Antimicrobial metabolites produced by endophytic fungi associated with the leaves of Vochysia divergens.

Investigation of the endophytic fungi Nigrospora sphaerica, Nigrospora oryzae, and Pseudofusicoccum stromaticum MeOH fractions isolated from the leaves of Vochysia divergens, a medicinal species from the Brazilian Pantanal, led to the identification of five compounds, namely a new compound (1E,8Z)-10,11-dihydroxy-5,5,8-trimethyl-4-oxocycloundeca-1,8-diene-1-carbaldehyde (1) and four known compounds: 5-methylmellein (2), sclerone (3), daldinone A (4), and lasiodiplodin (5). All compounds were identified using spectroscopic methods, and 1 was corroborated with mass spectrometry, while the known compounds were compared with data in the literature. The relative configuration of compound 1 was determined based on theoretical conformational studies as well as the J experimental values between the hydroxymethyne hydrogens. The antimicrobial activity of the compounds was evaluated. Promising results were obtained for compounds 2, 4, and 5 since they inhibited the bacterium Pseudomonas aeruginosa, an opportunistic pathogen, suggesting the potential of these microorganisms as a source of new antibacterial agents.

New Isoquinoline Alkaloids from Paraphaeosphaeria sporulosa F03, a Fungal Endophyte Isolated from Paepalanthus planifolius.

As part of our continuing efforts to discover new bioactive compounds from endophytic fungal sources, we have investigated the extract of the Paraphaeosphaeria sporulosa F03 strain. The study led to the isolation of four new 3-methyl-isoquinoline alkaloids (1:  - 4: ) and four known polyketides (5:  - 8: ). The structures of compounds 1:  - 4: were elucidated by 1D and 2D NMR experiments and HRMS analysis. The absolute configuration of 4: was determined by comparison of its experimental electronic circular dichroism spectrum with calculated data. Compounds 1:  - 4: exhibited antifungal activity with minimal inhibitory concentration values ranging from 6.25 - 50 µg/mL against six Candida species but they did not present any cytotoxic activity against the human tumor cell lines A549 (lung), MCF-7 (breast), and HepG2 (hepatocellular). In addition, compound 4: exhibited antiplasmodial activity in the low micromolar range (IC50 = 4 µM).

Structure predictions of two Bauhinia variegata lectins reveal patterns of C-terminal properties in single chain legume lectins.

Bauhinia variegata lectins (BVL-I and BVL-II) are single chain lectins isolated from the plant Bauhinia variegata. Single chain lectins undergo post-translational processing on its N-terminal and C-terminal regions, which determines their physiological targeting, carbohydrate binding activity and pattern of quaternary association. These two lectins are isoforms, BVL-I being highly glycosylated, and thus far, it has not been possible to determine their structures. The present study used prediction and validation algorithms to elucidate the likely structures of BVL-I and -II. The program Bhageerath-H was chosen from among three different structure prediction programs due to its better overall reliability. In order to predict the C-terminal region cleavage sites, other lectins known to have this modification were analysed and three rules were created: (1) the first amino acid of the excised peptide is small or hydrophobic; (2) the cleavage occurs after an acid, polar, or hydrophobic residue, but not after a basic one; and (3) the cleavage spot is located 5-8 residues after a conserved Leu amino acid. These rules predicted that BVL-I and -II would have fifteen C-terminal residues cleaved, and this was confirmed experimentally by Edman degradation sequencing of BVL-I. Furthermore, the C-terminal analyses predicted that only BVL-II underwent α-helical folding in this region, similar to that seen in SBA and DBL. Conversely, BVL-I and -II contained four conserved regions of a GS-I association, providing evidence of a previously undescribed X4+unusual oligomerisation between the truncated BVL-I and the intact BVL-II. This is the first report on the structural analysis of lectins from Bauhinia spp. and therefore is important for the characterisation C-terminal cleavage and patterns of quaternary association of single chain lectins.

