J. of Chromatogr. A 1534, 170-178 (2018). HPTLC of flavonoid aglycones in eleven commercial Cistus incanus herbal teas using three independent methods (multi-development on amino phase and two two-dimensional developments on silica gel phase). HPTLC on silica gel with chloroform - methanol - ethyl acetate 15:3:2. Detection at UV 254 and 366 nm and by derivatization with aluminium chloride (1 % methanolic solution), ferric chloride (0.5 g FeCl₃ in 2.5 mL water and 47.5 mL ethanol), NP-PEG (0.5 % methanolic NP solution, and after drying, 5 % ethanolic PEG solution), PABA (0.5 g PABA in 18 mL glacial acetic acid diluted with 20 mL water, plus 1 mL o-phosphoric acid and 60 mL acetone), or DPA reagents (1 g aniline and 1 g diphenylamine in 100 mL acetone and 10 mL o-phosphoric acid, heated for 5 min at 110°C). Confirmation of the presence of glucose by HPTLC on amino phase with in situ acid hydrolysis: incubation in HCl vapor followed by heating at 100°C, pre-development with acetonitrile, drying, development with acetonitrile - water 7:3, heating for 20 min at 170°C and dipping in paraffin - n-hexane 1:2 follwed by drying. TLC-direct bioautography by immersion of the developed and dried plates in a bacterial cell suspension of either Bacillus subtilis or Aliivirio fischeri strains. Analysis of the compounds isolated from the bioactive zones by HPLC-diode array detector (DAD)-electrospray ionization (ESI)-MS. The presented TLC/HPTLC platform allowed identification of the antibacterial components apigenin, kaempferide, cis- and trans-tiliroside, and the isomers of the p-coumaric acid-conjugated tiliroside,  all of them inhibiting both B. subtilis and A. fischeri.

Int. J. Morphol. 37, 1164-1171 (2019). HPTLC of transresveratrol in traditional fermented soybean seed coat on silica gel with chloroform - ethyl acetate - formic acid 25:10:1. Qualitative identification under UV light at 254 and 366 nm. The hRF value for transresveratrol was 64.

Rev. Bras. Farmacogn. 29, 177-181 (2019). HPTLC of chlorogenic acid (1), 3,4-O-dicaffeoylquinic acid (2), and 3,5-O-dicaffeoylquinic acid (3) in the leaves of Pluchea indica on silica gel with ethyl acetate - water - formic acid - toluene 20:2:2:1. Quantitative determination by absorbance measurement at 326 nm. The hRF values for (1) to (3) were 34, 63 and 79, respectively. Linearity was between 100 and 400 ng/zone for (1) to (3). Intermediate precisions were below 3 % (n=3). The LOD and LOQ were 9.9 and 30.1 ng/zone for (1), 17.6 and 53.3 ng/zone for (2) and 6.7 and 20.2 ng/zone for (3), respectively. Recovery rate was 99.0 % for (1), 97.5 % for (2) and 99.6 % for (3).

J. of Chromatogr. A 1533, 180-192 (2018). HPTLC-UV/Vis/FLD-(bio)assay-HRMS of polar (phenolics) and nonpolar (tanshinones) extracts of Salvia miltiorrhiza Bunge root (Danshen), followed by streamlined scale-up to preparative layer chromatography with 1H-NMR. For phenolics, HPTLC on silica gel first with toluene - chloroform - ethyl acetate - methanol - formic acid 4:6:8:1:1 and second development with petroleum ether - cyclohexane - ethyl acetate 25:14:11. Confirmation of the acetylcholinesterase inhibitors salvianolic acid B (1), lithiospermic acid (2), rosmarinic acid (3), cryptotanshinone (4) and 15,16-dihydrotanshinone I (5). In the polar extracts, compounds (1), (2) and (3) exhibited free radical scavenging activity in the 2,2-diphenyl-1-picrylhydrazyl assay (DPPH* radical reagent), (4) and (5) were active against Bacillus subtilis and Aliivibrio fischeri (LOD of 12 ng/zone for (4), and 5 ng/zone for (5). For the first time, the unidentified, most active zone of the nonpolar Danshen extract was identified as a co-eluting zone of 1,2-dihydrotanshinone and methylenetanshinquinone 2:1.

J. Planar Chromatogr. 32, 447-451 (2019). HPTLC of Fritillaria cirrhosa on silica gel with ethyl acetate - methanol - ammonia solution - water 180:20:10:1. Bioautography by dipping into a 0.15 mg/mL solution of substrate Gly-Pro-p-nitroanilide hydrochloride in 50 % of ethanol, followed by ethanol removal in the hood and dipping into a 10 U/L DPP IV enzyme solution in TrisHCl buffer (pH 8.2, 70 mM), followed by incubation at 37°C for 40 min. Detection by dipping into a solution of 0.5 % sodium nitrite in 1.2 M hydrochloric acid, followed by drying slightly for 5 min and dipping into 0.05 % N-(1-naphthyl)ethylenediamine dihydrochloride solution. Further analysis by mass spectrometry using a TLC interface. The hRF value for the dipeptidyl peptidase IV inhibitor was 58.

J. Planar Chromatogr. 32, 467-474 (2019). HPTLC of quercetin in the fresh fruits of Benincasa hispida on silica gel with toluene - ethyl acetate - formic acid 25:20:1. Quantitative determination by absorbance measurement at 262 nm. The hRF value for quercetin was 39. Linearity was between 100 and 1200 ng/zone. Intermediate precision was below 2 % (n=6). The LOD and LOQ were 20 and 60 ng/zone. Recovery rate was 94.3 %.

J. Planar Chromatogr. 32, 461-465 (2019). HPTLC of betulinic acid (1), oleanolic acid (2) and lupeol (3) on silica gel with benzene - ethyl acetate - formic acid 679:227:94 for (1), n-hexane - ethyl acetate - glacial acetic acid 40:20:1 for (2) and n-hexane - ethyl acetate 4:1 for (3). Detection by spraying with anisaldehyde sulfuric acid, followed by heating at 105-110 ºC for 5-10 min. Quantitative determination by absorbance measurement at 530 nm. The hRF values for (1) to (3) were 79, 46 and 44, respectively. Intermediate precision was below 2 % (n=3).

J. Planar Chromatogr. 32, 379-384 (2019). HPTLC of trigonelline (1) and diosgenin (2) in the seeds of Trigonella foenum-graecum L. on silica gel with acetonitrile - water 3:1. Quantitative determination by absorbance measurement at 267 nm for (1) and at 430 nm after derivatization with vanillin - sulfuric acid for (2). The hRF values for (1) and (2) were 29 and 17, respectively. Linearity was between 200 and 1400 ng/zone for (1) and 50 and 300 ng/zone for (2). Intermediate precision was below 2 % (n=6). The LOD and LOQ were 7 and 1 ng/mL for (1) and 7 and 19 ng/mL for (2), respectively. Recovery rate was between 97.8 and 99.1 % for (1) and 98.2 and 99.3 % for (2), respectively.