Should we ban total phenolics and antioxidant screening methods? The link between antioxidant potential and activation of NF-κB using phenolic compounds from grape by-products

Optimizing the potential bioactivity of isoflavones from soybeans via ultrasound pretreatment: Antioxidant potential and NF-κB activation

Soybean consumption has been associated with health benefits. However, the effect of ultrasound (US) soybean pretreatment in terms of potential health benefits has not been investigated so far. Accordingly, the total phenolic content (TPC) and the total aglycone content (TAC) were optimized using the Box-Behnken design. Contrasting samples regarding isoflavones aglycones and TPCs were screened for their antioxidant and anti-inflammatory potentials using RAW 264.7 macrophages. US pretreated soybeans (55°C, 15 min, and 24 W/cm2 ) showed greater TPC and TAC compared to the control and this translated to higher antiradical activity and reduction of nuclear factor kappa B (NF-κB) activation. The concentration of genistein in treated soybeans increased by 95%. Furthermore, US pretreated soybeans rendered phenolic extracts that reduced the NF-κB activation by 86%. Therefore, this contribution demonstrates the beneficial effects of US pretreatment of soybeans, which provides a better feedstock for the functional food industry. PRACTICAL APPLICATIONS: Soybeans can be consumed as such or used as a feedstock to produce soy yogurt, fermented soymilk, tofu, and protein concentrate, among others. The greatest bioavailability of isoflavones compared to other flavonoids has recently been highlighted, and this has been explained by the relatively moderate lipophilicity of isoflavones as aglycones. The present contribution supports the use of US pretreatment of soybeans to obtain a feedstock with improved contents of isoflavones as aglycones. We have confirmed that phenolic extracts obtained from the US pretreated samples showed higher bioactivity as radical scavengers and by reducing the activation of nuclear factor kappa B (NF-κB) in a cell model, which is mediated by oxidative species. The clinical importance of NF-κB activation is derived mainly from its role in inflammatory responses. Therefore, our investigation may have a practical application in the procurement of soybean products and/or ingredients with improved functional properties related to their health benefits.

Impact of Cold versus Hot Brewing on the Phenolic Profile and Antioxidant Capacity of Rooibos (Aspalathus linearis) Herbal Tea

Consumption of rooibos (Aspalathus linearis) as herbal tea is growing in popularity worldwide and its health-promoting attributes are mainly ascribed to its phenolic composition, which may be affected by the brewing conditions used. An aspect so far overlooked is the impact of cold brewing vs regular brewing and microwave boiling on the poly(phenolic) profile and in vitro antioxidant capacity of infusions prepared from red ('fermented', oxidized) and green ('unfermented', unoxidized) rooibos, the purpose of the present study. By using an untargeted metabolomics-based approach (UHPLC-QTOF mass spectrometry), 187 phenolic compounds were putatively annotated in both rooibos types, with flavonoids, tyrosols, and phenolic acids the most represented type of phenolic classes. Multivariate statistics (OPLS-DA) highlighted the phenolic classes most affected by the brewing conditions. Similar antioxidant capacities (ORAC and ABTS assays) were observed between cold- and regular-brewed green rooibos and boiled-brewed red rooibos. However, boiling green and red rooibos delivered infusions with the highest antioxidant capacities and total polyphenol content. The polyphenol content strongly correlated with the in vitro antioxidant capacities, especially for flavonoids and phenolic acids. These results contribute to a better understanding of the impact of the preparation method on the potential health benefits of rooibos tea.

Current Issues in Antioxidant Measurement

The rationale and scope of the main issues of antioxidant measurement are presented, with basic definitions and terms in antioxidant research (such as reactive species and related antioxidative defenses, oxidative stress, and antioxidant activity and capacity) in a historical background. An overview of technical problems and expectations is given in terms of interpretation of results, precision and comparability of methods, capability of simulating physical reality, and analytical performance (sensitivity, selectivity, etc.). Current analytical methods for measuring antioxidant and antiradical activity are classified from various viewpoints. Reaction kinetics and thermodynamics of current analytical methods are discussed, describing physicochemical aspects of antioxidant action and measurement. Controversies and limitations of the widely used antioxidant assays are elaborated in detail. Emerging techniques in antioxidant testing (e.g., nanotechnology, sensors, electrochemistry, chemometry, and hyphenated methods) are broadly introduced. Finally, hints for the selection of suitable assays (i.e., preferable for a specific purpose) and future prospects are given.

Isolation of Strong Antioxidants from Paeonia Officinalis Roots and Leaves and Evaluation of Their Bioactivities

Paeonia officinalis extracts from leaves and roots were tested for their antioxidant potential using in vitro chemical (Folin-Ciocalteu, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), oxygen radical absorbance capacity (ORAC), hydroxyl radical antioxidant capacity (HORAC), hydroxyl radical scavenging capacity HOSC)) and cellular antioxidant activity (CAA) assays. Leaf extracts were stronger antioxidants than root extracts, while methanol was a more effective solvent than water in chemical assays. However, the selected water extract of leaves was a stronger antioxidant in CAA than the methanol extract (0.106 vs. 0.046 µmol quercetin equivalents/mg). Twenty compounds were identified by ultra performance liquid chromatography-quadrupole-time-of-flight (UPLC-Q-TOF) mass spectrometer, while on-line screening of their antioxidant capacity by high performance liquid chromatography (HPLC) with a DPPH^•-scavenging detector revealed that gallic acid derivatives are the major peony antioxidants. Root water and leaf methanol extracts inhibited α-amylase in a dose dependent manner. The IC₅₀ value for the strongest inhibitor, the methanol extract of leaves, was 1.67 mg/mL. In addition, the cytotoxicity assessment of extracts using human Caco-2 cells demonstrated that none of them possessed cytotoxic effects.

Is Chickpea a Potential Substitute for Soybean? Phenolic Bioactives and Potential Health Benefits

Legume seeds are rich sources of protein, fiber, and minerals. In addition, their phenolic compounds as secondary metabolites render health benefits beyond basic nutrition. Lowering apolipoprotein B secretion from HepG2 cells and decreasing the level of low-density lipoprotein (LDL)-cholesterol oxidation are mechanisms related to the prevention of cardiovascular diseases (CVD). Likewise, low-level chronic inflammation and related disorders of the immune system are clinical predictors of cardiovascular pathology. Furthermore, DNA-damage signaling and repair are crucial pathways to the etiology of human cancers. Along CVD and cancer, the prevalence of obesity and diabetes is constantly increasing. Screening the ability of polyphenols in inactivating digestive enzymes is a good option in pre-clinical studies. In addition, in vivo studies support the role of polyphenols in the prevention and/or management of diabetes and obesity. Soybean, a well-recognized source of phenolic isoflavones, exerts health benefits by decreasing oxidative stress and inflammation related to the above-mentioned chronic ailments. Similar to soybeans, chickpeas are good sources of nutrients and phenolic compounds, especially isoflavones. This review summarizes the potential of chickpea as a substitute for soybean in terms of health beneficial outcomes. Therefore, this contribution may guide the industry in manufacturing functional foods and/or ingredients by using an undervalued feedstock.