Synthesis of A-ring-modified lupane, oleanane and ursane type triterpenoid conjugates with spermidine through an aldimine linkage or diethylentriamine via an amide bond is described. These derivatives were evaluated for their in vitro antimicrobial properties against human pathogens. Except for derivatives 1 and 7, all compounds have moderate to weak minimum inhibitory concentrations (MICs) against Gram-positive Staphylococcus aureus bacteria, with MICs varying from 3.125 to 200 µM. Compound 11 is efficient against Escherichia coli and Pseudomonas aeruginosa, with MICs of 25 and 50 µM, respectively, while all other derivatives do not possess important antimicrobial activities against these Gram-negative bacteria.

: Recently, extensive researches have emphasized the fact that polyamines conjugates are becoming important in all the biological and medicinal fields. In this review we will focus our attention on natural polyamines and highlight recent progress in both fundamental mechanism studies and interest for the development and application for a therapeutic human use of polyamine derivatives.

No abstract

An improved, fast, and accurate procedure for regioselective microwave Oppenauer oxidation of sterol derivatives is reported leading to the expected corresponding ketosterols in moderate to excellent isolated yields ranging from 58 to 81%. The influence of different parameters dealing with the nature of the solvent and of the Lewis acid/ketone couple used, the reaction temperature as well as the hydrolysis conditions were also investigated on the outcome of the reaction.