The phenolic content and antioxidant activity of infusions from Mediterranean medicinal plants

We prepared cold and hot water infusions from ten Mediterranean medicinal plant species and compared their total phenolic content, capacity to scavenge hydroxyl and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, ability to reduce Fe3+ and chelate Fe2+, and ability to inhibit Fe2+-induced lipid peroxidation in mouse brain homogenates. In all ten species, the phenolic content of hot infusions (from 147.05 ± 2.32 to 1359.10 ± 33.18 molGAE gdw −1) was significantly greater than that of cold infusions (from 106.11 ± 8.10 to 1006.05 ± 54.43 molGAE gdw −1) but the difference was greatest in Lavandula viridis. All of the extracts contained antioxidants, but infusions from Myrtus communis, Pistacia lentiscus, L. viridis and Cistus albidus were the most potent and provided evidence that the free radical scavenging and metal-chelating effects of these extracts might contribute to the prevention of Fe2+-induced lipid peroxidation. We observed a positive correlation between the total phenolic content and the antioxidant activity as measured using all the methods listed above with the exception of hydroxyl radical scavenging. Our results provide a scientific basis for the use of these plant species in folk medicine as well as additional resources for the discovery of novel antioxidants.S. Gonçalves and P. Costa acknowledge a grant from the Portuguese Science and Technology Foundation (SFRH/BPD/31534/2006 and SFRH/BD/63505/2009, respectively)