Comparison of Analytical Methods in Chemometric Fingerprinting of Metallicolous and Non-metallicolous Populations of Echium vulgare L

INTRODUCTION

Adverse environmental conditions usually change plant biochemical pathways resulting in accumulation or decreased content of both primary and secondary metabolites. The chemometric fingerprinting analysis proves to be a useful tool to reveal phytochemical differentiation between plants inhabiting heavy metal-contaminated and uncontaminated areas.

OBJECTIVE

Development and assessment of four analytical techniques - high performance capillary electrophoresis (HPCE), thin-layer chromatography (TLC), mass spectrometry (MS), and Fourier transform infrared (FTIR) spectroscopy in chemometric fingerprinting of metallicolous and non-metallicolous populations of Echium vulgare L.

MATERIAL AND METHODS

Twenty-one crude methanol extracts of shoot samples representing three populations of Echium vulgare L., two originating from highly metal polluted areas and one from an unpolluted area, were investigated using four analytical methods: HPCE, TLC, MS, and FTIR spectroscopy. Data pre-processing (denoising, background subtracting, horizontal alignment) followed by principal component analysis (PCA), hierarchical clustering analysis (HCA), and phytochemical difference index (DI) calculations facilitated exploration of the differences and similarities between the populations.

RESULTS

Clear phytochemical divergence between metallicolous and non-metallicolous populations of Echium vulgare was found. The suitability of the analytical techniques for revealing phytochemical markers and discrimination of individuals originating from different populations differed and in general increased in the order: TLC < MS = HPCE < FTIR.

CONCLUSION

The chemometric methods applied were successful in discrimination between samples from polluted and unpolluted areas, showing a potential perspective for environmental quality control. Copyright © 2016 John Wiley & Sons, Ltd.

TLC Profiles of Selected Cirsium Species with Chemometrics in Construction of Their Fingerprints

The dried aerial parts of 12 plants of Cirsium species were extracted with the Soxhlet apparatus using dichloromethane and methanol as solvents. Next, the extracts were separated by TLC methods to obtain the fingerprint chromatograms. The analysis was performed on silica gel or RP-18 layers as stationary phases using the following eluents: ethyl acetate/formic acid/acetic acid/water (12/1.5/1.5/4; v/v) for silica gel, and 5% (v/v) aqueous solution of formic acid/methanol (70/30; v/v) for the first development and the same system in the proportion of 50/50 (v/v) for the second development for RP-18. The double development was applied in the case of RP-18 plates. The analysis was performed for all Cirsium methanolic extracts and five selected standards (naringin, apigenin, rutin, caffeic acid and chlorogenic acid). The results were analyzed using chemometrics. The comparison of individual Cirsium species and the identification of unknown species were performed using the similarity indices (Pearson's correlation coefficient, determination coefficient and congruence coefficient), distance indices (Euclidean distance, Manhattan distance and Chebyshev's distance) and Multi-Scale Structural SIMilarity. Based on chemometric analysis, the first extract of the widely grown species is identified as Cirsium arvense and the second one as Cirsium rivulare.

The Stimulatory Effect of Strontium Ions on Phytoestrogens Content in Glycine max (L.) Merr

The amount of secondary metabolites in plants can be enhanced or reduced by various external factors. In this study, the effect of strontium ions on the production of phytoestrogens in soybeans was investigated. The plants were treated with Hoagland's solution, modified with Sr(2+) with concentrations ranging from 0.5 to 3.0 mM, and were grown for 14 days in hydroponic cultivation. After harvest, soybean plants were separated into roots and shoots, dried, and pulverized. The plant material was extracted with methanol and hydrolyzed. Phytoestrogens were quantified by HPLC. The significant increase in the concentration of the compounds of interest was observed for all tested concentrations of strontium ions when compared to control. Sr(2+) at a concentration of 2 mM was the strongest elicitor, and the amount of phytoestrogens in plant increased ca. 2.70, 1.92, 3.77 and 2.88-fold, for daidzein, coumestrol, genistein and formononetin, respectively. Moreover, no cytotoxic effects were observed in HepG2 liver cell models after treatment with extracts from 2 mM Sr(2+)-stressed soybean plants when compared to extracts from non-stressed plants. Our results indicate that the addition of strontium ions to the culture media may be used to functionalize soybean plants with enhanced phytoestrogen content.

GC-MS fingerprints of mint essential oils

Essential oils from eleven Mentha species were obtained by Deryng hydrodistillation and analysed by GC–MS: 44 compounds were identified. The most abundant were menthone, isomenthone, menthol, carvone, piperitone oxide, D-limonene and eucalyptol. Chemometric similarity measures and principal component analysis were calculated, allowing comparisons based on secondary metabolite content. The fingerprints may be helpful in chemotaxonomy.