1,721,090 research outputs found
Biosynthesis, oxidation and conjugation of aliphatic polyamines in higher plants
No full textThis chapter will focus on polyamine biosynthesis, oxidation, conjugation processes, mainly to hydroxycinnamic acids, and compartmentation of enzymes, substrates and products, giving an overview about recent results especially in higher plants. New research advances regarding the cloning of the main cDNA encoding for polyamine biosynthetic and oxidative enzymes, will be taken into consideration
Putative ornithine decarboxylase activity in Arabidopsis thaliana: Inhibition and intracellular localisation
No full textIn this work we studied putative ornithine decarboxylase activity (ODC, EC 4.1.1.17) in leaves of Arabidopsis thaliana L. (ecotype Columbia) plants at non-flowering stage (about 21 d of culture). Putative ODC activity was higher in the particulate than in the soluble fraction and activity was pH-dependent, increasing linearly with the pH. Inclusion of 10 mM arginine in the assay showed that the incidence of ornithine transcarbamoylase activity (EC 2.1.3.3) accounted for about 35% in the particulate fraction, but that its contribution was negligible in the soluble fraction. Increasing concentrations of the irreversible inhibitor alpha-difluoromethylornithine (DFMO) progressively inhibited putative ODC activity with a 40% inhibition at 20 mM DFMO. Taking into consideration the incidence of ornithine transcarbamoylase activity, the total inhibition of putative ODC activity was of about 75%. Fractionation experiments permitted measurement of putative ODC activity in the nuclei- and chloroplast-enriched fractions. The assays performed on membranes and stromal fractions isolated from gradient purified chloroplasts showed that the enzyme activity was associated almost totally with the plastid membranes
Free and coniugated polyamine content in Citrus sinensis Osbeck, cultivar Brasiliano N.L. 92, a Navel orange, at different maturation stages
No full textBiogenic amines, synthesized during physiological metabolic processes of all living organisms, are present in food. At low concentrations, polyamines are essential for cell renewal and growth, but they can be detrimental when consumed in high amount through the diet as they could support abnormal cell growth pathologies. The daily human diet contains more putrescine than spermidine or spermine, mostly derived from fruits. In general, orange fruits contain high levels of put, a fact that could limit their utilization in the daily diet besides the benefits contributed by their strong antioxidant properties. There is therefore an increasing interest in finding plant foods with low polyamine contents, which could provide a staple diet for patients. This paper reports the amounts of free and conjugated polyamines in the flesh and peel (flavedo plus albedo) of unripe, ripe and over ripe fruits of the cultivar Brasiliano, a Navel group orange. The analyses reveal that this particular orange cultivar has low polyamine content and could be suitable for a low polyamine diet. (C) 2004 Elsevier Ltd. All rights reserved
Polyamine binding to plasma membrane vesicles isolated from zucchini hypocotyls
No full textThe general features of [14C]spermidine binding to plasmalemma vesicles isolated from zucchini (Cucurbita pepo L.) etiolated hypocotyls are reported in the present paper. The specific interaction of the polyamine with the plasma membranes was reversible and thermolabile, since it decreased by about 50% in the assay performed at 4O°C compared to that carried out on ice. On the contrary, nonspecific binding was unaffected by temperature. Specific spermidine binding showed a pH dependence with a maximum at pH 8.0 and it reached saturation between 0.75 and 1 mM external spermidine concentration. The value of the dissociation constant calculated from Scatchard analysis was 4.4 × 10-5 M. Specific spermidine interaction appeared to be sensitive to detergents and was markedly reduced by the presence of divalent cations, such as Mg2+ and Ca2+, whereas it was stimulated by monovalent cations. Polyamine binding sites were highly sensitive to pronase treatment. Competition experiments, performed using a series of compounds structurally related to spermidine, may provide some indication of the characteristics of spermidine binding sites. The results presented here suggest that specific spermidine binding occurs mainly with the protein component of the plasma membrane
Editorial: New green extraction methods for the sustainable recovery of functional plant secondary metabolites
No full textSecondary metabolites are small molecules synthesized by plants to make them
adaptive and competitive in their own environment. More than 200,000 phytochemicals
are known to display a wide range of effects on living organisms, including plants, animals
