Development of a rapid method for the determination of the antioxidant capacity in cereal and legume milling products using the radical cation DMPD+

Bioresource Utilization of Djulis (Chenopodium formosanum) Biomass as Natural Antioxidants

Djulis (Chenopodium formosanum) is a yearly, fast-growing, under-utilized pseudo-cereal with a high proportion of biomass content. We used the hulls, which are usually removed from djulis as crop residue, to evaluate the free-radical scavenging and antioxidant capacity of djulis. We studied the antioxidant capacity of ethanol- and water-extracted hulls and roots by using various in vitro methods. Ascorbic acid was the reference sample. The extract samples were used at 200, 400, 600, 800, and 1000 µg/mL. Total sugar content, total phenolic content, and total flavonoid content were assessed. Antioxidant activity was assessed by using the Trolox equivalent antioxidant capacity, ferric reducing antioxidant power, cupric ion reducing antioxidant capacity, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, and N, N-dimethyl-ρ-phenylenediamine. Ethanol- and water-extracted red djulis hulls showed high amounts of total sugar, total phenolic content, total flavonoid content, and antioxidant capacity. Moreover, ethanol- and water-extracted red djulis roots showed moderate antioxidant capacity. However, ethanol- and water-extracted yellow djulis hulls showed limited antioxidant activities. Utilization of the biomass of djulis hulls and roots as natural antioxidant resources may be environmentally friendly and foreseeable.

Selectedin vitro methods to determine antioxidant activity of hydrophilic/lipophilic substances

The topic of free radicals and related antioxidants is greatly discussed nowadays. Antioxidants help to neutralize free radicals before damaging cells. In the absence of antioxidants, a phenomenon called oxidative stress occurs. Oxidative stress can cause many diseases e.g. Alzheimer’s disease and cardiovascular diseases. Therefore, antioxidant activity of various compounds and the mechanism of their action have to be studied. Antioxidant activity and capacity are measured by in vitro and in vivo methods; in vitro methods are divided into two groups according to chemical reactions between free radicals and antioxidants. The first group is based on the transfer of hydrogen atoms (HAT), the second one on the transfer of electrons (ET). The most frequently used methods in the field of antioxidant power measurement are discussed in this work in terms of their principle, mechanism, methodology, the way of results evaluation and possible pitfalls.

Direct measurement of total antioxidant capacity of cereals: QUENCHER-CUPRAC method

Polyphenols in cereal samples are distributed as free, soluble-esterified, and insoluble-bound forms either esterified or etherified to cell wall constituents. In the evaluation of total antioxidant capacity (TAC) of cereals, rather difficult and time-consuming acid, alkaline and enzymatic treatments of residue have been applied to complete the extraction of bound phenolic compounds. Thus, this work is aimed to measure the TAC of cereals (i.e. barley, wheat, rye, oat) by the 'QUENCHER procedure' (involving forced solubilization of bound phenolics by oxidizing TAC reagents) with the direct use of copper(II)-neocuproine (Cu(II)-Nc) reagent of the CUPric Reducing Antioxidant Capacity (CUPRAC) assay. In this novel 'QUENCHER-CUPRAC' method, reaction time and solvent composition parameters were optimized, and the method was applied to cereal samples with CUPRAC reagent dissolved in 1:1 (v/v) ethanol-water mixture. The antioxidant capacities of soluble and insoluble fractions were simultaneously measured to give a hierarchic TAC order of cereals as: barley>rye>oat>wheat. The TAC values of cereals measured by QUENCHER-CUPRAC were higher than those of original QUENCHER method using ABTS(•+) and DPPH reagents. Polyphenolic mixtures in a cellulose matrix gave additive TAC values with QUENCHER-CUPRAC. The proposed method correlated linearly with QUENCHER-ABTS(•+) (r=0.956) and QUENCHER-DPPH (r=0.976).

Effect of magnetic nanoparticles on tobacco BY-2 cell suspension culture

Nanomaterials are structures whose exceptionality is based on their large surface, which is closely connected with reactivity and modification possibilities. Due to these properties nanomaterials are used in textile industry (antibacterial textiles with silver nanoparticles), electronics (high-resolution imaging, logical circuits on the molecular level) and medicine. Medicine represents one of the most important fields of application of nanomaterials. They are investigated in connection with targeted therapy (infectious diseases, malignant diseases) or imaging (contrast agents). Nanomaterials including nanoparticles have a great application potential in the targeted transport of pharmaceuticals. However, there are some negative properties of nanoparticles, which must be carefully solved, as hydrophobic properties leading to instability in aqueous environment, and especially their possible toxicity. Data about toxicity of nanomaterials are still scarce. Due to this fact, in this work we focused on studying of the effect of magnetic nanoparticles (NPs) and modified magnetic nanoparticles (MNPs) on tobacco BY-2 plant cell suspension culture. We aimed at examining the effect of NPs and MNPs on growth, proteosynthesis - total protein content, thiols - reduced (GSH) and oxidized (GSSG) glutathione, phytochelatins PC2-5, glutathione S-transferase (GST) activity and antioxidant activity of BY-2 cells. Whereas the effect of NPs and MNPs on growth of cell suspension culture was only moderate, significant changes were detected in all other biochemical parameters. Significant changes in protein content, phytochelatins levels and GST activity were observed in BY-2 cells treated with MNPs nanoparticles treatment. Changes were also clearly evident in the case of application of NPs. Our results demonstrate the ability of MNPs to negatively affect metabolism and induce biosynthesis of protective compounds in a plant cell model represented by BY-2 cell suspension culture. The obtained results are discussed, especially in connection with already published data. Possible mechanisms of NPs' and MNPs' toxicity are introduced.