Lipid peroxidation rosemary

Linalool is one of the main compounds (up to 15%) of the EO obtained from Rosmarinus officinalis L. (rosemary, Lamiaceae). The EO was tested using two different methods radical scavenging with the DPPH assay and the p-carotene bleaching test. The oil was able to reduce the stable free radical DPPH and showed a slightly weaker scavenging activity than the standard trolox. But the efficiency of rosemary oil was clearly weaker than that of the reference oil Thymus porlock. By the P-carotene bleaching test it could be shown that this EO has the ability to prevent the lipid peroxidation with a capacity close to the used standards. 

Carotinoids also can act as scavengers for alkyl radicals. Radicals stabilized by resonance are formed (Formula 3.84), unable to initiate lipid peroxidation. P-Carotenes are most active at a concentration of 5 10 mol/1, while at higher concentrations the prooxidative effect is predominant. Also the partial pressure of oxygen is critical, it should be below 150 mm Hg. Phenolic compounds (cf. 18.1.2.5) which are widely distributed in plant tissues, act as natural antioxidants. The protective effect of several herbs, spices (e. g. sage or rosemary) and tea extracts against fat (oil) oxidation is based on the presence of such natural antioxidants (cf. 21.2.5.1 and 22.1.1.4). The antioxidative effect of phenols depends on the pH. It is low in an acidic medium (pH 4) and high in an alkaline medium (pH 8) when phenolation occurs. 

Asai, A., Nakagawa, K., and Miyazawa, T., Antioxidative effects of turmeric, rosemary and capsicum extracts on membrane phospholipid peroxidation and liver lipid metabohsm in mice, Biosci. Biotechnol. Biochem., 63, 2118-2122, 1999. 

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