Dang-shen, radix Codonopsis is one of the best-known traditional Chinese medicines and is used mainly as a tonic agent. Nine commercial products belong to three species of Codonopsis genus, Codonopsis tangshen, Codonopsis pilosula var. modesta and a cultivated species of Codonopsis pilosula, which were purchased from drug stores in Taipei and Taichung, Taiwan. To determine the chemical differences between samples of Dang-shen, a method combining solvent partition and HPLC-UV was used. An enriched fraction of n-butanol was obtained, after partition. Then, the chemical profile was determined using a C18 reversed column chromatography in a gradient solvent system with 10–40% acetonitrile in 0.1% formic acid, for 60 min. A comparison of the constituents in the nine commercial products of Dang-shen showed that compounds codonopyrrolidum A, B and codonoside A only exist in C. tangshen, but not in C. pilosula var. modesta and C. pilosula. A predominate compound, codonopyrrolidum A, can be used to distinguish the herbs, C. tangshen from C. pilosula var. modesta and C. pilosula. Low secondary metabolite content was found in the cultivated species of C. pilosula.

A sensitive and efficient liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of gentiopicroside, geniposide, baicalin, and swertiamarin in rat plasma. To avoid the stress caused by restraint or anesthesia, a freely moving rat model was used to investigate the pharmacokinetics of herbal medicine after the administration of a traditional Chinese herbal prescription of Long-Dan-Xie-Gan-Tang (10 g/kg, p.o.). Analytes were separated by a C18 column with a gradient system of methanol–water containing 1 mM ammonium acetate with 0.1% formic acid. The linear ranges were 10–500 ng/mL for gentiopicroside, geniposide, and baicalin, and 5–250 ng/mL for swertiamarin in biological samples. The intra- and inter-day precision (relative standard deviation) ranged from 0.9% to 11.4% and 0.3% to 14.4%, respectively. The accuracy (relative error) was from −6.3% to 10.1% at all quality control levels. The analytical system provided adequate matrix effect and recovery with good precision and accuracy. The pharmacokinetic data demonstrated that the area under concentration-time curve (AUC) values of gentiopicroside, geniposide, baicalin, and swertiamarin were 1417 ± 83.8, 302 ± 25.8, 753 ± 86.2, and 2.5 ± 0.1 min µg/mL. The pharmacokinetic profiles provide constructive information for the dosage regimen of herbal medicine and also contribute to elucidate the absorption mechanism in herbal applications and pharmacological experiments.

Chemical examination of the n-butanol extract of the root of Codonopsis tangshen led to the isolation of four new compounds named codonosides A (1) and B (2) and codonopyrrolidiums A (3) and B (4), with seven known compounds [(Z)-2-(β-glucopyranosyloxy)-3-phenylpropenoic acid (5), lobetyolin (6), lobetyol (7), luteolin (8), friedelin (9), 5,6,9-trihydroxy-octadec-7-enoic acid (10), and adenosine (11)]. Based on spectroscopic evidence, the structures of codonosides A (1) and B (2) were established as phenolic glycosides, and those of codonopyrrolidiums A (3) and B (4) as pyrrolidines. The relative configuration of 3 was determined by X-ray crystallographic analysis.