Myoglobin microplate assay to evaluate prevention of protein peroxidation

Exploiting Kinetic Features of ORAC Assay for Evaluation of Radical Scavenging Capacity

The analysis and interpretation of data retrieved from Oxygen Radical Absorbance Capacity (ORAC) assays represent a challenging task. ORAC indexes originate from different mathematical approaches often lacking correct elucidation of kinetic features concerning radical scavenging reactions by antioxidant compounds. In this work, the expression of ORAC values as area under fluorescein (FL) decay curves (AUC) and lag time are critically compared. This multi-parametric analysis showed the extension of radical scavenging reactions beyond the lag time period for caffeic acid, gallic acid, reduced glutathione and quercetin, extending their antioxidant protection of FL. Ethanol delayed the reaction of both FL and antioxidant compounds with free radical species generated from 2,2'-azobis(2-amidinopropane) dihydrochloride thermolysis. Trolox equivalent values, commonly used to express ORAC values, were more affected by the differences in radical scavenging kinetics between the reference and the tested antioxidant compounds when calculated from AUC than from lag time. These findings stressed the importance of choosing calibrator compounds presenting ORAC kinetics similar to samples to prevent biased estimation of the antioxidant capacity. Additionally, the framework proposed here provides a sustainable analytical method for the evaluation of antioxidant capacity, with an AGREE score of 0.73.

Recombinant Expression of Archaeal Superoxide Dismutases in Plant Cell Cultures: A Sustainable Solution with Potential Application in the Food Industry

Superoxide dismutase (SOD) is a fundamental antioxidant enzyme that neutralises superoxide ions, one of the main reactive oxygen species (ROS). Extremophile organisms possess enzymes that offer high stability and catalytic performances under a wide range of conditions, thus representing an exceptional source of biocatalysts useful for industrial processes. In this study, SODs from the thermo-halophilic Aeropyrum pernix (SOD_Ap) and the thermo-acidophilic Saccharolobus solfataricus (SOD_Ss) were heterologously expressed in transgenic tomato cell cultures. Cell extracts enriched with SOD_Ap and SOD_Ss showed a remarkable resistance to salt and low pHs, respectively, together with optimal activity at high temperatures. Moreover, the treatment of tuna fillets with SOD_Ap-extracts induced an extension of the shelf-life of this product without resorting to the use of illicit substances. The results suggested that the recombinant plant extracts enriched with the extremozymes could find potential applications as dietary supplements in the nutrition sector or as additives in the food preservation area, representing a more natural and appealing alternative to chemical preservatives for the market.

The effects of rosmarinic acid on oxidative stress parameters and inflammatory cytokines in lipopolysaccharide-induced peripheral blood mononuclear cells

Rosmarinic acid (RA) is a potential herbal medicine and has received considerable attention due to its strong antioxidant properties. The aim of this study is to investigate the impact of RA on inflammation and oxidative stress induced by lipopolysaccharide (LPS) in peripheral blood mononuclear cells (PBMCs). PBMCs were pre-treated with various contents of RA (20, 40, 80 µM) for 24 h, then, stimulated with LPS (10 ng/ml) for more 6 h. ELISA and Real-time PCR were done to detect the levels of IL-6, TNF-α, COX-2, IL-1β and IL-10. Western blot was done to investigate the phosphorylated amounts of P65-NF-κB and JNK. Inflammatory cytokines and oxidant-antioxidant parameters were determined by colorimetric and ELISA methods. The results indicated that LPS augmented the protein levels of IL-6, TNF-α, and IL-1β cytokines as well as the mRNA levels of IL-6, TNF-α, IL-1β, COX-2, and IL-10 cytokines in in PBMCs. However, pretreatment with RA could reduce the impact of LPS on inflammatory markers. In addition, RA inhibited P65-NF-κB and JNK phosphorylation. LPS also caused a decrease in antioxidant enzymes, total thiol, and total antioxidant capacity as well as an increment in malondialdehyde and nitric oxide metabolite contents that RA abrogated them. Collectively, our finding demonstrated that RA ameliorates LPS-induced inflammation in PBMCs. RA reduces oxidative stress by preventing lipid peroxidation and nitric oxide production as well as restarting the activity of the GPx and SOD enzymes. Furthermore, our findings indicated that RA was able to protect PBMCs from inflammation via inhibiting the NF-κB and JNK MAPK pathways. This evidence shows a promising therapeutic role for RA in inflammatory status.