We synthesized nanostructured AgNbO 3 silver perovskite oxide, which prevents the proliferation of microbial cells without undergoing corrosion. The compound was tested for antimicrobial activity against Grampositive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. We confirmed that the antimicrobial activity of the compound was not related to its high dielectric and piezoelectric properties. While the measured activity, as quantified by the minimum inhibitory concentration, was similar to the activity of Ag 2 O particles subjected to the same mechanical treatments, the level of silver ion release of Ag 2 O was 60 times higher than that of AgNbO 3 . This indicated that the antimicrobial activity of AgNbO 3 is not due to corrosion resulting in silver ion release to the media.

Chemotherapy against the neglected tropical disease visceral leishmaniasis (VL) is suboptimal with only four licensed drugs. Amphotericin B (AmB), despite its toxicity, remained a second line drug for a long time. However, the demonstration that liposomal AmB is highly effective against VL propelled it, despite its cost, to a first line drug in many countries. While several ongoing efforts are aiming at finding cheaper and stable AmB-formulations, an alternative strategy is the development of less-toxic AmB derivatives. We show here that two less-toxic AmB derivatives with the carboxylate at position 16 of AmB derivatized to a methyl urea (AmB-MU) or amino urea (AmB-AU) are active in vitro against Leishmania donovani, both as free-living parasites as well as their intracellular form. Both less-toxic derivatives, similarly to AmB, target the ergosterol pathway of L. donovani. While the AmB-AU derivative showed female-specific liver toxicity in vivo, the AmB-MU derivative was well-tolerated and more effective than AmB against experimental VL. These studies are an important step for improving AmB-based therapy against a prevalent parasitic disease.