Protective effect of the oligomeric acylphloroglucinols from Myrtus communis on cholesterol and human low density lipoprotein oxidation

Myrtle (Myrtus communis L.), a culinary spice and flavouring agent for alcoholic beverages widespread in the Mediterranean area and especially in Sardinia, contains the structurally unique oligomeric non-prenylated acylphloroglucinols, semimyrtucommulone and myrtucommulone A, whose antioxidant activity was investigated during the oxidative modification of lipid molecules implicated in the onset of cardiovascular diseases. Both acylphloroglucinols showed powerful antioxidant properties during the thermal (140 °C), solvent-free degradation of cholesterol. Moreover, the pre-treatment with semimyrtucommulone and myrtucommulone A significantly preserved LDL from oxidative damage induced by Cu²⁺ ions at 2 h of oxidation, and showed remarkable protective effect on the reduction of polyunsaturated fatty acids and cholesterol, inhibiting the increase of their oxidative products (conjugated dienes fatty acids hydroperoxides, 7β-hydroxycholesterol, and 7-ketocholesterol). Taking into account the widespread culinary use of myrtle leaves, the results of the present work qualify the natural compounds semimyrtucommulone and myrtucommulone A as interesting dietary antioxidants with potential antiatherogenicity.