Table 1.
Protection of LDL from oxidation
| Study type | Anti-oxidant capacity measurement | Conclusion | Reference |
|---|---|---|---|
| Incubation of hydroxytyrosol and two conjugated of HOTYR with isolated LDL | Concentration Vit.E in LDL in presence of copper sulfate with different concentration HOTYR | HOTYR and conjugated, copper sulfate-induced LDL oxidation | (39) |
| TBARS level | |||
| Levels of lipid peroxide | |||
| Conjugated dienes formation | |||
| Refined olive oil, common olive oil and virgin olive oil were added to isolated low-density lipoprotein | Conjugated dienes formation was monitored after copper-mediated LDL oxidation | Oils with higher content of phenolic compounds showed the greatest protection of LDL oxidation | (42) |
| Dietary study in human beings consuming virgin olive oil | Variables used to study the resistance of LDL: lag time, maximum amount of dienes and maximal oxidation rate | Decrease in LDL cholesterol and LDL oxidation during one week period consuming 25 ml of olive oil. Significantly levels of MUFA and anti-oxidants in LDL | (43) |
| Double-blind, crossover, randomized, controlled clinical trial to investigate the effects of olive oil with differences in their phenolic content on LDL oxidation | Ox-LDL was determined in plasma by a sandwich ELISA procedure. The LDL resistance to oxidation was determined by formation of conjugated dienes after copper oxidation of isolated LDL | Decrease in vivo LDL oxidation and resistance to ex vivo (isolated) LDL oxidation | (44) |
| Double-blind, randomized, crossover experimental trial in human beings consuming olive oil | Ox-LDL measured by the ELISA method | Significant decrease in plasma oxidized LDL in dose-dependent manner in relation with the phenolic content of the olive oil ingested | (45) |
| Multicenter controlled human intervention consuming olive oil with differences in their phenolic content (EUROLIVE) | Ox-LDL measured by a sandwich ELISA procedure using murine monoclonal antibody mAb-4E6 | Significant decrease in plasma oxidized LDL in dose-dependent manner in relation with the phenolic content of the olive oil ingested | (46) |
| Dietary study in human beings consuming olive oil with differences in their phenolic content | Ox-LDL measured by enzyme immunoassay using murine monoclonal antibody mAb-4E6 | Dose-dependent response between the intake of polyphenols and the decrease in LDL peroxidation | (47) |
| Subsample of EUROLIVE study. Human intervention consuming olive oil with differences in their phenolic content | Ox-LDL in plasma measured by a sandwich ELISA with murine monoclonal antibody mAb-4E6. Anti-oxidant capacity of biological metabolites of phenolic compounds (hydroxytyrosol monosulphate and homovanillic acid sulfate) | Inverse relationship between these metabolites and the degree of LDL oxidation | (48) |
HOTYR, hydroxytyrosol; LDL, low-density lipoproteins; Vit. E, vitamin E; CuSO4, copper sulfate; TBARS, thiobarbituric acid-reacting substances; ELISA, enzyme-linked immunosorbent assay; MUFA, monounsaturated fatty acids; Ox-LDL, oxidized low-density lipoproteins.