Characterization of isoquinoline alkaloids, diterpenoids and steroids in the Chinese herb Jin‐Guo‐Lan (Tinospora sagittata and Tinospora capillipes) by high‐performance liquid chromatography/electrospray ionization with multistage mass spectrometry

Abstract

This study sought to determine the primary components (isoquinoline alkaloids, diterpenoids and steroids) in crude extracts of the Chinese herb Jin-Guo-Lan, prepared from the roots of Tinospora sagittata and T. capillipes, by liquid chromatography/electrospray ionization multistage mass spectrometry coupled with diode-array detection (LC-DAD/ESI-MS(n)). After separation on a reversed-phase C(18) column using gradient elution, positive and negative ESI-MS experiments were performed. In positive ion mode, the three types of compounds showed very different characteristic ions: strong [M](+) or [M+H](+) ions were observed for isoquinoline alkaloids; [M+NH(4)](+) and/or [M+H-CO(2)](+) for diterpenoids; [M+H-nH(2)O](+) (n=1-3) for steroids. These adduct ions and/or fragments were used to deduce the mass and categories of known and unknown components in crude extracts, and their structures were further confirmed by ESI-MS(n) in positive ion mode. Moreover, UV absorption peaks obtained from DAD provided useful functional group information to aid the MS(n)-based identification. As a result, 11 compounds were unambiguously identified by comparing with standard compounds and 13 compounds were tentatively identified or deduced according to their MS(n) data. Two of these compounds (13-hydroxycolumbamine and 13-hydroxyjatrorrhizine) were found to be new compounds and another one (13-hydroxypalmatine) was detected for the first time as a natural product. In addition, a [M-*CH(3)-H(2)O](*+) ion in MS(2) of [M](+) after in-source collision-induced dissociation was used to differentiate positional isomers of protoberberine alkaloids, columbamine and jatrorrhizine. Although the roots of T. sagittata and T. capillipes contain almost identical compounds, the content of the compounds in them is dramatically different, suggesting the necessity for further comparison of the bioactivities of the two species.

Identification of major alkaloids and steroidal saponins in rat serum by HPLC‐diode array detection‐MS/MS following oral administration of Huangbai‐Zhimu herb‐pair Extract

“…6). These results are consistent with those of palmatine (C 21 H 22 NO 4 , MW 352; Huang et al, 2007;Lu and Yang, 2004;Zhang et al, 2006). The mechanistic pathway for fragments formed may be explained according to Scheme 3.…”

“…5). These results are consistent with those of menisperine (C 21 H 26 NO 4 , MW 356; Ma et al, 2006;Zhang et al, 2006). The proposed mechanistic pathway for fragments formed in MS 2 is shown in Scheme 2.…”

Identification of Major Alkaloids in Rat Urine by HPLC/DAD/ESI‐MS/MS Method Following Oral Administration of Cortex Phellodendri Decoction

“…5). These results are consistent with those of menisperine (C 21 H 26 NO 4 , molecular weight 356) [13] which is present in Cortex Phellodendri [17]. A proposed mechanistic pathway for fragments formed in MS 2 is shown in Scheme 3.…”

“…4), suggesting a demethyleneberberine moiety which is one of the metabolites of berberine in vivo [13] [15]. Moreover, berberine is an abundant alkaloid in Cortex Phellodendri [16].…”

Identification of the major chemical constituents and their metabolites in rat plasma and various organs after oral administration of effective Erxian Decoction (EXD) fraction by liquid chromatography‐mass spectrometry

“…Among them, fi ve alkaloids were unambiguously identifi ed as magnofl orine, menisperine, jatrorrhizine, palmatine and berberine by a direct comparison with those standard compounds. The molecular structures of the alkaloids were deduced from the positive molecular ion peak at m/z [M]+ as well as the corresponding sub-fragments in their MS n spectra (Table 1) (Ma et al, 2008;Hua et al, 2007;Lu et al, 2006;Zhang et al, 2006 O]+ were typical for the aporphine alkaloids (6, 13) in the present study. Another nine phenols were all unambiguously identifi ed by a direct comparison with the reference compounds.…”