Synthesis and Characterisation of a New Amphotericin B– Methoxypoly(ethylene Glycol) Conjugate Milosˇ Sedla´k, a, * Vladimı ´ r Buchta, b Lenka Kubicova´, c Petr S ˇ imu˚nek, a Michal Holcˇapek d and Pavla Kasˇparova´ e a Department of Organic Chemistry, University of Pardubice, C ˇ s. legiı´ 565, 532 10 Pardubice, Czech Republic b Department of Biological and Medical Sciences, Faculty of Pharmacy, Charles University, 500 05 Hradec Kralove, Czech Republic c Department of Inorganic and Organic Chemistry, Faculty of Pharmacy, Charles University, 500 05 Hradec Kralove, Czech Republic d Department of Analytical Chemistry, University of Pardubice, C ˇ s. legiı´ 565, 532 10 Pardubice, Czech Republic e Department of Colloid Chemistry, Max-Planck-Institute for Colloids and Interfaces, Forschungcampus Golm, 14424 Potsdam, Germany Received 26 April 2001; revised 20 July 2001; accepted 31 July 2001 Abstract—The reaction of methoxypoly(ethylene glycol)-4-nitrophenyl carbonate with amphotericin B has been used to prepare a new conjugate of amphotericin B (mPEG-AmB). A preliminary screening of in vitro antifungal activity has suggested that mPEG- AmB posseses a similar effect and a similar spectrum of activity as the conventional amphotericin B formulated with sodium des- oxycholate. # 2001 Elsevier Science Ltd. All rights reserved. Amphotericin B (AmB) is a polyene macrocyclic mem- brane-active antifungal antibiotic produced by Strepto- myces nodosus M4575, which for as long as 40 years has been a salvaging medical drug in the treatment of sys- temic fungal diseases. 1 The drug is very efficient, having predominantly a fungicidal effect, and is particularly applied to immunosuppressed patients, including solid organ and bone marrow transplant (BMT) 2 recipients, acquired immunodeficiency syndrome (AIDS) persons 3 and patients with solid tumours and haematological malignancies. 4 However, the clinical application of AmB is hampered on one hand by its poor solubility in water and the lack of peroral drug formulation for sys- temic use and on the other hand by increased occur- rence of adverse effects, especially nephrotoxicity. 5 Conjugates of AmB and its liposomal form have been prepared in order to increase the therapeutic index of AmB. These new drug formulations improve the phar- macological profile of AmB in terms of increased water solubility and decreased nephrotoxicity. 6 The con- jugates used so far are non-covalent lipid complexes of the type of amphotericin B Lipid Complex (ABLC), 7 colloid systems composed of biodegradable phospholipid matrices [e.g., dimyristoylphosphatidyl choline (DMPC) 7 ] of modified poly(ethylene glycols) [e.g., distearoyl- N- [(monomethoxy)poly(ethylene glycol)succinyl]phos- phatidylethanolamine (DSPE-PEG) 8 ] with AmB. Such forms of AmB usually possess lower in vitro antifungal activity as compared with the desoxycholate AmB, which is, however, outbalanced by better pharmaco- kinetic properties and possibility of higher dosages of these preparations. In the literature, we have not found any case describing AmB bound by covalent bond to a carrier. At present, systems are being developed in which the drug is gra- dually released from a carrier in several phases in such a way that the individual bond types are split step by step, which ensures a relatively constant drug level in the organism. A drawback of such systems lies in the necessity of their multi-step synthesis. 9 The aim of our work was to prepare, by a simple method, AmB bound to a suitable carrier in such a way that one part of AmB would be bound by covalent bonds and the other by non-covalent interactions. 7 During its application, the ‘non-covalent’ AmB would be released first. 10 The covalent bond should be of such nature that ‘covalent’ AmB would be released by action of hydrolytic enzymes. 11 As a carrier, we have chosen methoxypoly(ethylene glycol) (mPEG, M r =5000 g/mol) which fits two basic requirements: first, according to the 0960-894X/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0960-894X(01)00532-7 Bioorganic & Medicinal Chemistry Letters 11 (2001) 2833–2835 *Corresponding author. Fax: +42-40-603-7068; e-mail: milos. sedlak@upce.cz