J Strait Pharm 33 (8), 46-48 (2021). Yinling Heji is a TCM drug, containing Artemisia capillaris Thunb., Scutellaria L., Radix Rehmanniae Preparata etc. It clears heat and dampness, is mainly used for the prevention and treatment of neonatal jaundice, and has a good effect on children with mild diseases. For quality control, microemulsion thin-layer chromatography on polyamide layer, (A) for Herba Artemisiae Scopariae, of methanol extracts of the test sample (TCM prescription drug), methanol extracts of the test sample without Herba Artemisiae Scopariae, methanolic extracts of Herba Artemisiae Scopariae and standard chlorogenic acid in methanol, (B) for Scutellaria L., methanol extracts of the test sample, methanol extracts of the test sample without Scutellaria L., methanolic extracts of Scutellaria L. and standard baicalin in methanol, (C) for Rhei Radix et Rhizoma, methanol extracts of the test sample, methanol extracts of the test sample without Rhei Radix et Rhizoma, methanolic extracts of Rhei Radix et Rhizoma, and standard emodin in methanol. Development with (sodium dodecyl sulfate - n-butanol - cyclohexane - water 27:63:10:300) - formic acid 9:1.

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.

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).

Antioxidants, 10(1), 117 (2019). Samples were methanolic extracts of Camellia sinensis leaves or commercial black, white or green tea powdered extracts (Theaceae), as well as standards of caffeine (methylxanthine alkaloid), of flavonols (quercetin, rutin) and of flavanols (catechin, catechin-gallate, epicatechin, epicatechin-gallat, epigallocatechin, epigallocatechin-gallate, gallocatechin, and the thearubigin theaflavin). HPTLC on RP18-W phase (with classical irregular particles (SP1) vs. LiChrospher phase with spherical particles (SP2)), prewashed with methanol – water 4:1 and dried 20 min at 110 °C, developed with citric acid 0,295 % in acetonitrile – water 3:10 for SP1, with citric acid 0,17 % in acetonitrile – water 1:2 for SP2. Visualization under white light, UV 254 nm and 366 nm. Absorbance densitometry was performed at UV 275 nm (deuterium lamp). Derivatization with A) Fast Blue B salt reagent followed by 3 min heating at 100 °C, and by absorbance densitometry at 546 nm for flavanols (mercury lamp); B) natural product reagent (on the same plate), followed by fluorescence densitometry of flavonols at FLD 366/>400 nm (mercury lamp); C) anisaldehyde sulfuric acid reagent, followed by 2 min heating at 110 °C, to detect all flavonoids. Effect-directed analysis was performed using piezoelectric spraying: A) for free radical (DPPH•) scavengers (vs. gallic acid as positive control); B) for activity against Gram-negative Aliivibrio fischeri (bioluminescence assay, vs. caffeine) or Gram-positive Bacillus subtilis (vs. tetracycline); C) for enzymatic inhibition of acetyl-cholinesterase, α- and β-glucosidase, β-glucuronidase, tyrosinase (vs. rivastigmine, acarbose, imidazole, D–saccharolactone and kojic acid, respectively). When SP2 was used, previous neutralization was required through spraying of sodium bicarbonate buffer (2.5 %, pH 8). AChE inhibition assay was performed with indoxyl acetate (0.1 % in ethanol) as substrate, sprayed before the enzyme. After incubation (30min at 37°C), inhibition bands appeared indigo or blue under white light, but the substrate coloured theaflavin in yellow.