J. Planar Chromatogr. 35, 287-297 (2022). HPTLC of species of the grass family (Poaceae), coming from genera: Agrostis, Alopecurus, Anthoxanthum, Apera, Arrhenatherum, Avena, Brachypodium, Briza, Bromus, Calamagrostis, Corynephorus, Cynosurus, Dactylis, Danthonia, Deschampsia, Digitaria, Echinochloa, Elymus, Eragrostis, Festuca, Glyceria, Helictotrichon, Hierochloe, Holcus, Hordeum, Koeleria, Leymus, Lolium, Milium, Molinia, Nardus, Panicum, Phalaris, Phleum, Phragmites, Poa, Saccharum and Setaria on silica gel with ethyl acetate - methanol - water 4:1:1. Detection under UV light at 210, 254, 312 and 366 nm and in fluorescence mode with 312/370, 366/420 and 366/550 nm of excitation and emission filter, respectively. Principal component analysis (PCA) allowed the identifiation of six orthogonal trends in phytochemical composition. 
 

J. Planar Chromatogr. 35, 339-344 (2022). HPTLC of four goldenrod Solidago species (S. gigantea, S. canadensis, S. virgaurea and S. gramnifolia) on silica gel with n-hexane - isopropyl acetate - acetone 16:3:1. Detection by dipping into the cell suspension of the bioluminescent A. fischeri, followed by recording with 50 s exposure time. Further analysis was performed using high-resolution mass spectrometry. Main bioactive markers of the species were Z,Z-matricaria ester from S. virgaurea, solidagenone from S. canadensis, solidagoic acid A, and a dialdehyde clerodane diterpene from S. gigantea, and Z-dehydromatricaria ester from S. graminifolia. 

J Chromatogr Sci, 60 (4), 364-371 (2022). Borage oil, extracted from Borago officinalis Linn., is a well-known medicinal compound with various benefits. Development of an affordable, simple, reliable, rapid and easily accessible method for the estimation of gamma-linolenic acid (GLA) in borage oil by HPTLC on silica gel with hexane - toluene - glacial acetic acid 3:7:1. The hRf value of GLA was 53 ± 4. Quantiative determination by densitometry at 200 nm with an LOD and LOQ of 221 and 737 ng/band, respectively. The method was validated by investigation for parameters like linearity, accuracy, specificity and precision, and found to be highly sensitive for the estimation of GLA in the herbal oil samples and formulations.

J. Strait Pharm. 33 (1), 63-66 (2021). Xiaoer Yanbian Keli granule is a TCM drug for clearing heat and detoxification, reducing phlegm, benefiting the pharynx, and relieving pain, and is mainly used for the treatment of sore throat and cough. For quality control, TLC of methanol extracts of the drug for (A) Lonicera japonica Thunb., on polyacetamide layer with acetic acid, detection in UV 366 nm, identification by fingerprint comparison; for (B) Belamcanda chinensis (L.) Redouté, TLC on silica gel with dichloromethane - butanone - methanol 3:1:1, detection in UV 254 nm, identification by fingerprint comparison; for (C) Radix Tinosporae, Eustoma grandiflorum (Raf.) Shinners and Scrophularia ningpoensis Hemsl., TLC of samples and standards palmatine chloride, harpagoside and platycodin D, on silica gel with n-butanol - glacial acetic acid - water 7:1:2, detection (1) in UV 366 nm, (2) by spraying with 2 % vanillin sulfuric acid solution and viewing in daylight, (3) by spraying with 2 % vanillin sulfuric acid solution, followed by heating at 105°C and viewing in daylight, identification by fingerprint comparison. The presented method was specific and well repeatable, and reduced the sample amount, simplified the sample processing steps, improved the detection efficiency, and reduced the detection costs.

J. Chromatogr. Sci. 60 (3), 267-273 (2022). HPTLC for the selective detection of the diuretic drug triamterene in pure form, tablets and human plasma, on silica gel with ethyl acetate - dimethylformamide - ammonia 70:27:3. Quantitative determination by fluorescence measurement at 440 nm improved the method sensitivity 250-fold compared with previously reported studies, and enabled the detection of triamterene in the linear concentration range of 0.8 to 60 ng/band for the pure drug and 1.0 to 60 ng/band for biological samples (human plasma).

