Hans Becker

Amides and other constituents from acmella ciliata

Abstract Fourteen highly unsaturated amides were isolated from Acmella ciliata. Their structures were determined by means of high field 1H NMR including 2D-NMR, high resolution mass spectrometry and GC-MS. Some considerations on the biosynthesis of the amides are made.

Spilanthol-related amides from Acmella ciliata

Abstract From the flower heads of Acmella ciliata amides closely related to spilanthol were isolated. They possess isobutylamine, 2-phenylethylamine and 2-methylbutylamine parts. In the acidic part deca-2E,6Z,8E-trienoic acid, known from spilanthol, and its 2,3-dihydro derivative were found. Two compounds bear ester groups, a novelty for unsaturated amides. The structures were elucidated by means of high field 1H NMR and high resolution mass spectrometry.

Diterpenoids with a novel skeleton from the liverwort Anastrophyllum minutum

Abstract Six diterpenoids with a novel carbon skeleton were isolated from the liverwort Anastrophyllum minutum . Their structures were determined by means of high field NMR spectroscopy including proton—proton and proton—carbon shift correlation 2D-techniques, NOE difference spectroscopy and high resolution mass spectrometry. Sphenolobane is the proposed name of the new skeletal type and its biogenetic origin is briefly considered. Inhibitory activity against the growth of shoots and roots of rice was shown by 3α,4α-epoxy-5α-acetoxy-18-hydroxysphenoloba-13 E , 16 E -diene.

Separation of Labile Terpenoids by Low Temperature HPLC

Abstract Semipreparative low temperature HPLC was used to isolate two sesquiterpene hydrocarbons, i. e. anastreptene and β-barbatene, that could not be separated at ambient temperature. A linear relationship was observed between the logarithm of capacity factor and the reciprocal of column temperature. This was consistent with previous reports (4, 5, 8). It could be demonstrated that differences in enthalpy and entropy may cause a temperature-dependent resolution for both compounds. Low temperature H-NMR revealed that separation was not due to a fixation of conformation.

Terpene hydrocarbons in Pimpinella anisum L.

The essential oil of anise (fruits and shoots) was investigated focusing on the composition of the hydrocarbon fraction. Several sesquiterpenes were identified by GC-MS and the relative composition of the fractions was established by GC analysis. γ-Himachalene and the diterpene neophytadiene were isolated by TLC and column chromatography at low temperatures. Their structures were determined by MS and NMR including1H-1H correlated COSY and NOE experiments.

Influence of colchicine treatment on chromosome number and growth rate of tissue cultures of Valeriana wallichii DC

Cell cultures of Valeriana wallichii were treated with 0.05%, 0.2% and 0.5% of colchicine. The treatment with 0.05% and 0.2% colchicine resulted in well growing cultures. At the highest dose the cells died. The colchicine treatment could be repeated after six alkaloid free passages. The chromosome numbers shifted to polyploidy (n>96) under the treatment but had a strong tendency to the initial pattern.

Growth Inhibition of a Valeriana wallichii Cell Culture by Branched-chain Amino Acids

Summary The growth of a Valeriana wallichii DC cell culture is inhibited by each of the three branched-chain amino acids isoleucine, valine and leucine. In combination only isoleucine/valine/leucine and isoleucine/valine do not inhibit the growth of the cell culture. Acetohydroxyacid synthetase (EC 4.1.3.18) of Valeriana wallichii cells is also inhibited by the branched-chain amino acids. Feedback inhibition of this enzyme and inhibition of growth appear to be correlated.

Flavone C-glycosides of Phoradendron tomentosum from different host trees

Abstract Apigenin, three known apigenin C-glycosides, vitexin, schaftoside and isoschaftoside together with apigenin 4′-O-glucoside have been identified in leaves of Phoradendron tomentosum growing on different hosts.

Isolation and characterization of cell lines of Valeriana wallichii resistant to trifluoroleucine

Summary Two cell lines of Valeriana wallichii DC resistant to the leucine analogue 5′,5′,5′-trifluoro-D,L-leucine have been isolated. The two lines (V125, V 500) accumulated higher amounts of aspartic acid (up to 5 fold) and glutamic acid (up to 57 fold) compared to the initial cultures; furthermore, V 500 accumulated comparatively high amounts of valine (R∼15 fold) and leucine (∼ 37 fold). The activity of acetohydroxyacid-synthetase, the key enzyme in the biosynthetic pathway of branched-chain amino acids, was little affected by these amino acids in V 500. In V 125 the enzyme showed no change in feedback control properties. While in the literature there is some evidence that leucine degradation products are incorporated into terpenoid compounds, the high pool of leucine in V 500 did not induce a higher accumulation of terpenoid derived compounds such as valepotriates, volatile terpenes and sterols.

Untersuchungen des Lignins der Mistel (Viscum album L.) in abhängigkeit von der jeweiligen Wirtspflanze

Summary Investigations of lignin from European mistletoe ( Viscum album L.) in dependence from its host. The suggestion that the lignin from European mistletoe ( Viscum album L.) is similiar to that from its host has been examined by the following methods: histochemistry, nitrobenzene-oxidation, thermofractography and NMR-spectroscopy. All analytical data found by these methods disprove the hitherto existing suggestion. Not only the lignin from mistletoe on angiosperms (apple, poplar) but also the lignin from mistletoe on gymnosperms (pine, spruce) has to be classified as hardwood-lignin.