Selective extraction and stabilization of bioactive compounds from rosemary leaves using a biphasic NADES

Abstract

Rosemary (Rosmarinus officinalis) is a natural source of bioactive compounds that have high antioxidant activity. It has been in use as a medicinal herb since ancient times, and it currently is in widespread use due to its inherent pharmacological and therapeutic potential, in the pharmaceutical, food, and cosmetic industries. Natural deep eutectic systems (NADESs) have recently been considered as suitable extraction solvents for bioactive compounds, with high solvent power, low toxicity, biodegradability, and low environmental impact. The present work concerns the extraction of compounds such as rosmarinic acid, carnosol, carnosic acid, and caffeic acid, from rosemary using NADESs. This extraction was carried out using heat and stirring (HS) and ultrasound-assisted extraction (UAE). A NADES composed of menthol and lauric acid at a molar ratio of 2:1 (Me:Lau) extracted carnosic acid and carnosol preferentially, showing that this NADES exhibits selectivity for nonpolar compounds. On the other hand, a system of lactic acid and glucose (LA:Glu (5:1)) extracted preferentially rosmaniric acid, which is a more polar compound. Taking advantage of the different polarities of these NADESs, a simultaneous extraction was carried out, where the two NADESs form a biphasic system. The system LA:Glu (5:1)/Men:Lau (2:1) presented the most promising results, reaching 1.00 ± 0.12 mg of rosmarinic acid/g rosemary and 0.26 ± 0.04 mg caffeic acid/g rosemary in the more polar phase and 2.30 ± 0.18 mg of carnosol/g of rosemary and 17.54 ± 1.88 mg carnosic acid/g rosemary in the nonpolar phase. This work reveals that is possible to use two different systems at the same time and extract different compounds in a single-step process under the same conditions. NADESs are also reported to stabilize bioactive compounds, due to their interactions established with NADES components. To determine the stability of the extracts over time, the compounds of interest were quantified by HPLC at different time points. This allows the conclusion that bioactive compounds from rosemary were stable in NADESs for long periods of time; in particular, carnosic acid presented a decrease of only 25% in its antioxidant activity after 3 months, whereas the carnosic acid extracted and kept in the methanol was no longer detected after 15 days. The stabilizing ability of NADESs to extract phenolic/bioactive compounds shows a great promise for future industrial applications.

Towards a Greener Approach for Biomass Valorization: Integration of Supercritical Fluid and Deep Eutectic Solvents

“…Ultrasound-assisted extractions were carried out at temperatures 30 and 60 °C, for 30 min, with an ultrasonic power of 100 W, and frequency of 50–60 Hz (Grant XUB5, UK). Extractions were conducted in cycles of 15 min, with stirring in a vortex for 1 min between cycles to speed up the extraction, according to Vieira et al [ 52 ]. Flasks were positioned in the same position in the ultrasound bath during each extraction.…”

Rosemary: Unrevealing an old aromatic crop as a new source of promising functional food additive—A review

“…Usually, conventional methods such as Soxhlet extraction, maceration with stirring, heat reflux, hydrogenated distillation, and dry leaf decoction were used as extraction techniques for the major phenolic compounds (rosmarinic acid, carnosic acid, and carnosol) in rosemary (Sharma et al., 2020; Sik et al., 2020). In recent years, UAE, SFE, MAE, PLE, re‐extraction of UAE with supercritical CO 2 , natural deep eutectic systems, subcritical extraction, and other unconventional extraction processes have been extensively used in the preparation of rosemary products (Dhouibi, Manuguerra et al., 2023; Hirondart et al., 2020; Lefebvre et al., 2021; Vieira et al., 2022). Notably, the SFE and subcritical extraction techniques were widely used as modern processes to produce high‐quality products without any residual solvent in the rosemary extraction industry.…”

Pharmaceutical applications of therapeutic deep eutectic systems (THEDES) in maximising drug delivery

“…This work disclosed that employing two different systems simultaneously could assist in the extraction of different compounds using a single-step procedure under similar experimental conditions. The extracted bioactives were stable in NADES for a prolonged time, as quantified by HPLC at different time points [ 91 ]. In conclusion, the application of THEDES enables the stabilization of bioactive compounds, safeguarding them from degradation and enhancing their stability.…”