Radical Scavenging Activity and Performance of Novel Phenolic Antioxidants in Oils During Storage and Frying

Plant-derived and dietary phenolic cinnamic acid derivatives: Anti-inflammatory properties

Cinnamic acids are aromatic acids primarily found in plants and plant-derived food. Phenolic cinnamic acids, with one or more hydroxyl groups in the aromatic ring, often contribute to the biological activities attributed to these compounds. The presence of hydroxyl groups and a carboxyl group makes cinnamic acids very hydrophilic, preventing them from crossing biological membranes and exerting their biological activities. To alleviate this condition, a panel of synthetic modifications have been made leading to a diverse set of phenolic cinnamic structures. In this review, an overview of the natural phenolic cinnamic acid derivatives and their plant sources (more than 200) is described. The synthetic approaches to obtain the referred derivatives (more than 200) namely esters and amides are reviewed. Further, their anti-inflammatory activity (more than 70 compounds) is scrutinized. Finally, future directions will be indicated to translate the research on phenolic cinnamic derivatives into potentially effective anti-inflammatory drugs.

Fluorescence and UV-VIS Spectroscopy to Determine the Quality Changes of Rapeseed Oil Fortified with New Antioxidant After Storage Under Various Conditions

This work focused on the application of synchronous fluorescence (SF) spectroscopy, excitation-emission matrix (EEM) fluorescence spectroscopy and modified UV-VIS methods for characterization of oxidative status and antioxidant activity (AA) of refined rapeseed oils fortified with the novel antioxidant octyl sinapate (OSA) at two concentrations and butylated hydroxyanisole (BHA) stored in different types of packages under various storage conditions. Quality parameters such as amounts of the primary and secondary oxidation products in rapeseed oils increased after storage under various conditions, whereas the AA of oils decreased. However, OSA strongly inhibited the generation of primary oxidation products in oils exposed to light. The AA of rapeseed oil with 0.5% of OSA packed in transparent glass after exposure to light was 6 times higher than the AA of non-supplemented oil. Moreover, the intensities of bands attributed to tocopherols and phenolic compounds decreased during storage depending on the storage conditions, but characteristic peaks for generation of oxidation products appeared. Interestingly, the fluorescence spectra of oil fortified with 0.5% of OSA contained the information of a new fluorescent product. Moreover, the potential usefulness of EEM to study the effect of antioxidants on degradation of stored rapeseed oils was demonstrated. Fluorescence spectroscopy can be used to investigate the oxidation state of rapeseed oils packed in various containers during storage at different conditions. The addition of the lipophilic antioxidant to rapeseed oil effectively delayed the oxidation process and significantly increased its AA.

Heterocyclic Schiff bases as non toxic antioxidants: Solvent effect, structure activity relationship and mechanism of action

Phenolic heterocyclic imine based Schiff bases from Thiophene-2-carboxaldehyde and Pyrrole-2-carboxaldehyde were synthesized and characterized as novel antioxidants. The solvent effects of these Schiff bases were determined and compared with standard antioxidants, BHA employing DPPH assay and ABTS assay. Fixed reaction time and Steady state measurement were used for study. IC₅₀ and EC₅₀ were calculated. Structure-activity relationship revealed that the electron donating group in the phenolic ring increases the activity where as the electron withdrawing moiety decreases the activity. The Schiff base derivatives showed antioxidant property by two different pathways namely SPLET and HAT mechanisms in DPPH assay. While in ABTS method, the reaction between ABTS radical and Schiff bases involves electron transfer followed by proton transfer (ET-PT) mechanism. The cytotoxicity of these compounds has been evaluated by MTT assay. The results showed that all these compounds are non toxic in nature.

The role of cyclodextrins in ORAC-fluorescence assays. antioxidant capacity of tyrosol and caffeic acid with hydroxypropyl-β-cyclodextrin

Tyrosol and caffeic acid are biophenols that contribute to the beneficial properties of virgin olive oil. The influence of hydroxypropyl-β-cyclodextrin (HPβ-CD) on their respective antioxidant capacities was analyzed. The ORAC antioxidant activity of tyrosol (expressed as μM Trolox equivalents/μM Tyrosol) was 0.83 ± 0.03 and it increased up to 1.20 ± 0.11 in the presence of 0.8 mM HPβ-CD. However, the ORAC antioxidant activity of caffeic acid experienced no change. The different effect of HPβ-CD on each compound was discussed. In addition, the effect of increasing concentrations of different cyclodextrins in the development of ORAC-fluorescence (ORAC-FL) assays was studied. The ORAC signal was higher for HPβ-CD, followed by Mβ-CD, β-CD, γ-CD and finally α-CD. These results could be explained by the formation of inclusion complexes with fluorescein.

Novel antioxidants are not toxic to normal tissues but effectively kill cancer cells

Free radicals are formed as a result of cellular processes and play a key role in predisposition to and development of numerous diseases and of premature aging. Recently, we reported the syntheses of a number of novel phenolic antioxidants for possible application in food industry. In the present study, analyses of the cellular processes and molecular gene expression effects of some of the novel antioxidants in normal human tissues and in cancer cells were undertaken. Results indicated that whereas the examined antioxidants showed no effects on morphology and gene expression of normal human oral and gingival epithelial tissues, they exerted a profound cell killing effect on breast cancer cells, including on chemotherapy-resistant breast cancer cells and on oral squamous carcinoma cells. Among the tested antioxidants, N-decyl-N-(3-methoxy-4-hydroxybenzyl)-3-(3,4-dihydroxyphenyl) propanamide and N-decyl-N-(3,5-dimethoxy-4-hydroxybenzyl)-3-(3,4-dihydroxyphenyl) propanamide were the most promising, with excellent potential for cancer treatment. Moreover, our gene expression databases can be used as a roadmap for future analysis of mechanisms of antioxidant action.