TY - JOUR
T1 - NMR methodology for a rational selection of ionic liquids: extracting polyphenols
AU - Barrulas, Raquel V.
AU - Paiva, Tiago G.
AU - Corvo, Marta C.
N1 - The project was funded by FCT -Portuguese Foundation for Science and Technology, Portugal, under the project with the reference PTDC-EPH-PAT-0224-2014. Also, by FEDER, European funds, through the COMPETE 2020 Program, Portugal (POCI-01-0145-FEDER-007688; UID/CTM/50025/2013). Tiago Paiva acknowledges FCT for the SFRH/BD/133447/2017 PhD fellowship. LabNMR-CENIMAT is part of RNRMN, supported by FCT, Portugal (ROTEIRO/0031/2013 - PINFRA/22161/2016, co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT through PIDDAC).
PY - 2019/8/15
Y1 - 2019/8/15
N2 - Extracts from plants have considerable significance as bioactive compounds with several pharmacological applications. Polyphenols have attracted the attention as anti-inflammatory and anti-oxidative materials. Nonetheless, the amount of these compounds in the extracts is typically very low. Consequently, green extraction techniques with higher efficiency for phenolic compounds are of paramount importance. Ionic liquids (ILs), which are also known as designer solvents can be used to extract polyphenols, however the search for ideal solvents is mostly done by trial and error. In this work, nuclear magnetic resonance (NMR) is used to study the profile of ILs molecular interactions with model compounds that mimic polyphenols. The ILs that exhibit the strongest molecular interactions were proven to have the highest efficiency when extracting polyphenols from matcha Japanese green tea, known to be extremely rich in these compounds. Both the IL cation and anion have an influence on the solvent behaviour. The best IL solvents for matcha polyphenols were imidazolium derivatives with shorter alkyl side chains and weakly basic anions such as tricyanomethanide, dicyanamide and triflate. Thus, the NMR approach avoids an exhaustive testing and allows the rational selection of the best ILs for the extraction.
AB - Extracts from plants have considerable significance as bioactive compounds with several pharmacological applications. Polyphenols have attracted the attention as anti-inflammatory and anti-oxidative materials. Nonetheless, the amount of these compounds in the extracts is typically very low. Consequently, green extraction techniques with higher efficiency for phenolic compounds are of paramount importance. Ionic liquids (ILs), which are also known as designer solvents can be used to extract polyphenols, however the search for ideal solvents is mostly done by trial and error. In this work, nuclear magnetic resonance (NMR) is used to study the profile of ILs molecular interactions with model compounds that mimic polyphenols. The ILs that exhibit the strongest molecular interactions were proven to have the highest efficiency when extracting polyphenols from matcha Japanese green tea, known to be extremely rich in these compounds. Both the IL cation and anion have an influence on the solvent behaviour. The best IL solvents for matcha polyphenols were imidazolium derivatives with shorter alkyl side chains and weakly basic anions such as tricyanomethanide, dicyanamide and triflate. Thus, the NMR approach avoids an exhaustive testing and allows the rational selection of the best ILs for the extraction.
KW - Green solvent
KW - Ionic liquid
KW - Molecular interactions
KW - Nuclear magnetic resonance spectroscopy
KW - Polyphenols
UR - http://www.scopus.com/inward/record.url?scp=85063335441&partnerID=8YFLogxK
U2 - 10.1016/j.seppur.2019.03.077
DO - 10.1016/j.seppur.2019.03.077
M3 - Article
AN - SCOPUS:85063335441
SN - 1383-5866
VL - 221
SP - 29
EP - 37
JO - Separation and Purification Technology
JF - Separation and Purification Technology
ER -