J. of China Pharm. 23 (20), 38-40 (2014). Nicotine is a toxic substance in tobacco. Studies have shown that nicotine may prevent and treat Alzheimer's disease (AD) and Parkinson's syndrome (PD). At present, the most effective method to treat AD is by inhibiting the activity of acetylcholinesterase (AChE), thus enhancing the cholinergic activity indirectly. In order to clarify the mechanism of nicotine reducing the incidence of AD, the activity of natural AChE inhibitors in Xinjiang Mohe tobacco was screened by TLC on silica gel with (A) ethyl acetate – methanol – ammonium hydroxide 70:30:1, followed by detection via enzyme inhibition (this is not bioautography, as stated in the title): firstly by spraying with 1.0 U/mL AChE (AChE 500 U + tris-HCl buffer solution of pH 7.8 500 mL + bovine serum albumin 500 mg), followed with 1.5 g/L alpha-naphthyl acetate (150 mg in ethanol 40 mL + water 60 mL) and then with 0.5 g/L Fast blue B salt, resulting in white zones on purple background; (B) toluene – ethyl acetate - diethylamine 7:2:1, detection by spraying with 0.2 mmol/L 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical reagent, resulting in white to yellow zones on pale purple background. The results indicated that nicotine in Xinjiang Mohe tobacco could bind to AChE and thus inhibit its activity.

CBS 120, 5-7 (2018). HPTLC of extracts of broad-leaved dock (Rumex obtusifolius) on silica gel with toluene – ethyl acetate – formic acid 1:8:1 over 75 mm. Detection by 3-step derivatization using automated spraying: 1) natural product reagent (NP), 2) NP in combination with polyethylene glycol solution (PEG), 3) vanillin-sulfuric acid reagent followed by heating at 100 °C for 3 min. To derivatize areas of the same plate with different reagents, the areas, which were to be evaluated underivatized by TLC-MS, were covered with a suitable segment of a used HPTLC plate, the layer turned upwards. Evaluation under UV 254 and 366 nm, white light, and by densitometry in absorbance measurement at 280 nm. Direct elution of target zones into a triple quadrupole mass spectrometer with electrospray ionization and recording in the negative ionization mode allowed a quick and easy screening of constituents. Overall, many flavan-3-ols, procyanidins, anthraquinones and naphthyl glycosides were detected in Rumex obtusifolius. The stilbenes frequently found in other Polygonaceae (Rheum spec.) were present only in small quantities.

Chromatographia 18, 546-549 (1984). TLC of curcumine in turmeric root powder and spice-mixtures on silica with chloroform - acetic acid 8:2. Detection by UV or spraying with boric acid - oxalic acid - reagent. Fluorometry after spraying.

Chinese Traditional Med. (Zhongyao Tongbao) 10, 36-37 (1985). (Chinese) (Application of TLC scanning method on the study of the quality of Chinese patent medicines. Quantitative analysis of herberine in five Chinese patent medicines.) TLC of berberine on silica with butanol - acetic acid - water 7:1:2. Visualization under UV light. Quantification by densitometry.

TLC of strychnine and brucine on silica with methanol -4 N NH3 9:1 Determination by densitometry at 255 nm for strychnine and 295 nm for brucine.

Detection by exposing to iodine vapor. Quantification by densitometry at 290 nm.

J. Chinese Herb Med. 18, 394-396 (1987) (Zhong Caoyao). TLC on silica with the upper phase of butanol - 36% acetic acid - water 2:1:1. Quantification by fluorodensitometry at 334 nm.

Screening-Methoden [HPLC, DC) zum Nachweis. (Salicylates in medicinal plants; HPLC, TLC methods for identification.) Dtsch. Apoth. Ztg. 127, 2401-2407 (1987). TLC of salicin derivatives on silica with ethyl acetate - methanol - water 77:13:10 and methylene chloride - ethyl acetate - methanol - water 50:30:20:5. Detection by spraying with 10% sulfuric acid in ethanol and heating for 5 min. at 110°C or with 0.8 g vanillin in 40 mL acetic acid and heating 5- 10 min. at 100 °C. Detection limit about 0.1%.