Nanoparticle treatment of maize analyzed through the metatranscriptome: compromised nitrogen cycling, possible phytopathogen selection, and plant hormesis.

BACKGROUND: The beneficial use of nanoparticle silver or nanosilver may be confounded when its potent antimicrobial properties impact non-target members of natural microbiomes such as those present in soil or the plant rhizosphere. Agricultural soils are a likely sink for nanosilver due to its presence in agrochemicals and land-applied biosolids, but a complete assessment of nanosilver's effects on this environment is lacking because the impact on the natural soil microbiome is not known. In a study assessing the use of nanosilver for phytopathogen control with maize, we analyzed the metatranscriptome of the maize rhizosphere and observed multiple unintended effects of exposure to 100 mg kg-1 nanosilver in soil during a growth period of 117 days. RESULTS: We found several unintended effects of nanosilver which could interfere with agricultural systems in the long term. Firstly, the archaea community was negatively impacted with a more than 30% decrease in relative abundance, and as such, their involvement in nitrogen cycling and specifically, nitrification, was compromised. Secondly, certain potentially phytopathogenic fungal groups showed significantly increased abundances, possibly due to the negative effects of nanosilver on bacteria exerting natural biocontrol against these fungi as indicated by negative interactions in a network analysis. Up to 5-fold increases in relative abundance have been observed for certain possibly phytopathogenic fungal genera. Lastly, nanosilver exposure also caused a direct physiological impact on maize as illustrated by increased transcript abundance of aquaporin and phytohormone genes, overall resulting in a stress level with the potential to yield hormetically stimulated plant root growth. CONCLUSIONS: This study indicates the occurrence of significant unintended effects of nanosilver use on corn, which could turn out to be negative to crop productivity and ecosystem health in the long term. We therefore highlight the need to include the microbiome when assessing the risk associated with nano-enabled agriculture. Video Abstract.

Antioxidant activity and bioactive compound contents before and after in vitro digestion of new tomato hybrids.

BACKGROUND: The antioxidant properties and bioactive compound contents of fresh new tomato hybrids before and after in vitro digestion were investigated. To this aim, the antioxidant activities of lipophilic, hydrophilic and polyphenolic extracts of tomato hybrids were determined by ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), DMPD (N,N-dimethyl-p-phenylenediamine dihydrochloride) and DPPH (2,2-diphenyl-1-picrylhydrazyl) methods respectively, while the bioactive compound contents were estimated via Folin-Ciocalteu (polyphenols), pH differential (anthocyanins) and high-performance liquid chromatography (lycopene and ß-carotene) methods. RESULTS: After the digestion process, a marked loss (ranging from 37 to 77%) of antioxidant capacity linked to the hydrophilic fraction was observed. In contrast, the lipophilic and methanolic fractions showed an increase in antioxidant activity (ranging from 9 to 40%) after gastric digestion, and a rapid decrease was observed after total digestion. Moreover, the presence of anthocyanins and carotenoids after simulated digestion was a notable result. CONCLUSION: The bioavailability of bioactive metabolites from nutraceutical food and their healthful properties in humans are strictly dependent on the digestion process. © 2017 Society of Chemical Industry.

Effects of Industrial Processes on Antioxidant Power and Polyphenols Profile in Cherry Tomato Cultivar.

The antioxidant capacity and the polyphenolic profile of fresh and processed cherry tomatoes were analyzed with the aim of investigating the effect of industrial processes on the nutritional qualities of fruits. The results exhibited a decrease of antioxidant activity mainly in the lipophilic fraction of processed tomatoes compared with fresh products. No great difference in the antioxidant capacity was detected in the hydrophilic and methanolic extracts of fresh tomatoes and processed tomato juices. Moreover, a decrease of polyphenolic content, estimated by means of high-performance liquid chromatography analysis and Folin-Ciocalteu method, was observed in all tomato juices. The overall polyphenolic profile of both fresh and processed tomatoes did not change significantly and, among all juices, a higher polyphenolic content was detected in juice containing peels and seeds in comparison to those without. From our data on antioxidant power and the bioactive metabolite content, tomato juice could be used as a valid and easily available source of antioxidants in everyday diet to preserve human health.

Cyclic dipeptides produced by marine sponge-associated bacteria as quorum sensing signals.

