Aromatic and medicinal plants are a source of biologically active secondary metabolites such as polyphenols. These substances have many biological properties, such as antimicrobial, anti-inflammatory and antioxidant ones. The aim of our work is to valorize two aromatic and medicinal plants growing wild in Moroccan Eastern High Atlas through quantifying phenolic compounds of both species and evaluation of extracts' antioxidant activity. These species are Rosmarinus officinalis and Thymus satureioides
Both plants were subjected to a phytochemical screening to highlight their secondary metabolites' qualitative composition. This analysis shows the presence of flavonoids, tannins, saponins, sterols and triterpenes, free anthraquinones and catechols. But alkaloids, carotenoids and reducing compounds were not observed.
Total polyphenols extraction was made by maceration in methanol 80%. Yields were approximately 13.06% and 11.66% for Rosmarinus officinalis and Thymus satureioides. Then, methanol's crude extract was fractionated using successively three organic solvents of various polarities: chloroform, ethyl acetate and n-butanol.
Polyphenol dosage with Folin Ciocalteu's reagent showed that ethyl acetate fractions of both species Rosmarinus officinalis and Thymus satureioides, are more rich in phenolics than the other fractions.
Antioxidant activities of ethyl acetate extracts by DPPH test were quantified by spectrophotometry and 50% inhibitory concentrations' values (IC50) were determined graphically. They were equal to 103,86μg / ml and 109,98μg / ml for Rosmarinus officinalis and Thymus satureioides respectively. The concentration 52,5μg / ml was obtained for ascorbic acid used as a reference.
In this present study, fractionation method with solvents used in polyphenols'extraction indicates phenolics richness of both species. These substances have an important antioxidant power.