Hepatocyte targeting of adenine‐9‐β‐D‐arabinofuranoside 5′‐monophosphate (ara‐AMP) coupled to lactosaminated albumin

Lactosaminated human serum albumin as hepatotropic drug carrier

“…Ara-A monophosphate (ara-AMP) was coupled to L-HSA by the use of 1-ethyl-3-(dimethylaminopropyl)carbodiimide [10]. Knowing that the amount of galactosyl residues bound to albumin decreases during ara-AMP coupling [10], we obtained 22 and 43 galactosyl residue conjugates when starting from L34-HSA and L57-HSA respectively.…”

“…Knowing that the amount of galactosyl residues bound to albumin decreases during ara-AMP coupling [10], we obtained 22 and 43 galactosyl residue conjugates when starting from L34-HSA and L57-HSA respectively. After gel chromatography on a Sephadex G-100 column, equilibrated and eluted with 0.05% NaC1 solution, the fractions corresponding to the monomeric form of the conjugate (about 70% of the whole conjugate preparation) were pooled, dialyzed against water and lyophilized.…”

“…The experiments were performed as previously described [10] with the difference that 9-erythro-(2-hydroxyl-3-nonyl)-adenine (ENHA), ara-A (free or coupled to L-HSA) and [methyl-3H]thymidine were administered 45, 30 and 15 min, respectively, before animals were killed.…”

“…However this drug produces dose-dependent side effects [6][7][8] which might be avoided or reduced by selectively delivering ara-A to hepatocytes. In mice, liver targeting of ara-A has been obtained by conjugation with asialofetuin (AF) [9] or with lactosaminated serum albumin (L-SA) [10], two galactosyl-terminating glycoproteins which penetrate by a receptor-mediated endocytosis only in hepatocytes where they are digested in lysosomes [11][12][13][14][15][16]. AF-ara-A and L-SA-ara-A conjugates, administered to mice with Ectromelia virus-hepatitis, inhibited virus DNA synthesis in liver without producing significant inhibition of cellular DNA synthesis in intestine and bone marrow [9,10].…”

“…In mice, liver targeting of ara-A has been obtained by conjugation with asialofetuin (AF) [9] or with lactosaminated serum albumin (L-SA) [10], two galactosyl-terminating glycoproteins which penetrate by a receptor-mediated endocytosis only in hepatocytes where they are digested in lysosomes [11][12][13][14][15][16]. AF-ara-A and L-SA-ara-A conjugates, administered to mice with Ectromelia virus-hepatitis, inhibited virus DNA synthesis in liver without producing significant inhibition of cellular DNA synthesis in intestine and bone marrow [9,10]. L-SA has a definitive advantage over AF as hepatotropic carrier of ara-A since conjugates prepared with lactosaminated homologous albumin are not immunogenic, at least in mice, to the contrary of AF conjugates which are strong antibody inducers [17].…”