Planta Medica 84(1), 26-33 (2018). For the monitoring of the multi-step fractionation through VLC (vacuum liquid chromatography) of the chloroform-soluble parts of a methanol – water 7:3 percolate of Hippophae rhamnoides (Eleagnaceae) fruit peels, TLC on silica gel and RP-18, detection by spraying with sulfuric acid and heating. Preparative TLC on silica gel with cyclohexane – dichloromethane – methanol 5:15:1 to isolate, from VLC subfractions, three lignans (nectandrin B, fragransin A2, saucernetindiol) that are diastereoisomers of each other.

Planta Medica 83(17), 1329-1334 (2017). Two acetone-soluble subfractions of an n-hexane maceration of Hypericum denudatum aerial parts (Hypericaceae) were submitted to repeated centrifugal planar chromatography (CPC) on silica gel using n-hexane – ethyl acetate (gradient from 100:0 to 90:10), obtaining four dimeric acylphloroglucinols (denudatin A, hyperbrasilol A, uliginosin B and isouliginosin B), which were purified by crystallisation with n-hexane – dichloromethane 9:1. From the most apolar CPC eluates, a monomer (selancin A) was isolated on preparative TLC silica gel layer by elution with n-hexane – ethyl acetate 97:3. Furthermore, all the purification steps were monitored through TLC on silica gel with n-hexane – ethyl acetate 19:1 or with n-hexane – dichloromethane 1:1. Detection under UV light after derivatization with anisaldehyde – sulfuric acid, monomeric acylphloroglucinols appeared purple, whereas dimers appeared yellow-orange.

J. of Chromatogr. Sci. 57 (2), 130-138 (2019). Development of a method for the simultaneous determination of thalidomide (THD) and dexamethasone (DEX) in rat plasma using paracetamol as an internal standard by HPTLC on silica gel with methylene chloride - acetone - ethyl acetate 7:4:1. Detection by absorption measurement at 235 nm. Linearity was in the range of 0.02 - 100 µg/zone for THD and 0.02 - 3 µg/zone for DEX. LOD and LOQ were 7 and 20 ng/zone both for THD and DEX. Validation by testing all parameters using quality control samples as per FDA guidelines. Successful application of the method to study the pharmacokinetic parameters of both THD and DEX after their intra-peritoneal administration.

J. of Modern Trad. Chinese Med. 20 (8), 975-978 (2018). Panax notoginseng is a traditional Chinese medicinal herb which activates blood circulation, anti-platelet aggregation and anti-thrombosis. TLC for quality control of ginsenoside Rb1 (1), notoginsenoside R1 (2) and ginsenoside Rg1 (3) on silica gel with the lower phase of chloroform – methanol – water 13:7:2 (after standing for 12 h at below 10˚C). Detection by spraying with 10% sulfuric acid in ethanol and heating at 110 ˚C until the zones are visible, evaluation under UV 365 nm. Quantification by densitometric absorption measurement at 510 nm. Validation by investigation of the linearity ranges of 0.5-5.0 µg/zone (r=0.998) for (1), 0.5-5.01 µg/zone (r=0.999) for (2) and 0.5-4.9 µg/zone (r=0.998) for (3). The plate-to-plate precision % RSD (n=12) was 1.5 %, 1.1 % and 1.9 % for (1) to (3). Recovery from standard sample addition was 96.4 % (%RSD 1.4 %, n=6) for (1), 96.9 % (%RSD 0.9 %, n=6) for (2), and 98.9% (%RSD 1.7 %, n=6) for (3).

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.

J. Planar Chromatogr. 32, 411-420 (2019). HPTLC of torsemide (1) and eplerenone (2) on silica gel aluminum foil with toluene - ethyl acetate - glacial acetic acid 70:30:1. Quantitative determination by absorbance measurement at 297 nm. The hRF values for (1) and (2) were 24 and 50, respectively. Linearity was between 50 and 300 ng/zone for (1) and 125 and 1225 ng/zone for (2). Intermediate precision was below 2 % (n=3). The LOD and LOQ were 3 and 10 ng/zone for (1) and 2 and 7 ng/zone for (2), respectively. Recovery rate was between 102.6 and 108.8 % for (1) and (2).

J. Planar Chromatogr. 32, 505-510 (2019). HPTLC of rivaroxaban on silica gel with toluene - methanol 7:3. Quantitative determination by absorbance measurement at 250 nm. The hRF value for rivaroxaban was 63. Linearity was between 100 and 600 ng/zone.  Intermediate precision was below 2 % (n=3). The LOD and LOQ were 3 and 9 ng/zone. Recovery rate was between 101 and 102.3 %.

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.