Antioxidant properties of various extracts from selected wild Moroccan aromatic and medicinal species

Antioxidant properties of various extracts from different wild Moroccan aromatic and medicinal plants (Achillea ageratum L., Salvia officinalis L., Thymus satureoiedes Cosson., Mentha suaveolens subsp. timija (Briq.) Harley and Cotula cinerea Del.) were examined by applying DPPH free radical-scavenging activity, β-carotene/linoleic acid bleaching and reducing power assays. Total phenol and flavonoid contents of the extracts were also determined. Antioxidant activity was compared with that of synthetic antioxidants including butylated hydroxytoluene (BHT) and quercetin. Overall, the highest antioxidant properties were shown by the hot water and methanolic extracts obtained from all species studied. The hot water extract of M. suaveolens subsp. timija (Briq.) presented the best contribution in DPPH and reducing power assays (IC50=14.04 ± 0.14 and 17.36 ± 0.1 µg/mL, respectively) which was significantly associated with its high phenolic content (134.49 ± 2.14 µg GAE/mg extract). However, in β-carotene-linoleic acid bleaching assay, the hot water extract of S. officinalis L. was the most effective with an IC50 value of 14.49 ± 0.40 µg/mL. These findings may provide new information on the considerable potential of the five Moroccan medicinal and aromatic plants as rich a source of natural antioxidant substances. Therefore, they could be suitable for using as antioxidative additives in the food and pharmaceutical industries.