Molecules 25 (17), E3928 (2020). Samples were curcumin (as standard) and methanolic extracts of Curcuma xanthorrhiza and C. aeruginosa (Zingiberaceae) rhizomes, both separately and in mixtures. Separation on TLC silica gel with chloroform – methanol – formic acid 94:3:3. Densitometry of curcumin (hRF 50) in absorption mode at UV 427 nm. This method was validated with curcumin standard for selectivity (vs. demethoxycurcumin hRF 32), linearity range (250 - 450 ng), LOD (21 ng) and LOQ (69 ng), accuracy and precision. Curcumin contents were between 0.74 and 1.23 % in pure C. xanthorrhiza extracts, but decreased when adulterated with C. aeruginosa.

Plant Cell, Tissue and Organ Culture (PCTOC) 146 (2), 225–236 (2021). Samples were hydro-ethanolic extracts of Musa acuminata and M. balbisiana (Musaceae) plantlets, obtained from in vitro meristem-derived gel cultures with saccharose, temperature or jasmonic acid as elicitors of production of secondary metabolites. HPTLC on silica gel  (RP18W phase for genotoxicity assay) with ethyl acetate – toluene – formic acid – water 34:5:7:5. Evaluation under white light, UV 254 nm and 366 nm. Effect-directed assays (EDA) were performed (by immersion or by automated piezoelectrical spraying) for free radical (DPPH•) scavengers, and, after neutralization, for enzymatic inhibitors (acetyl-cholinesterase, α-glucosidase) and for genotoxicity (SOS response – UMU-C test). For comparison, positive control standards were applied but not developed, before the assays (gallic acid, physostigmine, acarbose, nitroquinoline-1-oxide, respectively). After the first assay, absorbance densitometry was performed through inverse scanning at 546 nm using mercury lamp (fluorescence mode without optical filter). Antioxidant activity was found the highest when cultures were maintained at 20 °C (vs. 15 and 26 °C) and supplemented with saccharose (40-50 g/L) or jasmonic acid (200 µM).

ALTEX - Alternatives to animal experimentation, 38(3), 387-397 (2021). Samples were standards of food contact contaminants with genotoxicity (4-nitroquinoline-1-oxide (NQO), aflatoxin B1, hexachloroethane, nitroso-ethylurea, phenformin, PhIP) or negative controls (alosetron, mannitol), and extracts of coated tin cans (extracted with n-hexane – acetone at 25°C for 16 h or by heating at 60 °C with ethanol 95 % for 240 h). HPTLC on RP18W layer, pretreated to harden the binder by heating 1 h at 120 °C, prewashed with methanol and with ethyl acetate and dried 4 min in cold air stream after each development. Application areas were focused to their upper edges by a two-fold elution with ethyl acetate, followed by 1 min drying in cold air stream. Development with toluene – ethyl acetate 8:5, followed by 5 min drying, neutralization with citrate buffer (pH 12) and 4 min drying. Effect-directed analysis for genotoxicity (SOS response – UMU-C test, using NQO as positive control) by immersion (speed 3.5 cm/s, time 3 s) into Salmonella typhimurium suspension and, after 3 h incubation at 37 °C and 4 min drying in cold air stream, into one of two fluorogenic substrate solutions (methylumbelliferyl- vs. resorufin-galactopyranoside). After 1 h incubation at 37 °C, visualization of mutagenic compounds as (blue vs. red) fluorescent zones at FLD 366 nm, and densitometry performed with mercury lamp for fluorescence (at  366 / >400nm vs. 550 / >580 nm, respectively). Further validation experiments, including spiking extracts with NQO, were performed showing good mean reproducibility, no quenching or other matrix effects. Lowest effective concentration of NQO was 0.53 nM (20 pg/band), 176 times lower than in the corresponding microtiter plate assays.