Elsevier

Food Chemistry

Volume 241, 15 February 2018, Pages 232-241
Food Chemistry

Improved LC-MSn characterization of hydroxycinnamic acid derivatives and flavonols in different commercial mate (Ilex paraguariensis) brands. Quantification of polyphenols, methylxanthines, and antioxidant activity

https://doi.org/10.1016/j.foodchem.2017.08.085Get rights and content

Highlights

Abstract

Yerba mate is a beverage rich in bioactive compounds popular in South America. Polyphenols and methylxanthines were qualitatively and quantitatively analyzed in four commercial brands of yerba mate, as well as the antioxidant capacity of the beverages. Using LC/MSn analysis, 58 polyphenols were observed of which 4-sinapoylquinic acid, di- and tri-methoxycinnamoylquinic acids, two isomers of trimethoxycinnamoylshikimic acid and four isomers of caffeoyl-2,7-anhydro-3-deoxy-2-octulopyranosonic acid were identified for the first time in mate. Additionally, 46 polyphenols and 2 methylxanthines were quantified by HPLC-DAD. Hydroxycinnamic acid derivatives and flavonols comprised 90% and 10% of mate phenols, respectively, 3-caffeoylquinic (26.8–28.8%), 5-caffeoylquinic (21.1–22.4%), 4-caffeoylquinic (12.6–14.2%) and 3,5-dicaffeoylquinic acids (9.5–11.3%) along with rutin (7.1–7.8%) were the most abundant polyphenols, whereas caffeine was the main methylxanthine (90%). Ilex paraguariensis is an important source of polyphenols with moderate methylxanthines content; therefore its high antioxidant capacity was mainly associated to its polyphenolic composition.

Introduction

Ilex paraguariensis (St. Hil.) is a plant native to the subtropical regions of South America. Its leaves have been traditionally used to prepare yerba mate drink, which is the main alternative beverage to coffee or tea in countries such as Brazil, Argentina, Paraguay or Uruguay, where daily mate consumption has been estimated at more than 1 L/person. Popularity of yerba mate has increased worldwide due to its nutritional and medicinal properties, having been considered as a functional food (Bracesco, Sanchez, Contreras, Menini, & Gugliucci, 2011). In indigenous tribal medicine, yerba mate has been used for the treatment of numerous pathologies. Indeed, many recent studies documented the pharmacological activities of this beverage, demonstrating in vitro and in vivo antioxidant, anti-inflammatory, anti-obesity and anti-carcinogenic properties, among others (Arçari et al., 2009, de Mejía et al., 2010).

The nutritional and health benefits associated with the intake of yerba mate have been attributed to its high content in bioactive components, specifically methylxanthines and polyphenols. Methylxanthines are a group of purine alkaloids with a xanthine base that caffeine, theophylline, theobromine and paraxanthine have in common. Traditionally, negative health effects have been attributed to these compounds due to their stimulatory properties on the central nervous system. However, recent evidences support relevant health effects of methylxanthines, showing neuroprotective, hypoglycemic, anti-inflammatory or cardioprotective effects, among others (de Mejia and Ramirez-Mares, 2014, Martínez-Pinilla et al., 2015). On the other hand, most therapeutic applications of yerba mate have been associated with its phenolic composition due to the well-known antioxidant, anti-inflammatory, anti-carcinogenic, anti-diabetic or neuroprotective capacities of dietary polyphenols (Del Rio et al., 2013). Hydroxycinnamate esters, commonly known as hydroxycinnamic acids or chlorogenic acids, are a family of esters in which a hydroxycinnamic acid moiety is linked to (−)-quinic acid. Caffeic, p-coumaric, ferulic, dimethoxycinnamic, and trimethoxycinnamic acids are the hydroxycinnamic acids usually present in yerba mate, in which one or more hydroxyl moieties of quinic acid are esterified forming a series of positional isomers (Clifford, 2000). Additionally, flavonols, hydroxycinnamic acids bonded to carbohydrates, and hydroxycinnamoylshikimates have also been identified in mate. The latter, usually called hydroxycinnamoylshikimic acids, are esters of hydroxycinnamic acids with shikimic acid, which is chemically derived from the dehydratation of quinic acid (Jaiswal, Sovdat, Vivan, & Kuhnert, 2010).

Previous works have identified different hydroxycinnamoylquinic acids and hydroxycinnamoylshikimates in yerba mate using HPLC-LC/MSn, the technique most commonly employed to characterize phenolic compounds due to its robustness, reproducibility and sensitivity. In addition, fragmentation of the compounds depends on the particular stereochemistry of the molecule, related to the substitution position on quinic acid, thus allowing to discriminate between individual isomers without previous isolation of the pure compounds (Clifford et al., 2003, Clifford et al., 2005, Clifford et al., 2006, Clifford et al., 2006).

Plant variety and pathophysiology, in addition to environmental conditions and processing, can induce important modifications in the main constituents of yerba mate (Cardozo et al., 2007, Zielinski et al., 2014). Considering the variability of the phytochemical composition, and thus the antioxidant capacity and biological activity of yerba mate, which in turn influences the health effects of the beverage, the aim of the present study was to qualitatively and quantitatively characterize by HPLC-LC/MSn and HPLC-DAD the phenolic and methylxanthine composition of four different commercial brands of yerba mate, as well as their antioxidant capacity.

Section snippets

Materials and reagents

Four different commercial brands (A–D) of yerba mate (Ilex paraguariensis), selected among the most widely consumed brands in Argentina, were purchased in a local supermarket in Madrid (Spain). The four brands were elaborated from selected Ilex paraguariensis leaves that had been slightly roasted for short time at temperatures under 100 °C, dried, minced, and stored at ambient temperature (“estacionado natural”) during 12 months before packaging; the specific elaboration procedures are protected

Identification and characterization of polyphenols in yerba mate extracts

Samples were analyzed by high-resolution mass spectrometry using an ESI-QToF detector in the negative ion mode and selected ion monitoring (SIM) and subsequently subjected to LC-MSn analysis by collision-induced dissociation mass spectrometry, allowing to assign compounds at regioisomeric level and, therefore, to characterize the detected chromatographic peaks. UV-spectra evaluation was also considered to support phenolic compounds’ characterization. Most of the constituents displayed similar

Acknowledgments

This work was funded by the Spanish Ministry of Economy and Competitivity (MINECO-FEDER), projects AGL2010-18269 and AGL2015-69986-R. G.B. is a FPI fellow (BES-2011-047476) funded by the Spanish Ministry of Science and Innovation and performed most experiments. All authors revised and approved the final version of the manuscript. The technical assistance of ICTAN’s Analytical Techniques Service (USTA) is acknowledged.

Conflicts of interest

The authors declare no conflicts of interest.

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    Raquel Mateos and Gema Baeza have contributed equally to this work.

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