Kinetic modeling of the reversal of antioxidant potency of α-, ß-, γ- and δ-tocopherols in methyl linoleate peroxidation.

Extended, chemically detailed kinetic models at the molecular basis are constructed to identify the reactions involved in the reversal of the antioxidant action of α-, ß-, γ- and δ-tocopherols during methyl linoleate oxidation. The reaction mechanisms were numerically simulated and subjected to analysis to quantify the significance of individual chemical steps by the value-based method. Results of the obtained kinetic models agreed well with the experimental data. The significant individual reactions contributing to the observed antioxidant and pro-oxidant behavior of the different tocopherols were identified. It is revealed that the reverse order of antioxidant potency and a complex nonlinear dependency of the antioxidant potency of tocopherols with the increase in their concentration are due to the increasing contribution of pro-oxidant relative to the antioxidant reactions. Once the approach presented here can be applied to more complex systems, engineered optimization of antioxidant protection strategies may be reached.

A more efficient synthesis and properties of saturated and unsaturated starch esters.

This work presents a series of starch esters synthesized via 1,5,7-triazabicyclo[4.4.0]-dec-5-ene (TBD) catalyzed transesterifications in dimethyl sulfoxide (DMSO). The reaction was performed with saturated and unsaturated fatty acids (8, 11, and 18 carbon atoms). The degree of substitution (DS) was raised by purging the reaction flask with nitrogen instead of simply performing the reaction under a nitrogen atmosphere. The increase of DS was most obvious for long-chain fatty acids, as an almost complete DS was observed for starch stearate (2.8) and starch oleate (2.7). The products were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction. Starch esters from unsaturated fatty acids have a lower Tg than their saturated analogues. Moreover, contact angle and moisture uptake measurements showed increased hydrophobicity for all starch esters in comparison to pristine starch. Our results show a more efficient method for synthesizing a biobased material that steers into the direction of a material that could replace conventional plastics.

Characterization of xanthine oxidase inhibitory activities of phenols from pickled radish with molecular simulation.

Pickled radish is a general source of natural bioactive compounds that include phenols. Here, we used molecular docking, fluorescence quenching, circular dichroism spectroscopy and molecular dynamics simulations to identify potential inhibitors against xanthine oxidase from a library of pickled radish compounds. The most effective compounds were selected for validation through in vitro experiments including enzyme activity inhibition tests, and cell-based assays. Molecular docking results revealed that 2,6-Dihydroxyacetophenone, 4-Hydroxyphenethyl alcohol, and 4-Hydroxybenzaldehyde exhibited significant effects on xanthine oxidase inhibition. Three phenols have varying degrees of inhibition on xanthine oxidase, which is driven by hydrophobic interactions and hydrogen bonds and affects the secondary structure and hydrophobic homeostasis of xanthine oxidase. The stability of xanthine oxidase inhibition by three phenols was analyzed by molecular dynamics simulation. Finally, cellular experiments confirmed that three phenols reduced uric acid levels by inhibiting the xanthine oxidase enzyme activity of BRL 3A cells.

Antioxidant ability of tyrosol and derivative-compounds in the presence of O2(1Δg)-species. Studies of synergistic antioxidant effect with commercial antioxidants.

The exposure of fatty products to environmental light can trigger lipid oxidation in food through a sensitized-photooxidation process, which involves the participation of the species singlet oxygen (O2(1Δg)). Therefore, preservation of food quality represents a subject of great economic interest to the food industry. In this sense, the phenolic compounds are natural antioxidants widely used in food industry. In this contribution we studied the interactions of phenolic derivatives (Phd), tyrosol and tyrosol derived isomers, with O2(1Δg) and their possible protective effect against the oxidative degradation of unsaturated fatty acids and amino acids. Besides, a potential synergistic interaction between Phd and antioxidants used in food industry were investigated. Phd substrates showed properties as antioxidant additives due to their high ability deactivating O2(1Δg) through a physical process and synergistic effect in the presence of commercial antioxidants. Phd presented an antioxidant protective effect toward O2(1Δg)-mediated degradation of methyl linoleate and tryptophan.

