Hepaticae sesquiterpenoids

Adams RM (1990) Forestry workers. In Adams RM (ed) Occupational skin disease. Saunders, Philadelphia, pp 625-626 Asakawa Y (1982) Chemical constituents of the Hepaticae. Prog Chem Org Nat Products 42 1-285 Asakawa Y, Benezra C, Ducombs G, Foussereau J, Muller JC, Ourisson G (1974) Cross-sensitization between Frullania and Laurus nobilis the allergen of laurel. Arch Dermatol 110 957 Asakawa Y, Matsuda R, Toyota M, Takemoto T, Connolly JD, Phillips WR (1983) Sesquiterpenoids from ChiloscyphuSy Clasmatocolea and Frullania species. Phytochem 22 961-964 Barbier P, Benezra C (1982) Stereospecificity of allergic contact dermatitis (ACD) induced by two natural enantiomers, (+)-and (-)-frullanolides, in guinea pigs. Naturwissenschaften 69 296-297... 

As in the case of monoterpenoids, both antipodal forms of certain sesquiterpenoids have been found to occur in higher plants, though to a much restricted extent. Occurrence of racemic modification is rare, though a few examples are known (305). However, it may be pointed out that several sesquiterpenoids isolated from Hepaticae have been found to be enantiomeric to those from the higher plants (13,266). 

Already in 1905 Muller 265) reported the chemical constituents of the oil bodies found in the Hepaticae to be sesquiterpenoids, but the chemical constituents of the Hepaticae were not further investigated until 1965. Fujita et al. 123) reported that the essential oil of Bazzania pompeana was composed of the sesquiterpene hydrocarbons. In 1967, Huneck and Klein 160) reported the isolation of the two enantiomeric sesquiterpenes... 

Early studies on the chemistry of the bryophytes have been summarized by Benesova and Herout 86), Hegnauer 141), Huneck 150 —153,156), Martensson and Nilsson 205a), Spencer 303) and Suire 307). A review of heterocyclic compounds found in the bryophytes was also presented (37). Recently, Markham and Porter 199) have reviewed the chemical constituents of the bryophytes their review includes sesquiterpenoids, water soluble flavonoids, lignins, lipids and bibenzyls published prior to 1978, flavonoid chemistry and chemosystematic approaches to the Marchantiales being discussed in detail. In the three years since publication of this review, 121 papers on the chemistry of the Hepaticae have been published. 

The oil bodies of most species of the Hepaticae are contain sesquiterpenoids which are found in the four orders Calobryales, Jungermanniales, Metzgeriales and Marchantiales. Except for barbatane-, pinguisane- and 2,3-isecoaromadendrane-type sesquiterpenoids, the sesquiterpenoids isolated from or detected in the Hepaticae are identical with or very similar to those found in the Phanerogams. 

Bicyclogermacrene (228) is widespread in the Hepaticae and an important biosynthetic intermediate for aromadendrane-, 2,3-secoaroma-dendrane- and maaliane-type sesquiterpenoids which are often coexist with (228) 21, 64). 

These results establish that both antipodes, (-h)- and (—)-, of cuparane-type sesquiterpenoids occur in the Hepaticae. 

Ejudesmane-type sesquiterpenoids are very widely distributed in the Hepaticae, particularly in the Jungermanniales. 

The germacranolides isolated from the Hepaticae have the same 6a,7p-configuration as those found in the higher plants although the Hepaticae generally elaborate sesquiterpenoids antipodal to those found in higher plants. 

Pseudoguaiane-type sesquiterpenoids occur generally in Compositae, but the discovery of the pseudoguaiane-type sesquiterpene (430) is the first instance of such an occurrence in the Hepaticae. 

Huneck and Klein (160) reported isolation and characterization of the essential oil obtained from seven Jungermanniales species and one Metzgeriales species. From Scapania undulata, (—)-longifolene (439) and (—)-longiborneol (443) were isolated and their structures established by comparison of their spectral data with those of authentic samples. This represented first isolation of terpenoids from the Hepaticae and of sesquiterpenoids antipodal to those found in higher plants. The presence of longifolene (439) and isolongifolene (440) in Scapania species was revealed by GC-MS analysis (314). 

Gorham(72< ) reported that lunularin (595) and lunularic acid (598) were found in the Hepaticae, but not in the Musci and the Anthocerotae. Chemical differentiation between the Hepaticae and the Musci is also observed with respect to terpenoids and lipophilic aromatic compounds. The Hepaticae produce mono-, sesqui- and diterpenoids as well as lipophilic aromatic compounds. By contrast neither mono- and sesquiterpenoids nor lipophilic aromatic compounds have been found in the Musci which have been analyzed so far, except for the presence of one kaurane-type diterpene (508) in Saelania species (272). This characteristic difference in chemical constituents is due to the following fact. Most species of the Hepaticae possess oil bodies which contain the terpenoids and the lipophilic aromatic compounds, whereas, the Musci do not contain oil bodies. Terpenoids and aromatic compounds are major constituents of the Hepaticae and can be used as important chemosystematic markers at different taxonomic levels 13a, 19, 21, 25a, 26—29, 33, 34, 45—47, 67, 69, 74, 334). Although flavonoids are not major components of the Hepaticae, these can also be used as chemical markers (187—198, 200—205, 259, 264, 310—312, 328, 329). Taxonomic use of biochemical data for all hierarchical levels of the bryophytes was reviewed by Suire and Asakawa (310—312). The chemosystematics of the Marchantiales were reviewed by Markham and Porter (199). 

Chart 10. Sesquiterpenoids (curcumene, calacorenes, caryophyllene and cedrenes) found in the Hepaticae. 46... 

Chart 17. Sesquiterpenoids (farnesane and monocyclofarnesane) found in the Hepaticae. 66... 

Connolly, J. D., A. E. Harding, and I. M. S. Thornton Gymnomitrol, a Novel Tricyclic Sesquiterpenoid from Gymnomitrion obtusum (Lindb.) Pears. (Hepaticae). Chem. Commun. 1972, 1320. 

---