Determining the true content of quercetin and its derivatives in plants employing SSDM and LC–MS analysis
Determining the true content of quercetin and its derivatives in plants employing SSDM and LC-MS analysis
Dorota Wianowska 0
Andrzej L. Dawidowicz 0
Katarzyna Bernacik 0
Rafał Typek 0
0 Department of Chromatographic Methods, Faculty of Chemistry, Maria Curie-Sklodowska University , Pl. Maria Curie-Sklodowska 3, 20-031 Lublin , Poland
1 Dorota Wianowska
Reliable plant analysis is a challenging task due to the physical character and chemical complexity of plant matrices. First of all, it requires the application of a proper sample preparation procedure to fully isolate the analyzed substances from the plant matrix. The high-temperature liquid-solid extraction is commonly applied for this purpose. In the light of recently published results, however, the application of high-temperature extraction for polyphenolics analysis in plants is disputable as it causes their transformation leading to erroneous quantitative estimations of these compounds. Experiments performed on different plants show that the transformation/degradation of quercetin and its glycosides is not induced by sea sand disruption method (SSDM) and prove the method to be most appropriate for the estimation of quercetin and its derivatives in plants. What is more, the application of SSDM in plant analysis allows the researcher, to determine which quercetin derivatives are native plant components and what is their true concentration. In other word, the application of SSDM in plant analysis eliminates errors in the study of plant metabolism involving quercetin and its derivatives.
Sea sand disruption method; Quercetin derivatives; Rutin transformation; Compound degradation; Plant analysis; Sample preparation
Introduction
Quercetin is one of the most widely distributed
polyphenolics in plants. This aglycone compound occurs in fruits,
vegetables, leaves and grains, often in the form of glycoside
derivatives. Rutin (quercetin-3-O-rutinoside), isoquercitrin
(quercetin-3-O-glucoside) and quercitrin
(quercetin-3-Orhamnoside) are the most ubiquitous quercetin glycosides
[
1
]. In view of the antioxidant, anti-inflammatory and
anticancer properties of quercetin and its glycosides, research
interest in the natural occurrence and medical properties of
these compounds has been growing [
2–4
].
Reliable plant analysis is a challenging task due to the
physical character and chemical complexity of plant
matrices. First of all, it requires the application of a proper
sample preparation procedure to fully isolate the analyzed
substances from the plant matrix. The high-temperature
liquid–solid extraction is commonly applied for this
purpose. Yet, the results reported in the literature [
5–8
] reveal
that the high-temperature extraction of polyphenolics with
methanol and its water mixtures, i.e. the extractants
typically used for the isolation of phenolics from plants, not
only causes the hydrolysis of glycosides but also results
in the formation of alcoholic derivatives of glycosides and
aglycones, and in degradation of the latter. In the light of
these findings, the application of high-temperature
extraction as a sample preparation technique for
polyphenolics analysis in plants is disputable and makes the results
obtained for a given plant unreliable. These doubts are
justified by the results presented in our earlier work [9]
showing that at least 23 compounds are formed from rutin, the
most abundant quercetin glycoside, during its extraction
under reflux.
Recently, research work has been focused on sample
preparation methods which would limit or even eliminate
the degradation/transformation of the analyzed plant
constituents. One of such method is the sea sand disruption
method (SSDM) combining the homogenization,
extraction and purification processes into a single step [
8, 10
].
There are many examples showing that the effectiveness of
this simple, quick and cheap low-temperature method is an
alternative not only to the traditional high-temperature
solvent extractions (under reflux and in the Soxhlet apparatus)
but also to the supported ones (pressurized liquid
extraction, supercritical fluid extraction, ultrasound-assisted
solvent extraction and microwave-assisted solvent extraction)
[
10–13
].
This paper presents and discusses the results of research
work on the application of SSDM for the evaluation of the
true content of quercetin and its derivatives in the
following plants: flowers of black elder (Sambucus nigra L.) and
hawthorn (Crataegus L.); leaves of green tea, nettle (Urtica
dioica L.) and yerba maté (Ilex paraguariensis A.St.-Hil.);
the heartsease herb (Viola tricolor Linn.), St John’s wort
(Hypericum perforatum L.), and artichoke (Cynara
cardunculus) flower buds. The results obtained using SSDM
are compared to those revealed by the traditional extraction
under reflux.
Materials and methods
Plant material and chemicals
The following plants were used in the experiments:
flowers of black elder (S. nigra L.) and hawthorn (Crataegus
L (...truncated)