EH et al. (3 more authors) (2021) Application of ultrasound-assisted extraction method to recover betalains and polyphenols from red beetroot waste. ACS Sustainable Chemistry and Engineering, 9 (26). pp. 8736-8747.

No abstract

The present study aimed to compare the absorption and transport patterns of three main betalains, betanin, vulgaxanthin I and indicaxanthin, into intestinal epithelial cells and to assess their distinct molecular effects on inflammatory and redox-related cell signalling in association with their radial scavenging potencies. All three betalains showed anti-inflammatory effects (5–80 μM), reflected by attenuated transcription of pro-inflammatory mediators such as cyclooxygenase-2 and inducible NO-synthase. Concomitant increases in antioxidant enzymes such as heme oxygenase-1 were only observed for betanin. Moreover, betanin uniquely demonstrated a potent dose-dependent radical scavenging activity in EPR and cell-based assays. Results also indicated overall low permeability for the three betalains with Papp of 4.2–8.9 × 10−7 cm s−1. Higher absorption intensities of vulgaxanthin and indicaxanthin may be attributed to smaller molecular sizes and greater lipophilicity. In conclusion, betanin, vulgaxanthin I and indicaxanthin have differentially contributed to lowering inflammatory markers and mitigating oxidative stress, implying the potential to ameliorate inflammatory intestinal disease. Compared with two betaxanthins, the greater efficacy of betanin in scavenging radical and promoting antioxidant response might, to some extent, compensate for its poorer absorption efficiency, as demonstrated by the Caco-2 cell model.

Oxidative stress caused by free radicals is one of the great threats to inflict intracellular damage. Here, we report a convenient approach to the synthesis, characterization, and evaluation of the radical activity of titanium-based composites. We have investigated the potential of natural antioxidants (curcumin, quercetin, catechin, and vitamin E) as radical scavengers and stabilizers. The titanium oxide composites were prepared via three steps including sol–gel synthesis, carboxylation, and esterification. The characterization of the titanium–phenol composites was carried out by FTIR, PXRD, UV–vis and SEM methods. The radical scavenging ability of the novel materials was evaluated using DPPH and an in vitro LPO assay using isolated rat liver mitochondria. The novel materials exhibit both a higher stability and an antioxidant activity in comparison to bare TiO2. It was found that curcumin and quercetin based composites show the highest antioxidant efficiency among the composites under study followed by catechin and vitamin E based materials. The results from an MTT assay carried out on the Caco-2 cell line indicate that the composites do not contribute to the cytotoxicity in vitro. This study demonstrates that a combination of powerful antioxidants with titanium dioxide can change its functional properties and provide a convenient strategy against oxidative stress.

Scope: Betalain pigments are increasingly highlighted for their bioactive and anti‐inflammatory properties, although research is lacking to demonstrate contributions of individual betalains. The work herein aimed to compare effects of four main betalains on inflammatory and cell‐protective markers and to highlight potential structure‐related relationships of the two main subgroups: betacyanins vs betaxanthins. Methods and results: Murine RAW 264.7 macrophages were stimulated with bacterial lipopolysaccharide following incubation with betacyanins (betanin, neobetanin) and betaxanthins (indicaxanthin, vulgaxanthin I) in concentrations from 1 to 100 µM. All betalains suppressed expression of pro‐inflammatory markers IL‐6, IL‐1β, iNOS, and COX‐2 with tendency for stronger effects of betacyanins compared to betaxanthins. In contrast, HO‐1 and gGCS showed mixed and only moderate induction, while more emphasized effects were observed for betacyanins. While all betalains suppressed mRNA levels of NADPH oxidase 2 (NOX‐2), a superoxide generating enzyme, only betacyanins were able to counteract hydrogen peroxide induced reactive oxygen species (ROS) generation, in alignment with their radical scavenging potential. Furthermore, betaxanthins exerted pro‐oxidant properties, elevating ROS production beyond hydrogen peroxide stimulation. Conclusion: In summary, all betalains display anti‐inflammatory properties, although only betacyanins demonstrate radical scavenging capacities, indicating potential differing responses under oxidative stress conditions, which requires further research.