Four bacterial strains belonging to the genera Vibrio, Pseudoalteromonas and Photobacterium were isolated from the marine sponges Dysidea avara and Geodia cynodium. A Bacillus strain was isolated from Ircinia variabilis. A screening of molecules involved in quorum sensing (QS) was carried out by TLC-overlay and a new "plate T-streak" test. To analyze quorum quenching (QQ), a plate T-streak was performed with Chromobacterium violaceum. Strains of Vibrio isolated from both marine sponges and a strain of Photobacterium isolated from G. cynodium, activated QS bioreporters. A strain of Pseudoalteromonas isolated from D. avara showed QQ activity. Finally, it is reported that cyclic dipeptides isolated from strains of Vibrio sp. and Bacillus sp. (isolated from D. avara and I. variabilis, respectively) were involved in the QS mechanism. The simultaneous presence of bacteria that showed contrasting responses in bioassays for QS signal molecule synthesis in marine sponges could add an interesting dimension to the signalling interactions which may be happening in sponges.

Antioxidant and cytotoxic activities investigation of tomato seed extracts.

Biological activities of different varieties of tomato seed extracts were evaluated to verify the potential antioxidant and/or antiproliferative activity of the bioactive metabolites present in them. Findings demonstrated that among all the varieties investigated (San Marzano Rosso, San Marzano Giallo, Corbarino, Black Tomato and San Marzano/Black Tomato hybrid) San Marzano Rosso seed extract exhibited the highest free radical-scavenging activity with 68% of 2,2-Diphenyl-1-picrylhydrazyl radical inhibition, and the best cytotoxic activity evaluated by using the brine shrimp test (LD50: 23,198 ppm) and 3-(4,5-dimethylthiazol-2-yl)-2,5-phenyl-2H-tetrazolium bromide assay on A375 cell line (IC50: 137.7 µg/mL).

Bioactivity of tomato hybrid powder: antioxidant compounds and their biological activities.

The antioxidant and cytotoxic activities and the polyphenolic and anthocyanin contents of tomato hybrid powders were studied. Tomato powders were obtained, starting from the fresh fruits that had undergone an industrial process of drying and pulverization at two different temperatures. Antioxidant activities were evaluated in different extracts by using spectrophotometric assays: 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid and N,N-dimethyl-p-phenylenediamine dihydrochloride cation radical inhibition for lipophilic and hydrophilic extracts, respectively, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay for polyphenolic extracts. Moreover, polyphenolic and anthocyanin contents were also carried out to detect the presence of these bioactive compounds. The effect of cytotoxic activity in vitro of tomato hybrid powder extracts on T47D (human breast carcinoma) cells was also evaluated. Results showed good antioxidant activities in lipophilic, polyphenolic, and hydrophilic extracts of samples that were obtained at a lower temperature. Extracts of the sample obtained at a higher temperature presented moderate antioxidant activity, lower than the extracts of other samples, which was probably due to the loss of labile antioxidant compounds during the industrial process. Very interesting was the presence of anthocyanins in both samples, even if in traces, and also a moderate cytotoxicity of a lipophilic extract on T47D cells. Therefore, tomato hybrid powders, on the basis of their multifunctional properties, could have a biotechnological application in agri-food or cosmetic industries as an additive for improving nutritional and/or bioactive qualities of commercial products used in daily nutrition and cosmetics.

Evaluation of antioxidant properties, total phenolic content, and biological activities of new tomato hybrids of industrial interest.

The objective of the present work was to establish the antioxidative ability linked to lipophilic, hydrophilic, and polyphenolic fractions of new tomato hybrids of industrial interest, grown in an outdoor field, named "Medugno", situated in the Agro-Nocerino Sarnese area (Province of Salerno, Campania Region, Italy). Antioxidant activities of lipophilic, hydrophilic, and polyphenolic extracts of tomato hybrids determined by the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), N,N-dimethyl-p-phenylenediamine dihydrochloride, and 2,2-diphenyl-1-picrylhydrazyl methods, respectively, showed the best results in hybrids obtained between the pure San Marzano and Black Tomato lines. Antioxidant activity tests, performed also on the San Marzano × Black Tomato hybrid (pulped tomatoes), indicated that the industrial transformation process of this new tomato hybrid did not cause a significant loss of antioxidant activity. The in vitro production of nitrite by lipopolysaccharide-stimulated macrophages J774A.1 performed on lipophilic extracts showed that only two hybrids (San Marzano × Black Tomato and Marmande × Black Tomato) inhibited, in a concentration-related manner, nitric oxide release. Results suggested that genotypic factors could determine the nutritional quality of tomato because of the content of biologically active compounds and their biosynthesis. Moreover, the new tomato hybrid achieved could have a potential for the agri-food industry because of its nutritional quality and because it lends itself in processes of industrial transformation.