Authors:Mirosław Hawrył, Małgorzata Niemiec, and Monika Waksmundzka-Hajnos
Two-dimensional separations were performed on polar bonded stationary phase of type cyanopropyl-silica and diol-silica by use of non-aqueous eluents (polar modifier dissolved in n-heptane) as the first direction eluents and aqueous eluents (organic modifier — MeOH dissolved in water) as the second direction eluents. The chromatographic process was performed in micro scale using 5 × 5 cm plates, small volumes of eluents, and 10 μL of plant extracts to obtain satisfying separation. Plates developed in horizontal chambers were dried and observed in UV light (254 nm and 366 nm) photographed by digital camera and derivatized by 1,1-diphenyl-2-picrylhydrazyl (DPPH) to detect antioxidants (free radical scavengers) or derivatized by Naturstoff reagent to detect phenolic compounds (characteristic luminescence of some phenolic compounds). The above experiments give the possibility to construct fingerprints for investigated Mentha species and varieties and preparations containing the herb. It can be used in quality control of the plant material and its antioxidative activity.
Authors:Mirosław A. Hawrył, Anna Hawrył, Ryszard Świeboda, Małgorzata Niemiec, and Monika Waksmundzka-Hajnos
Seven different Scutellaria species were analyzed using the extraction procedure (Soxhlet apparatus, dichloromethane, and methanol as solvents) and thin-layer chromatography method. Selected standards of flavonoids and phenolic acids (caffeic acid, chlorogenic acid, ferulic acid, baicalein, wogonin, baicalin, chrysin, quercetin, scutellarin, hesperetin, hesperidin, apigenin, luteolin, rutin, and kaempferol) were separated using silica gel thin-layer chromatography (TLC) plates with the mobile phase consisting of ethyl acetate—toluene—formic acid (5:4.9:0.1, v/v) for dichloromethane and methanolic extracts. Dichloromethane extracts were also developed using cyanopropyl-bonded silica gel with the following mobile phases: propan-2-ol—n-heptane—formic acid (5:4.9:0.1, v/v) and methanol—water—formic acid (6:3.9:0.1, v/v), and after drying, they were sprayed using the anisaldehyde reagent. In the case of methanolic extracts, the same non-aqueous eluent was used and the aqueous eluent consisting of methanol—water—formic acid (4:5.9:0.1, v/v). The presence of selected standards in Scutellaria species was confirmed. The similarities between the obtained fingerprint chromatograms were performed using chemometric methods, the similarity coefficients (Pearson’s correlation coefficient, determination coefficient, and congruence coefficient), distance indices (Euclidean distance, Manhattan distance, and Chebyshev’s distance), and multi-scale structural similarity (MS-SSIM).