Multigram Scale Synthesis of A21, A New Antibiotic Equally Effective and Less Toxic than Amphotericin B

A21 (<b>2</b>) is a new polyene macrolide Amphotericin B amide antibiotic derived from amphotericin B AmB (<b>1</b>), which has been tested extensively on preclinical trials showing the same antimycotic effectiveness and increased margin of safety over AmB (<b>1</b>). We present the multigram scale synthesis, isolation, purity assessment by HPLC, and key aspects of its characterization by NMR studies of A21 (<b>2</b>)

X‑ray Accelerated Photo-Oxidation of As(III) in Solution

We performed near edge X-ray absorption spectroscopy (XANES) measurements on the arsenic K-edge of As­(III) in solution under acidic and basic conditions, after exposure of the solutions to air. Spectra were recorded for increasing exposure times to the X-rays used to perform absorption spectroscopy measurements. We did not find changes for the solution under acidic conditions, whereas we observed significant changes in the case of solution under alkaline conditions. To interpret these changes, we compared the obtained spectra with XANES spectra of As­(III) and As­(V) solutions under alkaline conditions, not exposed to air, and used as standards. Principal component fits using these standards indicate an accelerated conversion of As­(III) to As­(V) due to the exposure to X-rays