Comparative study of different techniques to extract rosmarinic acid from Melissa offidnalis L.

Due to the great demand ofconsumers for an increasingly healthy diet, the food industry hás been interested in natural alternatives, namely from plant kingdom, in view of replacing artificial additives [1,2]. Thus, the development ofthese natural ingredients requires preliminary studies that evaluate the best extraction methodologies and conditions, in order to obtain the highest leveis ofthe target compounds [3,4]. The aim of this study was to optimize the extraction of rosmarinic acid from Melissa officinalis L. (lemon balm), comparing three dififerent techniques: maceration, microwave assisted extraction and ultrasonic assisted extraction. The response surface methodology was applied to obtain the conditions that maximize the extraction of rosmarinic acid, using a circumscribed central composite design with three variables and five leveis, being the relevant variables time, temperature or power, and ethanol concentration. The amount of rosmarinic acid (obtained by HPLC-DAD) and the extraction yield were used as responses. Ultrasonic extraction proved to be the most efficient technique, leading to 86 ± 4 mg ofrosmarinic acid/g ofplant (dryweight) under optimal extraction conditions: 33 ± 3 min, 372 ± 19W and40 ± 1% ethanol. The results obtained highlight that M. officinalis species is a source ofrosmarinic acid and reveal the best extraction conditions to obtain the highest leveis ofthis molecule, with great interest for the food industry.Acknowledgements: The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financiai support to CIMO (UID/AGR/00690/2013), C. Caleja (SFRH/BD/93007/2013) and L. Barros contract; To FEDER-Interreg Espana-Portugal programme for financiai support through the project 0377_Iberphenol_6_E. Junta de Galicia for the financiai support to M.A. Prieto.