Olive oil contains several phenolic compounds with antioxidant activity, whose levels depend strongly on the kind of cultivar grown, fruit ripening effects and the oil extraction process. Therefore, the beneficial effects exerted by olive oil consumption on the resistance of low density lipoproteins (LDLs) to oxidation depend not only on an increased intake of mono-unsaturated fatty acids (e.g. oleate) which are less prone to oxidation, but also phenolic antioxidants. The aim of this study was to analyze in vitro effects exerted on the oxidative modification of Cu-stimulated human LDL by two olive oil biophenols, i.e. 3,4-dihydroxyphenylethanol-elenolic acid (3,4-DHPEA-EA) and protocatecuic acid. These compounds have not been investigated in as much detail as the better-known olive oil biophenols - such as tyrosol (p-HPEA), o-coumaric acid, vanillic acid, caffeic acid, oleuropein and 3,4-dihydroxyphenylethanol (3,4-DHPEA). Modification of LDL was tested by measuring the formation of intermediate and end products of lipid peroxidation such as conjugated dienes, lipid hydroperoxides, cholesterol and cholesteryl ester oxides, as well as studying the decrease in oxidizable substrates like polyunsaturated fatty acids. In addition, the increase in LDL negative charges was evaluated. The results demonstrate the two-tested olive oil biophenols show high antioxidant activities. In particular, protocatecuic acid and 3,4-DHPEA-EA show an antioxidant activity comparable with that of caffeic acid, oleuropein and 3,4-DHPEA. They are not only able to retard lipid peroxidation, but also to reduce the extent of its activity.
This paper reports the first group of results on alkylphenol (APE) contamination of seafood in the Adriatic Sea, in the framework of a national project on the quality of this Sea (PRISMA 2). Nonylphenol (NP), octylphenol (OP), and their ethoxylates (NPE and OPE) were detected in edible molluscs, either filter feeders or predators (clams, mussels, cuttlefishes, and squids), caught from 15 harbors along the Italian coast in the Adriatic Sea in 1997. NP was the compound found always at levels much higher than the other APEs in all the examined species. It reached the maximum concentration of 696 ng/g fresh weight in the squids from the central Adriatic Sea. OP generally occurred at levels 30 times lower than NP. OP was found up to a level of 18.6 ng/g in squids from central Adriatic Sea. OPE was the compound always spotted at the lowest concentrations, up to 0.43 ng/g. NPE was always below the detection limit. The pattern of contamination in the three areas examined was different between bivalve and cephalopod species. No exhaustive risk assessment for marine organisms and human health can be conducted on the basis of these results because data are insufficient. Yet, the occurrence of NP suggests a negligible risk for mussels, which represent the only molluscs for which data are adequate. As to the possible human health implications, the consumption of molluscs of the Adriatic Sea implies APE intakes that are some orders of magnitude lower than those responsible for toxic effects in laboratory animals. Despite these apparently low risks for mussels and human health, the reasons for concern still remain because the levels of alkylphenols found in this study indicate a general contamination of the Adriatic Sea even far from the cost. Furthermore, these levels might represent an unacceptable hazard for other marine organisms. Finally, they contribute to the general environmental estrogen pool.
Virgin olive oil stability to autoxidation is mainly due to phenolic compounds naturally occurring
in it, but contrasting data have been published on the effectiveness of the same antioxidant
compounds. With thermogravimetric analysis (TGA) it is possible to have an estimation of oil
resistance to oxidation, having a measure of weight gain percent due to reaction of sample with
oxygen during the oxidation, and of initial and final oxidation temperatures. The following samples
were examined: virgin olive oil, olive oil, and olive oil spiked with different amounts of some
antioxidants. Tested phenols were p-HPEA, 3,4-DHPEA, 3,4-DHPEA-EA, caffeic acid, oleuropein,
and, moreover, BHT and BHA. Data showed that natural antioxidant addition (especially oleuropein,
3,4-DHPEA, and 3,4-DHPEA-EA) could extend the olive oil shelf life and could protect oil from
decomposition naturally occurring during thermal treatments (such as cooking process).
Keywords: Biophenols; olive oil stability; lipid autoxidation; thermogravimetric analysis
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