J. of Chromatogr. Sci. 59 (7), 634-641 (2021). TLC of ledipasvir on silica gel with ethylacetate – hexane – acetonitrile – trimethylamine 12:7:3:1. Detection by exposure to strong UV irradiation to enhance the fluorescence properties of ledipasvir and densitometric scanning at 315 nm⁠. The hRF of ledipasvir was 28 and of sofosbuvir 36. Linearity was in the range of 5-50 ng/band⁠. The method is suitable for the specific determination of ledipasvir in pharmaceutical tablets without interference from sofosbuvir or excipients, thus for the estimation of ledipasvir in fecal specimens with adequate recovery and for testing the content uniformity of ledipasvir in the pharmaceutical tablets.

Planta Med. 85(3), 195-202 (2019). The dichloromethane fraction of an ethanolic extract from Gloeophyllum odoratum sporocarp (Gloeophyllaceae, Basidiomycetes) was submitted to a multistep purification process (conventional, flash and supercritical fluid column chromatography). At each step, fractions were monitored on TLC silica gel with dichloromethane – methanol – water 40:4:1. Detection under white and UV light after derivatization with vanillin sulfuric acid 5 % in methanol and heating. Eight triterpenes were isolated for further identification: eburicodiol, gloeophyllins B and K, hydroxylanosterol, trametenolic acid B (all five from the lanostane type), gloeophyllins A and L (C‑nor-D-homoergosteroid type), and ergosterol peroxide (ergostane type).

Planta Med. 85(2), 154-159 (2019). Two new cycloartane triterpene heterosides (cimiheraclein F and a shengmanol derivative) isolated from Actaea heracleifolia aerial parts (Ranunculaceae) were submitted to acid hydrolysis (HCl 0.4 M in methanol 60 %, 90°C, 2 h). The glycone moieties were purified and developed on TLC silica gel with ethyl acetate – chloroform – methanol – water 3:2:2:1. Detection after spraying with sulfuric acid 10 % in water and heating. The glycones were identified in both cases as L-arabinopyranose by comparison of the RF values (and of specific optical rotation) to a standard.

Planta Med. 85(2), 112-117 (2019). A fraction of an ethanolic extract of Dolichos trilobus roots (Fabaceae) was eluted on a silica gel column with different mixtures of petroleum ether and acetone. This fractionation was monitored by TLC on silica gel (eluent not given), derivatization by spraying with sulfuric acid 10 % (in ethanol) and heating (100 °C). Further isolation steps allowed the identification of eight coumestans in two subfractions: dolichosins A–D, isosojagol, phaseol, psoralidin, dehydroisopsoralidin.

Heliyon 6(8), e04654 (2020). HPTLC of ethanolic extracts of three algae (100µg/band) on silica gel, along with carotenoid standards (10µg/band), developed with toluene – acetone 7:3. Detection under white light. Carotenoids appeared orange or yellow, chlorophylls green, pheophytins dark khaki. Carotenoid patterns of the algae were very different depending on the family: red alga Eucheuma denticulatum (Solieriaceae) contained mainly zeaxanthin and lutein (hRF 44) and β-carotene (hRF 88), but also β-cryptoxanthin (hRF 69-71) and fucoxanthin (hRF 39); brown alga Sargassum polycystum (Sargassaceae) contained mainly fucoxanthin, and also cryptoxanthin; green alga Caulerpa lentillifera (Caulerpaceae) contained mainly zeaxanthin, but also astaxanthin (hRF 61) and canthaxanthin (hRF 77) in smaller amounts. Separately, HPLC-MS was used to confirm and quantify these compounds, which was necessary for carotenoids with similar hRF values: zeaxanthin and lutein (hRF 44), and β-carotene and lycopene (hRF 88).

Heliyon 6(7), e04481 (2020). TLC of two successive stem-bark macerates (dichloromethane – methanol 1:1 and 0:1) of Kigelia africana (Bignonaceae) on unmodified silica gel, developed with dichloromethane – ethanol 19:1. Detection by spraying with stannic chloride (tin IV chloride) in chloroform – acetic acid – water 8:8:1 and heating at 100°C for 10 min. Visualization under UV showed terpenoids, phenols, steroids and flavonoids as indigo zones. The two extracts provided similar profiles but with different intensities.

J Pharm Bioallied Sci. 12(2), 139-145 (2020). An HPTLC method was validated for the fingerprint of flavonoids and other phenolic compounds (rutin, apigenin, luteolin, caffeic acid, chlorogenic acid, rosmarinic acid) in methanol macerates of dried aerial parts of five Lamiaceae (subfamily Nepetoideae: Dracocephalum moldavica, Lophanthus anisatus, Monarda fistulosa, Ocimum americanum, Satureja hortensis). HPTLC of extracts and standards on silica gel with chloroform – ethyl acetate – formic acid 5:4:1 or with ethyl acetate – formic acid – water 15:1:1. Detection under UV light before and after spraying with aluminium chloride 1 % in methanol. Rosmarinic acid was present and abundant in all extracts and was also quantified by densitometry at UV 366 nm without derivatization. The LOD was 29.2 µg/mL; the rosmarinic acid concentration range was between 12.6 mg/g (Lophanthus) and 24.8 mg/g (Dracocephalum).

Chem. Asian J. 15(19), 3044-3049 (2020). The studied rotaxane combines a dibenzocrown of 8 ethers (DB24C8) with an axle chain (Ax) containing two amines, one of them in an aniline group, allowing stability of the rotaxane even when the other one is unprotonated. TLC on silica gel in 4 steps, with detection under UV light or after derivatization with phosphomolybdic acid in ethanol. (1) Before the synthesis of the rotaxane, unprotonated Ax was isolated by preparative TLC of the protonated Ax obtained by addition of HCl or toluenesulfonic acid (TsOH); the mobile phases were chloroform – methanol 10:1 and toluene – tetrahydrofurane 3:2, respectively. The isolated molecules were confirmed as totally unprotonated Ax by NMR, suggesting a complete loss of HCl and TsOH on the silica gel layer. (2) After synthesis, unprotonated rotaxane, pure vs. monoprotonated by the addition of 10 different acids (and purified by column chromatography CC), was applied on TLC plates and developed with dichloromethane – acetone – water 3:16:1; the hRF values were very different, depending on the counter-anions from the used acids. (3) The same behavior (except with sulfuric acid) was observed under the same conditions when CC was omitted (unprotonated rotaxane samples were mixed with each of the acids, or with two acids at the same time for acid-competitive TLC analysis). (4) When unprotonated rotaxane was applied under the same conditions as in step (3) with the sodium salts instead of the acids, the behavior was similar (except for the shapes of the spots, due to the salts in excess). The rotaxane can thus be used for the TLC separation and detection of sodium salts, by forming salts of protonated rotaxane with the anion afforded by these sodium salts. The rotaxane protonation seems to be promoted by the methanol of the spotting mixture; indeed, when step (3) was performed with the mobile phase chloroform – methanol 10:1, a second zone appeared because methanol formed a salt with the rotaxane (identified by NMR).