Food Control. 136, 108840 (2022). HPTLC of flavonoids, coumarins, sesquiterpene lactones and phenolic acids in German Chamomile (Matricaria recutita L.) on silica gel with ethyl acetate - methanol - water - acetic acid 200:25:20:1 and ethyl acetate - toluene 2:1. Detection of flavonoids and phenolic acids by spraying with Natural product reagent. Detection of sesquiterpene lactones by spraying with anisaldehyde sulfuric acid reagent. Qualitative analysis under UV light at 366 nm. Principal component analysis (PCA) was used for reducing data dimensionality and representing samples across principal components.

Food Chem. 133992 (2023). HPTLC of kiwi peel extracts on silica gel with ethyl acetate - formic acid - acetic acid - water 100:11:11:26. Detection of phenolics and tanning agents by heating the plate at 100 °C for 2 min, followed by dipping into fast blue B (140 mg fast blue salt B in a mixture of 140 mL methanol, 10 mL water, and 50 mL dichloromethane). Detection of flavanols, phenols and further natural compounds by dipping into a NPA solution (1 g 2-aminoethyl diphenylborinate in 200 mL of ethyl acetate), followed by drying, detection under UV light at 366 nm, followed by dipping into the anisaldehyde reagent (0.5 mL anisaldehyde, 10 mL acetic acid, 85 mL methanol, and 10 mL sulphuric acid), followed by heating at 100 °C for 5 min. Antioxidants were detected by dipping into a DPPH solution (0.4 g 2,2-diphenyl-1-picrylhydrazyl in 200 mL of methanol), followed by incubation in dark for 30 min. 

Marine Drugs 17(3), 148 (2019). Samples were ethyl acetate extracts of seagrass Amphibolis antarctica (Cymodoceaceae), and of algae: Austrophyllis harveyana (Kallymeniaceae), Carpoglossum confluens, Cystophora harveyi, C. monilifera, C. pectinata and C. subfarcinata, Myriodesma integrifolium, Sargassum lacerifolium (Sargassaceae), Codium fragile subsp. tasmanicum (Codiaceae), Ecklonia radiata (Lessoniaceae), Hypnea valida, Rhodophyllis membaneacea (Cystocloniaceae), Hormosira banksii (Hormosiraceae), Perithalia caudata (Sporochnaceae), Phyllospora comoasa, Scytothalia dorycarpa (Seirococcaceae), Plocamium dilatatum (Plocamiaceae), and epiphytic brown algae. HPTLC on silica gel (pre-washed with methanol and heated 30 min at 100 °C) with n-hexane – ethyl acetate – acetic acid 15:9:1. Derivatization by immersion: A) into anisaldehyde – sulfuric acid reagent, followed by 10 min heating at 105 °C, for the detection of steroids and terpenes; B) into DPPH• (0.2 % in methanol), followed by 30 min incubation in the dark, for the detection of antioxydants; C) into Fast Blue B solution (0.1 % in 70 % ethanol) for detection of phenols (with alkylresorcinols detected as dark purple zones on colorless background). Effect-directed analyses were performed directly on the plates. D) α-Amylase inhibition assay by immersion into enzyme solution, incubation 30 min at 37 °C, immersion into substrate solution (starch 2 % in water), incubation 20 min at 37 °C and immersion into Gram’s iodine solution for detection (inhibition zones appear blue on white background). E) Acetylcholinesterase (AChE) inhibition assay (after neutralization by immersion into phosphate buffer) by immersion into enzyme solution, incubation 30 min at 37 °C, immersion into substrate solution (α-naphthyl acetate) and into dye reagent (Fast Blue Salt B). Densitometry through automated scanning, quantification expressed as equivalents to the respective standards used for calibration curves: A) β-sitosterol (LOQ 1.6 µg/band), B) gallic acid (LOQ 60 ng/band), D) acarbose (LOQ 173 µg/band), E) donepezil (LOQ 96 µg/mL). Alkylresorcinols were detected as antioxydant in C. harveyi and C. pectinata (hRF 88), and in C. subfarcinata (hRF 72, 81, 88). Enzymatic inhibitors in C. fragile were considered as a flavone (hRF 65) and a terpenoid (hRF 77), due to their absorption curves (densitometric scan in range 200-400 nm).

