ABSTRACT
ABSTRACT Aspergillus spp. cause economic impacts due to aflatoxins production. Although the toxicity of aflatoxins is already known, little information about their ecological roles is available. Here we investigated the compounds produced by Aspergillus nomius ASR3 directly from a dead leaf-cutter queen ant Atta sexdens rubropilosa and the fungal axenic culture. Chemical analyses were carried out by high-resolution mass spectrometry and tandem mass spectrometry techniques. Aflatoxins B1 and G1 were detected in both the axenic culture and in the dead leaf-cutter queen ant. The presence of these mycotoxins in the dead leaf-cutter queen ant suggests that these compounds can be related to the insect pathogenicity of A. nomius against A. sexdens rubropilosa.
ABSTRACT
Abstract Methanolic extracts of the Brazilian endemic ascidian Eudistoma vannamei have been extensively studied for their cytotoxic activity against several human cancer cell lines. Previous work reported the occurrence of purine derivatives and staurosporine alkaloids as the major nitrogen-containing compounds. In this study, we report the occurrence of three pyrimidine alkaloids in addition to cholesterol, sitosterol and stigmasterol.
ABSTRACT
The present study evaluated the chemical profile of polar extracts of Calendula officinalis L., Asteraceae, that were grown under different cultivation conditions: chemical fertilisation, organic fertilisation and mulching. Furthermore, we investigated metabolite variations during plant development by comparing the metabolites from harvested plants at 60 and 120 days after planting. We used HPLC-DAD-MS/MS to tentatively identify metabolites. In total, we identified seven known compounds: five flavonoid glycosides and two caffeoylquinic acids derivatives. There were no statistically significant differences in the expression of metabolites from plants grown under the examined soil treatments. However, five substances varied according to harvest time, suggesting that the biosynthesis of polar metabolites of Calendula officinalis is not affected by changes in soil composition. Therefore, this plant could represent a source for phytomedicines with a constant content of polar metabolites.
ABSTRACT
The MS/MS fragmentation of the alkali metal complexes of monensin A are studied. The increase in alkali metal ionic radii decreases the ability of the Grob-Wharton fragmentation mechanism to occur and reduces the overall degree of fragmentation. Conversely, the electronegativity of the metal cation is related to the number of fragment ions observed.
O presente trabalho relata os estudos de fragmentação por espectrometria de massas seqüencial de complexos formados pela monensina A e uma série de metais alcalinos. Foi observado que o aumento do raio iônico do metal alcalino levou a uma diminuição do mecanismo de fragmentação do tipo Grob-Wharton e ao grau de fragmentação. Por outro lado, a maior eletronegatividade mostrou estar relacionada ao número de fragmentos observados.
Subject(s)
Cations , Metals, Alkali , Mass SpectrometryABSTRACT
The labelled substrates phenylalanine and thephenylpropanoid Eisoeugenol were incorporated to 5-methoxy-4-O-methyl-Eisoeugenol (E-isoelemicin) and to the tetrahydrofuran lignan verrucosin biosynthesized in plantlets of Virola surinamensis (Myristicaceae)
Subject(s)
Lignans , Phenylalanine , Plants, Medicinal , Chromatography, High Pressure Liquid/methodsABSTRACT
The development and comparison of two analytical methods (HPLC and GC) for the quantification of the most common furanoheliangolides from Lychnophora is reported in this paper. Both methods are sensitive and suitable for quantification of these metabolites.