Optimization of microwave-assisted extraction of antioxidant compounds from spring onion leaves using Box-Behnken design.

Many studies have explored the extraction of bioactive compounds from different onion solid wastes, such as bulb, skin, and peel. However, onion leaves have received limited attention despite their potential as a valuable source of nutraceutical compounds. This study aimed to valorise, for the first time, the agricultural waste in the form of spring onion leaves (CN, Cipollotto Nocerino) to obtain antioxidant-rich polyphenolic extracts. A Box-Behnken design (BBD) was used to assess the impact of microwave-assisted extraction (MAE) variables (temperature, time, extraction volume, and ethanol concentration) on total polyphenol content (TPC) measured by Folin-Ciocalteu method and the antioxidant power determined by FRAP assay. Response surface methodology (RSM) was applied, and regression equations, analysis of variance, and 3D response curves were developed. Our results highlighted that the TPC values range from 0.76 to 1.43 mg GAE g-1 dw, while the FRAP values range from 8.25 to 14.80 mmol Fe(II)E g-1 dw. The optimal extraction conditions predicted by the model were 60 °C, 22 min, ethanol concentration 51% (v/v), and solvent volume 11 mL. These conditions resulted in TPC and FRAP values of 1.35 mg GAE g-1 dw and 14.02 mmol Fe(II)E g-1 dw, respectively. Furthermore, the extract obtained under optimized conditions was characterized by UHPLC-ESI-Orbitrap-MS analysis. LC/MS-MS platform allowed us to tentatively identify various compounds belonging to the class of flavonoids, saponins, fatty acids, and lipids. Finally, the ability of CN optimal extract to inhibit the intracellular reactive oxygen species (ROS) release in a hepatocarcinoma cell line using an H2O2-induced oxidative stress model, was evaluated. The results highlighted the potential of CN extract as a valuable source of polyphenols with significant antioxidant properties, suitable for various applications in the food and pharmaceutical industries.

Purification of Polyphenols from Distiller's Grains by Macroporous Resin and Analysis of the Polyphenolic Components.

We aimed to purify polyphenols from distiller's grain extract using macroporous resins and to identify its polyphenolic components. The influence of operational parameters on purification efficiency was investigated. The polyphenolic composition was analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and then quantified by UPLC-MS using authenticated standards. The results showed that the optimal purifying conditions were D101 resin with a dosage of 3 g, four hours adsorption, three hours desorption time, and 60% ethanol as the eluent, producing the highest purification rate of 51%. The purified distiller's grain extract exhibited stronger antioxidant activity than the unpurified extracts, which was assessed using DPPH and ABTS methods (IC50 DPPH = 34.03 and 16.21 µg/mL, respectively; IC50 ABTS = 20.31 and 5.73 µg/mL, respectively). UPLC-MS results indicated that (-)-epicatechin is the major compound found in distiller's grain extract which was quantified as 562.7 µg/g extract, followed by ferulic acid (518.2 µg/g), p-hydroxybenzoic acid (417.7 µg/g), caffeic acid (217.1 µg/g), syringic acid (158.0 µg/g) and quercetin (147.8 µg/g). Two compounds, vanillic acid (66.5 µg/g) and gallic acid (41.4 µg/g), were found in lower concentrations. The findings of this study suggest that purification of polyphenolic compounds from distiller's grain by macroporous resins is feasible, providing a new and effective method for the secondary use of distiller's grain resources.

Antioxidant, antibacterial, and anti-adhesive activities of biosurfactants isolated from Bacillus strains.

