A novel pyrazolo [3,4-d] pyrimidine, KKC080106, activates the Nrf2 pathway and protects nigral dopaminergic neurons.

The transcription factor nuclear factor-erythroid 2-related factor-2 (Nrf2) is known to induce neuroprotective and anti-inflammatory effects and is considered to be an excellent molecular target for drugs related to neurodegenerative disease therapy. Nrf2 activators previously tested in clinical trials were electrophilic, causing adverse effects due to non-selective and covalent modification of cellular thiols. In order to circumvent this issue, we constructed and screened a chemical library consisting of 241 pyrazolo [3,4-d] pyrimidine derivatives and discovered a novel, non-electrophilic compound: 1-benzyl-6-(methylthio)-N-(1-phenylethyl)-1H-pyrazolo[3,4-d]pyrimidine-4-amine (KKC080106). KKC080106 was able to activate Nrf2 signaling as it increases the cellular levels of Nrf2, binds to the Nrf2 inhibitor protein Keap1, and causes the accumulation of nuclear Nrf2. We also observed an increase in the expression levels of Nrf2-dependent genes for antioxidative/neuroprotective enzymes in dopaminergic neuronal cells. In addition, in lipopolysaccharide-activated microglia, KKC080106 suppressed the generation of the proinflammatory markers, such as IL-1ß, TNF-α, cyclooxygenase-2, inducible nitric oxide synthase, and nitric oxide, and inhibited the phosphorylation of kinases known to be involved in inflammatory signaling, such as IκB kinase, p38, JNK, and ERK. As a drug, KKC080106 exhibited excellent stability against plasma enzymes and a good safety profile, evidenced by no mortality after the administration of 2000 mg/kg body weight, and minimal inhibition of the hERG channel activity. Pharmacokinetic analysis revealed that KKC080106 has good bioavailability and enters the brain after oral and intravenous administration, in both rats and mice. In MPTP-treated mice that received KKC080106 orally, the compound blocked microglial activation, protected the nigral dopaminergic neurons from degeneration, and prevented development of the dopamine deficiency-related motor deficits. These results suggest that KKC080106 has therapeutic potential for neurodegenerative disorders such as Parkinson's disease.

Lead transfer into the vegetation layer growing naturally in a Pb-contaminated site.

The lead was one of the main elements in the glazes used to colour ceramic tiles. Due to its presence, ceramic sludge has been a source of environmental pollution since this dangerous waste has been often spread into the soil without any measures of pollution control. These contaminated sites are often located close to industrial sites in the peri-urban areas, thus representing a considerable hazard to the human and ecosystem health. In this study, we investigated the lead transfer into the vegetation layer (Phragmites australis, Salix alba and Sambucus nigra) growing naturally along a Pb-contaminated ditch bank. The analysis showed a different lead accumulation among the species and their plant tissues. Salix trees were not affected by the Pb contamination, possibly because their roots mainly develop below the contaminated deposit. Differently, Sambucus accumulated high concentrations of lead in all plant tissues and fruits, representing a potential source of biomagnification. Phragmites accumulated large amounts of lead in the rhizomes and, considering its homogeneous distribution on the site, was used to map the contamination. Analysing the Pb concentration within plant tissues, we got at the same time information about the spread, the history of the contamination and the relative risks. Finally, we discussed the role of natural recolonizing plants for the soil pollution mitigation and their capacity on decreasing soil erosion and water run-off.

Shifts in plant foliar and floral metabolomes in response to the suppression of the associated microbiota.

BACKGROUND: The phyllospheric microbiota is assumed to play a key role in the metabolism of host plants. Its role in determining the epiphytic and internal plant metabolome, however, remains to be investigated. We analyzed the Liquid Chromatography-Mass Spectrometry (LC-MS) profiles of the epiphytic and internal metabolomes of the leaves and flowers of Sambucus nigra with and without external antibiotic treatment application. RESULTS: The epiphytic metabolism showed a degree of complexity similar to that of the plant organs. The suppression of microbial communities by topical applications of antibiotics had a greater impact on the epiphytic metabolome than on the internal metabolomes of the plant organs, although even the latter changed significantly both in leaves and flowers. The application of antibiotics decreased the concentration of lactate in both epiphytic and organ metabolomes, and the concentrations of citraconic acid, acetyl-CoA, isoleucine, and several secondary compounds such as terpenes and phenols in the epiphytic extracts. The metabolite pyrogallol appeared in the floral epiphytic community only after the treatment. The concentrations of the amino acid precursors of the ketoglutarate-synthesis pathway tended to decrease in the leaves and to increase in the foliar epiphytic extracts. CONCLUSIONS: These results suggest that anaerobic and/or facultative anaerobic bacteria were present in high numbers in the phyllosphere and in the apoplasts of S. nigra. The results also show that microbial communities play a significant role in the metabolomes of plant organs and could have more complex and frequent mutualistic, saprophytic, and/or parasitic relationships with internal plant metabolism than currently assumed.

