The effect of common duckweed (Lemna minor L.) extract on the shelf-life of beef burgers stored in modified atmosphere packs: A metabolomics approach.

The impact of duckweed extracts (DEs) on the shelf-life of packaged beef burgers was evaluated through classical assays and untargeted metabolomics. Beef burgers were formulated with an antioxidants-free control (CON), 1 g/kg sodium ascorbate (ASC), and increasing levels of a DEs, namely 1 (DE1), 5 (DE5), and 10 (DE10) g/kg, packaged under modified atmosphere and stored at 4 °C for 19 days. The DEs, abundant in phytochemicals, determined no issues with the hygienic status of the product. DEs modulated the redox status, being ineffective in preserving linolenic acid from peroxidation. However, the oxidation marker 2-nonenoic acid was down-accumulated in the DE10 sample following 19 days of storage, recording a lower glutathione:glutathione disulfide ratio. The accumulation of adipate semialdehyde revealed the inefficiency of DEs in coping with protein oxidation, while DEs prevented the accumulation of biogenic amines. Therefore, this work suggests a potential pro-oxidant role of the formulated DEs.

The Combination of Untargeted Metabolomics with Response Surface Methodology to Optimize the Functional Potential of Common Duckweed (Lemna minor L.).

The present study was designed to evaluate the functional potential of common duckweed (Lemna minor L.) as a source of bioactive compounds of nutraceutical interest. The untargeted profiling of the bioactive components of common duckweed was carried out through ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS), in parallel with assessing in vitro antioxidant and enzymatic inhibition properties. The optimization of extraction parameters was determined using the response surface methodology (RSM) through a 3-factor central composite design. The process parameters included extraction temperature, % of ethanol, and ultrasound power, while the response variables were the phenolic content (considering each main phenolic class), total glucosinolates, total carotenoids, the antioxidant potential, and enzyme inhibition activities. The results revealed that common duckweed was a rich source of carotenoids and total flavonoids (mainly flavones and flavonols), followed by phenolic acids, low-molecular-weight phenolics, and glucosinolates. Interestingly, the total flavones, total flavonols and total carotenoid equivalents showed the highest and most positive correlation values with the bioactive properties measured. Finally, the combined RSM approach and unsupervised statistics allowed us to point out the pivotal impact of ethanol percentage in the extraction solvent to recover the highest amounts of bioactive compounds efficiently.

Interference of three herbicides on iron acquisition in maize plants.

The use of herbicides to control weed species could lead to environmental threats due to their persistence and accumulation in the ecosystems and cultivated fields. Nonetheless, the effect of these compounds on plant mineral nutrition in crops has been barely investigated. This study aimed at ascertaining the effect of three herbicides (S-metolachlor, metribuzin and terbuthylazine) on the capacity of maize to acquire iron (Fe). Interferences on plant growth and reductions on the Fe contents were found in the plants treated. Furthermore, root cell viability and functionality losses were ascertained following the treatments, which, in turn, decreased the amount of phytosiderophores (PSs) released by the roots. An investigation carried out in greater depth on root apices of treated plants using an FE-SEM (Scanning Electron Microscope) coupled with EDX (Energy Dispersive X-ray) indicated that the reductions on Fe content started in this part of the roots. Lastly, decreases were found also in copper (Cu+2), zinc (Zn+2) and manganese (Mn+2) content in root apices.

Effect of three safeners on sulfur assimilation and iron deficiency response in barley (Hordeum vulgare) plants.

