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Fragmentation of diketopiperazines from Aspergillus fumigatus by electrospray ionization tandem mass spectrometry (ESI-MS/MS)

✍ Scribed by Niege A. J. C. Furtado; Ricardo Vessecchi; José Carlos Tomaz; Sérgio E. Galembeck; Jairo K. Bastos; Norberto P. Lopes; Antonio E. M. Crotti

Publisher
John Wiley and Sons
Year
2007
Tongue
English
Weight
299 KB
Volume
42
Category
Article
ISSN
1076-5174

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✦ Synopsis

Abstract

Diketopiperazines (DKPs) corresponding to cyclic dipeptides have been reported to exhibit antimicrobial, antitumor, antimutagenic and antiviral properties. These compounds are commonly isolated from microorganisms and sponges and from a variety of tissues and body fluids. In this work, we used electrospray ionization tandem mass spectrometry (ESI‐MS/MS) to investigate the fragmentation of a series of DKPs previously isolated from Aspergillus fumigatus, which exhibit the same structural core. Loss of CO directly from the protonated molecule was found to be a fragmentation process common to all the compounds analyzed. However, our results revealed a series of ions that are diagnostic for the substituents at C(4) and C(9). In order to rationalize the differences in the fragmentation pathways of substituted and nonsubstituted DKPs, the relative Gibbs energies (Δ__G__) of the product ions and intermediate ions were estimated using the B3LYP/6–31 + + G(d,p) model. The data reported here can be used for the structural elucidation of DKPs from low sample amounts, as an alternative to NMR. Copyright © 2007 John Wiley & Sons, Ltd.

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