Evaluation of anti-nociceptive and anti-inflammatory activities of the methanol extract of Holigarna caustica (Dennst.) Oken leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Holigarna caustica (Dennst.) is commonly used in traditional medicine to treat a variety of painful conditions such as eye irritation, inflammation, arthritis, skin diseases, cuts and wounds. AIM OF THE STUDY: The present study was undertaken to investigate the anti-nociceptive and anti-inflammatory activities of the methanol extract of H. caustica leaves and to elucidate its possible mechanism(s) of action. MATERIALS AND METHODS: Fresh leaves of H. caustica were collected, dried, and extracted with methanol (MEHC). MEHC was subjected to activity testing, using chemical-induced (acetic acid and formalin test) and heat-induced (hot plate and tail immersion test) pain models. To determine the possible mechanism behind the anti-nociceptive activity of MEHC, the opioid antagonist naltrexone was used to evaluate the involvement of opioid receptors in the case of formalin, hot plate and tail immersion tests, while the involvement of the cGMP and ATP-sensitive K+ channel pathways were assessed using methylene blue and glibenclamide respectively, in the acetic acid-induced writhing test. In parallel, the carrageenan-induced paw oedema model was used to determine the anti-inflammatory potential of the extract. Exploratory and motor behaviours were evaluated by the open-field test. Various bioactive compounds potentially responsible for the anti-nociceptive and anti-inflammatory activities were ascertained using GC-MS analysis. RESULTS: MEHC showed strong, significant and dose-dependent anti-nociceptive activity in all chemical-induced and heat-induced pain models at all experimental doses. The association of opioid receptors with the observed anti-nociceptive effects was confirmed by using naltrexone. The cGMP and ATP-sensitive K+ channel pathway was also shown to be involved in the anti-nociceptive activity of MEHC. In addition, MEHC exhibited a dose-dependent inhibition of inflammatory oedema induced by carrageenan. MEHC was not connected with changes in either the locomotor activity or motor responses of mice. In a GC-MS analysis, 40 compounds were identified, among which twelve are documented bioactive compounds with potent analgesic and anti-inflammatory properties. CONCLUSIONS: Our current study revealed that MEHC possesses strong central and peripheral anti-nociceptive as well as anti-inflammatory activity. It may also be concluded that both opioid receptors as well as the cGMP and ATP-sensitive K+ channel pathway are involved in the anti-nociceptive mechanism of MEHC. This study rationalizes the ethnomedicinal use of H. caustica leaves in various painful conditions.

Lipid oxidation induced oxidative degradation of cereal beta-glucan.

In food systems, lipid oxidation can cause oxidation of other molecules. This research for the first time investigated oxidative degradation of ß-glucan induced by lipid oxidation using an oil-in-water emulsion system which simulated a multi-phased aqueous food system containing oil and ß-glucan. Lipid oxidation was monitored using peroxide value and hexanal production while ß-glucan degradation was evaluated by viscosity and molecular weight measurements. The study showed that while lipid oxidation proceeded, ß-glucan degradation occurred. Emulsions containing ß-glucan, oil and ferrous ion showed significant viscosity and molecular weight decrease after 1 week of oxidation at room temperature. Elevated temperature (40°C) enhanced the oxidation reactions causing higher viscosity drop. In addition, the presence of ß-glucan appeared to retard the hexanal production in lipid oxidation. The study revealed that lipid oxidation may induce the degradation of ß-glucan in aqueous food systems where ß-glucan and lipids co-exist.

Unsaturated lipid matrices protect plant sterols from degradation during heating treatment.

The interest in plant sterols enriched foods has recently enhanced due to their healthy properties. The influence of the unsaturation degree of different fatty acids methyl esters (FAME: stearate, oleate, linoletate and linolenate) on a mixture of three plant sterols (PS: campesterol, stigmasterol and ß-sitosterol) was evaluated at 180 °C for up to 180 min. Sterols degraded slower in the presence of unsaturated FAME. Both PS and FAME degradation fit a first order kinetic model (R(2)>0.9). Maximum oxysterols concentrations were achieved at 20 min in neat PS and 120 min in lipid mixtures and this maximum amount decreased with increasing their unsaturation degree. In conclusion, the presence of FAME delayed PS degradation and postponed oxysterols formation. This protective effect was further promoted by increasing the unsaturation degree of FAME. This evidence could help industries to optimize the formulation of sterol-enriched products, so that they could maintain their healthy properties during cooking or processing.

Effect of olive storage conditions on Chemlali olive oil quality and the effective role of fatty acids alkyl esters in checking olive oils authenticity.

The present paper accounts for the study of the storage of Chemlali olive fruits at two conditions of limited aerobiosis: in closed plastic bags and in open perforated plastic boxes for different periods before oil extraction. The ultimate objective is to investigate the effect of the container type of the postharvest fruit storage on the deterioration of the olive oil quality. The results have shown that the oil quality of Chemlali olives deteriorated more rapidly during fruit storage in closed plastic bags than in perforated plastic boxes. Therefore, the use of perforated plastic boxes is recommended for keeping the olives for longer periods of storage. The repeated measures analysis of variance of all parameters analyzed indicated that the olive oil quality is mainly affected by the olives storage conditions (containers type and storage periods). Finally, blends of extra-virgin olive oil and mildly deodorized low-quality olive oils can be detected by their alkyl esters concentrations.