Toxicity Mechanisms of Amphotericin B and Its Neutralization by 1 Conjugation with Arabinogalactan 2 Running Title : Activity and Toxicity Mechanisms of Amphotericin B

22 Amphotericin B (AMB) is an effective antifungal agent. However, its therapeutic use is 23 hampered by its toxicity, mainly due to channel formation across kidney cell membranes 24 and disruption of post-endocytic trafficking. We previously described a safe, injectable 25 AMB-arabinogalactan (AG) conjugate with neutralized toxicity. Here we studied the 26 mechanism of toxicity of free AMB and its neutralization by conjugation with AG. AMB 27 treatment of a kidney cell line modulated trafficking of three receptors (CXCR4, M128 receptor and hTfnR) due to an increase in endosomal pH. Similar data were also obtained 29 in yeast but with an increase in vacuolar pH and perturbation of Hxt2-GFP trafficking. 30 Conjugation of AMB to AG neutralized all of the elements of AMB toxic activity in 31 mammalian but not fungal cells. Based on these results, we provide an explanation of 32 how conjugation of AMB to AG neutralizes its toxicity in mammalian cells, and add to 33 the knowledge of free AMB's mechanism of action in both fungal and mammalian cells. 34 on O cber 3, 2017 by gest httpaac.asm .rg/ D ow nladed fom