Effects of Green Extraction Methods on Antioxidant and Antimicrobial Properties of Artichoke (Cynara scolymus L.) Leaves.

Research background: Artichoke leaves, an important waste product of the food industry, have an important antioxidant and antimicrobial capacity. Although there are several studies in the literature to determine their antioxidant and antimicrobial activity, a comparison of green extraction technologies including microwave, ultrasound probe and ultrasound bath methods in relation to the maceration technique has not been performed. Also, several parameters such as the extraction temperature, power, extraction mode and extraction time are important parameters for obtaining targeted compounds in the highest amount. For this reason, we aimed to compare various extraction methods including microwave-assisted extraction, ultrasound-assisted extraction with probe, ultrasound-assisted extraction in a water bath and maceration in terms of extraction parameters for obtaining bioactive compounds from artichoke leaves.

Experimental approach: Microwave-assisted extraction at two different power values, ultrasound-assisted extraction with probe in continuous or pulsed mode with two different extraction times each, ultrasound-assisted extraction in a water bath at two different power values with two different extraction times each and maceration with two different times were used for the extraction. The extraction temperature is an important parameter affecting the thermal degradation of bioactive compounds. We used a constant extraction temperature of 50 °C. Total phenolic and total flavonoid content, antioxidant capacity, phenolic compound profile analysis by LC-QTOF-MS and antimicrobial activity by agar diffusion and broth microdilution methods were determined.

Results and conclusions: The bioactive compounds were found to be significantly affected by the parameters used in each extraction method. The microwave-assisted extraction method was more efficient than the other extraction methods at both power values. This method also required the shortest extraction time. The ultrasound-assisted probe extraction method was the second most efficient method. The type of process, continuous or pulsed, did not affect the results, but shortening the extraction time led to lower results. A longer extraction time of the ultrasound-assisted extraction in a water bath method led to better results, similar to the ultrasound-assisted probe extraction, regardless of the used power. The extracts were highly effective against many opportunistic and pathogenic microorganisms.

Novelty and scientific contribution: This study provides valuable insights into the extraction parameters of different extraction methods to obtain bioactive compounds from artichoke leaves, which could have potential applications in the food and pharmaceutical industries.