Evaluation of antioxidant and antimicrobial properties of ethanolic extracts extracted from Caper (Capparis spinosa) fruit by ultrasound method using the RSM

Extracts and essential oils of medicinal plants have many bioactive agents, including phenolic compounds with significant antioxidant and antimicrobial properties. Choosing the suitable extraction method affects the quantity and quality of antioxidant and antimicrobial compounds. The aim of this study was to evaluate the efficiency of ultrasound waves in extracting phenolic, antioxidant and antimicrobial compounds of Caper fruit. Response surface methodology (RSM) and Box–Behnken design were used to optimize the extraction factors, including extraction time (10, 25, 40 min) and ultrasound intensity (40, 70, 100 %) with ethanolic solvent (70 %). From the results of the tests performed with the response surface methodology, ultrasound intensity was recognized as the most effective factor in extracting phenolic, antioxidant and antimicrobial compounds of Caper fruit and by increasing time and ultrasound intensity, the extraction of these compounds increased. The optimum conditions for extraction of antioxidant and antimicrobial compounds of Caper fruit were determined extraction time 36 minutes and ultrasound intensity 91 percent. In these optimum conditions, the amount of total phenolic contents and IC50 index of ethanolic extracts extracted from Caper fruit were obtained 23.63 mg/g and 45.30 μg/mg, respectively, the optimum amount of minimum inhibitory concentration of coagulase positive Staphylococcus aureus and Bacillus cereus were obtained 0.19 and 6.07 mg/ml, respectively, and the optimum amount of minimum batericidal concentration of coagulase positive Staphylococcus aureus was obtained 11.81 mg/ml. Also, the extracts extracted at time 36 minutes and ultrasound intensity 91 percent had the ability to inhibit the activity of Escherichia coli O157: H7 and Pseudomonas aeruginosa at concentrations of 25 and 25 mg/ml, respectively, and had the batericidal ability of Bacillus cereus, Escherichia coli O157: H7 and Pseudomonas aeruginosa at concentrations of 25, 50 and 50 mg/ml, respectively.