COMPLEXATION OF AMPHOTERICIN-B WITH EGG PHOSPHATIDYLCHOLINE LIPOSOMES

The complexation and physical characteristics of egg phosphatidylcholine (PC) liposome containing amphotericin B (AmB) were investigated through circular dichroism (CD) spectra, the size distribution, the turbidity change, and the calcein release. CD spectra of AmB-containing egg PC mixture exhibited a positive peak around 330 nm indicative of complexation of AmB and four negative peaks. The positive peak increased up to 2.2 millidegree/mu g AmB as AmB contents increased up to 12 % (w/w), suggesting that AmB-phospholipid complexation was promoted by the antibiotics. The effective diameter of liposomes by dynamic light scattering decreased from 450 nm to 220 nm as the amount of AmB in liposomes increased from 0 to 30 % (w/w). The complexation may be responsible for the reduction in size. On the other hand, at around 1 mM deoxycholate (DOC), the relative turbidities of 5 and 10 % (w/w) AmB-containing liposome suspension were less than 1 probably due to the solubilization of the complex, while those of pure PC liposome suspension were larger than 7 at the same concentration. Deoxycholate-induced release of calcein entrapped in AmB-containing liposomes was lower than those of pure egg PC liposomes, indicating the intercalation of the drug into the bilayers. Therefore, it is concluded that in AmB/egg PC/water system, AmB-phospholipid complex coexists with AmB-containing liposomes.