Assignment of sugar arrangement in branched steviol glycosides using electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

Abstract

Those steviol glycosides with a monosaccharide or less hindered disaccharides at position C-19 are cleaved at low collision energy (10 eV) while highly hindered disaccharides and trisaccharides are cleaved at 40 eV. However, sugars attached at C-13 cleave at highest collision energies in the following order: the C-3 sugar, followed by the C-2 sugar and finally the sugar directly linked at C-13. Copyright © 2016 John Wiley & Sons, Ltd.

Development of a high‐performance liquid chromatography procedure to identify known and detect novel C‐13 oligosaccharide moieties in diterpene glycosides from Stevia rebaudiana (Bertoni) Bertoni (Asteraceae): Structure elucidation of rebaudiosides V and W

“…An intense product ion at m/z 773.3610 (84.8%, 40 eV) characteristic of the loss of two glucoses (–324 Da) at position C‐19 indicates the presence of a disaccharide with 1–2 interlinkage. Further sequential loss of one glucose unit at m/z 611.3083 (46.4%, 70 eV) from the C‐13 moiety followed by a loss of one xylose and glucose units m/z 479.2669 (19.4%, 70 eV) and 317.2110 (17.8%, 70 eV) to finally afford the aglycone, most probably steviol . The aglycone‐C13 arrangement previously assigned by the HPLC was corroborated by HRESI–MS/MS.…”

“…HRESI–MS/MS of compound 1 was previously reported . A molecular ion at m/z 1097.4676 [M–H] − , (calculated m/z 1097.4658 [M–H] – for C 49 H 78 O 27 ) was observed.…”

“…Iso‐stevioside A and iso‐stevioside where prepared under acidic condition from rebaudioside A and stevioside. Steviol is the main aglycone found in DGs being the core of 33 of the compounds studied, whereas the endocyclic 15‐ene steviol isomer is the main aglycone of iso‐stevioside, iso‐steviolbioside, and iso‐rebaudiosides A and B. Iso‐compounds elute in RP‐C18 a little later than their naturally occurring exocyclic isomers . Compounds with one glucose at C‐19 and two different kinds of sugars at position C‐13 showed an elution trend in C18 reverse phase HPLC as follows: Glcβ(1–2)Glcβ 1 – < Xylβ(1–2)Glcβ 1 – < Rhaα(1–2)Glcβ 1 – < Glc(1–3)Glcβ 1 .…”

“…The MS/MS dissociation pattern of steviol glycosides has been recently described, where it was observed that sugars linked at C‐19 are first cleaved at lower collision energies followed by stepwise fragmentation of the C‐13 moiety such that interlinkage assignments (without stereochemistry of linkage) of the C‐13 oligosaccharide could be deduced. . However, we are not able to get direct information for the C‐19 interlinkage if substituent is other than a monosaccharide moiety .…”

“…. However, we are not able to get direct information for the C‐19 interlinkage if substituent is other than a monosaccharide moiety . Thus, only by extensive 1D and 2D NMR analyses it is possible to elucidate unambiguously the stereochemistry of the C‐13 and the linkages of the oligosaccharide of the C‐19 portion.…”