Further examination of abscission zone cells as ethylene target cells in higher plants.

BACKGROUND AND AIMS: Two aspects of the competence of abscission zone cells as a specific class of hormone target cell are examined. The first is the competence of these target cells to respond to a remote stele-generated signal, and whether ethylene acts in concert with this signal to initiate abscission of the primary leaf in Phaseolus vulgaris. The second is to extend the concept of dual control of abscission cell competence. Can the concept of developmental memory that is retained by abscission cell of Phaseolus vulgaris post-separation in terms of the inductive/repressive control of beta-1,4-glucan endohydrolase (cellulase) activity exerted by ethylene/auxin be extended to the rachis abscission zone cells of Sambucus nigra? METHODS: Abscission assays were performed using the leaf petiole-pulvinus explants of P. vulgaris with the distal pulvinus stele removed. These (-stele) explants do not separate when treated with ethylene and require a stele-generated signal from the distal pulvinus for separation at the leaf petiole-pulvinis abscission zone. Using these explants, the role of ethylene was examined, using the ethylene action blocker, 1-methyl cyclopropene, as well as the significance of the tissue from which the stele signal originates. Further, leaf rachis abscission explants were excised from the compound leaves of S. nigra, and changes in the activity of cellulase in response to added ethylene and auxin post-separation was examined. KEY RESULTS: The use of (-stele) explants has confirmed that ethylene, with the stele-generated signal, is essential for abscission. Neither ethylene alone nor the stelar signal alone is sufficient. Further, in addition to the leaf pulvinus distal to the abscission zone, mid-rib tissue that is excised from senescent or green mid-rib tissue can also generate a competent stelar signal. Experiments with rachis abscission explants of S. nigra have shown that auxin, when added to cells post-separation can retard cellulase activity, with activity re-established with subsequent ethylene treatment. CONCLUSIONS: The triggers that initiate and regulate the separation process are complex with, in bean leaves at least, the generation of a signal (or signals) from remote tissues, in concert with ethylene, a requisite part of the process. Once evoked, abscission cells maintain a developmental memory such that the induction/repression mediated by ethylene/auxin that is observed prior to separation is also retained by the cells post-separation.

Effects of copper on Sambucus nigra L. seedlings studied by electron paramagnetic resonance and atomic absorption spectroscopies.

We present in this work preliminary results on the translocation of copper, manganese and iron from soil to leaves of Sambucus nigra L. seedlings in the presence of increasing copper concentrations in the growth medium. The use of electron spin resonance spectroscopy and the comparison with atomic absorption spectroscopy is not presently common in the study of metal absorption in plants. This approach gave promising results both on the detection of some metal ions, as well as of radical species related to the presence of Cu2+ in plant tissues. Copper was found to act synergistically in manganese uptake.

Biochemical, molecular and structural analysis of multiple thaumatin-like proteins from the elderberry tree (Sambucus nigra L.).

Thaumatin-like proteins (TLPs) were isolated and characterized from fruits and leaves of elderberry (Sambucus nigra) and their corresponding genes cloned. In addition, the developmental regulation and induction of the different TLPs was followed in some detail. Ripening berries accumulated a fruit-specific TLP during the final stages of maturation. This fruit-specific TLP had no antifungal activity and was devoid of beta-glucanase activity. Leaves constitutively expressed a TLP that closely resembled the fruit-specific homologue. Treatment with jasmonate methyl ester induced two additional TLPs in leaves but did not induce or enhance the expression of TLPs in immature berries. In contrast to jasmonate methyl ester, both ethephon and garlic extract induced the expression of a TLP in unripe berries that normally do not express any TLP. Sequence analysis and molecular modeling indicated that all elderberry thaumatin-like proteins share a high sequence similarity with group-5 pathogenesis-related proteins. However, the proteins encoded by the different sequences differed from each other in isoelectric point and the distribution of the charges on the surface of the molecule.