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Drought represents one of the most relevant abiotic stress affecting growth and yield of crop plants. In order to improve the agricultural productivity within the limited water and land resources, it is mandatory to increase crop yields in presence of unfavorable environmental stresses. The use of biostimulants, often containing seaweed extracts, represents one of the options for farmers willing to alleviate abiotic stress consequences on crops. In this work, we investigated the responses of Arabidopsis plants treated with an extract from the brown alga Ascophyllum nodosum (ANE), under drought stress conditions, demonstrating that ANE positively influences Arabidopsis survival. Pre-treatment with ANE induced a partial stomatal closure, associated with changes in the expression levels of genes involved in ABA-responsive and antioxidant system pathways. The pre-activation of these pathways results in a stronger ability of ANE-treated plants to maintain a better photosynthetic performance compared to untreated plants throughout the dehydration period, combined with a higher capacity to dissipate the excess of energy as heat in the reaction centers of photosystem II. Our results suggest that drought stressed plants treated with ANE are able to maintain a strong stomatal control and relatively higher values of both water use efficiency (WUE) and mesophyll conductance during the last phase of dehydration. Simultaneously, the activation of a pre-induced antioxidant defense system, in combination with a more efficient energy dissipation mechanism, prevents irreversible damages to the photosynthetic apparatus. In conclusion, pre-treatment with ANE is effective to acclimate plants to the incoming stress, promoting an increased WUE and dehydration tolerance.

Among the commercial ethylenediamine-N,N′-bis(2-hydroxy)phenylacetic acid/iron(III) derivatives, ethylenediamine-N,N′-bis(2-hydroxy-5-sulphophenylacetic) acid/iron(III) (EDDHSA/Fe) represents one of the promising chelates for the treatment of chlorotic plants. Industrial synthesis of EDDHSA/Fe leads to relevant amounts of o,o-EDDHSA condensation products (o,o-EDDHSAcps) and other secondary products that might have important relevance from the agronomic point of view. However, their chemical structures have remained unknown to date. Analysis of iron complexes by ion-pair reversed-phase chromatography, coupled with electrospray tandem mass spectrometry revealed the presence of the meso-o,o-EDDHSA/Fe, rac-o,o-EDDHSA/Fe, o,p-EDDHSA/Fe regioisomers, the hydroxyl derivative of o,o-EDDHSA/Fe, and the three main EDDHSA condensation products chelating the iron(III) (EDDHSAcps/nFe). However, the chromatographic peaks of EDDHSAcps/Fe are not well resolved due to the large numbers of stereoisomers and the poor efficiency of the ion-pair reversed-phase separation method. An alternative chromatographic method is based on porous graphitic carbon (PGC) separation after pre-column decomplexation of the chelates with trifluoracetic acid, which was developed to allow detection of EDDHSA stereo/regioisomers, EDDHSAcps, and low-molecular-weight by-products. This extensive PGC–HPLC–ESI-MS/MS investigation provides quantitative determination of meso-o,o-EDDHSA, rac-o,o-EDDHSA and o,p-EDDHSA, in addition to characterisation of EDDHSAcps and the low-molecular-weight by-products. PGC separation coupled to a triple quadrupole ESI-MS detector allowed characterisation of free ligands using collision-induced dissociation experiments in positive and negative ionisation mode, providing comparative evaluation of EDDHSAcps in three commercial samples. For detection, the PGC–HPLC–ESI-MS/MS is the best method according to the limit of quantification and limit of detection (picomolar and sub-picomolar detection, respectively) for determination of meso-EDDHSA and rac-o,o-EDDHSA. Synthesis, purification and quantification of o,o-EDDHSA and o,p-EDDHSA by 1H-nuclear magnetic resonance are also reported

In the last years, metallic crushers substituted granite stone mill with some variations in the organoleptic oil characteristics. To control the influence of the crushing method on the yield and oil quality, the olive pastes were obtained using three different ways: (i) new metallic crusher at mobile knives; (ii) granite stone mill; (iii) double olive crushing by the metallic crusher and the granite stone mill. With the aim to ascertain the useful use of a new metallic crusher (at mobile knives), experimental tests were carried out in an industrial oil mill. This oil mill is equipped by a centrifugal decanter generating two oil flows: first and second extraction (recovery) oils. The results showed that the yields obtained by different methods were satisfactory. No statistically significant differences have been observed in terms of oil yield and quality when different crushing devices were used. All first extracted oils are extra virgin with similar organoleptic characteristics, especially for the fruity intensity and for the bitter and pungent taste, as confirmed by the composition of volatile substances and the content of phenolic oil compounds. The recovery oils (second extraction oils) showed, in contrast to first extraction oils, a more intense green colour and a higher content of total phenols. Practical applications: Processing of sound olives with the right ripening grade and good quality allows to easily obtain an extra virgin olive oil, with commercial qualitative parameters according to the European Union requirements. However, different olive crushing systems affect the concentrations of some compounds responsible of aroma and taste (phenolic compounds). The use of the more violent metallic crushers facilitates obtaining oils with total phenol content higher than when using a stone mill. Here we used a particular metallic crusher (at knives) that, however, is suitable to replace the granite stone mill when a less pungent and bitter oil is required.

