A capsule review of recent studies on the application of mass spectrometry in the analysis of Chinese medicinal herbs

The homoisoflavonoids in Ophiopogon japonicus (Thunb.) Ker-Gawler were analyzed by high-performance liquid chromatography-diode array detection-electrospray ion trap tandem mass spectrometry (HPLC-DAD-ESI-MS n ). Homoisoflavonoids gave prominent [M Ϫ H] Ϫ ions by electrospray ionization monitored in the negative ion mode. They could be classified into two types depending on the fragmentation behavior of their [M Ϫ H] Ϫ ions in the ion trap mass analyzer. The [M Ϫ H] Ϫ ions of homoisoflavonoids with a saturated C 2-3 bond underwent C 3-9 bond cleavage to lose the B-ring, which was followed by the loss of a molecule of CO. The [M Ϫ H] Ϫ ions of homoisoflavonoids with a C 2-3 double bond usually eliminated a CO molecule first, and then underwent the cleavage of C 3-9 or C 9-1= bonds. For homoisoflavonoids with a C-6 formyl group, however, the neutral loss of CO was the first fragmentation step; the presence of a methoxyl group at C-8 could lead to the cleavage of C-ring. No retro Diels-Alder (RDA) fragmentation characteristic for normal flavonoids was observed. The above fragmentation rules were reported for the first time, and were implemented for the analysis of homoisoflavonoids in O. japonicus. The CHCl 3 -MeOH extract was separated on a Zorbax Extend-C 18 column, eluting with a acetonitrile-0.3% acetic acid gradient. A total of 18 homoisoflavonoids, including seven new minor constituents, were identified or tentatively characterized based on the UV spectra and tandem mass spectra of the HPLC peaks. (J Am Soc Mass Spectrom 2005, 16, 234 -243)

Section: Mass Spectrometrymentioning

confidence: 99%

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confidence: 99%

Analysis of homoisoflavonoids in Ophiopogon japonicus by HPLC-DAD-ESI-MS

Guo

Guan

et al. 2005

“…Liquid chromatography coupled with mass spectrometry (LC/MS) is a powerful technique for the analysis of complex botanical extracts [15,16]. HPLC is efficient in separating chemical compounds in a mixture, and MS provides abundant information for structural elucidation of the compounds when tandem mass spectrometry (MS n ) is applied.…”

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confidence: 99%

Analysis of phenolic compounds in rhubarbs using liquid chromatography coupled with electrospray ionization mass spectrometry

Han

Chen

et al. 2007

228

157

Rhubarb is an important herbal medicine for the treatment of constipation, inflammation, and cancer. In this study, a facile method based on liquid chromatography coupled with electrospray ionization tandem mass spectrometry has been established for the analysis of bioactive phenolic compounds in rhubarbs. From six rhubarb species, official (Rheum officinale, R. palmatum, and R. tanguticum) and unofficial (R. franzenbachii, R. hotaoense, and R. emodi), a total of 107 phenolic compounds were identified or tentatively characterized based on their mass spectra. These compounds include sennosides, anthraquinones, stilbenes, glucose gallates, naphthalenes, and catechins. Ion chromatograms for the identified compounds of different rhubarbs were then compared. Consistent with previous reports, sennosides and rhein were only detected in official rhubarbs. Unexpectedly, we found that R. officinale contained very different phenolic compounds from the other two official species. Sennoside A, which has been considered as the major purgative component of rhubarb, was only detected in R. officinale, while its close isomers were observed in R. palmatum and R. tanguticum. In addition, the predominant anthraquinone glycosides in R. officinale were found to be rhein 8-O-glucoside and emodin 1-O-glucoside, whereas those in R. palmatum and R. tanguticum were rhein 1-O-glucoside and emodin 8-O-glucoside. Stilbenes, which are the major constituents of unofficial rhubarbs, were also different among the species. Our results clarify the chemical composition of rhubarbs comprehensively for the first time. Due to the significant differences in chemical components of rhubarbs, we suggest that different Rheum species be used separately in clinical practice. (J Am Soc Mass Spectrom 2007, 18, 82-91)

“…More recently, electrospray ionization (ESI) has become one of the most effective analytical tools for the structural characterization of a variety of polar and thermally labile molecules, e.g., polypeptides, carbohydrates and natural glycosides [19 -22]. Recent studies have reported the use of ESI-MS for determination of saponins with higher sensitivity and better reproducibility than the other types of ionization [23][24][25][26][27][28]. Moreover multistage mass spectrometry has great advantages for characterization of compounds by providing structural information [24,25,[27][28][29][30][31].…”

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Structural analysis of saponins from medicinal herbs using electrospray ionization tandem mass spectrometry

Liu

Cui

Liu

et al. 2004

111

100

The underivatized saponins from Tribulus terrestris and Panax ginseng have been investigated by electrospray ionization multi-stage tandem mass spectrometry (ESI-MS n ). In ESI-MS spectra, a predominant [M ϩ Na] ϩ ion in positive mode and [M Ϫ H] Ϫ ion in negative mode were observed for molecular mass information. Multi-stage tandem mass spectrometry of the molecular ions was used for detailed structural analysis. Fragment ions from glycoside cleavage can provide information on the mass of aglycone and the primary sequence and branching of oligosaccharide chains in terms of classes of monosaccharides. Fragment ions from cross-ring cleavages of sugar residues can give some information about the linkages between sugar residues. It was found that different alkali metal-cationized adducts with saponins have different degrees of fragmentation, which may originate from the different affinity of a saponin with each alkali metal in the gas phase. ESI-MS n has been proven to be an effective tool for rapid determination of native saponins in extract mixtures, thus avoiding tedious derivatization and separation steps. (J Am Soc Mass Spectrom 2004, 15, 133Ϫ141)