Structural Studies of Polyhydroxybis(tetrahydrofuran)acetogenins from Annona squamosa Using the Combination of Chemical Derivatization and Precursor-ion Scanning Mass Spectrometry

Article abstract of DOI:10.1002/oms.1210281225

The structure of squamocin polyhydroxybis(tetrahydrofuran)acetogenin from Annona squamosa L., was characterized by a combination of the chemical derivatization and precursor-ion scanning mass spectrometry.The lactone part of squamocin was modified with N,N-dimethylethylenediamine in the vapour phase to afford a strong positive charge at one end of the skeleton.The derivative was ionized by fast atom bombardment (FAB), and the product-ion spectrum from (+) and the precursor ion spectrum from the m/z 72 ion generated by low-energy collision were acquired.The structure of the derivative could be characterized by the precursor-ion spectrum from the m/z 72 ion, but little structural information could be obtained from the product-ion spectrum from (+) of the derivative.By the attachment of a tertiary amino group to one end of the skeleton, charge-remote fragmentation was facilitated and abundant and unique fragment ions were observed in the precursor-ion spectrum.Structural characterization of six other isolated compounds was also carried out, and two novel compounds were found by this technique.A similar derivatization was applied in the peptide leu-enkephalin, and full sequencing from the C-terminus using precursor-ion scanning from m/z 72 could be achieved.