J. Chromatogr. A 1594, 190-198 (2019). Quality assessment of herbal drugs, e.g. Morus alba L. root bark (sāng bái pí; SBP), using a HPTLC/bioautography method. Identification of the most bioactive constituents with radical scavenging (DPPH radical assay) and antimicrobial activities (Bacillus subtilis, Escherichia coli) of 18 different M. alba samples, supported by UPLC–MS/MS analysis. Higher both radical scavenging and antimicrobial activities were found for plant materials collected from Serbia (11 samples) compared to samples provided from China (7 samples). Confirmation of geographically different samples and recognization of their main markers responsible for differences between Serbian and Chinese samples by principal component analysis (PCA). The developed procedure allowed not only for a fast chemical profiling of the investigated samples and their unambiguous identification, but also for the disclosure of major and minor bioactive constituents present in SBP.

J. Chromatogr. Sci. 57 (5), 411-417 (2019). The high polarity of the has made it difficult to quantify the alkaloids. This study was designed to develop and validate a thin-layer chromatography (TLC) densitometric-based method using high-performance thin-layer chromatography for quantification of berberine. HPTLC of the protoberberine alkaloids in Coptis teeta rhizome on silica gel aluminium foil with butanol - ethyl acetate - formic acid - water 3:5:1:1. Quantitative determination by absorbance measurement at 351 nm. The hRf of berberine was 70. The linearity obtained graphically with a correlation coefficient of 0.997 was in the concentration range of 90-210 ng/band.LOD and LOQ were 30 and 70 ng/band, respectively. The berberine concentration in the methanol extract of C. teeta was 30.9 ± 0.6 mg in 100 mg of the crude drug. The method developed here in can be implemented in the analysis and routine quality control of herbal materials and formulations containing C. teeta and berberine.

J. Chromatogr. Sci. 57 (4), 312-322 (2019). Development of a method for simultaneous analysis of five antipsychotic and medicinally important β-carboline alkaloids (βCAs), namely, harmalol, harmaline, harmine, harmane and norharmane, by HPTLC on silica gel with chloroform - methanol - glacial acetic acid 39:11:1. Quantification by densitometry in fluorescence mode at 366 nm. The linearity range of standard βCAs was 25-250 ng/band, with r² between 0.97 and 0.99. The recovery was between 83.9 and 112.4 %, repeatability of the application 0.6-2.4 %, repeatability of measurement 1.9-3.1 % and intermediate precision 0.6-11.2 %). LOD and LOQ were 4.9-6.6 and 16.5-21.9 ng/band, respectively. The method proved to be simple, cost-effective, precise, sensitive and specific for the determination of βCAs in the herbs Fagonia schweinfurthii, Peganum harmala and Tribulus terrestris, and was useful in forensic and industrial analysis and fingerprinting of various βCAs containing herbs and drug formulations.

J. of Chromatogr. Sci. 57 (2), 149-155 (2019). Description of a selective stability indicating method for chromatographic separation of ascorbic acid (ASC), paracetamol (PAR) and guaifenesin (GUF) in presence of paracetamol toxic impurity [4-aminophenol (4-AP)] and guaifenesin related substance [impurity, (guaiacol) (GUC)] by HPTLC on silica gel with chloroform - acetone - trifluoroacetic acid 65:35:3, detection under UV 254 nm. Quantification by densitometry. The hRf values were 5 (ASC), 12 (4-AP), 24 (GUF), 41 (PAR), and 56 (GUC). The linearity was in the range of 0.4-2.4, 0.4-2.8 and 4-15 μg/band for ASC, PAR and GUF, respectively. Statistical comparison of the obtained results with those achieved by HPLC showed no significant difference. The HPTLC method proved to have advantages over HPLC, it was more sensitive and selective and permits its application in quality control of the drugs.

J. Chinese Trad. Patent Med. 40 (5), 1101-1105 (2018). For quality control of Fufang Tougucao Rongye solution, a herbal TCM drug for the treatment of fungal infection of the hand, TLC on silica gel with petroleum ether (60-90 ˚C) – ethyl acetate – formic acid 10:4:1. Detection by spraying with 10% sulfuric acid in ethanol and heating at 105 ˚C until the zones are visible. Evaluation under UV 366 nm. Identification by fingerprint comparison with the individual ingredients Phryma leptostachya L. subsp. asiatica (Hara) Kitamura and Zanthoxylum bungeanum Maxim. Comparison with HPLC fingerprint analysis. Quantification of quercetin by HPLC.

Planta Medica 84(6/7), 465-474 (2018). The new concept “Comprehensive HPTLC Fingerprinting” was applied to define specifications for the identification and purity assessment of Angelica gigas roots, and for the quantification of its markers: the coumarins decursin and decursinol angelate. Methanolic root extracts of A. gigas (10 reference materials, 24 commercial samples), of 26 other Apiaceae species (including 10 Angelica, 9 Ligusticum, 2 Notopterygium, 4 Peucedanum, and Levisticum officinale) and of mixtures, were developed with toluene - ethyl acetate - acetic acid 90:10:1 on HPTLC silica gel (at 33% relative humidity, chamber pre-saturated for 20 min with filter paper and developing solvent) and dried for 5 min. Detection under white and UV lights before and after derivatization by dipping into 10% sulfuric acid in methanol and then heating 3 min at 100°C. Quantitative evaluation by densitometry in fluorescence mode at UV 313 nm, and luminance was also calculated from the image pixels. The study showed the presence in A. gigas of nodakenin, decursinol, 7-demethylsuberosin, imperatorin, osthole, and isoimperatorin at hRF 0, 4, 15, 33, 38 and 44 respectively. Z-ligustilide (hRF 59) was absent from A. gigas, allowing 1) to distinguish it from several other Apiaceae species; 2) to identify in mixtures with A. gigas two common adulterants (A. acutiloba, A. sinensis) even at 1% in the root powder. Minimal content of A. gigas fingerprint markers (decursin + decursinol acetate, co-eluting at hRF 27) was assessed as 3% (w/w) based on the quantified peaks from A. gigas reference materials.

Planta Medica 84(2), 129-134 (2018). TLC of subfractions obtained from normal-phase LC and size-exclusion chromatography of an ethanolic extract of Bougainvillea spectabilis (Nyctaginaceae) stem-bark on RP-18 with methanol – water 2:3 and 1:1 to isolate six flavones (bougainvinones J, K, L, M, and two dimethylflavone derivatives).

Planta Medica 84(1), 59-64 (2018). A multi-step fractionation through silica gel column chromatography (CC) of a methanolic extract of Plectranthus africanus (whole plant, Lamiaceae) was monitored through TLC on silica gel with various solvent mixtures (n-hexane or dichloromethane with either acetone or methanol). Zones were detected under UV and further by spraying with sulfuric acid 20 % and heating at 100°C. For each fraction or TLC profile, the authors provide the CC gradient, the optimal proportions of the solvents used for the TLC mobile phase, as well as the RF values of the molecules isolated by this CC method: new abietane-type diterpenoids (plectranthroyleanones A, B, C), betulinic and oleanolic acids, heterosides of apigenin, rhamnetin and sitosterol.