Synthesis and Antioxidant Activity of Alkyl Nitroderivatives of Hydroxytyrosol

Abstract

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.

Keywords

• nitrocatechol
• alkyl nitrohydroxytyrosyl derivatives
• hydroxytyrosol
• antioxidant activity
• Parkinson’s disease