The antioxidant activity of hydroxytyrosol

Hydroxytyrosol is a natural polyphenolic compound mainly derived from olive leaves and olive oil, with strong antioxidant activity. The following is a comparative analysis of its in vitro and in vivo antioxidant activity studies:

I. In Vitro Experimental Studies

Free Radical Scavenging Capacity: Multiple studies have shown that hydroxytyrosol has good free radical scavenging ability. In the DPPH radical scavenging assay, the DPPH radical scavenging capacity of hydroxytyrosol increases with its concentration; when the concentration reaches 40µM, the scavenging rate can reach 90%. In the ABTS⁺ radical scavenging assay, hydroxytyrosol also exhibits a certain scavenging effect on ABTS⁺; at a concentration of 20µM, the scavenging rate can reach 90%.

Protective Effect on Cells: Taking the H₂O₂-induced HEK-293 cell damage model as an example, hydroxytyrosol can reduce intracellular ROS levels, restore the decreased GSH levels, and simultaneously reduce the expression level of 8-OHdG in HEK-293 cells, effectively preventing oxidative damage to cellular DNA. In addition, in the UVA-damaged human dermal fibroblast model, treatment with hydroxytyrosol can reduce the proportion of senescence-associated β-galactosidase-positive cells, delaying cellular senescence.

II. In Vivo Experimental Studies

Impact on Model Organisms: Using Caenorhabditis elegans as the experimental subject, a large amount of ROS accumulates in the nematodes after 1 hour of heat stress. The hydroxytyrosol-treated groups can reduce ROS content by 8.30%, 21.72%, and 21.79% respectively. Moreover, 10µg/mL of hydroxytyrosol can significantly reduce the MDA content in nematodes, while higher doses (50 and 100µg/mL) reduce the MDA content to 32.02% and 36.00% of that in the blank group, respectively, significantly improving the survival rate of nematodes.

Impact on Animal Organisms: In studies on offspring cognitive dysfunction caused by prenatal stress, supplementing pregnant mice with hydroxytyrosol (10 and 50 mg/kg body weight/day) showed that such supplementation significantly improved the cognitive ability of both male and female offspring mice, effectively inhibited oxidative damage in the hippocampal tissue of offspring mice, and alleviated mitochondrial metabolic disorders. In addition, olive oil rich in hydroxytyrosol can increase serum CAT, GSH-Px, and SOD activities, reduce MDA content, and enhance the body's antioxidant capacity.

III. Comparative Analysis

Similar Mechanisms of Action: Both in vitro and in vivo experiments show that hydroxytyrosol exerts its antioxidant effect mainly by scavenging free radicals and regulating the activity of antioxidant enzymes. For example, in vitro, it can reduce intracellular ROS levels; in vivo, it can decrease ROS and MDA levels in nematodes and animals, while increasing the activity of antioxidant enzymes such as SOD and CAT.

Differences in Effect Performance: In vitro experiments can more directly observe the effect of hydroxytyrosol on specific cells or molecules, and its antioxidant effect is often more obvious at higher concentrations. For instance, in DPPH and ABTS⁺ radical scavenging assays, a certain concentration is required to achieve a high scavenging rate. In contrast, due to the involvement of complex biological systems and metabolic processes in in vivo experiments, the antioxidant effect of hydroxytyrosol may need to be reflected more significantly through long-term supplementation and overall physiological regulation. For example, in animal experiments, it is necessary to continuously supplement animals with hydroxytyrosol for a period of time before improvements in the body's antioxidant capacity and related physiological indicators can be observed.