Hermann Muhle

Volatile constituents in mosses (Musci)

The essential oils of mosses of the genera Mnium, Plagiomnium, Homalia, Plagiothecium and Taxiphyllum (Musci) have been investigated by gas chromatography and mass spectrometry. The new sesquiterpenes (+)-10-epi-muurola-4,11-diene and 10,11-dihxdro-alpha-cuparenone were isolated by preparative gas chromatography and identified as major constituents of the hydrodistillation products of Mnium hornmum (Hedw.) using NMR and mass spectrometry. In addition, (+)-dauca-8,11-diene and two new butenolides, 3,4,5-trimethyl-5-pentyl-5H-furan-2-one and 3.4-dimethyl-5-pentyl-5H-furan-2-one were identified as constituents in Plagiomnium undulatum (Hedw.) T. Kop. Although the amounts of volatiles present in the investigated mosses are generally smaller than in liverworts, the spectrum of terpenoid compounds is similar. The investigated mosses also generate aliphatic compounds of greater abundance and structural variety.

The sesquiterpene constituents of the liverwort Preissia quadrata

Abstract The labile sesquiterpene hydrocarbon germacrene C is the main constituent of a chemotype of the liverworth Preissia quadrata collected in Southern Germany. Its temperature dependent rearrangement to racemic δ-elemene is observed by capillary gas chromatography using cyclodextrins as chiral stationary phases. In addition, the rarely found ent -sesquiterpenes (+)-germacrene D, (+)- trans - β -caryophyllene, (+)-β-caryophylleneoxide, (+)-cubebol and racemic alismol [1β,5α-guaia-6,10(15)-dien-4-ol] were identified as major constituents using spectroscopic methods and enantioselective gas chromatography. Minor constituents are (+)-α-copaene, (+)-δ-selinene, (−)-δ-cadinene, germacrene B and (−)-cascarilladiene (eudesma-5,7-diene).

Pacifigorgianes and tamariscene as constituents of Frullania tamarisci and Valeriana officinalis

The sesquiterpenoid constituents of the essential oils from the liverworts Frullania tamarisci, Frullania fragilifolia and of the angiosperm Valeriana officinalis were investigated. Tamariscene, a compound with a new sesquiterpene skeleton, valerena-4,7(11)-diene and five new pacifigorgiadienes, namely pacifigorgia-1,10-diene, pacifigorgia-1(6),10-diene, pacifigorgia-1(9),10-diene, pacifigorgia-2,10-diene, and pacifigorgia-2(10),11-diene were isolated and identified. Structure elucidation was carried out by NMR spectroscopy and chemical correlations to establish absolute configurations. Compounds present in both the essential oils of the Frullania species and Valeriana officinalis were enantiomeric to each other. A plausible biogenetic relationship between the pacifigorgiane, valerenane and tamariscane skeletons is postulated. Pacifigorgia-6,11-diene, not yet detected in nature, was generated by dehydration and rearrangement of natural (-)-tamariscol.

Volatile components from European liverworts Marsupella emarginata, M. aquatica and M. alpina

The hydrodistillation products of the liverworts Marsupella emarginata, M. aquatica and M. alpina were investigated by spectroscopic methods. A number of new compounds could be isolated by preparative gas chromatography (GC) and identified by spectroscopic techniques including GC-mass spectrometry, NMR and chemical correlations in conjunction with enantioselective GC. From M. emarginata, in addition to many known compounds, the sesquiterpene hydrocarbon (-)-7-epi-eremophila-1(10),8,11-triene (1) and the sesquiterpene derivatives (-)-4-epi-marsupellol (2), (-)-marsupellol acetate (18), (-)-4-epi-marsupellol acetate (4), (+)-5-hydroxymarsupellol acetate (5) and (-)-9-acetoxygymnomitr-8(12)-ene (24) could be identified. In M. aquatica the sesquiterpene hydrocarbons (-)-myltayl-8(12)-ene (7), ent-(+)-amorpha-4,11-diene (8), (-)-amorpha-4,7(11)-diene (9), the sesquiterpene alcohol (+)-9-hydroxyselina-4,11-diene (10) and (-)-2-acetoxyamorpha-4,7(11)-diene (11) were identified. In M. alpina (-)-trans-selina-4(15),11-dien-5-ol (12), (+)-8,9-epoxyselina-4,11-diene (13) and (+)-cis-selina-4(15),11-dien-5-ol (14) were found as new natural products.

Identification of (+)-β-caryophyllene in essential oils of liverworts by enantioselective gas chromatography

Abstract A combination of capillary columns with conventional and chiral stationary phases in a double-oven gas chromatograph (2D-GC) was employed to investigate the enantiomeric composition of β-caryophyllene in several liverworts. By comparison with a synthetic standard of racemic β-caryophyllene, enantioselective gas chromatography using heptakis(2,6-di- O -methyl-3- O -pentyl)- β -cyclodextrin as a chiral stationary phase revealed the presence of up to 85% (+)-β-caryophyllene in some specimens of Pellia endiviifolia and P. epiphylla .

Volatile constituents in the liverwort Tritomaria polita

The essential oil of the liverwort Tritomaria polita, collected in Otztal/Tyrol (Austria), was investigated by chromatographic and spectroscopic methods. Several new compounds were isolated by preparative gas chromatography (GC) and their structures investigated by mass spectrometry (MS) and NMR techniques. In addition to known constituents, the sesquiterpenoids (+)-eudesma-3,11-dien-8-one, (+)-eudesma-3,7(11)-dien-8-one, (+)-6,11-epoxy-eudesmane, (-)-6,7-seco-eudesm-7(11)-en-6-al, (+)-6beta-hydroxy-eudesm-11-ene, (-)-6alpha-hydroxy-eudesm-11-ene, (+)-6,11-epoxy-isodaucane could be identified as natural compounds for the first time.

(+)-Bisabola-2,10-diene[1,9]oxide, a constituent of the liverwort Calypogeia suecica

Abstract The sesquiterpene constituents of the liverwort Calypogeia suecica (Arn. and Perss.) K. Mull. were investigated. In addition to many known compounds a new sesquiterpene oxide, (+)-bisabola-2,10-diene[1,9]oxide, could be isolated and identified. The structure elucidation was carried out by NMR spectroscopic techniques and chemical conversions.

Isolepidozene, a diastereomer of bicyclogermacrene, in some liverworts

Isolepidozene, the diastereomer of the widespread sesquiterpene hydrocarbon, bicyclogermacrene, has been identified in several liverworts. This previously unknown sesquiterpene hydrocarbon is based on the rare trans-bicyclo[8.1.0]undecane skeleton.

Natural occurrence of α- and β-microbiotene

Abstract (−)-α-Microbiotene {(−)-(1S,5S)-2-methyl-5[(1S)-1,2,2-trimethylcyclopentyl]-bicyclo[3.1.0]hex-2-ene} (+)-β-microbiotene {(+)-(1S,2S)-2-methyl-5[(1S)-1,2,2-tri-methyl-cyclopentyl]-bicyclo[3.1.0.]hex-2(7)-ene} and (−)-cyclocupar-9-en-2-one have been isolated and identified from the essential oil of the liverwort Mannia fragrans and correlated with constituents of opposite configuration from Microbiota decussata (Cupressaceae).

Two aromadendrane type alcohols from the liverwort Conocephalum conicum

Abstract (−)-Aromadendran-5-ol and (+)-aromadendr-4-en-12-ol were isolated from the essential oil of a chemotype of Conocephalum conicum . The structures of the compounds were derived by NMR investigations and by conversion of the compounds into a series of products of known configuration by hydrogenation and dehydration.