Maria João Marcelo Curto

Catechols from abietic acid synthesis and evaluation as bioactive compounds.

Catechols from abietic acid were prepared by a short and good yielding chemical process and further evaluated for several biological activities namely, antifungal, antitumoral, antimutagenic, antiviral, antiproliferative and inhibition of nitric oxide. Their properties were compared with those of carnosic acid (6), a naturally occurring catechol with an abietane skeleton and known to possess potent antioxidant activity, as well as anticancer and antiviral properties. From all the synthetic catechols tested compound 2 showed the best activities, stronger than carnosic acid.

Antimicrobial activity of resin acid derivatives

The wide potential of resin acids as bioactive agents gave rise to a growing effort in the search for new applications of the natural forms and their derivatives. In some of these compounds, the antimicrobial activity is associated to the presence in the molecules of functional groups such as the hydroxyl, aldehyde, and ketone or to their cis or trans configurations. The resin acid family covers a spectrum of antimicrobial activities against several microorganisms, from bacteria to fungi, in which the mode of action was studied by electron microscopy. The morphological alterations are consistent with an unspecific mode of action causing inhibition of the fungal growth or damaging the fungal cells in parallel with a mechanism of resistance based on the retention of the compound by the lipid accumulation. The sterol composition of phytopathogenic fungi Botrytis cinerea and Lophodermium seditiosum treated with methyl cis-7-oxo-deisopropyldehydroabietate revealed the presence of ergosterol (M+ 396) and dihydroergosterol (M+ 398) in both cultures showing that this compound did not interfere with the ergosterol metabolic pathway of both fungi.

Antifungal activity of Bacillus subtilis 355 against wood-surface contaminant fungi

A strain of Bacillus subtilis was examined for antifungal activity against phytopathogenic and wood-surface contaminant fungi. The bacterium was grown in five culture media with different incubation times in order to study cell development, sporulation, and the production of metabolites with antifungal activity. The anti-sapstain and anti-mould activity of the bacterium grown in yeast extract glucose broth (YGB) medium in wood was also evaluated. In YGB, the bacterium inhibited the growth of several fungi and displayed a broader spectrum of activity than in the other media tested. A relationship between bacterial spore production and the formation of metabolites with antifungal activity was detected. YGB medium displayed effective control in wood block tests. YGB medium was extracted with solvents of increasing polarity and the dry residues were applied to silicagel plates, resolved with the appropriate solvent and sprayed with different solutions, detecting the presence, of amines, and higher alcohols. The bioautographic method revealed the presence of at least two active compounds against the blue-stain fungus Cladosporium cucumerinum.

Agelasidine A from Agelas clathrodes.

(-)-Agelasidine A was identified from the methanol extract of the marine sponge Agelas clathrodes for the first time together with zooanemonin, 1-carboxymethylnicotinic acid, hymenidin, mukanadins A and C, monobromodispacamide, agelasidine D, 2-amide-4-bromopyrrole, O-methyltryptophan and an agelasines mixture. The structures were characterized by spectroscopic methods. (-)-Agelasidine A was tested for antibacterial and antifungal activities and shown to act as a bacteriostatic agent as it inhibited the growth of Staphylococcus aureus and partially the growth of other bacteria.

NOVEL DIASTEREOSELECTIVE ROUTES FOR THE SYNTHESIS OF THE AMBERGRIS KETALS

New processes have been developed which allow the stereoselective syntheses of the ambergris ketals 8 alpha,13;13,17-diepoxi-14,15-dinorlabdane 1 and 8 beta,13;13,17-diepoxi-14,15-dinorlabdane 2, through selection of the appropriate catalyst for the delta,epsilon-epoxycarbonyl rearrangement of the key intermediate 3, which is, in turn, obtained by controlled oxidation of anticopalic acid 6.

NEW RESIN ACID DERIVATIVES : DIISOCYANATE, DIURETHANES AND DIUREIDES

Abstract New difunctional resin acids derivatives, diisocyanate, diurethanes and diureides were obtained via nitration of dehydroabietic acid followed by catalytic hydrogenation or reduction; carbonylation of the resulting amine and further reaction of the new diisocyanate with alcohols or amines.

Selective Ring-Opening of An Epoxide on Silica Supports

Abstract The intramolecular δ,ɛ-epoxycarbonyl rearrangement of 8α,17-epoxy-14,15-dinorlabdan-13-one I to give stereoselectively two diastereoisomeric ketals II or III was promoted in heterogeneous media using silicic porous solids as catalysts, making possible to choose a convenient selective system through an adequate combination of solvent, catalyst and temperature.