Bactérias associadas com esponjas marinhas produzem peptídeos cíclicos com atividade anti oomiceto.

Bactérias associadas com esponjas marinhas têm sido exaustivamente exploradas pela indústria farmacêutica como uma fonte rica de metabólitos secundários. Contudo, pouco esforço tem sido dedicado à descoberta de compostos agroquímicos a partir de produtos naturais marinhos. Neste trabalho, foram investigados os compostos produzidos por bactérias isoladas de esponjas marinhas, capazes de inibir o crescimento micelial de oomicetos fitopatogênicos pertencentes ao gênero Pythium. Os bioensaios mostraram que bactérias associadas às esponjas Didiscus oxeata e Scopalina ruetzleri inibem o crescimento de P. aphanidermatum, P. graminicola e P. ultimum. Subsequentemente, foi realizado o fracionamento do extrato bruto guiado por bioensaio usando cromatografia líquida de alta eficiência. A identificação estrutural dos compostos, presente na fração bioativa, foi realizada por espectrometria de massas sequencial (ESI-MS/MS). Esta ferramenta possibilitou a identificação de dipepitídeos cíclicos pertencentes à classe das dicetopiperazinas (DKPs), a partir de duas bactérias filogeneticamente distintas, classificadas com base no sequenciamento do gene 16S rRNA como Terrabacter sp. ASPSP 140 e Bacillus sp. ASPSP 434. Estes dados reforçam o potencial uso de bactérias associadas com esponjas marinhas para o controle de oomicetos fitopatogênicos e fornece a base para o futuro desenvolvimento de novos fungicidas de baixo impacto ambiental

Actinobacteria from Antarctica as a source for anticancer discovery.

Abstract: Although many advances have been achieved to treat aggressive tumours, cancer remains a leading cause of death and a public health problem worldwide. Among the main approaches for the discovery of new bioactive agents, the prospect of microbial secondary metabolites represents an effective source for the development of drug leads. In this study, we investigated the actinobacterial diversity associated with an endemic Antarctic species, Deschampsia antarctica, by integrated culture-dependent and culture-independent methods and acknowledged this niche as a reservoir of bioactive strains for the production of antitumour compounds. The 16S rRNA-based analysis showed the predominance of the Actinomycetales order, a well-known group of bioactive metabolite producers belonging to the Actinobacteria phylum. Cultivation techniques were applied, and 72 psychrotolerant Actinobacteria strains belonging to the genera Actinoplanes, Arthrobacter, Kribbella, Mycobacterium, Nocardia, Pilimelia, Pseudarthrobacter, Rhodococcus, Streptacidiphilus, Streptomyces and Tsukamurella were identified. The secondary metabolites were screened, and 17 isolates were identified as promising antitumour compound producers. However, the bio-guided assay showed a pronounced antiproliferative activity for the crude extracts of Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653. The TGI and LC50 values revealed the potential of these natural products to control the proliferation of breast (MCF-7), glioblastoma (U251), lung/non-small (NCI-H460) and kidney (786-0) human cancer cell lines. Cinerubin B and actinomycin V were the predominant compounds identified in Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653, respectively. Our results suggest that the rhizosphere of D. antarctica represents a prominent reservoir of bioactive actinobacteria strains and reveals it as an important environment for potential antitumour agents

Dereplication of Streptomyces sp. AMC 23 polyether ionophore antibiotics by accurate-mass electrospray tandem mass spectrometry.

