Rapid differentiation of isobaric and positional isomers of structurally related glycosides from Phytolacca bogotensis

Abstract

Through the action of glycosyltransferases, a plant can biosynthetically assemble small different aglycons or 'templates' to various polysaccharides to produce numerous glycoconjugates differing in the type of the attached aglycon, the anomeric configuration of C-1 of the glycosylating sugar, the type of sugar and the different position of attachments of the sugar unit present in the polysaccharide chain. The position of attachments and the anomeric configuration of the different sugar present in the polysaccharide create the opportunity to generate molecules with either the same or very close molecular weights, which have relative structural similarity--forming isobaric and positional isomers. Although isomeric differentiation was once considered outside of the domain of mass spectrometry, this task can now be resolved using tandem mass spectrometry. In a standardized purified glycoconjugate fraction (SPT01) from Phytolacca bogotensis, we report conventional electrospray ionization mass spectrometry and collision-induced dissociation (CID) MS/MS parameters which favored the formation of characteristic product ions. This allowed us to suggest the type of sugar linkages present in a specific glycoconjugate. Ten new glycoconjugate are described from this plant and another twelve known saponins were structurally characterized using the automatic MSn acquisition mode. The differentiation of two pairs of positional isomers and four isobaric glycosides and the production of a library of 30 glycosides present in P. bogotensis were accomplished.

A new liquid chromatography-high resolution Orbitrap mass spectrometry-based strategy to characterize Glucuronide Oleanane-type Triterpenoid Carboxylic Acid 3, 28-O-Bidesmosides (GOTCAB) saponins.A case study of Gypsophila glomerata Pall ex M. B. (Caryophyllaceae)

“…Five GOTCAB saponins (A-E), previously isolated from Gypsophila trichotoma roots, were used as references. Saponins were characterized on the basis of extensive NMR analysis ( 1 H, 13 C NMR, COSY, HSQC, HMBC, TOCSY, HSQC-TOCSY, ROESY), completed by HR-ESI-MS and ESI-MS n analyses [9]. The structures of the saponin references are given in Fig.…”

“…An aliquot of the crude extract (1 g) was fractionated by a low pressure liquid chromatography over a C18 column (310 × 25 mm,40-63 µm) (Merck, Germany) using a binary gradient of methanolwater (10:90 -100:0) to afford 20 fractions (each 25 ml). Fractions (10)(11)(12)(13) were separated by repeated semi-preparative HPLC on Kinetex C18 (150 x 10 mm, 5 µm) (Phenomenex, USA) and gave 18 fractions (each 5ml). Semi-preparative HPLC was performed on a chromatographic system Varian equipped with a ternary pump Model 9012, a Rheodyne injector with 200 µL loop and an UV/VIS detector Model 9050 set at 210 nm.…”

“…Based on their complexity, the structural elucidation of GOTCAB is a very challenging task, requiring the use of several analytical techniques. Technological advances that combine highperformance liquid chromatography with mass spectrometers enable the rapid identification of bioactive saponins in plant extracts by distinguishing previously identified ones [12][13][14]. Although a large number of Gypsophila mono-and bidesmosides have been characterized, only the complete GOTCAB profiling of Gypsophila trichotoma has been established by LC-HRMS [15].…”

HPLC-ESI-IT-MS/MS Analysis and Biological Activity of Triterpene Glycosides from the Colombian Marine Sponge Ectyoplasia ferox

“…By using the previously described approach [14], a total of twenty-five saponins were identified in a polar complex mixture from Ectyoplasia ferox , from which ulososides A and D, and urabosides A and B are well-known molecules (Figure 1 and Table 1). None of the other twenty-one identified compounds have been previously reported for this species.…”

Fragmentation trees for the structural characterisation of metabolites

“…Approaches to metabolite identification that use MS n fragmentation often require manual intervention by mass spectrometry experts. [9,[15][16][17] Recently, more automated approaches are reported that greatly facilitate this tedious analysis. [14,[18][19][20][21] Some of the methods focus on predicting fragmentation patterns in silico.…”