Biosurfactants are surface-active compounds that display a range of physiological functions. The present study investigated the antioxidant, antimicrobial, and anti-adhesive or anti-biofilm potential of biosurfactants isolated from Bacillus subtilis VSG4 and Bacillus licheniformis VS16. The antioxidant activity of the biosurfactants was studied in vitro using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. At 5 mg/mL of the biosurfactant concentration, the scavenging of DPPH and hydroxyl radicals was found to be between 69.1-73.5% and 63.3-69.8%, respectively. The biosurfactants also displayed significant antibacterial activities against both Gram-positive and Gram-negative bacteria. The anti-adhesive activities of the biosurfactants were evaluated against Staphylococcus aureus ATCC 29523, Salmonella typhimurium ATCC 19430, and Bacillus cereus ATCC 11778. The biosurfactants exhibited anti-adhesive activity, even at concentrations of 3-5 mg/mL. Moreover, both biosurfactants displayed notable anti-biofilm activities with a biofilm eradication percentage ranging from 63.9 to 80.03% for VSG4 biosurfactant, and from 61.1-68.4% for VS16 biosurfactant. Furthermore, VSG4 biosurfactant exhibited emulsification and surface tension stability over a wide range of pH (4-10) and temperature up to 100 °C. These results show that VSG4 and VS16 biosurfactants can be potentially used as natural antioxidants, antimicrobials, and/or anti-adhesive agents for food and biomedical applications.

Pyridoxamine driven selective turn-off detection of picric acid using glutathione stabilized fluorescent copper nanoclusters and its applications with chemically modified cellulose strips.

The present work reports the interaction of various vitamin B6 cofactors with the red emitting glutathione stabilized copper nanoclusters (GSH-CuNCs). Addition of pyridoxamine (PM) resulted a new turn-on band at 410nm due to the possible adsorption over the surface of GSH-CuNCs. The nano-assembly PM-GSH-CuNCs was applied for the selective detection of nitro-aromatic compounds. Upon addition of picric acid (PA), the fluorescence of PM-GSH-CuNCs was selectively quenched at 410nm and ~ 625nm among the other tested nitro-aromatic compounds. With a linearity range from 9.9µM to 43µM, the concentration of PA can be detected down to 2.74µM. The high selectivity exhibited by the nano-assembly allows to detect PA in real samples like tap water, river water and matchstick. Advantageously, the nano-assembly PM-GSH-CuNCs was chemically adsorbed over the cellulosic strips and applied for the naked-eye detection of PA down to 1µM.

Antifungal and antioxidant activity of fatty acid methyl esters from vegetable oils

ABSTRACT Fatty acid methyl esters (FAMEs) were obtained from vegetable oils of soybean, corn and sunflower. The current study was focused on evaluating the antifungal activity of FAMEs mainly against Paracoccidioides spp., as well as testing the interaction of these compounds with commercial antifungal drugs and also their antioxidant potential. FAMEs presented small IC50 values (1.86-9.42 μg/mL). All three FAMEs tested showed antifungal activity against isolates of Paracoccidioides spp. with MIC values ranging from 15.6-500 µg/mL. Sunflower FAMEs exhibited antifungal activity that extended also to other genera, with an MIC of 15.6 μg/mL against Candida glabrata and C. krusei and 31.2 μg/mL against C. parapsilosis. FAMEs exhibited a synergetic effect with itraconazole. The antifungal activity of the FAMEs against isolates of Paracoccidioides spp. is likely due to the presence of methyl linoleate, the major compound present in all three FAMEs. The results obtained indicate the potential of FAMEs as sources for antifungal and antioxidant activity.

Wild Edible Mushrooms from Turkey as Possible Anticancer Agents on HepG2 Cells Together with Their Antioxidant and Antimicrobial Properties.

This study was designed to reveal cell growth inhibitory potential of six different edible mushrooms: Ramaria flava, Agrocybe molesta, Volvopluteus gloiocephalus, Lactarius deliciosus, Bovista plumbea, and Tricholoma terreum on HepG2 cells together with their antioxidant and antibacterial power. Methanolic extracts of V gloiocephalus and aqueous extracts of R. flava had the most potential cytotoxic effects over HepG2 cells. The best results for 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities were obtained from both aqueous and methanolic extracts of R. flava. Methanolic extracts of T. terreum (IC50 = 1.62 mg/mL) and aqueous extracts of B. plumbea (IC50 = 0.49 mg/mL) showed maximum metal chelating activity. The highest reducing capacities were observed among the methanolic extracts of R. flava (EC50 = 1.65 mg/mL) and aqueous extracts of B. plumbea (EC50 = 1.71 mg/ mL). High-performance liquid chromatography analysis revealed the presence of many phenolic compounds in macrofungi; gallic acid and p-coumaric acid were the two main phenolics identified in all extracts. Antibacterial studies indicated that all six tested mushrooms showed antibacterial activity on at least three microorganisms. These results indicate that different extracts of the investigated mushrooms have considerable cytotoxic, antioxidant, and antibacterial properties and may be utilized as a promising source of therapeutics.

