Effect of the solvent types and extraction conditions on the quality and antimicrobial characteristics of Paeonia officinalis L. extract

Paeonia officinalis L. is one of the species of the Paeoniaceae family. Its root has different effective compounds e.g., polyphenols, flavonoids, triterpenoids, tannins, and monoterpenes. It shows biological activities such as antibacterial, anti-oxidative, relaxing and anti-pain properties. This study evaluated the effect of three solvents, ethanol/water, water, and water/ethanol/hexane on extracting the active ingredients. These solvents were applied by the methods of immersion, immersion with ultrasonic waves, and the use of supercritical fluid carbon dioxide with auxiliary solvents. The efficiency, qualitative characteristics (pH, polyphenolic compounds and antioxidant properties) and antimicrobial properties of the extracts were evaluated by the well-diffusion method against Escherichia coli, Staphylococcus aureus, Salmonella Typhimurium and Candida albicans. Also, the MIC and MBC of the extracts on the activity of these organisms were determined. The results showed that the independent variables significantly affect the quantity and quality of the produced extracts (P ≤ 0.05). Using the water/ethanol, and the immersion method in combination with ultrasonic waves, the highest extract efficiency (17.66± 0.34), of the phenolic compounds (33.5±0.65) and antioxidant property (76±1.44) was obtained. The diameter of the inhibition zone for E. coli, S. aureus and C. albicans in the vicinity of this sample was more than others. Meanwhile, the inhibition zone of S. Typhimurium was larger in the presence of watery extract using the immersion method. The quantity and quality of the extract using supercritical fluid was lower than others.