[Studies on the TLC scanning determination of lignans in Diphylleia sinensis Li]

A simple, sensitive and accurate method for the separation and determination of the lignans: podophylltoxone (I), isopicropodophyllone (II), picropodophyllone (III), dehydropodophyllotoxin (IV), picropodophyllin (V), podophyllotoxin (VI), 4'-demethylpodophyllotoxin (VII) and diphyllin (VIII) is described. The sample solution was applied at a point 1 cm from the bottom edge of the HPTLC silica gel plate (10 cm x 10 cm), dichloromethane-diethyl ether (4:1) was used as the developing solvent. The plate was saturated for 30 min and then developed twice for 9.5 cm using ascending technique. The plate was sprayed with 2.5% ammonium ceric sulphate--20% nitric acid and toasted for 15 min at 120 degrees C, then fumigated with ammonia solution for 20 min at room temperature to intensify the spot color. The spots were scanned with a Shimadzu CS-930 TLC scanner. The contents of eight lignans in Diphylleia sinensis was calculated by comparison with standards spotted on the same plate. The standard curves were linear in the range of 0.48-2.52 micrograms for the eight lignans. The method has been applied to the analysis of various samples and can be used for the quality control of Diphylleia sinensis, podophyllum and dysosma preparations used in clinic.