title: LC-ESI-QTOF-MS based screening and identification of isomeric jujubogenin and pseudojujubogenin aglycones in Bacopa monnieri extract.
abstract: Bacopa monnieri (L.) Wettst. (Scrophulariaceae) is an Ayurvedic medicinal plant used as a memory enhancer. Its major chemical constituents are Bacopa saponins consisting of jujubogenin and pseudojujubogenin glycosides. These two aglycones are isomers different at the positions of prenyl substitution i.e., at C-23 for jujubogenin and at C-22 for pseudojujubogenin. In this study, we demonstrate the rapid and comprehensive characterization of saponin glycosides in B. monnieri using liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometer (LC-ESI-QTOF-MS). This shows that ESI-QTOF-MS in positive-ion mode, jujubogenin and pseudojujubogenin glycosides could be discriminated by the peak abundance ratio of m/z 455 [Aglycone+H-H2O](+) to m/z of 473 [Aglycone+H](+). Furthermore, the sequence of sugar moieties can be observed. In a similar manner, the isomeric saponins; deoxyjujubogenin and deoxypseudojujubogenin glycosides can be distinguished using the m/z 437[Aglycone+H-H2O](+) and m/z 455[Aglycone+H](+) peak ratio. Use of the negative-ion mode with MS/MS fragmentation can provide information about the type of sugar linked to the aglycone i.e., at m/z 633 (aglycone+glucose) or at m/z 603 (aglycone+arabinose). With our method, 62 chemical constituents in B. monnieri including saponin glycosides, flavonoids, and alkaloids were identified. This is the first systematic study in structural characterization on isomeric saponins and other metabolites in B. monnieri using ESI-QTOF-MS.
authors.affiliation: Science Laboratory Centre, Faculty of Science, Naresuan University, Phitsanulok 65000, Thailand. Electronic address: nitran@nu.ac.th.
authors.forename: Nitra
authors.initials: N
authors.lastname: Nuengchamnong
authors.affiliation: Department of Pharmaceutical Chemistry and Pharmacognosy, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok 65000, Thailand.
authors.forename: Sontaya
authors.initials: S
authors.lastname: Sookying
authors.affiliation: Department of Pharmaceutical Chemistry and Pharmacognosy, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok 65000, Thailand.
authors.forename: Kornkanok
authors.initials: K
authors.lastname: Ingkaninan
mesh_terms: D034681:Bacopa; D002853:Chromatography, Liquid / Q000379:methods; D007536:Isomerism; D035261:Plant Components, Aerial; D010936:Plant Extracts / Q000032:analysis* / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014315:Triterpenes / Q000032:analysis* / Q000737:chemistry
chemical_list: C508084:3-O-(beta-D-glucopyranosyl-(1-3)-beta-D-glucopyranosyl) pseudojujubogenin; D010936:Plant Extracts; D014315:Triterpenes; C400159:jujubogenin
keywords: B. monnieri; Isomeric saponins; Jujubogenin; LC-ESI-QTOF-MS; Pseudojujubogenin