An efficient route for an alternative synthesis of gibberllin A1 from gibberellin A3 is described. Based on iodolactonisation the method provides access to gibberellin A1 labeled by deuterium with both high incorporation of the isotope and high stereoselectity at the positions 1β and 2α. The additional deuterium labeling at C‐17 was introduced via the corresponding 16‐norketone resulting in [1β,2α,17,17‐D4] gibberellin A1.

At early stages of germination, a special lipoxygenase is expressed in cotyledons of cucumber and several other plants. This enzyme is localized at the lipid storage organelles and oxygenates their storage triacylglycerols. We have isolated this lipid body lipoxygenase from cucumber seedlings and found that it is capable of oxygenating in vitro di- and trilinolein to the corresponding mono-, di-, and trihydroperoxy derivatives. To investigate the in vivo activity of this enzyme during germination, lipid bodies were isolated from cucumber seedlings at different stages of germination, and the triacylglycerols were analyzed for oxygenated derivatives by a combination of high pressure liquid chromatography, gas chromatography/mass spectrometry, and nuclear magnetic resonance spectroscopy. We identified as major oxygenation products triacylglycerols that contained one, two, or three 13S-hydroperoxy-9(Z),11(E)-octadecadienoic acid residues. During germination, the amount of oxygenated lipids increased strongly, reaching a maximum after 72 h and declining afterward. The highly specific pattern of hydroperoxy lipids formed suggested the involvement of the lipid body lipoxygenase in their biosynthesis.These data suggest that this lipoxygenase may play an important role during the germination process of cucumber and other plants and support our previous hypothesis that the specific oxygenation of the storage lipids may initiate their mobilization as a carbon and energy source for the growing seedling.

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A clone of an ubiquitin‐conjugating enzyme (UBC) was isolated from a λ‐ZAP‐cDNA library, generated from mRNA of tomato (Lycopersicon esculentum) cells grown in suspension for 3 days. The open reading frame called Le UBC1, encodes for a polypeptide with a predicted molecular mass of 21.37 kDa, which was confirmed by bacterial overexpression and SDS‐PAGE. Database searches with Le UBC1 showed highest sequence similarities to UBC1 of bovine and yeast. By Southern blot analysis Le UBC1 was identified as a member of a small E2 subfamily of tomato, presumably consisting of at least two members. As revealed by Northern blot analysis Le UBC1 is constitutively expressed in an exponentially growing tomato cell culture. In response to heat shock an increase in Le UBC1‐mRNA was detectable. A strong accumulation of the Le UBC1‐transcript was observed by exposure to heavy metal stress which was performed by treatment with cadmium chloride (CdCl2). The cellular uptake of cadmium was controlled via ICP‐MS measurements. The data suggest that like in yeast, in plants a certain subfamily of UBC is specifically involved in the proteolytic degradation of abnormal proteins as result of stress.

Changes in lipoxygenase (LOX) protein pattern and/or activity were investigated in relation to acquired resistance of cucumber (Cucumis sativus L.) leaves against two powdery mildews, Sphaerotheca fuliginea (Schlecht) Salmon and Erysiphe cichoracearum DC et Merat. Acquired resistance was established by spraying leaves with salicylic acid (SA) or 2,6‐dichloroisonicotinic acid (INA) and estimated in whole plants by infested leaf area compared to control plants. SA was more effective than INA. According to Western blots, untreated cucumber leaves contained a 97 kDa LOX form, which remained unchanged for up to 48 h after pathogen inoculation. Upon treatment with SA alone for 24 h or with INA plus pathogen, an additional 95 kDa LOX form appeared which had an isoelectric point in the alkaline range. For the induction of this form, a threshold concentration of 1 mM SA was required, higher SA concentrations did not change LOX‐95 expression which remained similar between 24 h and 96 h but further increased upon mildew inoculation. Phloem exudates contained only the LOX‐97 form, in intercellular washing fluid no LOX was detected. dichloroisonicotinic localization revealed LOX protein in the cytosol of the mesophyll cells without differences between the forms.

The germination process of oilseed plants is characterized by a mobilization of the storage lipids which constitute the major carbon source for the growing seedling. Despite the physiological importance of the lipid mobilization, the mechanism of this process is not well understood. Recently, it was found that a specific linoleate 13-lipoxygenase is induced during the stage of lipid mobilization in various oilseed plants and that this enzyme is translocated to the membranes of the lipid storage organelles, the so called lipid bodies. Lipoxygenase expression was paralleled by the occurrence of enantiospecific hydro(pero)xy polyenoic fatty acid derivatives in the storage lipids suggesting the in vivo action of the enzyme. Furthermore, it was reported that oxygenated polyenoic fatty acids, in particular as 13(S)-hydro(pero)xy-9(Z),11(E)-octadecanoic acid [13(S)-H(P)ODE], are cleaved preferentially from the storage lipids when compared with their non-oxygenated linoleate residues. These findings may suggest that 13(S)-H(P)ODE may constitute the endogenous substrate for β-oxidation during lipid mobilization of oilseed plants.

From Antidesma membrananeum, besides three feruloyl amides and (−)-syringaresinol, new phenolic compounds have been isolated. Their structures were established as two series of 2-alkylated 5,7-dihydroxychromones and 2,5,7-trihydroxychromanones, and the dimeric compound, 8,8-bis-(dihydroconiferyl)-diferuloylate, respectively, from their spectroscopic data.

One‐ and two‐dimensional NOE and ROE experiments were applied to investigate the relative configuration at the stereogenic biaryl axes of naphthylisoquinoline alkaloids, natural biaryl compounds mainly occurring as stable atropisomers. The influence of ortho substitution at the biaryl axes on the dynamic behavior of the atropo‐diastereomers and the determined NOE effects was investigated. As an example, the axial configuration of ancistrobrevine A was elucidated by the method.

Two new triterpenoids have been identified by spectroscopic methods from mycelia of Pisolithus tinctorius as 24-ethyllanosta-8,24(241)-diene-3β,22ξ-diol and (22S)-24,25-dimethyllanosta-8-en-22,241-epoxy-3β-ol-241-one (25-methylpisolactone) along with the two known triterpenoids 24-methyllanosta-8,24(241)-diene-3β,22ξ-diol and (22S)-24-methyllanosta-8-en-22,241-epoxy-3β-ol-241-one (pisolactone). Quantification of these compounds in fungal isolates (surface and suspension cultures) and Pinus sylvestris ectomycorrhizas showed that the amount of the new triterpenoids was markedly higher in the mycorrhizas as in the isolates.

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