Sociedade Brasileira de Espectrometria de Massas – BrMASS
Natural Products
“Mass spectrometry as an important toll to study the influence of media
composition in the cytochalasin´s production by endophytic fungus
isolated from Cupressus lusitanica”
Luciana S. Amaral1, Taicia P. Fill1, Edson Rodrigues Filho1
lu_samaral@yahoo.com.br, edson@dq.ufscar.br
Laboratório de Bioquímica Micromolecular de Micro-organismos (LaBioMMi)
– Departamento de Química - UFSCar
The cytochalasins are a class of fungal metabolite well known for their distinctive
biological activities [1]. Chemically, the cytochalasins are characterized by a highly
substituted perhydroisoindol ring system which is turn linked to a C16-C18 polyketide
ring system. The biosynthesis of cytochalasins involves the formation of an acetyl- and
methionine-derived polyketide chain and the attachment of an amino acid such as
phenylalanine, leucine, or tryptophan[2]. During our studies on the chemistry and
biochemistry aspects of plant microorganism’s interactions, we isolated an unidentified
endophytic fungus from leaves of Cupressus lusitanica which demonstrate a great
ability to produce cytochalasins in Czapeck media enriched with yeast extract. We
isolated and identificated the cytochalasin D (1), a mixture of cytochalasins C (2) and Q
(3), and detected some others, which contain a phenylalanine moiety. The ESI-MS of
cytochalasin D showed the ion [M+H]+ at m/z 508 and the MS/MS analyses of this was
carried out in order to obtain diagnostic product ions. The CID of the m/z 508
generated ions at m/z 490, 448, 430, 412 and 120, due to losses of water, acetic acid,
and the poliketide ring indicating the diagnostic ion related to phenylalanine moiety. It
is known that media composition can have a great impact on the production of
microbial products. Than, to verify the production of cytochalasins in this strain, we
screened a panel of extracts prepared from 5 different media (Czapeck, and Czapeck
supplemented with phenylalanie, tyrosine, alanine, tryptophan) and compared with the
extract from Czepck media enriched with yeast extract. In order to verify the presence
of the cytochalasins biosynthesized with the phenylalanine moiety in these different
media, we employed the LC/MS/MS precursor ion experiment, using the diagnostic ion
at m/z 120. The precursor ion at m/z 120 in the chromatogram showed the production
of the cytochalasins with a phenylalanine moiety in all different media. However the
media supplemented with phenylalanine showed more chromatographic peaks than the
others. We conclude that the MS is a powerfull toll to study the influence of media
composition on the fungal production of these secondary metabolites.
OH
(1)
HN
OH
HN
HN
OOAc
OH
O
(3)
O
(2)
OOAc
OH
O
OOAc
OH
O
Referências
[1] Feng, Y.; Blunt, J. W.; Cole, A. L. J.; Munro, M. H. G.; J. Mat. Prod. 2002, 65, 33 - 38.
[2] Lin, Z.; Zhu, T.; Wei, H.; Zhang, G.; Wang, H.; Gu, Q.; Eur. J. Org. Chem. 2009, 3045-3051
3º Congresso BrMass – 12 a 15 de Dezembro de 2009