Osvaldo J. Donadel

Direct stereoselective synthesis of enantiomerically pure anti-β-amino alcohols.

Enantiomerically pure anti-β-amino alcohols were synthesized from optically pure α-(N,N-dibenzylamino)benzyl esters, derived from α-amino acids, by the sequential reduction to aldehyde with DIBAL-H at -78 °C and subsequent in situ addition of Grignard reagents. Besides anti-β-amino alcohols, anti-2-amino-1,3-diols and anti-3-amino-1,4-diols were obtained in good yields (60-95%) and excellent stereoselectivity (de > 95%). Our technique is compatible with free hydroxyl groups present in the substrate. To demonstrate the versatility of the method, spisulosine and sphinganine were synthesized in two steps from the appropriate N,N-dibenzyl-l-aminobenzyl ester in 42% and 45% yield, respectively.

Allelochemical effects of eudesmane and eremophilane sesquiterpenes on Tribolium castaneum larvae.

Eight eudesmane and eremophilane sesquiterpenes administered to Tribolium castaneum larvae caused different allelochemical effects. Topical application of 3-oxo-γ-costic acid produced the greatest lengthening in the duration of the pupal stage. Morphological deformities were found, specifically when ilicic, costic, and γ-costic acids and costic aldehyde were used. Ilicic acid exhibited the major toxicity 72 hr following topical application. All compounds were significantly toxic at the end point of the experiment (60 days). Treated surface toxicity was lower than when topical assays were carried out. Responses to tessaric acid in choice bioassays had the highest attractive effect. Maximum repellency was caused by the 3-oxo-γ-costic acid. However, experimental series carried out using γ-costic acid, eremophilan-1(10),2,11(13)-trien-12-oic acid, costic aldehyde, and ilicic aldehyde showed no clear response.

Sesquiterpenes from Tessaria absinthioides

Abstract The sesquiterpenes tessaric acid, 2-deoxytessaric acid, ilicic acid, 3-oxo-4,11(13)-eudesmadien-12-oic acid and 3β,5α-dihydroxycostic acid have been isolated from the aerial parts of Tessaria absinthioides . The structure of a new eudesmane, 3β,5β-dihydroxicostic acid, was established by spectroscopic data.

Tessaric acid derivatives induce G2/M cell cycle arrest in human solid tumor cell lines

A series of analogs were synthesized in a straightforward manner from naturally available sesquiterpenes ilicic acid and tessaric acid. The in vitro antiproliferative activities were examined in the human solid tumor cell lines A2780, HBL-100, HeLa, SW1573, T-47D and WiDr. The most potent analog induced considerably growth inhibition in the range 1.9-4.5 microM. Cell cycle studies for tessaric acid derivatives indicated a prominent arrest of the cell cycle at the G(2)/M phase. Damage to the cells was permanent as determine by the so called 24+24 drug schedule.

Anti-listerial activity of plant essential oils from western region of Argentina

Listeria monocytogenes is an important foodborne pathogen due to the severity of infection with a high mortality rate. In the past few years, there has been an increase in the use of naturally derived compounds such as plant extracts or essential oils as antimicrobials in food. The objective of the present study was to determine the antimicrobial effect of theFlourensia oolepis, Baccharis salicifolia, andArtemisia echegarayi essential oils on fourteen strains ofL. monocytogenes, by the disk diffusion method. The results indicate that the essential oils tested could potentially be used to inhibitL. monocytogenes, but appropriate applications in food should be validated.

Biotransformation of eudesmanes by Tessaria absinthioides cell suspension cultures

Tessaria absinthioides callus and cell suspension cultures were established. The most appropriate plant growth regulator combination and culture conditions for cell growth and secondary metabolites were obtained on MS basal media supplemented with 20.0 μM IBA/ 18.0 μM BA at 22°C and using a photoperiod of 16 h light / 8 h dark. Meanwhile, submerged cultures were initiated by inocula of 5 and 10% (v/ v) and shaken at 120 rpm. The analysis of the presence of the sesquiterpenes in submerged cultures showed that only the eremophilane tessaric acid was accumulated once stationary phase was reached. When ilicic acid was added, only tessaric acid was recovered from biotransformation procedure. However, since no eudesmanes were detected, it is more likely that ilicic acid is not converted to further oxidised eudesmanes. But its disappearance, together with the increase in tessaric acid accumulation, showed that it has been metabolised into the above-mentioned eremophilane. The eudesmanic acid 3-oxo-γ-costic acid was obtained by bioconversion of the precursor γ-costic acid by cell suspension cultures, together with 3β,5β-dihydroxycostic and 3β,5α-dihydroxycostic acids.

Hydroxylation of Ilicic Acid by Bioconversion with Cultures of Cunningamella Echinulata

Abstract Cunningamella echinulata cultures monohydroxylate ilicic acid at C-1 and C-2 cis to the methyl groups at C-4 and C-10.