Indução de resistência em arroz contra Bipolaris oryzae Breda de Hann, através da expressão constitutiva de um gene de quitinase / Induction of resistance in rice against Bipolaris oryzae Breda de Hann by constitutive expression of achitinase gene

Este trabalho objetivou a transformação genética da cultivar de arroz BRS Taim, para obtenção de resistência ao fungo Bipolaris oryzae, agente da mancha parda. Para a transformação das plantas foi utilizada a cepa LBA 4404 de Agrobacterium tumefaciens transformada com o plasmídeo pMOG 22 que codifica o gene da quitinase do fungo entomopatogênico Metarhizium anisopliae. Mesocótilos de arroz foram imersos por 30 min. em solução bacteriana (OD600 = 0,7), contendo acetoceringona (100 Mm). Após os explantes foram co-cultivados por 72 horas em meio MS sem hormônio. Para seleção dos transformantes foi utilizado meio MS com 5 mg L-1 de BAP e 15 mg L-1 de higromicina, incubados a 25±1°C, fotoperíodo de 16 horas e densidade de fluxo de fótons de 42 µmol m-2 s-1. Foram obtidas 5 plantas transformadas, perfazendo uma média de eficiência de transformação de 1,53 %. A resistência das plantas foi observada somente por um dos isolados. Os resultados permitem concluir que as plantas de arroz transformadas com o gene da quitinase(Chit 1)podem reduzir o desenvolvimento do fungo B. oryzae, porém existe uma diferença na reação entre isolados.

This study aimed at a rice transformation for resistance to Bipolaris oryzae causal organism of Brown Spot, the cultivar BRS Taim and the line LBA 4404 of Agrobacterium tumefaciens transformed with plasmid pMOG 22 that codifies the chitinasegene Metarhizium anisopliae was used. Rice mesocotils immersed for 30 min in bacterial solution of OD600 = 0,7 with acetoceringone (100Mm), were co-cultivated for 72 hours in MS medium free of hormones and with 100Mm of acetoceringone. Mesocotils were then transferred to MS with 5mg L-1 de BAP and15 mg L-1 of higromicin for 45 days at 25°C and 16 ligth hours. The five transformed plants obtained (1,53 transformation rate) were inoculated with two B. oryzae isolates.Resistance was observed only with one of the isolates. The results indicate that rice plants transformed with chitinase gene (Chit 1)can reduce the colonization by some isolates of B. oryzae.

Biodegradation of microcystins by aquatic Burkholderia sp. from a South Brazilian coastal lagoon.

Biological degradation of cyanobacterial hepatotoxin microcystins in estuarine and coastal water samples from the Patos Lagoon estuarine system, a coastal lagoon situated at the southernmost region of Brazil, was observed. Samples of natural surface water were spiked with purified and semi-purified microcystins (MC-LR and [D-Leu(1)]MC-LR) and their concentrations were monitored by HPLC analysis. After 15 days, the toxins were no longer detectable and after 43 days less than 90% of the initial concentration added to the samples was detected by ELISA. The average degradation rates and the exponential decay rate constants from inside and outside of the estuary were similar. A microcystin degradative bacterium was isolated from the estuarine region. Partial sequence of the 16S rDNA showed a 96% homology with the Burkholderia genus. This genus belongs to the beta subdivision on proteobacteria. This is the first report showing the genus Burkholderia as a cyanobacterial toxin degrader.

Relationships in subtribe Diocleinae (Leguminosae; Papilionoideae) inferred from internal transcribed spacer sequences from nuclear ribosomal DNA.

The complete sequences of nuclear ribosomal DNA (nrDNA) internal transcribed spacer regions (ITS/5.8S) were determined for species belonging to six genera from the subtribe Diocleinae as well as for the anomalous genera Calopogonium and Pachyrhizus. Phylogenetic trees constructed by distance matrix, maximum parsimony and maximum likelihood methods showed that Calopogonium and Pachyrhizus were outside the clade Diocleinae (Canavalia, Camptosema, Cratylia, Dioclea, Cymbosema, and Galactia). This finding supports previous morphological, phytochemical, and molecular evidence that Calopogonium and Pachyrhizus do not belong to the subtribe Diocleinae. Within the true Diocleinae clade, the clustering of genera and species were congruent with morphology-based classifications, suggesting that ITS/5.8S sequences can provide enough informative sites to allow resolution below the genus level. This is the first evidence of the phylogeny of subtribe Diocleinae based on nuclear DNA sequences.