Optimization of microwave-assisted extraction and characterization of phenolic compounds in cherry laurel (Prunus laurocerasus) leaves

• Response surface methodology was used to optimize the process parameters of MAE from cherry laurel leaves.
• The optimum and economic extraction conditions were determined.
• Economic optimization of the MAE is an important and necessary step in the scale-up procedure.
• Seven phenolic compounds were identified with high accuracy by HPLC external standard method.

The objectives of this study were to optimize the operational conditions of the microwave-assisted extraction (MWE) of fresh cherry laurel leaves by the response surface method (RSM) and to analyze the composition of phenolic compounds in the extracts obtained under optimal conditions. Optimal conditions for MWE, proposed by the Design-Expert software, were microwave power of 598 W, plant material to solvent ratio of 0.11 g cm−3 and extraction time of 28.6 min, while economically the most acceptable conditions were 307.6 W, plant material to solvent ratio of 0.17 g cm−3 and 17.1 min. Independently of the chosen conditions, HPLC analysis of crude methanolic extracts of cherry laurel leaves showed the presence of seven phenolic compounds, namely: chlorogenic acid (major compound), luteolin 7-glucoside, apigenin 7-glucoside, kaempferol 3-glucoside, quercetin 3-glucoside, hydroxycinnamic acid and naringenin. The results showed that the developed model was suitable for describing the effects and relationship of the MWE operating variables on the extractive substance yield, that RSM could successfully be used for optimizing the extraction processes, and indicated that a MWE could be applied to extract a promising natural agent from fresh cherry laurel leaves.