title: Amphotericin B/sterol co-loaded PEG-phospholipid micelles: effects of sterols on aggregation state and hemolytic activity of amphotericin B.
abstract: OBJECTIVE
  To elucidate the effect of sterols on the aggregation of amphotericin B (AmB) in PEG-phospholipid micelles and its consequences on the hemolytic activity of AmB.
  
  
  METHODS
  AmB-incorporated PEG-phospholipid micelles co-loaded with ergosterol, cholesterol, or 7-dehydrocholesterol were prepared at 4:1:1 and 20:5:1 ratios of polymer-to-sterol-to-AmB. The aggregation state of AmB was elucidated by UV-vis spectroscopy. AmB/sterol co-loaded PEG-phospholipid micelles were incubated with red blood cells and the hemolytic activity of AmB assessed by measurement of free hemoglobin.
  
  
  RESULTS
  AmB in PEG-phospholipid micelles stayed mostly in a deaggregated state in the absence of sterol or with cholesterol, but aggregated in the presence of ergosterol or 7-dehydrocholesterol. The fraction of aggregated AmB in PEG-phospholipid micelles was lower at the 20:5:1 ratio. In an aggregated state or in the absence of sterol, AmB caused rapid and complete hemolysis. In contrast, deaggregated AmB co-loaded with cholesterol caused slower and incomplete hemolysis, especially at a 20:5:1 ratio.
  
  
  CONCLUSIONS
  The aggregation state of AmB in PEG-phospholipid micelles was sterol dependant. AmB/cholesterol co-loaded PEG-phospholipid micelles caused low in vitro hemolysis due to deaggregation of AmB and micellar stability, presumably owing to cholesterol/phospholipid versus cholesterol/AmB interactions in the interior core region.
authors: University of Wisconsin, Madison, Wisconsin, USA.
authors: Thomas A
authors: TA
authors: Diezi
authors: Glen
authors: G
authors: Kwon
mesh_terms: D000666:Amphotericin B / Q000008:administration & dosage* / Q000009:adverse effects* / Q000737:chemistry; D000818:Animals; D000935:Antifungal Agents / Q000008:administration & dosage* / Q000009:adverse effects* / Q000737:chemistry; D002417:Cattle; D002784:Cholesterol / Q000737:chemistry; D003684:Dehydrocholesterols / Q000737:chemistry; D004875:Ergosterol / Q000737:chemistry; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects*; D008823:Micelles; D010743:Phospholipids / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D012995:Solubility; D013261:Sterols / Q000737:chemistry*
chemical_list: D000935:Antifungal Agents; D003684:Dehydrocholesterols; D008823:Micelles; D010743:Phospholipids; D013261:Sterols; D011092:Polyethylene Glycols; D000666:Amphotericin B; D002784:Cholesterol; C016705:7-dehydrocholesterol; D004875:Ergosterol