Explaining the antioxidant activity of some common non-phenolic components of essential oils.
Limonene, linalool and citral are common non-phenolic terpenoid components of essential oils, with attributed controversial antioxidant properties. The kinetics of their antioxidant activity was investigated using the inhibited autoxidation of a standard model substrate. Results indicate that antioxidant behavior of limonene, linalool and citral occurs by co-oxidation with the substrate, due to very fast self-termination and cross-termination of the oxidative chain. Rate constants kp and 2kt, (M-1s-1) at 30°C were 4.5 and 3.5×106 for limonene, 2.2 and 9.0×105 for linalool and 39 and 1.0×108 for citral. Behavior is bimodal antioxidant/pro-oxidant depending on the concentration. Calculations at the M05/6-311+g(2df,2p) level indicate that citral reacts selectively at the aldehyde C-H having activation enthalpy and energy respectively lower by 1.3 and 1.8kcal/mol compared to the most activated allyl position. Their termination-enhancing antioxidant chemistry might be relevant in food preservation and could be exploited under appropriate settings.
['Baschieri|Andrea|A|', 'Ajvazi|Majlinda Daci|MD|', 'Tonfack|Judith Laure Folifack|JLF|', 'Valgimigli|Luca|L|', 'Amorati|Riccardo|R|']
D000975:Antioxidants D009822:Oils, Volatile D010084:Oxidation-Reduction D010936:Plant Extracts D017382:Reactive Oxygen Species
Antioxidant Essential oil Limonene Linalool Citral Autoxidation (R)-Limonene (PubChem CID: 440917) Citral (PubChem CID: 8843) Dodecanal (PubChem CID: 8194) Linalool (PubChem CID: 6549) Peroxyl radicals