Sesquiterpene and diterpene lactones from Melampodium leucanthum and the molecular structure of 4(5)-dihydromelampodin B

The aerial parts of Melampodium leucanthum afforded a novel diterpene-γ-lactone, 1,6,7-trihydroxy-17-acetoxymelcantholide, and two new sesquiterpene dilactones, 4(5)-dihydrocinerenin and 4(5)-dihydromelampodin C. The known melampolides, leucanthin A, melampodin A acetate, melampolidin and leucanthinin were also isolated. The structure determinations involved spectral and chemical methods. The molecular structure of 4(5)-dihydromelampodin B, determined by X-ray diffraction, is described.     

Predicting substituent effects on activation energy changes by static catalytic fields

Catalytic fields illustrate topology of the optimal charge distribution of a molecular environment reducing the activation energy for any process involving barrier crossing, like chemical reaction, bond rotation etc. Until now, this technique has been successfully applied to predict catalytic effects resulting from intermolecular interactions with individual water molecules constituting the first hydration shell, aminoacid mutations in enzymes or Si→Al substitutions in zeolites. In this contribution, hydrogen to fluorine (H→F) substitution effects for two model reactions have been examined indicating qualitative applicability of the catalytic field concept in the case of systems involving intramolecular interactions.

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Graphical abstract Hydrogen to fluorine (H→F) substitution effects on activation energy in [kcal/mol]

     

Factors influencing Manx Shearwater grounding on the west coast of Scotland

Grounding of thousands of newly fledged petrels and shearwaters (family Procellariidae) in built‐up areas due to artificial light is a global problem. Due to their anatomy these grounded birds find it difficult to take off from built‐up areas and many fall victim to predation, cars, dehydration or starvation. This research investigated a combination of several factors that may influence the number of Manx Shearwater Puffinus puffinus groundings in a coastal village of Scotland located close to a nesting site for this species. A model was developed that used meteorological variables and moon cycle to predict the daily quantity of birds that were recovered on the ground. The model, explaining 46.32% of the variance of the data, revealed how new moon and strong onshore winds influence grounding. To a lesser extent, visibility conditions can also have an effect on grounding probabilities. The analysis presented in this study can improve rescue campaigns of not only Manx Shearwaters but also other species attracted to the light pollution by predicting conditions leading to an increase in the number of groundings. It could also inform local authorities when artificial light intensity needs to be reduced.     

Transfer of Pectobacterium carotovorum subsp. carotovorum strains isolated from potatoes grown at high altitudes to Pectobacterium peruviense sp. nov.

Seven Gram-negative, rod-shaped pectinolytic bacteria strains designated as IFB5227, IFB5228, IFB5229, IFB5230, IFB5231, IFB5232, IFB5636, isolated from potato tubers cultivated in Peru at high altitude (2400–3800 m) were subjected to polyphasic analyses that revealed their distinctiveness from the other Pectobacterium species. Phylogenetic analyses based on five housekeeping genes (gyrA, recA, recN, rpoA and rpoS) clearly showed strains separateness, simultaneously indicating Pectobacterium atrosepticum, Pectobacterium wasabiae, Pectobacterium parmentieri and Pectobacterium betavasculorum as the closest relatives. In silico DNA–DNA hybridization of strain IFB5232^T with other Pectobacterium type strains revealed significant drop in DDH value below 70%, which is a prerequisite to distinguish Pectobacterium peruviense. The ANI values supported the proposition of delineation of the P. peruviense. Genetic REP-PCR fingerprint and detailed MALDI-TOF MS proteomic profile sealed the individuality of the studied strains. However, phenotypic assays do not indicate immense differences.Provided results of analyses performed for seven Peruvian strains are the basis for novel species distinction and reclassification of the strains IFB5227-5232 and IFB5636, previously classified as Pectobacterium carotovorum subsp. carotovorum. Here, we propose to establish the IFB5232 isolate as a type strain (=PCM2893^T = LMG30269^T = SCRI179^T) with the name Pectobacterium peruviense sp. nov.     

Eudesmane triols from Verbesina virgata

Chemical study of Verbesina virgata collected in several localities afforded two eudesmane triols as 4-cinnamates. Their structures were determined by chemical and spectroscopic means. The structure and stereochemistry of one of the triols was confirmed by X-ray crystallography.     

Quantifying above‐ and belowground biomass carbon loss with forest conversion in tropical lowlands of Sumatra (Indonesia)

Natural forests in South‐East Asia have been extensively converted into other land‐use systems in the past decades and still show high deforestation rates. Historically, lowland forests have been converted into rubber forests, but more recently, the dominant conversion is into oil palm plantations. While it is expected that the large‐scale conversion has strong effects on the carbon cycle, detailed studies quantifying carbon pools and total net primary production (NPP_total) in above‐ and belowground tree biomass in land‐use systems replacing rainforest (incl. oil palm plantations) are rare so far. We measured above‐ and belowground carbon pools in tree biomass together with NPP_total in natural old‐growth forests, ‘jungle rubber’ agroforests under natural tree cover, and rubber and oil palm monocultures in Sumatra. In total, 32 stands (eight plot replicates per land‐use system) were studied in two different regions. Total tree biomass in the natural forest (mean: 384 Mg ha^?1) was more than two times higher than in jungle rubber stands (147 Mg ha^?1) and >four times higher than in monoculture rubber and oil palm plantations (78 and 50 Mg ha^?1). NPP_total was higher in the natural forest (24 Mg ha^?1 yr^?1) than in the rubber systems (20 and 15 Mg ha^?1 yr^?1), but was highest in the oil palm system (33 Mg ha^?1 yr^?1) due to very high fruit production (15–20 Mg ha^?1 yr^?1). NPP_total was dominated in all systems by aboveground production, but belowground productivity was significantly higher in the natural forest and jungle rubber than in plantations. We conclude that conversion of natural lowland forest into different agricultural systems leads to a strong reduction not only in the biomass carbon pool (up to 166 Mg C ha^?1) but also in carbon sequestration as carbon residence time (i.e. biomass‐C:NPP‐C) was 3–10 times higher in the natural forest than in rubber and oil palm plantations.