Fragmentation Pathway of Gingerol Using Electrospray Ionization with Quadrupole Time-of-Flight Mass Spectrometry

A method of electrospray ionization with quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF MS/MS) was used to detect 13 gingerol compounds of 6 types at positive and negative ion modes, then analysis of the secondary fragments was carried out, and the fragmentation pathway of gingerol compounds was speculated. The results showed that 13 gingerol compounds in the ESI-MS can produce [M+H]+ and [M-H]- quasi-molecular ion peaks at positive and negative ion modes. By analyzing the MS/MS data of gingerol compounds, it was found that the same type of gingerol compounds have similar fragmentation pathways. Acetoxy-6-gingerol and acetoxy-8-gingerol had two fragmentation pathways at positive ion mode. One fragmentation pathway was to remove the hydroxyl group on the benzene ring to produce fragment loss of H2O, and then the side chain was broken. Another fragmentation pathway was the loss of the substituent on C5, and then the side chain was broken and provided characteristic fragment ions m/z 179, m/z 137. Acetoxy-6-gingerol and acetoxy-8-gingerol had three fragmentation pathways at negative ion mode. One fragmentation pathway was brokenness of O-CH3 on the benzene ring, losing a CH3, and then the side chain was broken to provide characteristic fragment ions m/z 135, m/z 121. The second fragmentation pathway was the loss of substituents on C5, and then the side chain was broken. The other fragmentation pathway was brokenness of C1-C2 bond on the side chain to provide high abundance of fragment ions. At positive ion mode, 6-shogaol and 10-shogaol only provided fragment ions of m/z 137. At negative ion mode, one of the fragmentation pathways was that the brokenness of O-CH3 on the benzene ring, losing a CH3, and then the side chain was broken, another fragmentation pathway was the brokenness of C1-C2 bond, losing 136 u (C8H8O2) to provide high abundance of fragment ions m/z 139, m/z 195. (4E, 6Z)-4-paradoldiene, (4E, 6E)-6-paradoldiene, (4E, 6E)-8-paradoldiene could provide high abundance of fragment ion m/z 137 at positive ion mode, C1-C2 bond was broken at negative ion mode, losing C8H8O2 to provide high abundance of fragment ions m/z 137, 165, 193, other gingerol compounds also had similar fragmentation pathways. These fragmentation behaviors are helpful to analyze and identify the structure of other gingerol compounds in Zingiberis Rhizoma, and will also provide a basis for the rapid analysis and identification of Chinese medicines which contain gingerol components. © 2021, Editorial Board of Journal of Chinese Mass Spectrometry Society. All right reserved.