Disaggregation of amphotericin B by sodium deoxycholate micellar aggregates

Amphotericin B (AmB) is present as aggregates in aqueous media. Sodium deoxycholate (NaDC) is known to cause disaggregation of AmB and to form monomers, as is observed by the increase of absorbance at 414 nm. By following the fluorescence intensity at 472 nm (lambda(ex) 335 nm), it was found that with increasing NaDC concentration there is a progressive disaggregation of AmB leading to increase in both monomeric and dimeric forms. Although the presence of dimeric AmB form in NaDC micellar media is known, observation of the growth of the dimeric species is novel. Studies in fluorescence lifetime and steady state fluorescence anisotropy also support this conclusion. As NaDC (at ca. 10 mM) is the preferred choice of medium for AmB delivery and AmB aggregation has been implicated for its toxicity, the observation of dimeric AmB at these NaDC concentrations assumes significance.