title: Fragmentation of diketopiperazines from Aspergillus fumigatus by electrospray ionization tandem mass spectrometry (ESI-MS/MS).
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 (DeltaG) 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.
authors: Núcleo de Pesquisas em Ciências Exatas e Tecnológicas, Universidade de Franca, Franca, SP, Brazil.
authors: Niege A J C
authors: NA
authors: Furtado
authors: Ricardo
authors: R
authors: Vessecchi
authors: José Carlos
authors: JC
authors: Tomaz
authors: Sérgio E
authors: SE
authors: Galembeck
authors: Jairo K
authors: JK
authors: Bastos
authors: Norberto P
authors: NP
authors: Lopes
authors: Antonio E M
authors: AE
authors: Crotti
mesh_terms: D001232:Aspergillus fumigatus / Q000737:chemistry*; D054659:Diketopiperazines / Q000737:chemistry*; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D054659:Diketopiperazines