J. Liq. Chromatogr. Relat. Technol. 44, 760-765 (2021). HPTLC of chrysin in chrysin loaded phytosomes on silica gel with n-hexane - ethyl acetate - methanol - formic acid 40:40:5:1. Quantitative determination by absorbance measurement at 268 nm. The hRF value for chrysin was 78. Linearity was between 50 and 250 ng/zone. Inter-day and intra-day precisions were below 2 % (n=3). The LOQ was 77 ng/zone. 

J Chromatogr A, 1625, 461230 (2020). Samples were extracts of Chinese plants: Acorus tatarinowii (= Acorus calamus var. angustatus) rhizomes (Araceae / Acoraceae) (1), Angelica sinensis roots (Apiaceae) (2), Gynura japonica rhizomes (Asteraceae) (3), Phellodendron chinense bark (Rutaceae) (4), Picrasma quassioides twigs and leaves (Simaroubaceae) (5), Rheum sp. roots and rhizomes (R. palmatum, R. tanguticum and/or R. officinale) (Polygonaceae) (6), Sophora flavescens roots (Fabaceae) (7), Dendrobium stems (D. aphyllum, D. aurantiacum var. dennaeanum, D. chrysanthum, D. chrysotoxum, D. gratiosissimum, D. hercoglossum, D. thyrsiflorum, D. trigonopus and D. williamsonii) (Orchidaceae) (8). Standards were: gigantol (from D. sonia); methoxycarbonyl-β-carboline (MCC from (5)); caffeic acid, emodin; senecionine and β-asarone; crategolic acid (= maslinic acid), corosolic acid, oleanic acid, ursolic acid; sesquiterpenoids (atractylenolides I – III) from Atractylodes macrocephala (Asteraceae); flavonoids (baicalein, baicalin, daidzin, hesperidin, wogonin) from Scutellaria baicalensis roots (Lamiaceae). HPTLC on silica gel with 10 mobile phases, depending on the samples. Detection under UV 254 nm and white light. For (3), derivatization with Dragendorff’s reagent (bismuth potassium iodide solution) for visualization of alkaloids. Zones of interest on underivatized plates were identified by a triple-quadrupole ­– linear ion-trap MS, the compounds being removed from the layer by a continuous-wave (445 nm) diode laser pointer through a DART interface (Direct Analysis in Real-Time, helium as gas for plasma-based ambient ionization, discharge needle voltage 1.5 kV, grid voltage 350 V, capillary temperature 300 °C and voltage 40 V, full scan in positive ionization mode in m/z range 150-800). Pigment standards were used for validation of this laser-assisted HPTLC-DART-MS method: malachite green, crystal violet, chrysoidin, auramine O, rhodamine B, Sudan red I – IV, Sudan red G, dimethyl yellow. Afterwards, the same HPTLC-MS method was applied to the origin / species determination of Dendrobium samples, based on the presence of four bibenzyl compounds erianin, gigantol, moscatilin, tristin. Erianin was present only in D. chrysotoxum, whereas none of these were detected in D. hercoglossum. Several components of the extracts were thus identified: asarone (a phenylpropanoid) in (1); phthalide lactones (butenylphthalide, ligustilide and chuanxiong lactone) in (2); co-eluting pyrrolizidine alkaloids (senecionine and seneciphylline) in (3); benzylisoquinoline alkaloid berberine in (4); alkaloids (canthinone alkaloids and MCC) in (5); anthraquinones (rhein, aloe-emodin, emodin, emodin methyl ether, chrysophanol) and (in negative mode) caffeic acid (a hydroxycinnamic acid) and corosolic, maslinic and oleanic acids (triterpenoids) in (6); quinolizidine alkaloids (matrine, oxymatrine, oxysophocarpine, sophoridine) in (7).

