Electrospray ionization ion‐trap time‐of‐flight tandem mass spectrometry of two furofurans: sesamin and gmelinol

Abstract

High-resolution electrospray ionization multistage tandem mass spectrometry (MS(1-7)) in positive ion mode was used to determine the accurate masses and the fragmentation pathways of two furofurans, sesamin and gmelinol. The protonated molecules [M+H]+ were absent in the conventional mass spectra of both compounds, but two characteristic ions, [M+H-H(2)O]+ and [M+H-H(2)]+, were always observed. Successive losses of CH(2)O and CO are the common characteristic fragmentations. Based on the exact masses acquired from 21 different tandem mass spectra, two or three fragmentation pathways for each compound are proposed. The consecutive losses of two H(2)O molecules and one H(2) molecule readily take place from the furan rings for both sesamin and gmelinol, resulting in the absence of the protonated molecules in the single-stage experiments. HCHO loss is observed at least three times in the tandem mass spectra, mainly from methylenedioxy groups (OCH(2)O) for sesamin but only from tetrahydrofuran rings for gmelinol. Moreover, CO loss is found at least three times in the tandem mass spectra of both sesamin and gmelinol from the 3,4-methylenedioxyphenyl (ArOCH(2)O) moieties for sesamin and from both the dimethoxyphenyl and the tetrahydrofuran ring moieties for gmelinol. In addition, the disubstituted benzyl cation ArCH(2)+ at m/z 135 for sesamin and at m/z 151 for gmelinol was found in the MS(3) spectra of both sesamin and gmelinol, which is very helpful in the identification of the compositions of 3,4-disubstituted groups on the benzene rings of the furofurans.

Furofuranic glycosylated lignans: a gas‐phase ion chemistry investigation by tandem mass spectrometry

“…In the CAD mass spectrum of sodiated (+)‐8‐hydroxypinoresinol 4‐ O ‐β‐D‐glucopyranoside ( 3 ), in addition to the ions at m/z 397 (loss of 162 Da), 309 and 185, the ion at m/z 395 arising from m/z 397 by loss of H 2 was detected. This fragmentation, previously described in the CAD mass spectra of protonated gmelinol,20 was not observed for sodiated (+)‐pinoresinol 4‐ O ‐β‐D‐glucopyranoside and suggests the pivotal role of the OH substituent in the C8 position.…”

“…High‐resolution tandem mass spectrometric experiments performed by an electrospray ion trap instrument equipped with a time‐of‐flight analyzer (ESI‐IT‐TOFMS n ), and operating in the positive ion mode, have been used to determine the accurate masses of two furofuranoid lignans, sesamin and gmelinol, and to hypothesize their fragmentation pathways 20…”

A critique on the structural analysis of lignins and application of novel tandem mass spectrometric strategies to determine lignin sequencing

“…The tentative fragmentation pathways for sesaminol in the negative and positive ionization modes are presented in Fig. …”

Structural characterization of bisretinoid A2E photocleavage products and implications for age-related macular degeneration

“…In addition, the presence of a stable 5; 8∕5 0 ; 8 0 -monofuran would be consistent with previously described mechanisms (13,17) whereas the C-C single bond associated with the peroxide at the 5, 6 (or 5 0 , 6 0 ) position in the cyclohexenyl ring would remain intact despite O-O bond photocleavage (13). In addition, the structures proposed for the precursor molecular ions were guided by mass spectrometry principles (18): (i) direct MS/MS cleavage at double bonds does not occur because of the high energy requirements (19); (ii) MS/MS fragmentation processes generally involve a loss of water from a substituted ethanol group and a loss of CO from an aldehyde; in the case of an aldehyde conjugated to the pyridinium ring, no loss of CO is observed; (iii) even-mass fragment ions containing the positive charge of the pyridinium group would form via homolytic cleavages at charge remote sites; (iv) oddmass product ion peaks would be radicals due to charge remote radical homolytic cleavages wherein the charge resides on the pyridinium group and a free radical resides at the fragmentation site; (v) homolytic charge remote site reactions would involve hydrogen and/or methyl rearrangements; (vi) oxygens could be added to aldehyde structures to satisfy elemental compositions and peroxides could undergo losses of atomic oxygen; and (vii) the C12-C13 and C14 0 -C15 0 single bonds of A2E would be strengthened by the C11-C12 and C13 0 -C14 0 double bonds, respectively, that are conjugated with double bonds situated in the aromatic ring (20,21). Importantly, the proposed structures of the precursor and product ions of the 8 photocleavage products, were also supported by exact-mass measurements performed utilizing ESI-Fourier transform-ion cyclotron resonance (FT-ICR) MS and MS/MS.…”