Alkaloids from plants of the genus Erythrina display important biological activities, including anxiolytic action. Characterization of these alkaloids by mass spectrometry (MS) has contributed to the construction of a spectral library, has improved understanding of their structures and has supported the proposal of fragmentation mechanisms in light of density functional calculations. In this study, we have used low-resolution and high-resolution MS analyses to investigate the fragmentation patterns of erythrinian alkaloids; we have employed the B3LYP/6-31+G(d,p) model to obtain their reactive sites. To suggest the fragmentation mechanism of these alkaloids, we have studied their protonation sites by density functional calculation, and we have obtained their molecular electrostatic potential map and their gas-phase basicity values. These analyses have indicated the most basic sites on the basis of the proton affinities of the nitrogen and oxygen atoms. The protonated molecules were generated by two major fragmentations, namely, neutral loss of CH OH followed by elimination of H O. High-resolution analysis confirmed elimination of NH by comparison with the losses of H and •CH . NH was eliminated from compounds that did not bear a substituent on ring C. The benzylic carbocation initiated the dissociation mechanism, and the first reaction involved charge transfer from a lone pair of electrons in the oxygen atoms. The second reaction consisted of ring contraction with loss of a CO molecule. The presence of hydroxy and epoxy groups could change the intensity or the occurrence of the fragmentation pathways. Given that erythrinian alkaloids are applied in therapeutics and are promising leads for the development of new drugs, the present results could aid identification of several analogues of these alkaloids in biological samples and advance pharmacokinetic studies of new plant derivatives based on MS and MS/MS analyses. Copyright © 2017 John Wiley & Sons, Ltd.

Leishmaniasis is one of the World's most problematic diseases in developing countries. Traditional medicines to treat leishmaniasis have serious side effects, as well as significant parasite resistance problems. In this work, two alkaloids 1 and 2 were obtained from Corydalis govaniana Wall and seven alkaloids 3-9, were obtained from Erythrina verna. The structures of the compounds were confirmed by mass spectrometry and 1D-and 2D-NMR spectroscopy. The leishmanicidal activity of compounds 1-9 against Leishmania amazonensis was tested on promastigote forms and cytotoxicity against J774 (macrophage cell line) was assessed in vitro. Compound 1 showed potent activity (IC 50 = 0.18 µg/mL), compared with OPEN ACCESSMolecules 2014, 19 5693 the standard amphotericin B (IC 50 = 0.20 µg/mL). The spirocyclic erythrina-alkaloids showed lower leishmanicidal activity than dibenzoquinolizine type alkaloids.

Preto -SP, BrasilRecebido em 1/6/12; aceito em 23/8/12; publicado na web em 28/9/12 APPLICATION OF ELECTRON IONIZATION MASS SPECTROMETRY FOR MULUNGU ALKALOID ANALYSIS. Erythrina verna is a medicinal plant used to calm agitation popularly known as mulungu. We purchased the barks of E. verna from a commercial producer and analyzed the alkaloid fraction of the bark by CG-MS and HRESI-MS. Five erythrinian alkaloids were identified: erysotrine, erythratidine, erythratidinone, epimer, and 11-hydroxieritratidinone. Here we report the compound 11-hydroxieritratidinone for the first time as a natural product.Keywords: E. verna; alkaloids; fragmentation pattern. INTRODUÇÃOO Prof. Otto Richard Gottlieb dedicou sua vida científica ao entendimento da natureza para que se pudesse utilizá-la de forma racional. Com uma visão à frente de seu tempo, o Prof. Otto já discutia a análise de perfis químicos para se entender um organismo de maneira completa. Para isso, o referido professor também se dedicou ao estudo e desenvolvimento de aplicações de ferramentas analíticas que pudessem auxiliar nas diferentes áreas de pesquisa em produtos naturais. Isso pode ser confirmado pela publicação de um dos primeiros livros em língua portuguesa sobre espectrometria de massas.1 Essa técnica hoje, junto com a ideia de análise de perfil químico é um dos pilares da Metabolômica, área que vem crescendo de forma vertiginosa nos diversos campos da ciência e que tem como uma de suas propostas o entendimento mais amplo de metabolismo de um organismo.Nesse contexto, uma das teorias do Prof. Otto aventou o efeito de borda de diferentes ambientes na expressão do metabolismo secundário. Nesse caso, espécies de um ambiente, quando em áreas de borda como, por exemplo, zona de interface entre o Cerrado e a Mata Atlântica ou o Cerrado e a Floresta Amazônica, poderiam ter amplificado suas substâncias de defesa ou seus mecanismos alelopá-ticos. Estudos químicos com a espécie L. ericoides, conhecida popularmente como arnica da serra, revelou que as populações de campus rupestris, habitat natural da espécie, apresentavam um perfil muito semelhante com predomínio de flavonoides e ácidos clorogênicos e sem nenhuma atividade citotóxica significativa.2 Por outro lado, a população na região de transição mostrou um acúmulo dos fenólicos citados anteriormente junto com uma intensa expressão de lactonas sesquiterpênicas com alta atividade citotóxica. A análise conjunta de todos os dados obtidos nesse trabalho, levou os autores a proporem que existia sim um possível efeito de borda, alertando para o cuidado sobre a origem da matéria-prima para uso como fitoterápico.3 Essa discussão também tem sido ampliada com outras plantas medicinais brasileiras. Um gênero em especial, o Erythrina (família Fabaceae), tem sido alvo de discussão em virtude de possíveis variações em seu marcador químico. Este gênero compreende aproximadamente 115 espécies tropicais e subtropicais distribuídas nos hemisférios norte e sul.4 O nome Erythrina é proveniente do grego "erythros", que significa ver...

