Asian Journal of Plant Sciences 9(1), 44-50 (2010). Beta-sitosterol is one of the major phytoconstituents in cornsilk (style and stigma of Zea mays Linn.). An HPTLC method for the standardization of cornsilk as a bioavailable source of beta-sitosterol is reported. HPTLC of methanolic extracts of dried cornsilk and plasma of rabbits (1 h after injection of plant slurry) on silica gel with toluene - ethyl acetate - methanol - glacial acetic acid 80:10:5:3 with chamber saturation for 30 min. Detection by treatment with Liebermann-Burchard reagent. Beta-sitosterol was well resolved with an hRf value of 48. Quantitative determination by fluorescence measurement at 366 nm. The method was suitable for the pharmacokinetic study (absorption - elimination). The study confirmed the bioavailability of beta-sitosterol from cornsilk, which is therefore a potential natural source of beta-sitosterol.

Ind. J. Pharma. Sci. 72(1), 39-45 (2010). The Ayurvedic Pharmacopoeia of India recognized roots of the three plants Cissampelos pareira, Cyclea peltata, and Stephania japonica (all Menispermaceae) as source for the marketed drug Patha. HPTLC fingerprint analysis of methanolic extracts of roots of all three plants on silica gel with n-butanol - ethyl acetate - formic acid - water 3:5:1:1. Detection under UV 365 nm (crude extract) and 295 nm (total alkaloids). Quantification of the marker berberine by HPLC. The three plants exhibit significantly different physico-chemical features and chromatographic fingerprints. Roots of C. pareira contained the highest concentration of berberine, S. Japonica contained very low amounts and C. peltata no berberine at all.

Acta Chromatographica 22 (2), 227-236 (2010), DOI:10.1556/AChrom.22.2010.2.6. TLC of piperine, the bioactive constituent of black pepper (Piper nigrum), on silica gel with dichloromethane – ethyl acetate 9:1 at 30 °C in a twin-trough chamber saturated for 30 min. Detection under UV light at 254 nm and documentation with a digital camera. Based on the image a density profile plot was established by Scion Image software, which allowed to calculate the concentration of piperine by comparison of the peak areas of samples and piperine standards. The linearity was in the range of 24-84 ng/zone (r2=0.9927). The limits of detection and quantitation were 0.35 and 1.05 ng/zone, respectively. Precision (repeatability, n=6) and intermediate precision (2 days, n=12) both are below 2.6 %RSD. Recovery is between 96.7-101.4 %.

J. Pharm. Biomed. Anal. 54, 422-425 (2011). HPTLC of aloin in several aloe dried extracts and related commercial formulations on silica gel with ethyl formate – methanol – water 200:29:20. Evaluation under 254 nm. Detection by immersion in 10 % H3BO3 in methanol, followed by heating at 110 °C for 10 min. Quantitative determination by fluorescence measurement at 365/K540 nm.

International J. Research in Ayurveda & Pharmacy 1(1), 131-134 (2010). Dried leaves of Calendula officinalis were extracted with petroleum ether, chloroform, methanol and water, the solvents were removed and the extracts were subjected to phytochemical analysis for amino acids, essential oils, triterpens, alkaloids, saponins, sterols, and fatty acids. TLC on silica gel with n-hexan – acetic acid – water 12:3:5, detection by spraying with ninhydrin solution, followed by heating at 105 °C revealed violet bands which indicated the presence of amino acids. For essential oils TLC on silica gel with dichloromethane – chloroform – ethyl acetate – n-propanol 94:90:4:5, followed by spraying with vanillin-sulfuric acid reagent and heating at 105 °C for 2 min. Pink brown coloured zones indicated the presence of essential oils. For triterpenoids TLC on silica gel with n-butanol – 2M ammonia 1:1 , detection by spraying with antimony trichloride solution. Purple coloured zones indicated the presence of triterpenoids. For alkaloids TLC on silica gel with chloroform – methanol 1:1, detection by alkaloids-reagent. For saponins TLC on silica gel with chloroform – methanol 12:1, detection by spraying with vanillin-sulfuric acid reagent. For sterols TLC on silica gel with chloroform – methanol 3:4, detection by anisaldehyde reagent. For fatty acids TLC on silica gel with n-hexane – ethyl acetate 19:1, detection by KMnO4 reagent.

Planta Med. 75, 1618-1624 (2009). TLC of gentiopicroside and methanolic plant extracts on silica gel containing 1 % CMC-Na with ethyl acetate - ethanol - water 20:2:1. Detection by spraying with 2 % vanillin-sulfuric acid reagent and by evaluation under UV 254 nm.

J. Planar Chromatogr. 24, 352-356 (2011). HPTLC of extracts of dried powdered rhizoms of A. galanga and three phenylpropanoids (1-acetoxychavicol acetate (1), acetoxyeugenol acetate (2), and trans-p-coumaryl diacetate(3)) on silica gel with n-hexane - ethyl acetate 4:1 with chamber saturation for 1 h. After drying second development with the same mobile phase. Quantitative determination by densitometry at the wavelength of maximum absorption. Linearity was between 0.6-1.8 µg/band, 0.4-1.5 µg/band and 0.1-0.3 µg/band for (1), (2), and (3), respectively. The LOD and LOQ was 150 and 500 ng/band for (1), 100 and 334 ng/band for (2), and 23 and 77 ng/band for (3). The repeatability of application and repeatability of measurement (%RSD, n = 6) was 0.9 and 0.5 % for (1), 0.5 and 0.3 % for (2), and 1.8 and 0.9 % for (3). The intra-day and inter-day precision was below 5 % for all compounds. The hRf value was 53, 37, and 43 for (1), (2), and (3), respectively.

J. Planar Chromatogr. 24, 253-256 (2011). HPTLC of yohimbine on silica gel, prewashed with methanol, with toluene - ethyl acetate - diethyl amine 7:2:1 in a twin trough chamber saturated with mobile phase for 10 min at 25 +/- 2 °C. Quantitative determination by densitometry in absorbance mode at 285 nm. Linearity was between 400 and 1200 ng/band. The hRf value was 39. The repeatability as system precision and method precision (n = 6) was 0.9 and 0.8 % CV. The limit of detection and quantification was 80 ng and 260 ng. The instrument precision (n = 6), intra-day and inter-day precision (n = 3, %RSD) were 0.2, 0.1, and 0.1 %, respectively.