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Optimization of extraction of carnosic acid and carnosol from sage (Salvia officinalis L.) in deep eutectic solvents

Given the growing use of bioactive components in the industry, rapid development of various methods for their extraction and separation is required. For the last few years, deep eutectic solvents (DESs), which are composed of a hydrogen bond acceptor (HBA) (usually choline chloride) and hydrogen bond donor (HBD) components, stand out as a promising substitution to conventional solvents due to non-toxicity, thermal stability, easy preparation, biodegradability and price. Sage (Salvia officinalis L.), a member of Lamiaceae family, is an aromatic and medicinal plant used in everyday life due to the various positive effects on health associated with its composition. The most important components with antioxidant activity in sage are diterpenes such as carnosic acid, carnosol and methyl carnosate which can be extracted by various extraction techniques, most commonly solid-liquid extraction and supecritical fluid extraction. The aim of this paper was to select the most suitable choline chloride based deep eutectic solvent for the extraction of carnosic acid and carnosol from sage and then optimize extraction conditions for conventional extraction with mixing and ultrasound-assisted extraction. Screening revealed that among 17 different DESs, the most suitable solvent is choline chloride: lactic acid (1:1). In addition, the influence of extraction temperatures (30, 50, 70 °C), time (30, 60, 90 min) and amount of water added (10%, 30%, 50%) on the carnosic acid and carnosol content in extracts obtained by using choline chloride: lactic acid as solvent was determined. A content of carnosic acid in extracts was significantly affected by water content and extraction time, while carnosol content was dependent of content of water, temperature and extraction time. Extraction by mixing showed better results than ultrasound-assisted extraction. Carnosic acid content obtained by extraction with mixing was 147.35-604.95 mg/100 g of plant while by ultrasound-assisted extraction was 150.65-405.43 mg/100 g of plant, depending on the parameters used. Carnosol content obtained by extraction with mixing was 56.79- 282.89 mg/100 g of plant while by ultrasound-assisted extraction was 40.65- 165.54 mg/100 g of plant, depending on the parameters used.

deep eutectic solvents, extraction, sage, optimization

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