Antioxidant activity of oxidation products of α‐tocopherol and of its model compound 2,2,5,7,8‐pentamethyl‐6‐chromanol

A variety of oxidation products (4–29) of α‐tocopherol, 1 and of its model compound, 2,2,5,7,8‐pentamethyl‐6‐chromanol (2) has been tested for antioxidant activity against autoxidizing safflower oil (ASO) and autoxidizing methyl linoleate (AML). The following compounds showed good antioxidant activity against both substrates: 5‐hydroxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (4), 5‐(2,2,5,7,8‐pentamethyl‐6‐chromanoxy)methyl‐2,2,7,8‐tetramethyl‐6‐chromanol (15), 1,2‐ bis (2,2,7,8‐tetramethyl‐6‐chromanol‐5‐)ethane (16), 5‐ethoxymethyl‐7,8‐dimethyltocol (19), 5‐mthoxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (21), 5‐ethoxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (20), 5‐propoxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (22), 5‐butoxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (23), 5‐(2‐methyl‐1‐propoxy)methyl‐2,2,7,8‐tetramethyl‐6‐chromanol (24), 5‐(2‐methyl‐2‐propoxy)methyl‐2,2,7,8‐tetramethyl‐6‐chromanol (25), 5‐heptoxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (26), 5‐undecoxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (27), 5‐phytoxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (28) and 5‐cholesteroxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol (29). 2,2,7,8‐Tetramethylchroman‐5,6‐dione (17) and 1,2‐ bis (2,2,7‐trimethylchroman‐5,6‐dione‐8‐)ethane (18) showed significant antioxidant activity against ASO but not against AML. If the corresponding oxidation products of 1 are formed in vivo it means that the antioxidant activity of 1 is not lost on oxidation. This may help to explain the outstanding capacity of 1 to protect cell membranes.