2-2--azino-di-(3-ethylbenzothiazoline)-6-sulfonic-acid and 3-4-dihydroxyphenylethanol

Antioxidants have been the subject of intense research interest due to their numerous health benefits. In this work, a series of new conjugates of hydroxytyrosol and coumarin were synthesized and evaluated for their free radical scavenging, toxicity and antioxidant mechanism in vitro. The all target compounds 14a-t exhibited better radical scavenging activity than BHT, hydroxytyrosol, and coumarin in both DPPH radical and ABTS

Topics: Antioxidants; Apoptosis; Benzothiazoles; Biphenyl Compounds; Cell Line; Cell Survival; Coumarins; Dose-Response Relationship, Drug; Humans; Hydrogen Peroxide; Molecular Structure; Phenylethyl Alcohol; Picrates; Reactive Oxygen Species; Structure-Activity Relationship; Sulfonic Acids

A series of alkyl nitrohydroxytyrosyl ether derivatives has been synthesized from free hydroxytyrosol (HT), the natural olive oil phenol, in order to increase the assortment of compounds with potential neuroprotective activity in Parkinson's disease. In this work, the antioxidant activity of these novel compounds has been evaluated using Ferric Reducing Antioxidant Power (FRAP), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and Oxygen Radical Scavenging Capacity (ORAC) assays compared to that of nitrohydroxytyrosol (NO₂HT) and free HT. New compounds showed variable antioxidant activity depending on the alkyl side chain length; compounds with short chains (2-4 carbon atoms) maintained or even improved the antioxidant activity compared to NO₂HT and/or HT, whereas those with longer side chains (6-8 carbon atoms) showed lower activity than NO₂HT but higher than HT.

Topics: Antioxidants; Benzothiazoles; Carbon; Fluorescence Recovery After Photobleaching; Free Radical Scavengers; Humans; Nitrogen Dioxide; Oxidation-Reduction; Oxygen; Phenol; Phenols; Phenylethyl Alcohol; Reactive Oxygen Species; Sesame Oil; Sulfonic Acids

The use of natural compounds as antiglycative agents to reduce the load of advanced glycation end products from diet is very promising. Olive mill wastewater is a by-product of the olive oil extraction processes with a high content of hydroxytyrosol, hydroxytyrosol derivatives and molecules containing o-dihydroxyl functions such as verbascoside. Two powders were obtained after the ultrafiltration and nanofiltration of olive mill wastewater, and successive spray drying with maltodextrin and acacia fiber. The samples were characterized by phenolic composition and antioxidant capacity. Antiglycative capacity was evaluated by in vitro BSA-glucose and BSA-methylglyoxal assays, formation of Amadori products and direct trapping of reactive dicarbonyls (methylglyoxal and glyoxal). Both ultrafiltered and nanofiltered olive mill wastewater powders had an activity comparable to quercetin and hydroxytyrosol against the inhibition of protein glycation (IC50 = 0.3 mg mL(-1)). The antiglycative activity of the powder was further investigated after separation by reverse phase solid extraction. Fractions extracted with the methanol content higher than 40% and rich in hydroxytyrosol and verbascoside exerted the highest reactivity against dicarbonyls. Data confirmed that the direct trapping of dicarbonyl compounds is the main route explaining the antiglycative action rather than of the already known antioxidant capacity. Results support further investigations to evaluate the technological feasibility to use olive mill wastewater powders as antiglycative ingredients in foods or in pharmacological preparations in future.

