Interaction of olive oil phenol antioxidant components with low-density lipoprotein.

Phenolic compounds have shown to inhibit LDL oxidation in vitro and ex vivo; however, they are hydrosoluble compounds while LDL is a lipoprotein. Analysis of phenolic compounds in LDLs by HPLC is necessary to demonstrate their binding capacity to lipoproteins. We developed and validated a solid phase extraction method (SPE) that allowed us the purification of LDL samples and their analysis by HPLC. This methodology allowed us to demonstrate the in vitro binding capacity of tyrosol, one of the main phenolic compounds in olive oil, to LDL. In the intervention dietary study with volunteers, food rich in phenolic compounds affected LDL composition. Changes in LDL phenolics composition are not observed after the short-term ingestion of food rich in phenolic compounds. However, after one week of olive oil consumption and Mediterranean diet there was an increase in phenolics (p=0.021). An accumulative effect seems necessary to observe significative differences in LDL phenolic composition.