Proposed mechanisms for the fragmentation of doubly allylic alkenamides (tingle compounds) by low energy collisional activation in a triple quadrupole mass spectrometer

Abstract

Tingle compounds are a class of alkenamides with organoleptic properties that include a numbing or a pins and needles effect that is generally perceived on the lips and in the mouth when consumed. They occur in nature in a number of botanical species. Spilanthol and Pellitorine are important examples of tingle compounds. A number of homologs and analogs were synthesized to study the effect of chain length, double bond location, and amide moiety on the tingle effect. This also provided the opportunity to study the behavior of these compounds in the collision cell of a triple quadrupole mass spectrometer. The doubly allylic 2E,6Z-alkenamides, which made up the largest class studied, fragmented in a characteristic way to produce a distonic radical cation and a cyclopropene cation. Mechanisms for the formation of these ions are proposed. The mechanisms are supported by energy-resolved mass spectrometric data, the analysis of deuterated analogs and homologs that are not doubly allylic, and exact mass measurements. Exceptions to the proposed mechanisms are also presented. These data represent the first attempt to apply mechanistic principles to the product ions observed in the MS/MS spectra of these compounds. The authors believe the results of this study will facilitate the identification of these and similar compounds and contribute to the fundamental understanding of the behavior of alkenamides in the collision cell of a triple quadrupole mass

Structure and mechanism of formation of an important ion in doping control

“…For a given MS/MS-derived product ion, a breakdown curve consists of a plot of the relative abundance of the product ion versus collision energy. When breakdown curves for several product ions are displayed together, information on relative ease of formation and the identities of second, third, and subsequent generation product ions can be obtained [13]. Breakdown curves for all steroids analyzed were found to be nearly identical to that of epimetendiol (7) (Fig.…”

Isolation and identification of antiplasmodial N-alkylamides from Spilanthes acmella flowers using centrifugal partition chromatography and ESI-IT-TOF-MS

“…Compound name D10 IC50 (g/mL) n = 3 CHO IC50 (g/mL) n = 3 and 2-phenylethylamides revealing different characteristic Nisobutylamide and 2-methylbutylamide fragmentation ions by CID [29][30][31], have been identified [11]. N-alkylamide fragmentation by CID often forms an acyllium ion, with a m/z value indicative for the amount of carbon atoms in the alkyl chain.…”

Characterization of polyphenol compounds from the roots and stems of Parthenocissus laetevirens by high‐performance liquid chromatography/tandem mass spectrometry

“…The energy-resolved breakdown curves [25][26][27] and HPLC/ DAD-UV spectra were utilized to differentiate isomers. The breakdown curves of four pairs of trans-and cis-isomers (5 and 7, 9 and 8, 10 and 14, 11 and 15) were generated by the relative abundance of selected fragment ions versus collision energy.…”