Antioxidant activity of some Moroccan marine microalgae: Pufa profiles, carotenoids and phenolic content.

In order to promote Moroccan natural resources, this study aims to evaluate the potential of microalgae isolated from Moroccan coastlines, as new source of natural antioxidants. Different extracts (ethanolic, ethanol/water and aqueous) obtained from 9 microalgae strains were screened for their in vitro antioxidant activity using DPPH free radical-scavenging assay. The highest antioxidant potentials were obtained in Dunalliela sp., Tetraselmis sp. and Nannochloropsis gaditana extracts. The obtained results indicate that ethanol extract of all microalgae strains exhibit higher antioxidant activity, when compared to water and ethanol/water extracts. Therefore, total phenolic and carotenoid content measurement were performed in active ethanol extracts. The PUFA profiles of ethanol extracts were also determined by GC/MS analysis. The studied microalgae strains displayed high PUFA content ranging from 12.9 to 76.9 %, total carotenoids content varied from 1.9 and 10.8mg/g of extract and total polyphenol content varied from 8.1 to 32.0mg Gallic acid Equivalent/g of extract weight. The correlation between the antioxidant capacities and the phenolic content and the carotenoids content were found to be insignificant, indicating that these compounds might not be major contributor to the antioxidant activity of these microalgae. The microalgae extracts exerting the high antioxidant activity are potential new source of natural antioxidants.

Chemical composition, olfactory evaluation and antioxidant effects of essential oil from Mentha x piperita.

The chemical composition of the essential oil from peppermint (Mentha x piperita L.) was analyzed by GC/FID and GC-MS. The main constituents were menthol (40.7%) and menthone (23.4%). Further components were (+/-)-menthyl acetate, 1,8-cineole, limonene, beta-pinene and beta-caryophyllene. Peppermint oil possessed antiradical activity with respect to DPPH (diphenyl picryl hydrazyl) and hydroxyl (OH*) radicals, exercising stronger antioxidant impact on the OH* radical. The concentrations required for 50% inhibition of the respective radical (IC50) were 860 microg/mL for DPPH and 0.26 microg/mL for OH*. Peppermint essential oil demonstrated antioxidant activity in a model linoleic acid emulsion system in terms of inhibiting conjugated dienes formation by 52.4% and linoleic acid secondary oxidized products generation by 76.9% (at 0.1% concentration).

Coupling poly-(methacrylic acid-co-ethylene glycol dimethacrylate) monolith microextraction to capillary electrophoresis for the determination of phenols in water samples.

In the present work, a simple, selective, and sensitive method has been proposed for the determination of four phenols (catechol, resorcinol, 2,6-dimethylphenol, and 2,4,6-trinitrophenol) in water samples. The method is based on poly-(methacrylic acid-co-ethylene glycol dimethacrylate) monolith microextraction (PMME) and capillary electrophoresis-ultraviolet (CE-UV) analysis. The operation parameters including sample pH, sample flow rate, sample volume, and eluent flow rate have been studied and optimized. Under the optimal experimental conditions the limits of detection for catechol, resorcinol, 2,6-dimethylphenol, and 2,4,6-trinitrophenol based three times of standard deviations of blank by seven replicates are 0.085, 0.030, 0.159 and 0.006 microg/mL, respectively. The intra-day and inter-day relative standard deviations are less than 5.6% and 5.9%. The proposed method has been successfully applied to the determination of the four phenols in water samples and the accuracy is assessed through recovery experiments.

Some comments on extraction analysis of cations complexed with a crown ether.

A brief review is given on the use of crown ethers in solubilizing salts of alkali and alkaline earth ions in organic polar or apolar solvents. Use of crown ethers can also be made in testing e.g. lithium salts for potassium by extraction as LKpicrate, L being 18-crown-6.