Amphotericin B Microemulsion Reduces Toxicity and Maintains the Efficacy as an Antifungal Product

Amphotericin B remains the drug of choice for the treatment of most of the systemic fungal infections in immunodeficient patients. Because of the high incidence of adverse drug reactions the clinical use of Amphotericin B is rather limited. To reduce its toxicity new drug delivery systems has been suggested. Nevertheless, these carriers present several technological drawbacks that impair the development of a marketable product. The aim of this work was to develop an Amphotericin B microemulsion in order to increase its efficacy and decrease its toxicity compared to Fungizon (TM), the widely know inexpensive micellar system of Amphotericin B. Amphotericin B loaded microemulsion showed an average size close to 300 nm by photon correlation spectroscopy. In the UV spectrum, the observation of the monomeric peak at 405 nm, which was independent of the sample dilution, revealed that the Amphotericin B molecules were strongly and individually bound to the microemulsion droplets. The new microemulsion formulation had the same efficacy than Fungizon (TM) against C. albicans. Concerning toxicity, Amphotericin B loaded microemulsion showed lower toxicity against human red blood cells compared to the commercial product. Taken together, these results suggested that microemulsion is an eligible drug carrier for Amphotericin B or other water insoluble molecules, and it has potential applications to targeting fungal cells. Additionally, a novel formulation of Amphotericin B-loaded microemulsion was prepared by a straightforward and fast procedure.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Iron overload of human colon adenocarcinoma cells studied by synchrotron-based X-ray techniques

Fast- and slow-proliferating human adenocarcinoma colorectal cells, HT-29 and HCA-7, respectively, overloaded with transferrin (Tf), Fe(III) citrate, Fe(III) chloride and Fe(II) sulfate were studied by synchrotron radiation total-reflection X-ray spectrometry (TXRF), TXRF-X-ray absorption near edge structure (TXRF-XANES), and micro-X-ray fluorescence imaging to obtain information on the intracellular storage of overloaded iron (Fe). The determined TfR1 mRNA expression for the investigated cells correlated with their proliferation rate. In all cases, the Fe XANES of cells overloaded with inorganic Fe was found to be similar to that of deliquescent Fe(III) sulfate characterized by a distorted octahedral geometry. A fitting model using a linear combination of the XANES of Tf and deliquescent Fe(III) sulfate allowed to explain the near edge structure recorded for HT-29 cells indicating that cellular overload with inorganic Fe results in a non-ferritin-like fast Fe storage. Hierarchical cluster analysis of XANES spectra recorded for Fe overloaded HT-29 and HCA-7 cells was able to distinguish between Fe treatments performed with different Fe species with a 95 % hit rate, indicating clear differences in the Fe storage system. Micro-X-ray fluorescence imaging of Fe overloaded HT-29 cells revealed that Fe is primarily located in the cytosol of the cells. By characterizing the cellular Fe uptake, Fe/S content ratios were calculated based on the X-ray fluorescence signals of the analytes. These Fe/S ratios were dramatically lower for HCA-7 treated with organic Fe(III) treatments suggesting dissimilarities from the Tf-like Fe uptake