New stereoselective titanium reductive amination synthesis of 3-amino and polyaminosterol derivatives possessing antimicrobial activities.

A series of 3-amino and polyaminosterol analogues of squalamine and trodusquemine were synthesized involving a new stereoselective titanium reductive amination reaction in high chemical yields of up to 95% in numerous cases. These derivatives were evaluated for their in vitro antimicrobial properties against human pathogens. Activity was highly dependent on the different compounds' structures involved and best results have been obtained with aminosterol derivatives 4b, 4e and 6i exhibiting activities against yeasts, Gram positive and Gram negative bacteria at average concentrations of 6.25-12.5 microg/mL.

Antimicrobial activities of 3-amino- and polyaminosterol analogues of squalamine and trodusquemine.

A series of 3-amino- and polyaminosterol analogues of squalamine and trodusquemine were synthesized and evaluated for their in vitro antimicrobial properties against human pathogens. The activity was highly dependent on the structure of the different compounds involved and the best results were obtained with aminosterol derivatives 4b, 4e, 8b, 8e and 8n exhibiting minimum inhibitory concentrations (MICs) against yeasts, Gram positive and Gram negative bacteria at average concentrations of 3.12-12.5 microM.

Synthesis of oxysterols and nitrogenous sterols with antileishmanial and trypanocidal activities.

Two sterol families have been synthesized: the first one is nitrogenous sterols containing amino, N-hydroxyimino or cyano group and the second one is oxysterols such as ketosterol and hydroxysterols. These compounds were then evaluated in vitro against Leishmania donovani promastigotes and Trypanosoma brucei brucei trypomastigotes. The most active compounds against L. donovani promastigotes were 7beta-aminomethylcholesterol and 7alpha,beta-aminocholesterol (IC50 in a range from 1 to 3 microM, pentamidine: 2.8 microM). These compounds were active on intramacrophage amastigotes with IC50 of 1.3 microM. Such an activity justifies further in vivo antileishmanial evaluation. Against T. b. brucei, (24R,S)-24-hydroxy-24-methylcholesterol (MEC, 12.5 microM) was the most active compound from these series.

Squalamine: a polyvalent drug of the future?

The purpose of this mini-review is to summarize and highlight the different advances in our understanding of the antimicrobial and antiangiogenic activity of squalamine, a cationic steroid isolated in 1993 from the dogfish shark Squalus Acanthias. Indeed, squalamine has shown to be useful for the treatment of important diseases such as cancers (lung, ovarian, brain and others), age-related macular degeneration (AMD) and the control of body weight in man. All these results led to a question: could we consider squalamine as a polyvalent drug of the future?

Synthesis and antifungal activity of oxygenated cholesterol derivatives.

A series of oxygenated cholesterol derivatives were prepared from new synthetic methods and evaluated for their in vitro antimicrobial properties against human pathogens. The activity was highly dependent on the structure of the different compounds involved. The best results were obtained with hydroxy ketones 2, 4 and 5 and diketone 7 exhibiting activities against S. cerevisiae (ATCC 28383) and Candida albicans (CIP 1663-86). For example, compound 2 exhibited high activities against C. albicans (CIP 1663-86) and Amphotericine B and miconazole resistant strain C. albicans (CIP 1180-79) at a concentration of 1.5 microg/mL.

Synthesis and antifungal activity of cholesterol-hydrazone derivatives.

A series of hydrazones synthesized from various cholesterol derivatives were evaluated for their in vitro antimicrobial properties against human pathogens. The activity was highly dependent on the structure of the different compounds involved. The best results have been obtained with tosylhydrazone cholesterol derivatives 8 and 9 exhibiting activities against Candida albicans (CIP 1663-80) at a concentration of 1.5 microg/ml.

A comparison of three rapid and accurate bioluminescent antibiotic susceptibility tests.

INTRODUCTION: Rapid determination of microorganisms' antibiotic susceptibility remains a great challenge for the clinical diagnosis of infectious diseases. In this study, we compare three rapid bioluminescent antibiotic susceptibility tests with the conventional normalised microdilution method. METHODS: The susceptibility of two bacterial and two fungal strains to a 6h incubation with one of eight standard antibiotics was investigated by the ATP, AK and QNO bioluminescent methods. RESULTS: Three rapid and accurate antibiotic susceptibility testing were investigated performing ATP, AK and QNO bioluminescent assays. All the results were in accordance with those obtained using a standard microdilution assay. All these methods were sensitive and faster than the previously well-known ones. DISCUSSION: The development of bioluminescent determination methods could lead to accurate and useful antibiotic susceptibility testing.

Squalamine: an appropriate strategy against the emergence of multidrug resistant gram-negative bacteria?

We reported that squalamine is a membrane-active molecule that targets the membrane integrity as demonstrated by the ATP release and dye entry. In this context, its activity may depend on the membrane lipid composition. This molecule shows a preserved activity against bacterial pathogens presenting a noticeable multi-resistance phenotype against antibiotics such as polymyxin B. In this context and because of its structure, action and its relative insensitivity to efflux resistance mechanisms, we have demonstrated that squalamine appears as an alternate way to combat MDR pathogens and by pass the gap regarding the failure of new active antibacterial molecules.