Extraction and optimization of phenolic compounds from butterbur plant (Petasites hybridus) by ultrasound-assisted extraction and determination of antioxidant and antimicrobial activity of butterbur extracts

Butterbur (Petasites hybridus), which is a perennial herb native to Europe, Asia and North America, is used as food in the Black Sea region of Turkey. In this study, it was aimed to identify the natural microflora of the root, stem and leaf parts of the butterbur plant, to optimize the extraction of phenolic compounds in these parts by ultrasound-assisted extraction (UAE) using the response surface methodology (RSM), and to determine the antioxidant and antimicrobial activities of these extracts. For this purpose, the effects of temperature (30–70 °C), extraction time (30–60 min) and ethanol concentration (0–70%) on total phenolic compounds (TPC) of phenolic extracts obtained from the butterbur plant parts were determined. As a result of the extractions carried out at optimum conditions, TPC (4.73, 0.64 and 3.78 μg GAE/mg extract), ABTS (17.57, 7.57 and 12.84 µg TE/mg extract), DPPH (2.51, 1.84 and 2.27 µg TE/mg extract) and FRAP (3.64, 2.95 and 3.14 µg TE/mg extract) values of the extracts obtained from root, stem and leaf were determined. Antimicrobial activity of the root, stem and leaf extracts were investigated on Escherichia coli O157:H7, Salmonella Typhimurium, Bacillus cereus, Staphylococcus aureus, Lactobacillus plantarum and Lactobacillus brevis microorganisms by the 96-well microtiter plate method and also disc diffusion method. Minimum inhibition concentration (MIC) values of the extracts ranged between 0.39 and 87.50 mg/mL for all extracts and all tested microorganisms, while inhibition zone diameters ranged between 6.05 and 20.30 mm. In conclusion, extracts obtained from the butterbur plant can extend the shelf life of food products due to their antimicrobial activities.