An analytical and theoretical approach for the profiling of the antioxidant activity of essential oils: The case of Rosmarinus officinalis L.

The antioxidant constituents of essential oils (EOs) of Rosmarinus officinalis L (alpha-pinene chemotype) were isolated at the flowering (A), post-flowering (B), and vegetative stages (C). GC-MS was used to analyze total chemical composition, Folin-Ciocalteau and Prussian blue methods for reducing substances. Radical scavenging capacity (DPPH test, IC(50) 36.78 +/- 0.38, 79.69 +/- 1.54, 111.94 +/- 2.56 mu L) and anti-lipoperoxidant activity (TBARS, IC(50) 0.42 +/- 0.04, 1.20 +/- 0.06 mu L, 4.07 +/- 0.05 mu L) differed widely in the three stages. Antioxidant activity, identified after silica gel fractionation chromatography, was closely related (R(2) = 0.9959) to each EO's content of hydroxilated derivatives, (containing alcohols, phenols and 1,8 cineole): 15.26 +/- 0.12%, 7.22 +/- 0.06%, and 5.09 +/- 0.10% in EOs from A, B, and C. Modeling the C, H, O terpenes in a simulated phospholipid bilayer indicated that anti-lipoperoxidant activity depended on the stability and rapidity of their interactions with the membrane bilayer components, and their positioning over its surface. (C) 2011 Elsevier B.V. All rights reserved.