BACKGROUND: Safeners are agrochemicals used in agriculture to protect crops from herbicide injuries. They act by stimulating herbicide metabolism. As graminaceous plants, to cope with iron (Fe) deficiency, activate sulfur (S) metabolism and release huge amounts of Fe-chelating compounds, or phytosiderophores (PSs), we investigated, in barley plants (Hordeum vulgare, L.) grown in Fe deficiency, the effects of three safeners on two enzymes of S assimilation, cysteine (Cys) and glutathione (GSH), and PS release. Finally, we monitored the root Fe content in plants treated with the most effective safener. RESULTS: Generally, all the safeners activated S metabolism and increased Cys and GSH contents. In addition, the safened plants excreted higher levels of PSs. Given that mefenpyr-diethyl (Mef) was the most effective in causing these effects, we assessed the Fe concentration in Mef-treated barley and found higher Fe levels than those in untreated plants. CONCLUSION: The three safeners, in different ways but specifically, activated S reductive metabolism and regulated Cys and GSH contents, PS release rate and Fe content (Mef-treated barley). The results of this research provide new indications of the biochemical and physiological mechanisms involved in the safening action. © 2016 Society of Chemical Industry.

Iron deficiency in barley plants: phytosiderophore release, iron translocation, and DNA methylation.

All living organisms require iron (Fe) to carry out many crucial metabolic pathways. Despite its high concentrations in the geosphere, Fe bio-availability to plant roots can be very scarce. To cope with Fe shortage, plants can activate different strategies. For these reasons, we investigated Fe deficient Hordeum vulgare L. plants by monitoring growth, phytosiderophores (PS) release, iron content, and translocation, and DNA methylation, with respect to Fe sufficient ones. Reductions of plant growth, roots to shoots Fe translocation, and increases in PS release were found. Experiments on DNA methylation highlighted significant differences between fully and hemy-methylated sequences in Fe deficient plants, with respect to Fe sufficient plants. Eleven DNA bands differently methylated were found in starved plants. Of these, five sequences showed significant alignment to barley genes encoding for a glucosyltransferase, a putative acyl carrier protein, a peroxidase, a ß-glucosidase and a transcription factor containing a Homeodomin. A resupply experiment was carried out on starved barley re-fed at 13 days after sowing (DAS), and it showed that plants did not recover after Fe addition. In fact, Fe absorption and root to shoot translocation capacities were impaired. In addition, resupplied barley showed DNA methylation/demethylation patterns very similar to that of barley grown in Fe deprivation. This last finding is very encouraging because it indicates as these variations/modifications could be transmitted to progenies.

A comparative study on the interference of two herbicides in wheat and italian ryegrass and on their antioxidant activities and detoxification rates.

A study was carried out to compare the effects of treating wheat (Triticum aestivum) and Italian ryegrass (Lolium multiflorum) with atrazine and fluorodifen. The herbicides interfered with photosynthesis and dark respiration, depending on the species. Atrazine decreased photosynthesis in both species and dark respiration in wheat, while fluorodifen caused decrements of photosynthetic activity of wheat. Antioxidant enzymes, such as ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), were generally more active in untreated and treated wheat with respect to Italian ryegrass, which explains why oxidative damage, expressed as malondialdehyde (MDA) content, was only found in ryegrass. Investigations on the activity of herbicide-detoxifying enzyme, glutathione S-transferase (GST), and on the accumulation and persistence of the herbicides in the plants showed higher detoxification rates in wheat than in the grass.

Triosephosphate isomerases in Italian ryegrass ( Lolium multiflorum ): characterization and susceptibility to herbicides.

The effect of treatments with four herbicides and a safener on the activity of triosephosphate isomerase (TPI) extracted from shoots of Italian ryegrass was investigated. It was found that atrazine and fluorodifen, herbicides which interfere with photosynthesis, caused a decrease in measured enzyme activity. In addition, the in vitro effect of oxidized glutathione (GSSG), a compound produced in situations of oxidative stress, on TPI activity was investigated. It was shown that GSSG was a strong inhibitor of enzyme activity, at low concentrations in a dose-time-dependent manner. The enzyme extracts were submitted to chromatographic purifications and to two-dimensional electrophoresis. Some spots had molecular masses ranging between 20 and 30 kDa and were characterized and identified by LC-ESI-MS/MS as TPIs. The mass spectrometry also made it possible to identify the presence of cysteine residues that could be subjected to S-glutathionylation, which regulate the enzyme activity.