Food Chem. 334, 127562 (2021). HPTLC of five seaweed cultivars, namely three Saccharina japonica and two Undaria pinnatifida on silica gel with n-hexane - ethyl acetate - formic acid 30:50:1. Detection by spraying with anisaldehyde sulfuric acid reagent (1.5 mL of anisaldehyde was mixed with 210 mL of ethanol, 25 mL acetic acid and 13 mL conc. sulfuric acid), followed by heating at 120 °C for 3 min. Qualitative identification under UV light at 366 nm. HPTLC-bioautography antimicrobial assays by dipping into B. subtilis cell suspension, followed by incubation at 37 °C for 30 min and E. coli suspension, followed by incubation at 37 °C for 1 h. Visualization by dipping into a solution of MTT dye with triton X-100 (1 mg/mL). Stearidonic, eicosapentaenoic, and arachidonic acids were identified by HPLC-MS.

Chemosphere. 261, 127706 (2020). HPTLC of water samples from four riverbank filtration sites in Germany on silica gel with a gradient development consisting of methanol - formic acid 2000:1 (v/v), dichloromethane and n-hexane in 16 steps. Effect-directed analysis using four bioassays. Baseline toxicity was detected via inhibition of natural bioluminescence of Aliivibrio fischeri (AF). In Bacillus subtilis (BS) assay, metabolic activity of BS cells was detected via the yellow substrate 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT). Neurotoxic effects was analyzed by AChE assay, spraying the substrate indoxyl-acetate onto enzyme-incubated HPTLC plates. In YES assay, estrogenic effects are detected via Saccharomyces cerevisiae BJ3505 strain. 

J. Food Biochem. 44, e13137 (2020). HPTLC of kaempferol-3-O-rutinoside (1) and rutin (2) in Musa acuminata Colla on silica gel with ethyl acetate - toluene - formic acid - water 34:5:7:5. Detection by dipping into natural products reagent (0.5 % methanolic solution of 2-aminoethyl diphenylborinate), followed by dipping into a 5 % methanolic polyethylene glycol 400 solution. Qualitative identification under UV light at 366 nm. Radical scavenging activity was studied by dipping into a 0.2% methanolic DPPH* solution. The hRF values for (1) and (2) were 32 and 25, respectively. 

Front. Pharmacol. 12, 755941 (2021). High-throughput eight-dimensional (8D) hyphenation of normal-phase HPTLC with multi-imaging by ultraviolet, visible and fluorescence light detection as well as effect-directed assay and heart-cut of the bioactive zone to orthogonal reversed-phase high-performance liquid chromatography-photodiode array detection-heated electrospray ionization mass spectrometry. The method allowed the analysis of 68 powdered plant extracts (botanicals) which are added to food products in food industry and the study of antibacterials, estrogens, antiestrogens, androgens, and antiandrogens, as well as acetylcholinesterase, butyrylcholinesterase, α-amylase, α-glucosidase, β-glucosidase, β-glucuronidase, and tyrosinase inhibitors in an array of 1,292 profiles.

J. Agric. Food Chem. 69, 12686-12694 (2021). HPTLC of 2Z,8Z- and 2E,8Z-matricaria esters in European goldenrod (Solidago virgaurea) and E- and Z-dehydromatricaria esters in grass-leaved goldenrod (Solidago graminifolia) and showy goldenrod (Solidago speciosa) on silica gel with n-hexane − acetone 17:3. Detection by dipping into mycelium suspension of F. avenaceum and B. sorokiniana, followed by incubation in a vapor chamber at 21 °C for 48−72 h. The lack of visible white (F. avenaceum) or dark gray (B. sorokiniana) fungal mycelia indicated the inhibition zones on the bioautograms. Compounds were further analyzed by high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy.

Journal Chromatogr A, 1641, 461727 (2021). HPTLc of an ethanolic maceration of Solidago gigantea roots (Asteraceae) on silica gel with n-hexane – isopropyl acetate – acetone 16:3:1, or n-hexane – isopropyl acetate – acetic acid 40:9:1. With the second mobile phase, acid residues had to be eliminated by 20 min automated drying or by 2 h incubation with potassium hydroxide in the opposite twin trough (followed by 15 min cold air streaming); this latter mobile phase allowed to obtain higher hRF values, but some butyrylcholinesterase (BChE) inhibiting activities were lost. The chromatograms were documented at UV 254 nm and 365 nm and white light before and after A) derivatization with vanillin – sulfuric acid reagent; B) enzymatic reaction by immersion into acetylcholinesterase, BChE, glucosidase and amylase solutions; C) Aliivibrio fischeri and Xanthomonas euvesicatoria bioassays, to detect activity against Gram-negative bacteria; D) Bacillus subtilis bioassay to detect activity against Gram-positive bacteria; E) a new antifungal assay with Fusarium avenaceum. For this assay, the chromatograms were immersed 6 s into the isolated mycelium suspension (diluted to OD600 0.4-0.8) and incubated in a vapor chamber at 21 °C for 48-72 h. Inhibition zones were indicated by the lack of visible white fungal hyphae. An aqueous solution of iodonitrotetrazolium (INT, 1 mg/ml) was sprayed on the plate to enhance the contrast (bright zones on a purple background). Benomyl (a benzimidazole fungicide) was used as positive control. Eight clerodane diterpenes (including kingidiol, hautriwaic lactone, and solidagoic acids A and B) were identified from six multipotent zones by bioassay-guided purification through preparative flash chromatography and HPLC, followed by HRMS and NMR, as well as by HPTLC hyphenated to quadrupole-orbitrap HRMS: A) by eluting with methanol (flow 100 µL/min) the compounds from the plate through the oval elution head of an interface of heated electro-spray ionization (spray voltage 3.5 kV, capillary temperature 270 °C, nitrogen as sheath and auxiliary gas, full scan in negative and positive ionization modes in m/z range 50-750); B) without eluent with a DART interface (Direct Analysis in Real-Time, needle voltage 4 kV, grid voltage 50 V, helium as gas, temperature 500 °C, full scan in positive ionization mode in m/z range 100-750).

J. Planar Chromatogr. 35, 181-187 (2022). HPTLC of gallic acid (1) and gallic acid ester (2) in Turkish gall on silica gel with dichloromethane - ethyl acetate - formic acid 5:3:1. Detection by spraying with 2 % ferric chloride ethanol solution. Quantitative determination by absorbance measurement at 280 nm. The hRF values for (1) and (2) were 67 and 81, respectively. Linearity was between 507 and 3045 ng/zone for (1) and 499 and 2994 ng/zone for (2). Interday and intra-day precisions were below 2 % (n=6). Average recovery was 100.6 % for (1) and 97.8 % for (2). The method was used to analyze the changes in the content of components which was treated by static simulated gastrointestinal digestion.

J. Planar Chromatogr. 35, 169-179 (2022). HPTLC of arjungenin (1) and arjunetin (2) in the bark of Terminalia arjuna on silica gel with toluene - ethyl acetate - formic acid 5:4:1. Detection by spraying with 10 % solution of sulfuric acid dissolved in methanol. Quantitative determination by absorbance measurement at 420 and 475 nm for (1) and (2). The hRF values for (1) and (2) were 43 and 67, respectively. Linearity was between 100 and 1000 ng/zone for (1) and (2). The method facilitated the detection of traces amount of adulterants in herbal products.