Motivation Annotation of the mass signals is still the biggest bottleneck for the untargeted mass spectrometry analysis of complex mixtures. Molecular networks are being increasingly adopted by the mass spectrometry community as a tool to annotate large scale experiments. We have previously shown that the process of propagating annotations from spectral library matches on molecular networks can be automated using Network Annotation Propagation (NAP). One of the limitations of NAP is that the information for the spectral matches is only propagated locally, to the first neighbor of a spectral match. Here we show that annotation propagation can be expanded to nodes not directly connected to spectral matches using random walks on graphs, introducing the ChemWalker python library. Results Similarly to NAP, ChemWalker relies on combinatorial in silico fragmentation results, performed by MetFrag, searching biologically relevant databases. Departing from the combination of a spectral network and the structural similarity among candidate structures, we have used MetFusion Scoring function to create a weight function, producing a weighted graph. This graph was subsequently used by the random walk to calculate the probability of ’walking’ through a set of candidates, departing from seed nodes (represented by spectral library matches). This approach allowed the information propagation to nodes not directly connected to the spectral library match. Compared to NAP, ChemWalker has a series of improvements, on running time, scalability and maintainability and is available as a stand alone python package. Availability ChemWalker is freely available at https://github.com/computational-chemical-biology/ChemWalker Supplementary information Supplementary data are available at Bioinformatics online.

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Marsypianthes chamaedrys (Vahl.) Kuntze, known as paracari, erva de cobra, bóia-caá or betônia brava, is a common herb in Brazil (North and Northeast regions). The aerial parts (leaves and stem) of this plant were used to essential oil extraction. The essential oil obtained was evaluated against Tetranychus urticae showing no significant acaricidal activity. Analysis by GC-MS was performed and 29 compounds were identified and the main compounds were the sesquiterpenes β-caryophyllene (12.2%), bicyclogermacrene (17.9%) and germacrene D (34.1%).

Annotation of the mass signals is still the biggest bottleneck for the untargeted mass spectrometry analysis of complex mixtures. Molecular networks are being increasingly adopted by the mass spectrometry community as a tool to annotate large scale experiments. We have previously shown that the process of propagating annotations from spectral library matches on molecular networks can be automated using Network Annotation Propagation (NAP). One of the limitations of NAP is that the information for the spectral matches is only propagated locally, to the first neighbor of a spectral match. Here we show that annotation propagation can be expanded to nodes not directly connected to spectral matches using random walks on graphs, introducing the ChemWalker python library. Similarly to NAP, ChemWalker relies on combinatorial in silico fragmentation results, performed by MetFrag, searching biologically relevant databases. Departing from the combination of a spectral network and the structural similarity among candidate structures, we have used MetFusion Scoring function to create a weight function, producing a weighted graph. This graph was subsequently used by the random walk to calculate the probability of 'walking' through a set of candidates, departing from seed nodes (represented by spectral library matches). This approach allowed the information propagation to nodes not directly connected to the spectral library match. Compared to NAP, ChemWalker has a series of improvements, on running time, scalability and maintainability and is available as a stand alone python package. ChemWalker is freely available at https://github.com/computational-chemical- biology/ChemWalker.