and humans. In this context, food, nutraceutical, pharmaceutical, cosmetic, agricultural
and new material industries are actively seeking for new plant sources to recover active
compounds while aiming at sustainable natural resource utilization and protection of the
environment. New green extraction techniques are being developed to substitute the
standard not-environmentally friendly chemical and solvent-based methodologies. Several
possibilities have been explored, such as natural deep eutectic solvents (NADES), power
ultrasound or microwave radiation, enzymatic hydrolysis, supercritical or pressurized
liquid extractions. Depending on the final aim, the applied methods can lead to total
phytochemical extract or to the selective recovery of specific classes of plant-derived
compounds. Yield and extraction specificity are usually among the most important
parameters considered. The interference of molecules co-extracted with the target
compounds should be minimized, as well as degradation of target compounds or
artifacts formation, while the techno-functional features of the targeted molecules must
be ensured both during and after extraction
Trace metal accumulation and phytoremediation potential of four crop plants cultivated on pure sewage sludge
Full text linkPhytoremediation is a viable strategy to remove trace metal contaminants from sewage sludge but still is poorly investigated. The aim of this study was to quantify the trace metal removal of B. napus, B. juncea, H. annuus, Z. mays grown on pure sewage sludge. Each species was grown on six different sewage sludge for 8 weeks and sludge were analysed for trace metal content and physico-chemical characteristics. Our results confirmed that all the tested sludge supported plant growth. The tested sludge showed a plant vigorousness lower (46% of sludge) or similar/increased (54% of sludge) compared to control treatment. B. juncea and B. napus were the most efficient species in the bioaccumulation, of trace metals. The average percentage of metals removed by the selected species was 0.2% for As, 0.85% for Cd, 0.09% for Cr, 0.36% for Cu, 0.36% for Ni, 4.2% for Se, 1.2% for Zn. In conclusion, our results showed that phytoremediation can be applied to sewage sludge, despite the chosen species have low efficiency in trace element removal. Further studies using hyperaccumulator species are needed which may lead to a higher efficiency of the process opening up new possibilities for the management strategies of this waste
Endosperm rice fiber by-product as source of bioactive phenolic compounds
No full textThis study investigated the valorization of rice industrial starch production fiber
by-products, as source of valuable antioxidant phenolic compounds. Six enzymes and acid or
alkaline solvents were tested. Total phenols yield and antioxidant activity were measured for
best treatment selection. Specific phenols were identified by HPLC-DAD. Overall, 2% v/w Celluclast
was identified as the best performing enzyme, leading to 436 μg gallic acid eq/gFW phenol
yield and increasing the recovery of ferulic and p-coumaric acids with respect to control and
other enzymatic treatments. Among chemical treatments, NaOH was more efficient than HCl
and H2SO4 and was more specific for ferulic acid release. All digestates showed antioxidant capacity,
up to 243 and 502 μg ascorbic acid eq/gFW for 2% v/w Celluclast and 1 M NaOH respectively.
Both enzymatic and chemical treatments were successfully applied and, depending
on extraction conditions, the release of specific phenolic compounds to obtain enriched digestates
was achieved
Induction of hormesis in plants by urban trace metal pollution
Full text linkHormesis is a dose–response phenomenon observed in numerous living organisms, caused by low levels of a large number of stressors, among which metal ions. In cities, metal levels are usually below toxicity limits for most plant species, however, it is of primary importance to understand whether urban metal pollution can threaten plant survival, or, conversely, be beneficial by triggering hormesis. The effects of Cd, Cr and Pb urban concentrations were tested in hydroponics on three annual plants, Cardamine hirsuta L., Poa annua L. and Stellaria media (L.) Vill., commonly growing in cities. Results highlighted for the first time that average urban trace metal concentrations do not hinder plant growth but cause instead hormesis, leading to a considerable increase in plant performance (e.g., two to five-fold higher shoot biomass with Cd and Cr). The present findings, show that city habitats are more suitable for plants than previously assumed, and that what is generally considered to be detrimental to plants, such as trace metals, could instead be exactly the plus factor allowing urban plants to thrive
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