Effect of extraction process on phytochemical composition and antioxidant properties of Rosmarius officinalis and Globularia alypum extracts
Keywords:phenolic compounds, solvent extraction, extraction method, antioxidant activity, Rosmarinus officinalis L.,, Globularia alypum L.
Rosmarinus officinalis and Globularia alypum are well known and commonly used in Algeria as species and medicinal plants. The composition and the biological activities of plants depend on several factors. We investigated the influence of one factor: the extraction process. Water and methanol (80%) were used as solvent in the extraction by infusion, decoction and cold maceration. The extracts were evaluated regarding yields, thin layer chromatography, phenolic content and antioxidant activity. Results showed that temperature increase plants extraction biomass efficiency (15.90% for rosemary and 28.10% for globular). Phytochemical screening of extracts revealed the presence of several phenolic classes, including flavonoids and tannins. In addition, G. alypum contains irridiods. Thin layer chromatography showed the presence of some phenolic compounds, particularly flavonoids, of which methanolic extracts gave the highest separation. Levels of total phenolics, flavonoïds and tannins were highly influenced by method and solvent system applied. Methanolic extracts were richest in flavonoïds (39.90 mg QE/g for rosmary and 17.97mg QE/g for globular). While, for both plants, higher concentrations of tannins were noted for aqueous extracts prepared by decoction (15.9 mg CE/g and 28.10 mg CE/g respectively). Regarding the antioxidant activity, the antiradical effect of the extracts against the DPPH radical was interesting with an IC50 between 0.024 and 0.33 mg/ml, noting that R. officinalis methanol extract was the most powerful. However, G. alypum extracts, presented a higher reductive power than rosemary. Aqueous extracts, were the most active, reaching optical densities of 1.41 for water infusion extract and 1.53 for water decoction extract.