Hydrophilic Interaction Liquid Chromatography to Characterize Nutraceuticals and Food Supplements Based on Flavanols and Related Compounds

Abstract

Purified extracts from different types of berries and medicinal plants are increasingly used as raw materials for the production of nutraceuticals and dietary supplements, mainly due to their high content in bioactive substances. This is, for instance, the case of phenolic compounds such as flavonoids, which exhibit a wide range of beneficial properties, including antioxidant, anti-inflammatory, antineoplastic and antimicrobial activities. This paper tackles the characterization of several kinds of nutraceuticals based on hydrophilic interaction liquid chromatography (HILIC) with fluorescence detection (FLD). The study focused on the determination of flavanols and related compounds such as condensed tannins. Analytes were recovered by solvent extraction using methanol:water:hydrochloric acid (70:29:1 v:v:v) as the extraction solvent under sonication for 30 min at 55 °C. Experimental design with response surface methodology was used to optimize the HILIC separation to achieve good resolution of the main components, using acetonitrile:acetic acid (99:1 v/v) (solvent A) and methanol:water:acetic acid, (95:3:2 v/v/v) (solvent B) as the components of the mobile phase. For the assessment of the elution gradient, factors under study were solvent B percentage and gradient time. The best conditions were achieved with 10% solvent B as the initial percentage and 30 min of linear gradient to reach 25% solvent B. Principal component analysis and partial least square-discriminant analysis were used to characterize and compare the compositional features of dietary supplements based on both targeted and non-targeted approaches. Results revealed that the sample distribution relied on the oligomeric nature of descriptors.

Total Polyphenol Content in Food Samples and Nutraceuticals: Antioxidant Indices versus High Performance Liquid Chromatography

“…Finally, pepper samples contained some flavonoids (e.g., quercetin) and phenolic acids (e.g., caffeic and 3,4-dihydroxybenzoic acids). These results agree with previous studies that focused on the characterization of each particular matrix [16,[20][21][22][23][24][25][26].…”

“…The extraction of polyphenols from solid samples relied on a solvent extraction procedure with an acidified methanolic solution, as described by Vidal-Casanella et al [ 16 ]. Briefly, 0.2 g of sample were mixed with 10 mL of MeOH/H 2 O/HCl (70:29:1, v : v : v ) in 15-mL conical tubes.…”

Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

“…As an alternative to the reverse-phase mode, the hydrophilic interaction chromatography (HILIC) has opened up great possibilities, especially for dealing with the most polar analytes that are weakly retained in RP columns. HILIC was used, for example, for the separation of flavanols and related compounds in dietary supplements and nutraceuticals from berries, grapes, or artichoke extracts [75] (see Figure 4). The mobile phase consisted of acidified acetonitrile and methanol solutions, applying an elution gradient based on increasing the percentage of methanol.…”

Liquid Chromatographic Fingerprints for the Characterization of Flavanol-Rich Nutraceuticals Based on 4-Dimethylaminocinnamaldehyde Precolumn Derivatization

“…Chromatographic methods working with underivatized catechins seem to be a good option to gain more detailed information on monomeric and oligomeric flavanols. In this regard, several studies were published in which concentrations of flavanols were exploited as a source of analytical information of the characterization of medicinal extracts such as berry-based products [25,44]. Weseler and Bast reviewed the relevance of grape seed extracts as a rich source of flavanols and other phenolic compounds with indications in the treatment of vascular and inflammatory alterations [50].…”

“…The main aim of this research is the characterization of nutraceutical products made with cranberry, raspberry, grapevine, red grape, artichoke, and mixtures of berries with other plant ingredients, using the composition of flavanols as the source of analytical information. The extraction of flavanols in the nutraceutical fruit samples was carried out by ultrasound-assisted extraction (UAE) using an acidified hydro-organic solvent according to a previously established procedure [25,44]. The chromatographic method used was HPLC-UV/Vis with precolumn flavanol derivatization with DMAC.…”