Posted by linkadge on July 7, 2006, at 18:12:27
I read this, from:
http://vm.cfsan.fda.gov/~frf/forum04/abs04ct.html
A-21
Analysis of Germander (Teucrium chamaedrys L.) Diterpenoids by High Performance Thin-Layer Chromatography (HPTLC)
R. J. Michelson1 , P. R. Sundaresan2 , J. I. Rader2 , 1JIFSAN, 2FDAGermander (T. chamaedrys L.) has been identified as an adulterant in several skullcap (Scutellaria lateriflora L.) herbal preparations and is known to be hepatotoxic. Several important diterpenoids have been isolated and identified from this species (Teucrins1-9). No reference standards are commercially available and therefore in-house standards must be developed for these compounds. In this study, we utilized a standard TLC solvent system. This will be followed by High Performance Flash Chromatography (HPFC) and HPLC procedures in the isolation and identification of in-house standards. TLC analysis was performed on a methanol extract of the powdered aerial parts of authenticated T. chamaedrys L. Varying concentrations (10-50 µL) of the methanol extract were spotted (Linomat V sample applicator) on 10x10 cm silica gel 60 F254 HPTLC plates. Plates were developed in a solvent system of methylene chloride:methanol (19:1) for ~25 min, sprayed with Ehrlich's reagent, exposed to concentrated HCl vapor for 30 min., then heated for 10 minutes at 100°C. This procedure yielded poor band separation. However, a solvent system of 10:10:4 hexane:ethyl acetate:methanol provided good separation, indicating 8-10 well defined bands. Pre-washing the plates in methanol and drying thoroughly before spotting also improved the separations. Standards of Teucrin compounds (Teucrin 1, 5, 6, 7) were gifts from the NCNPR, University of Mississippi. Different standards were developed alongside the methanol extract of Germander and Rf values were compared. We will correlate the Rf values found in the HPTLC analysis to column volumes for the HPFC method to further improve the efficiency of preparing in-house standards.
poster:linkadge
thread:664945
URL: http://www.dr-bob.org/babble/alter/20060704/msgs/664945.html