Optimization of Microwave-Assisted Extraction of Phenolic Compounds from Medicinal and Aromatic Plants: Sideritis raeseri, Sideritis scardica and Origanum vulgare

Background: Medicinal plants consist a rich source of natural pharmacologically active compounds. The aim of the current work, was the study and optimization of the extraction conditions of phenolic constituents from important medicinal and aromatic plants, id. Sideritis raeseri, Sideritis scardica and Origanum vulgare, implementing microwave assisted extraction technique. Methods: Optimization was based on various parameters affecting extraction procedure, such as the duration of microwave radiation, the ratio of plant material mass to the solvent, the type and the concentration of the solvent. Results: The results revealed that 10 min of microwave radiation provided the maximum extraction yield of the phenolic constituents. The ratio of the plant material mass and the solvent had minor effect to the extraction efficiency. Conclusion: The examined solvents provided an extraction yield of phenolic constituents following the order: EtOH < MeOH < H2O < MeOH:H2O (80:20, v/v) < EtOH:H2O (60:40, v/v), in the case of Sideritis raeseri and Sideritis scardica and the order: H2O < MeOH:H2O (80:20, v/v) < EtOH:H2O (60:40, v/v) < MeOH < EtOH in the case of Origanum vulgare.