphyllic acid, methyl ester, K26 Homoterpenyl methyl ketone, Tl Homothujadicarboxylic acid, T7 Hopane, T4S Hopeaphenol, YIS Hopenone I, T4S Humulene dioxide, T30 Humulene epoxides, T30 Humulenols, T30 Hunteracine, K14 Hunterbumine, K8 Huratoxin, T39 Hydrastines, K3 Hydratropic acid, A41 3j8-hydroxyallocholanic acid, T49 Hydroxycitric acid, A30... 

Damodaran N P, Sukh Dev 1968 b Studies in sesquiterpenes. XXXVIII. Structure of humulene epoxide-I and humulene epoxide-II. Ifetrahedron 24 4123-4132... 

Gupta A S, Sukh Dev 1971 a Studies in sesquiterpene. XLVI. Sesquiterpenes from the oleoresin of Dipterocarpus pilosus humulene epoxide-III, caryophyllenol-I and caryophyllenol-II. Tetrahedron 27 635-644... 

---