Effect of sub and super critical fluids on the antioxidant capacity and chemical composition of some important medicinal plants

In this study, the effect of extraction methods on chemical composition and antioxidant activity of medicinal aromatic plants such as Anethum graveolens, Nigella sativa, Coriandrum sativum, Artemisia annua, and Micromeria fruticosa is investigated. Sub/supercritical fluid extractions were performed by using subcritical water, subcritical ethanol and supercritical CO2. Effect of these methods is compared with steam distillation, organic solvent extraction under reflux, organic solvent extraction under ultrasonic irradiation methods. Antioxidant activity determination was carried out by radical scavenging activity assay (DPPH), total antioxidant capacity cupric reducing antioxidant capacity (CUPRAC) and total phenol content assay(FOLIN).The results showed that components and concentrations of the extracts strongly depend on extraction method. The extraction method may be chosen according to the goal of extract usage. Economically important oxygenated compounds were acquired mostly by subcritical water extraction. Fatty acids were obtained more by supercritical fluid extraction in Nigella sativa seeds. It was determined that the best effective method in antioxidant activity determination was ethyl alcohol extraction and the best effective plant was Micromeria fruticosa.