Electrospray tandem mass spectrometric analysis of a dimeric conjugate, salvialeriafone and related compounds.
BACKGROUND
Electrospray tandem mass spectrometry approach is widely used for the rapid characterization of natural products. This paper describes the gas-phased ESI-MS/MS fragmentation of abietane-type diterpenoids and their novel dimeric conjugate, salvialeriafone (1) using both positive and negative ion electrospray ionization quadropole time-of-flight mass spectrometry (ESI-QqTOF-MS/MS) hybrid instrument. Diterpenoids are widely distributed throughout the plant kingdom and posses interesting biological activities.


RESULTS
ESI-QqTOF-MS (positive ion mode) of diterpenoids 1-6 under collision-induced dissociation tandem mass spectrometric analysis (CID-MS/MS) showed the characteristic losses of water, carbonmonoxide and propene molecules, while analysis in negative ion mode showed the characteristic losses of water, carbon monoxide, methane molecules and methyl radical. Results demonstrated the differences in the product ions and base peaks due to the differences in the skeleton. A novel dimeric conjugate, salvialeriafone (1) showed characteristic fragmentation pattern and was found to be more prone to form radical ions, as compared to monomeric diterpenoids. The fragmentation pathways of characteristic fragments were proposed with the aid of HRESIMS.


CONCLUSIONS
Extensive tandem mass spectrometric studies of salvialeriafone (1) and related diterpenoids 2-6 were conducted and their characteristic fragments were identified. The knowledge of the fragmentation pattern of these diterpenoids will be useful for the characterization of new dimers of this class of compounds.
H,E,J, Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan. musharraf1977@yahoo.com.
Syed
S
Ghulam Musharraf
Madiha
M
Goher
Amjad
A
Hussain
M Iqbal
MI
Choudhary