Topics: Antioxidants; Benzothiazoles; Food Industry; Glucose; Glucosides; Glycation End Products, Advanced; Olive Oil; Oxidative Stress; Phenol; Phenols; Phenylethyl Alcohol; Pyruvaldehyde; Sulfonic Acids; Wastewater

Potato, tomato, eggplant and pumpkin were deep fried, sautéed and boiled in Mediterranean extra virgin olive oil (EVOO), water, and a water/oil mixture (W/O). We determined the contents of fat, moisture, total phenols (TPC) and eighteen phenolic compounds, as well as antioxidant capacity in the raw vegetables and compared these with contents measured after cooking. Deep frying and sautéing led to increased fat contents and TPC, whereas both types of boiling (in water and W/O) reduced the same. The presence of EVOO in cooking increased the phenolics identified in the raw foods as oleuropein, pinoresinol, hydroxytyrosol and tyrosol, and the contents of vegetable phenolics such as chlorogenic acid and rutin. All the cooking methods conserved or increased the antioxidant capacity measured by DPPH, FRAP and ABTS. Multivariate analyses showed that each cooked vegetable developed specific phenolic and antioxidant activity profiles resulting from the characteristics of the raw vegetables and the cooking techniques.

Topics: Antioxidants; Benzothiazoles; Chlorogenic Acid; Chromatography, High Pressure Liquid; Cluster Analysis; Cooking; Cucurbita; Dietary Fats; Furans; Iridoid Glucosides; Iridoids; Lignans; Multivariate Analysis; Olive Oil; Phenols; Phenylethyl Alcohol; Rutin; Solanum lycopersicum; Solanum melongena; Solanum tuberosum; Sulfonic Acids; Vegetables

A large panel of novel catecholic antioxidants and their fatty acid or methyl carbonate esters has been synthesized in satisfactory to good yields through a 2-iodoxybenzoic acid (IBX)-mediated aromatic hydroxylation as the key step. The new catechols are structural analogues of naturally occurring hydroxytyrosol (3,4-DHE). To evaluate structure/activity relationships, the antioxidant properties of all catecholic compounds were evaluated in vitro by ABTS assay and on whole cells by DCF fluorometric assay and compared with that of the corresponding already known hydroxytyrosyl derivatives. Results outline that all of the new catechols show antioxidant capacity in vitro higher than that of the corresponding hydroxytyrosyl derivatives. Less evident positive effects have been detected in whole cells experiments. Cytotoxicity experiments, using MTT assay, on a representative set of compounds evidenced no influence in cell survival.

Topics: Animals; Antioxidants; Benzothiazoles; Catechols; Cell Line; Cell Survival; Esters; Fatty Acids; Iodobenzenes; Iodobenzoates; Myoblasts; Phenylethyl Alcohol; Rats; Structure-Activity Relationship; Sulfonic Acids

New lipophilic esters of tyrosol, a naturally occurring phenol with interesting biological properties, have been synthesized in good yields by a chemoselective procedure, using lipase from Candida antarctica or p-toluenesulfonic acid as catalysts. Their antioxidant activities have been evaluated by the Rancimat test in lipophilic food matrices, as well as by FRAP and ABTS assays in methanolic solutions, and compared with those of previously synthesized hydroxytyrosyl esters. Free tyrosol, hydroxytyrosol, butylhydroxytoluene, and alpha-tocopherol were used as standards. All methods used for the antioxidant activity evaluation emphasized the high influence of the ortho-diphenolic structure on the antioxidant capacity, tyrosol and its derivatives being less active than hydroxytyrosol and its analogues and even less than BHT and alpha-tocopherol. In addition, the Rancimat test revealed a lower activity for ester derivatives than for their respective reference compounds (HTy or Ty), in agreement with the polar paradox. On the other hand, FRAP and ABTS methods reported an opposite behavior between the synthetic esters and their respective references. Thus, hydroxytyrosyl esters were more active than HTy, whereas tyrosyl esters were less active than Ty. The length and nature of the acyl side chain did not seem to play an important role in the antioxidant activity of either the hydroxytyrosyl or tyrosyl ester series, since no significant differences were observed among them.

Topics: Antioxidants; Benzenesulfonates; Benzothiazoles; Candida; Drug Stability; Esters; Ferric Compounds; Lipase; Phenylethyl Alcohol; Structure-Activity Relationship; Sulfonic Acids