J Chromatogr A, 1625, 461230 (2020). Samples were methanolic extracts of commercial supplements containing Magnolia sp. bark (Magnoliaceae), as well as honokiol (1) and magnolol (2) (biphenyl neolignans) as separated or mixed standards. TLC and HPTLC on silica gel with n-hexane – ethyl acetate – ethanol 16:3:1. Visualization under UV 254 nm. Quantification of (1) and (2) by densitometric scanning in absorbance mode at 290 nm (hRF were 34 and 39, LOQ 200 ng and 280 ng/spot, respectively). Variability between samples from the same brand supplement was also determined, as well as extraction yields. Effect-directed analysis with 3 assays: A) to detect radical scavengers, immersion into DPPH• 0.02 % solution; B) to detect activity against Gram-negative bacteria, immersion into Aliivibrio fischeri suspension, followed by recording the bioluminescence; C) to detect activity against Gram-positive bacteria, immersion into Bacillus subtilis, followed by incubation 2 h at 28 °C and immersion into MTT 1 g/L. Compounds (1) and (2) were active in all assays. Identification of zones of interest by eluting with methanol from untreated TLC layer through the oval elution head of a TLC-MS interface directly to a single Quadrupole MS (electrospray ionization, interface temperature 350°C, heat block temperature 400°C, desolvation line temperature 250°C, detector voltage 4.5kV). Full mass scan spectra were recorded in the positive and negative ionization modes in m/z range 150–800. Other molecules (from other ingredients) were identified: piperine (alkaloid) and/or its geometrical isomers (active on A, hRF 29-30); and daidzein (active on A and B, hRF 18), isoflavone from Pueraria montana root (Fabaceae). Stability was assessed through 2D-HPTLC, by repeating the same development method in the orthogonal direction 4 h or 20 h after the first separation. Degradation products of (1) and (2) appeared after 20 h (but not at 4 h), including a honokiol dimer (formed in tracks of (1) and of (2)).

J Chromatogr A, 1598, 196-208 (2019). Samples were acertone – water 7:3 extracts of Reynoutria japonica (= Fallopia japonica = Polygonum cuspidatum) rhizomes (Polygonaceae) as well as flavanols (catechin, epicatechin, epicatechin gallate, epigallocatechin gallate) and procyanidins (A1, A2, B1–B3 and C1) as standards. HPTLC on diol silica gel with: (MP1) acetonitrile; (MP2) ethyl acetate; (MP3) ethyl acetate – formic acid 90:1; or (MP4) toluene – acetone – formic acid 3:6:1. Prewashing of the plates with mobile phase was needed only with MP1. After drying under hot air stream, derivatization by automated immersion into DMACA (dimethylaminocinnamaldehyde) – HCl solution (60 mg in 13 mL HCl + 187 mL ethanol), followed by 2 min drying under warm air stream. Visualization under UV 366 nm and white light, densitometry in absorption/reflectance mode at 280 nm (before derivatization) or 655 nm (10 min after derivatization). Bands of interest were eluted from layer with acetonitrile – methanol 2:1 through the oval elution head of a TLC-MS interface pump, into a RP18 liquid chromatography guard column, followed by a quadrupole ion trap mass spectrometer. Full scan mass spectra (m/z 150–2000) were recorded in negative mode using electrospray ionization (spray voltage 4 kV, capillary temperature 200◦C, capillary voltage -38.8 V). Monomer gallates to hexamer gallates were detected, separated with MP1, MP2 or MP4; monomers and oligomers (not gallates) were separated with MP3 (up to hexamers) and with MP1 and MP4 (up to decamers). Moreover, enhanced absorption of standards was also studied for influence of mobile phases, of layers (diol silica gel vs. classical silica gel vs. cellulose) and of luminosity (light vs. dark).

J. Planar Chromatogr. 35, 439-451 (2022). HPTLC of withanoside IV (1), withanoside V (2), withaferin A (3), and kaempferol-based glucoside (4) in the roots and aerial parts of Withania somnifera on silica gel with ethyl acetate - chloroform - methanol - water 40:15:22:9. Detection of (1) to (3) by spraying with anisaldehyde sulfuric acid reagent, followed by heating at 100 °C for 3 min. Quantitative determination by absorbance measurement at 540 nm for (1) to (3) and 254 nm for (4). The hRF values for (1) to (4) were 33, 42, 62 and 21, respectively. Linearity was between 200 and 1000 ng/zone for (3) and (4) and 400 and 2000 ng/zone for (1) and (2). Interday and intra-day precisions were below 4 % (n=6). The LOD and LOQ were 180 and 544 ng/zone for (1), 215 and 652 ng/zone for (2), 170 and 516 ng/zone for (3) and 48 and 144 ng/zone for (4). Recovery was between 95.9 and 99.6 % for (1) and (4).