To evaluate N -hydroxyurea as zinc binding group in the design of MMP inhibitors, two peptidyl 1-hydroxyureas were prepared by N -hydroxycarbamoylation of the diastereomeric dipeptides H-Leu-Phe-NHMe and H- d -Leu-Phe-NHMe. Peptidyl 1-hydroxyureas were more potent than the parent peptides, but dramatically weaker (4–5 orders of magnitude) than the isosteric ( R )-succinylhydroxamate analogue, which displays IC 50 in the range of nM vs MMP-1, -3, -7 and sub-nM vs MMP-2, -8, and -9. The peptidyl 1-hydroxyurea 1a attained an IC 50 of 20 μM vs MMP-9, and substantially approaches inhibition of known N -hydroxyureas based on aminoacids or peptides against other zinc metalloenzymes and non-peptidic N -hydroxyureas against MMPs. Strong preference of the O–N1–C O unit for the antiperiplanar amide bond conformation seems to be the major limit for more effective zinc chelation. Methylation of a peptidyl 1-hydroxyurea at N3, to promote the synperiplanar O–N1–C O conformation required for zinc chelation and improve affinity, resulted in release of a methylimidazolidine-2,4-dione through an undesired intramolecular reaction reminiscent of the Edman peptide degradation.

EDDHSA/Fe is a promising substitute of EDDHA/Fe to fight iron chlorosis. o,o-EDDHSA structure contains two chiral carbons giving the racemic and meso couples of stereoisomers. Ion-pair HPLC and UHPLC–UV/Vis–ESI-MS/MS methods were developed for the determination of racemic and meso-o,o-EDDHSA/Fe in commercial samples of chelates. The lack of a commercial EDDHSA standard was overcome by sulfonation of a commercial available o,o-EDDHA standard and subsequent quantification by 1H-NMR. Assignment of configurations was carried out starting from racemic and meso-o,o-EDDHA/Fe by direct sulfonation to give the corresponding o,o-EDDHSA/Fe isomers. The performances of these methods were assessed in terms of intra and inter-day precision, linearity and selectivity. The high selectivity and lower detection limit (nanomolar) of the UHPLC–ESI-MS/MS method could allow to deepen the knowledge relative to meso and rac-o,o-EDDHSA/Fe interactions with plants, its fate in different soil conditions, its mobility and other environmental aspects.

(R)-alpha-Biphenylsulfonylamino 2-methylpropyl phosphonates attain nM potency against several MMPs and are the most effective inhibitors based on phosphonate as zinc binding group. Since their preparation by direct N-acylation of expensive, enantiopure, alpha-aminophosphonic acids proceeds in low yields, we devised and evaluated a stereoselective and straightforward method of synthesis that avoids the unfavourable step of N-acylation. The key intermediate (R)-4-bromophenylsulfonylamino 2-methylpropyl phosphonate 9 was obtained by highly stereoselective addition of dibenzylphosphite to the enantiopure (S)-N-isobutylidene-p-bromobenzenesulfinamide 3, followed by oxidation with m-CPBA. Suzuki coupling of 9 with the desired arylboronic acids, gave the expected biphenylsulfonylamino derivatives in satisfactory yields. Liberation of the phosphonic group by hydrogenolysis led to the desired (R)-alpha-biphenylsulfonylamino 2-methylpropyl phosphonates 14a-i. Screening of the new compounds on MMP-1, -2, -3, -7, -8, -9, -13 and -14 showed IC(50) in the range of nM in most cases.

The first crystallographic structure of an N-hydroxyurea inhibitor bound into the active site of a matrix metalloproteinase is reported. The ligand and three other analogues were prepared and studied as inhibitors of MMP-2, MMP-3, and MMP-8. The crystal structure of the complex with MMP-8 shows that the N-hydroxyurea, contrary to the analogous hydroxamate, binds the catalytic zinc ion in a monodentate rather than bidentate mode and with high out-of-plane distortion of the amide bonds. (c) 2005 Elsevier Ltd. All rights reserved.