Polyphenol Compounds as Antioxidants for Disease Prevention: Reactive Oxygen Species Scavenging, Enzyme Regulation, and Metal Chelation Mechanisms inE. coliand Human Cells

Larrea divaricata: anti-inflammatory and antioxidant effects of on macrophages and low density lipoproteins

Background

The oxidized low density lipoprotein (ox-LDL) contributes to inflammation and oxidative stress through the activation of macrophages under hyperglycemia contributing to the development of diabetes mellitus and to atherosclerosis. Plants are a source of effective and innocuous antioxidants. Larrea divaricata Cav. (Zygophyllaceae) is used in Argentina folk medicine for its anti-inflammatory properties.

Methods

The aim of this work was to study the antioxidant and anti-inflammatory effects of the aqueous extract (AE) of L. divaricata on macrophages under glucose stimulation and on human LDL and HDL particles under free radical generators.

Results

AE reduced the lipid peroxidation (17%), nitric oxide (NO) (47-50%), tumor necrosis factor-α (TNF-α) (32%) and free radicals (50%) induced by glucose on macrophages. Also prevented HDL nitration (28%), thus preserving its function and structure and inhibited LDL oxidation. The effect on the nitrosative stress was mainly driven by nordihydroguaiaretic acid (NDGA).

Conclusions

These results suggest a potential usefulness of AE as an adjuvant phytotherapy in patients with diabetes mellitus and atherosclerosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03547-8.

Nitroxide-functional PEGylated nanostars arrest cellular oxidative stress and exhibit preferential accumulation in co-cultured breast cancer cells

The limited application of traditional antioxidants to reducing elevated levels of reactive oxygen species (ROS) is potentially due to their lack of stability and biocompatibility when tested in a biological milieu. For instance, the poor biological antioxidant performance of small molecular nitroxides arises from their limited diffusion across cell membranes and their significant side effects when applied at high doses. Herein, we describe the use of nanostructured carriers to improve the antioxidant activity of a typical nitroxide derivative, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). Polymers with star-shaped structures were synthesised and were further conjugated to TEMPO moieties via amide linkages. The TEMPO-loaded stars have small hydrodynamic sizes (<20 nm), and are better tolerated by cells than free TEMPO in a breast cancer-fibroblast co-culture, a system exhibiting elevated ROS levels. At a well-tolerated concentration, the polymer with the highest TEMPO-loading capacity successfully downregulated ROS production in co-cultured cells (a significant decrease of up to 50% vs. basal ROS levels), which was accompanied by a specific reduction in superoxide anion generation in the mitochondria. In contrast, the equivalent concentration of free TEMPO did not achieve the same outcome. Further investigation showed that the TEMPO-conjugated star polymers can be recycled inside the cells, thus providing longer term scavenging activity. Cell association studies demonstrated that the polymers can be taken up by both cell types in the co-culture, and are found to co-locate with the mitochondria. Interestingly the stars exhibited preferential mitochodria targeting in the co-cultured cancer cells compared to accompanying fibroblasts. The data suggest the potential of TEMPO-conjugated star polymers to arrest oxidative stress for various applications in cancer therapy.

Artichoke extracts in cancer therapy: do the extraction conditions affect the anticancer activity?

Background

Artichoke is an edible plant that is grown in the Mediterranean region and is known for its antimicrobial, antifungal, antibacterial, antioxidant and anticancer activities. Different artichoke extraction methods can impressively affect the nature as well as the yield of the extracted components.

Main body

The different methods of artichoke extraction and the influence of the extraction conditions on the extraction efficiency are summarized herein. In addition, cancer causalities and hallmarks together with the molecular mechanisms of artichoke active molecules in cancer treatment are also discussed. Moreover, a short background is given on the common types of cancer that can be treated with artichoke extracts as well as their pathogenesis. A brief discussion of the previous works devoted to the application of artichoke extracts in the treatment of these cancers is also given.

Conclusion

This review article covers the extraction methods, composition, utilization and applications of artichoke extracts in the treatment of different cancers.

Regulation of Toll-Like Receptor (TLR) Signaling Pathway by Polyphenols in the Treatment of Age-Linked Neurodegenerative Diseases: Focus on TLR4 Signaling

Neuronal dysfunction initiates several intracellular signaling cascades to release different proinflammatory cytokines and chemokines, as well as various reactive oxygen species. In addition to neurons, microglia, and astrocytes are also affected by this signaling cascade. This release can either be helpful, neutral or detrimental for cell survival. Toll-like receptors (TLRs) activate and signal their downstream pathway to activate NF-κB and pro-IL-1β, both of which are responsible for neuroinflammation and linked to the pathogenesis of different age-related neurological conditions. However, herein, recent aspects of polyphenols in the treatment of neurodegenerative diseases are assessed, with a focus on TLR regulation by polyphenols. Different polyphenol classes, including flavonoids, phenolic acids, phenolic alcohols, stilbenes, and lignans can potentially target TLR signaling in a distinct pathway. Further, some polyphenols can suppress overexpression of inflammatory mediators through TLR4/NF-κB/STAT signaling intervention, while others can reduce neuronal apoptosis via modulating the TLR4/MyD88/NF-κB-pathway in microglia/macrophages. Indeed, neurodegeneration etiology is complex and yet to be completely understood, it may be that targeting TLRs could reveal a number of molecular and pharmacological aspects related to neurodegenerative diseases. Thus, activating TLR signaling modulation via natural resources could provide new therapeutic potentiality in the treatment of neurodegeneration.

Comparative study of the physicochemical, nutritional, and antioxidant properties of some commercial refined and non-centrifugal sugars

Three refined and four unrefined branded commercial sugars available in Korea were investigated in terms of pH, soluble solids, moisture, ash content, turbidity, color values, microbial profile, reducing power, 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities, cellular antioxidant activity, and total phytoconstituent (i.e. phenolic, flavonoid, mineral, sucrose, glucose, and fructose) contents using standard analytical protocols such as high-performance liquid chromatography, gas chromatography-flame ionization detector/mass spectrometry, and inductively coupled plasma atomic emission spectroscopy. All tested physicochemical parameters were within the recommended standard levels. Significantly high nutritional and antioxidant properties were observed for the unrefined sugars, especially AUNO® sugar, whereas a high sucrose content was detected for the refined sugars. Hence, this study revealed that the degree of purification affects the nutritional values and antioxidant potentials of sugars. The present findings also indicate that unrefined sugars can be used as sweeteners in sugar-based cuisine to obtain nutritional and antioxidant-rich foodstuff.

The Role of Punicalagin in Slowing Down the Decaying of Neurons

Punicalagin is an active compound found in the Pomegranate rind. The hallmark of the compound is its antioxidant properties which is more than most other sources such as Red wine. The poly-phenol donates hydrogen to free radicals like peroxynitrites and prevents it from oxidizing and destroying microglial cells in the brain. The compound has high bio-availability and is has reduced neuronal inflammation as well. The compound is useful for treating Alzheimer’s, Parkinson’s, Huntington’s and many other Dementia’s. Apart from its antioxidant properties, the compound is an antidermatophyte and antimicrobial. Punicalagin has also shown ability in down regulating virulent Quorum sensing genes in Salmonella.