J. Planar Chromatogr. 33, 59-70 (2020). HPTLC of metformin (1), saxagliptin (2) and dapagliflozin (3) on silica gel with chloroform - methanol - water - acetic acid 740:260:50:1. Quantitative determination by absorbance measurement at 224 nm. The hR_F values for (1) to (3) were 14, 50 and 66, respectively. Linearity was between 30 and 350 µg/mL for (1), 140 and 1500 µg/mL for (2) and 50 and 600 µg/mL for (3).  Intermediate precisions were below 2 % (n=6). LOD and LOQ were 7 and 23 µg/mL for (1), 39 and 130 µg/mL for (2) and 14 and 47 µg/mL for (3), respectively. Recovery rate was between 98.9 and 100.5 % for (1), 99.2 and 100.5 % for (2) and 99.2 and 100.7 % for (3). Comparable results were obtained when compared with a HPLC method.

J. of Chromatogr. Sci. 57 (8), 688 - 696 (2019). Tephrosia purpurea (L.) Pers., commonly known as “wild indigo”, is used in TCM to treat liver, spleen and kidney disorders. To investigate the seasonal effect on the quantity of its phytoconstituents lupeol, β-sitosterol and rotenone, analysis of the extracts from plant material collected in different seasons by HPTLC on silica gel with toluene - ethyl acetate - formic acid 9:1:1. The zones due to  β-sitosterol, rotenone and lupeol were observed at hRF 38, 45 and 52, respectively. Validation of the method in terms of precision, repeatability, specificity, sensitivity, linearity and robustness. The quantitative results obtained with this method showed that the content of these phytoconstituents varies from season to season. It was found that T. purpurea should not be collected in winter season for the preparation of therapeutic formulations because of the high content of rotenone, which is responsible for Parkinson’s disease and associated with heart failure, fatty liver and liver necrosis.

J. of Modern Trad. Chinese Med. 20 (7), 821-824 (2018). Mulusin, a class of isoprene flavonoids extracted from Mori Cortex, has anti-tumor, anti-inflammatory, hypoglycemic, hypolipidemic, analgesic, anti-spasm, and cholinesterase restricting activity. For quality control, TLC of mulusin on silica gel with petroleum ether - dichloromethane - ethyl acetate 15:8:10 at 25 ± 0.3 ˚C with chamber saturation for 30 min. Detection at UV 254 nm. The hRF of mulusin standard was 43. Quantitative absorbtion measurement of morusin by densitometry at 273 nm. Linearity was in the range of 200 - 1100 ng/zone (r=0.999), precision on one plate was RSD = 1.21 % (n=6) and on plate-to-plate RSD = 2.30 % (n=6). Recovery from standard sample addition was 99.2 % (RSD = 1.51, n = 6). The LOD was 20 ng/zone and LOQ 40 ng/zone.

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.