Gabriela M. Cabrera

Influence of growth temperature on cryotolerance and lipid composition of Lactobacillus acidophilus

In order to correlate the lipid composition of the membrane of Lactobacillus acidophilus CRL 640 with the freeze–thaw behaviour of the cultures grown at different temperatures, fatty acid methyl esters (FAMEs) from extracts grown at 25, 30, 37 and 40 °C were obtained and compared. Cultures grown at 25 °C (M25) exhibited more resistance to the freeze–thaw process probably because of an increase in C18:2 and C16:0 fatty acids. This culture also exhibited a lesser amount of phospholipids as shown by the sugar : phosphorus ratio. In all cases, the presence of the uncommon 10‐hydroxyoctadecanoic acid was determined. From the extracts of the M25 and M37 cultures, diacylphosphatidylglycerol, cardiolipin, diglycosyldiglycerides, triglycosyldiglycerides and neutral lipids were isolated and identified. The structural elucidation was carried out by FAMEs and sugar analysis and by mass spectrometry using fast atom bombardment ionization. The changes in lipid composition due to different growth temperatures could be indicative of the resistance of the bacteria to freeze–thaw processes.

Clonostachys rosea BAFC3874 as a Sclerotinia sclerotiorum antagonist: mechanisms involved and potential as a biocontrol agent.

Aims:  To establish the modes of action of the antagonistic fungal strain Clonostachys rosea BAFC3874 isolated from suppressive soils against Sclerotinia sclerotiorum and to determine its potential as a biocontrol agent.

5H-Furan-2-ones from fungal cultures of Aporpium caryae

Four furanones 1-4 with an unusual skeleton containing an acetylene unit, named aporpinones, were isolated from the culture of the basidiomycete Aporpium caryae and their structures were elucidated by spectroscopic methods. Compounds 3 and 4 showed weak to moderate antibacterial activity against Bacillus subtilis, Staphylococcus aureus and Escherichia coli.

Cyclosporine A from a nonpathogenic Fusarium oxysporum suppressing Sclerotinia sclerotiorum.

Aims:  To evaluate the antagonistic activity of Fusarium oxysporum nonpathogenic fungal strain S6 against the phytopathogenic fungus Sclerotinia sclerotiorum and to identify the antifungal compounds involved.

Indole alkaloids from a culture of the fungus Aporpium caryae

In a screening for antifungal metabolites, two indole compounds of mixed biogenesis, 1H-indole-3-carboxylic acid, 1-(1,1-dimethyl-2-propenyl) methyl ester and 1H-indole-3-carboxylic acid, 1-(2,3-dihydroxy-1,1-dimethylpropyl) methyl ester were isolated from a culture of the basidiomycete Aporpiums caryae. The structural elucidation of these compounds was accomplished by spectroscopic methods.

Synthesis and cytotoxic activity evaluation of dihydrocucurbitacin B and cucurbitacin B derivatives

Two cucurbitacins, dihydrocucurbitacin B (1) and cucurbitacin B (2), which can be obtained in large amounts from the roots of Wilbrandia ebracteata and from the fruits of Luffa operculata, respectively, were used as starting materials for the preparation of a library of 29 semi-synthetic derivatives. The structural changes that were performed include the removal, modification or permutation of functional groups in rings A and B as well as in the side chain. All new semisynthetic compounds, as well as 1 and 2, were tested in vitro for their cytotoxic effects on non-small-cell lung cancer cells (A549 cells). Some of these compound displayed potent to moderate activity against A549 tumor cells, especially those cucurbitacin B derivatives which were modified at ring A.

Cardenolide glycosides from the roots of mandevilla pentlandiana

Abstract From the roots of Mandevilla pentlandiana 13 cardenolide-type compounds were isolated. Besides free aglycones digitoxigenin and oleandrigenin, the structures of mono-, tri-, tetra- and pentaglycosides of both genins were characterized by means of chromatographic and spectroscopic methods.

1H,1′H-[3,3′]biindolyl from the terrestrial fungus Gliocladium catenulatum

Fil: Bertinetti, Brenda Veronica. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad de Microanalisis y Metodos Fisicos En Quimica Organica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanalisis y Metodos Fisicos En Quimica Organica; Argentina

Cryptoporic and isocryptoporic acids from the fungal cultures of Polyporus arcularius and P. ciliatus.

In a chemical study of several fungal cultures of Polyporus, a methyl ester of cryptoporic H was isolated from P. ciliatus, together with cryptoporic acid H and 5-hydroxymethylfuran-3-carboxylic acid. Furthermore, two additional compounds, named isocryptoporic acids H and I, were isolated from P. arcularius. These isocryptoporic acids are isomers of the cryptoporic acids with drimenol instead of albicanol as the terpenoid fragment; their structural elucidation was determined by application of spectroscopic methods.

Short-side-chain cycloartanes from Tillandsia usneoides

Abstract The short side-chain cycloartanes, 27- nor -cycloartan-3,25-dione, 24,25,26,27- tetranor -3-oxo-cycloartan-23-al and 25,26,27- trisnor -3-oxo-cycloartan-24-al, have been isolated from Tillandsia usneoides and identified by spectroscopic and chemical methods.