Broad range chemical profiling of natural deep eutectic solvent extracts using a high performance thin layer chromatography–based method

Abstract

Natural deep eutectic solvents (NADES) made mainly with abundant primary metabolites are being increasingly applied in green chemistry. The advantages of NADES as green solvents have led to their use in novel green products for the food, cosmetics and pharma markets. However, one of the main difficulties encountered in the development of novel products and their quality control arises from their low vapour pressure and high viscosity. These features create the need for the development of new analytical methods suited to this type of sample. In this study, such a method was developed and applied to analyse the efficiency of a diverse set of NADES for the extraction of compounds of interest from two model plants, Ginkgo biloba and Panax ginseng. The method uses high-performance thin-layer chromatography (HPTLC) coupled with multivariate data analysis (MVDA). It was successfully applied to the comparative quali- and quantitative analysis of very chemically diverse metabolites (e.g., phenolics, terpenoids, phenolic acids and saponins) that are present in the extracts obtained from the plants using six different NADES. The composition of each NADES was a combination of two or three compounds mixed in defined molar ratios; malic acid-choline chloride (1:1), malic acid-glucose (1:1), choline chloride-glucose (5:2), malic acid-proline (1:1), glucose-fructose-sucrose (1:1:1) and glycerol-proline-sucrose (9:4:1). Of these mixtures, malic acid-choline chloride (1:1) and glycerol-proline-sucrose (1:1:1) for G. biloba leaves, and malic acid-choline chloride (1:1) and malic acid-glucose (1:1) for P. ginseng leaves and stems showed the highest yields of the target compounds. Interestingly, none of the NADES extracted ginkgolic acids as much as the conventional organic solvents. As these compounds are considered to be toxic, the fact that these NADES produce virtually ginkgolic acid-free extracts is extremely useful. The effect of adding different volumes of water to the most efficient NADES was also evaluated and the results revealed that there is a great influence exerted by the water content, with maximum yields of ginkgolides, phenolics and ginsenosides being obtained with approximately 20% water (w/w).

Metabolic Profiling of Saponin-Rich Ophiopogon japonicus Roots Based on 1H NMR and HPTLC Platforms

“…In recent years, HPTLC has been proposed as a supplementary tool for metabolomics with applications to ginseng, ginkgo, and pine resins [17,18]. Its application for the study of the saponinrich O. japonicus seemed promising as a way of separating these compounds for better identification by 1 H NMR, for example.…”

“…Recently, high-performance thin-layer chromatography (HPTLC) has been revisited as a supplementary tool for metabolomics to expand its application from mere chemical screening to a versatile profiling tool [17,18]. This is due to advantages such as the availability of derivatization reagents, short run times, and the possibility of performing simultaneous, parallel analysis.…”

Application of deep eutectic solvents for the extraction of phenolic compounds from extra‐virgin olive oil

“…They are generally biodegradable and inexpensive and can be prepared relatively easily. When the components of DES are both naturally occurring molecules, they are called natural deep eutectic solvents (NADESs) [17,18].…”

Investigation of species and environmental effects on rhubarb roots metabolome using 1H NMR combined with high performance thin layer chromatography

“…In the active search for alternatives that can improve metabolomics data quality, the use of high performance thin layer chromatography (HPTLC), an efficient type of planar chromatography, was evaluated as a supplementary tool for metabolomics (Liu et al 2018 ). Thin layer chromatography is one of the oldest chromatographic techniques and since its introduction has been used for chemical screening purposes due to its relatively short separation times, capacity for parallel analysis and broad range of metabolite detection either by direct visualization or chemical derivatization if necessary.…”