Descripción: Four brassinosteroids analogs of homoteasterone and homotyphasterol bearing 5α-OH and 5α-F groups have been synthesized and their bioactivities evaluated.

Descripción: The addition of Grignard reagents to aldehydes in the presence of chiral aminoal-cohols shows a moderate enantioselectivity. The study carried out with a series of ligands allows the correlation between the structural characteristics and their reactivity.

Descripción: We have described a method for preparation of [10B]-enriched-8- dihydroxyborylharmine (III) and characterized it by their spectral properties (MS, IR and NMR). This compound is a potential BNCT agent.

Descripción: Lipases from different sources catalyze the polyesterification of glycerol and several dicarboxylic acids in presence or organic solvents.

Descripción: We report a study of 3,3-dimethyl substituted acylthioureas. X ray data and quantum mechanical calculations demonstrated that the "S" conformation is the most stable both for the acylthiour eas and the corresponding anions. The high regioselectivity towards S-alkylation is explained on the basis of the localization of the HOMO mainly over the sulfur atom.

Descripción: New organophosphorus insecticides of dialkylsulphoximines derived with activity upon acetylcholinesterase were synthesized. The obtained compounds were characterized by NMR and IR, and anticholinesterase activity and toxicity was measured. A simulation through computer was done in order to establish the relationship between structure and activity.

Descripción: 11α,12α-aziridinosteroids (2a, b, c) were prepared from 5β-H-11-pregnene-3, 20-dione (1) using different iminophenyliodinanes and cloramine aziridination reagents.

Descripción: A screening of metabolites guided by antimicrobial and citotoxic bioassays was conducted with several fungi. The bioactive compounds were isolated and identified from the active extracts.

Descripción: The phytochemical study of two species of Jaborosa caulescens (var. caulescens and var. bipinnatifida) yielded the four new withanolides 1-4. The structures of the new compounds were determined using a combination of spectroscopic techniques (including 1D and 2D NMR) and Molecular Modeling.

Descripción: Purification of the ethanolic extract of the starfish L. annulatus led to the isolation of two sulfated glycosides and a pentahydroxylated steroid. One of the saponins contains a novel pentasaccharide chain attached to C-6 of the steroidal aglycone.

Descripción: 4-O-Substituted D-glucuronic acid derivatives were synthesized from D-glucose in order to study the regioselectivity of sulfation.

Descripción: Fil:Caceres, J.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: Five disulfated steroids and a mixture of monosulfated steroids were isolated from the ethanolic extract of the antarctic ophiuroid Gorgonocephalus chilensis. The structures were determined by 1H-NMR, 13C-NMR and FABMS.

Descripción: 17(13→18)-Abeo and D-homo analogs of the natural neurosteroid 3α-hydroxy-5αH-pregnan-20-one were prepared by anionic or radical (mercury (II) hydride mediated) rearrangements of steroidal cyclopropylketones respectively.

Descripción: Cultures of the fungus epibiont from the herbaceous shrub B. coridifolia yielded four macrocyclic trichothecenes. As these toxins are the same as those found in B. coridifolia, the relationship between the plant and the epibiont must be considered as mutualistic.

Descripción: Seeds from Passiflora caerulea were defatted with n-hexane yielding 29,9% of crude oil (dry basis). The crude oil was examined in their physicochemical characteristics. Fatty acid composition value showed only three acids in significative proportion: 16:0, 18:1 and 18:2. The residual seed meal analysis included: moisture value, ash, metals content, sugars, crude fiber, protein and available lysine.

Descripción: The 75% isopropanol-soluble material from the endosperm of the legume-seed of Gleditsia triacanthos was isolated. The material extracted with boiling water was fractionated by ion-exchange chromatography and characterized. Besides minor amounts of galactomannans, major proportions of arabinans and/or arabinogalactans appear.

Descripción: The kinetics of the reaction of 2,4-dinitrochlorobenzene (DNClB) with aniline and substituted anilines such as p-anisidine, p-toluidine and N-methylaniline have been studied in toluene. Except for N-methylaniline the reactions have shown a third order in amine rate dependence which is consistent with aggregates of the amine acting as the nucleophile. On the other hand, the reaction of DNClB with N-methylaniline under the same conditions shows a linear dependence of the second order rate coefficient, kA, vs [amine], which is consistent with the previous mechanism.