Abstracts: Actinomycetes, especially those belonging to the genus Streptomyces, are economically important from a biotechnological standpoint: they produce antibiotics, anticancer compounds and a variety of bioactive substances that are potentially applicable in the agrochemical and pharmaceutical industries. This paper combined accurate-mass electrospray tandem mass spectrometry in the full scan and product ion scan modes with compounds library data to identify the major compounds in the crude extract produced by Streptomyces sp. AMC 23; it also investigated how sodiated nonactin ([M + Na]+) fragmented. Most product ions resulted from elimination of 184 mass units due to consecutive McLafferty-type rearrangements. The data allowed identification of four macrotetrolides homologous to nonactin (monactin, isodinactin, isotrinactin/trinactin and tetranactin) as well as three related linear dimer compounds (nonactyl nonactoate, nonactyl homononactoate and homononactyl homononactoate). The major product ions of the sodiated molecules of these compounds also originated from elimination of 184 and 198 mass units. UPLC-MS/MS in the neutral loss scan mode helped to identify these compounds on the basis of the elimination of 184 and 198 mass units. This method aided monitoring of the relative production of these compounds for 32 days and revealed that the biosynthetic process began with increased production of linear dimers as compared with macrotetrolides. These data could facilitate dereplication and identification of these compounds in other microbial crude extracts.201

Precursor Ion Scan Mode-Based Strategy for Fast Screening of Polyether Ionophores by Copper-Induced Gas-Phase Radical Fragmentation Reactions

The potential of copper­(II) to induce gas-phase fragmentation reactions in macrotetrolides, a class of polyether ionophores produced by Streptomyces species, was investigated by accurate-mass electrospray tandem mass spectrometry (ESI-MS/MS). Copper­(II)/copper­(I) transition directly induced production of diagnostic acylium ions with <i>m</i>/<i>z</i> 199, 185, 181, and 167 from α-cleavages of [macrotetrolides + Cu]²⁺. A UPLC-ESI-MS/MS methodology based on the precursor ion scan of these acylium ions was developed and successfully used to identify isodinactin (<b>1</b>), trinactin (<b>2</b>), and tetranactin (<b>3</b>) in a crude extract of Streptomyces sp. AMC 23 in the precursor ion scan mode. In addition, copper­(II) was also used to induce radical fragmentation reactions in the carboxylic acid polyether ionophore nigericin. The resulting product ions with <i>m</i>/<i>z</i> 755 and 585 helped to identify nigericin in a crude extract of Streptomyces sp. Eucal-26 by means of precursor ion scan experiments, demonstrating that copper-induced fragmentation reactions can potentially identify different classes of polyether ionophores rapidly and selectively

In vitro activities of pfaffia glomerata root extract, its hydrolyzed fractions and pfaffic acid against trypanosoma cruzi trypomastigotes

This article reports on the in vitro activity of the hydroalcoholic extract of Pfaffia glomerata roots, its hydrolyzed fractions, and pfaffic acid against Trypanosoma cruzi. The hydroalcoholic extract obtained from dried, milled P. glomerata roots was submitted to acid hydrolysis followed by partition with CHCl3. The concentrated CHCl3 fraction was suspended in MeOH/H2O and partitioned with hexane (F1), CHCl3 (F2), and AcOEt (F3), in this sequence. The trypanocidal activity of the hydrolyzed extract and its fractions was evaluated in vitro. The hydroalcoholic extract displayed low activity, but fraction F1 was active against trypomastigotes of the Y strain of T. cruzi, with IC50 = 47.89 g/ml. The steroids campesterol (7.7%), stigmasterol (18.7%), -sitosterol (16.8%), (7)-stigmastenol (4.6%), and (7)-spinasterol (7.5%) were the major constituents of F1, along with fatty acid esters (7.6%) and eight aliphatic hydrocarbons (30.1%). Fractions F2 and F3 exhibited moderate activity, and pfaffic acid, one of the main chemical constituents of these fractions, displayed IC50 = 44.78 m (21.06 g/ml). On the other hand, the hydroalcoholic extract of P. glomerata roots, which is rich in pfaffosides, was inactive. Therefore, the main aglycone of pfaffosides, pfaffic acid, is much more active against trypomastigotes of the Y strain of T. cruzi than its corresponding glycosides and should be further investigated141CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP303349/2013-12013/20094-