Influence of polyamine architecture on the transport and topoisomerase II inhibitory properties of polyamine DNA-intercalator conjugates.
An efficient five-step synthetic method was developed to access a series of spermine derivatives containing appended acridine, anthracene, and 7-chloroquinoline motifs. The derivatives were composed of a spermine fragment covalently tethered at its N4 and N9 positions to an aromatic nucleus via an aliphatic chain (e.g., 8: acridine -[C4 aliphatic tether]-spermine-[C4 aliphatic tether]-acridine). The distance separating the spermine and aromatic nuclei was altered via different tethers composed of four or five methylene units. These bis ligands (8, 9, 12, and 13) were shown to inhibit human DNA topoisomerase II (topo II) activity at 5 microM. Enzymatic activity was assessed as the ability to unknot (decatenate) and cleave kinetoplast DNA (kDNA). Polyamine conjugation did not disrupt the ability of the acridine-spermine conjugates 8 and 9 to inhibit topo II activity as compared with the 9-aminoacridine and 9-(N-butyl)aminoacridine controls (at 5 microM). The parent polyamines, spermine (5 microM) and spermidine (10 microM), had little effect on topo II activity. In general, the bis-substituted spermine derivatives (8, 9, 12, and 13) were more efficient topo II inhibitors at 5 microM than their monosubstituted spermidine counterparts (22-25) at 10 microM. Within the bisintercalator spermine series, insertion of an additional methylene unit (i.e., C5 tethers) increased potency 2-fold (8, bis-C4-acridine, 47 h IC(50) = 40 microM; 9, bis-C5-acridine, IC(50) = 17 microM). Comparison of the bis- and monoacridine spermine motifs (8 and 17) revealed a 4-fold increase in potency for the latter architecture (94 h IC(50) for 8, 74 microM; for 17, 17 microM). In general the bisintercalators (8, 9, 12, and 13) behaved as cytostatic agents, while the monosubstituted acridine and anthracene derivatives (22-25) were cytotoxic. Anthracene-containing conjugates were generally more toxic than their acridine counterparts in an L1210 (murine leukemia) cell assay. Of the conjugates tested the (monointercalator)-spermine motif (e.g., 17) had the highest affinity for the L1210 polyamine transporter as revealed by spermidine protection experiments.
Wang
L
L
Center for Discovery of Drugs and Diagnostics, Department of Chemistry, University of Central Florida, Orlando, FL 32816-2366, USA.
Price
H L
HL
Juusola
J
J
Kline
M
M
Phanstiel
O
O
D000166:Acridines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D000873:Anthracenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001693:Biological Transport, Active; D016831:Crithidia fasciculata; D018105:DNA, Kinetoplast / Q000737:chemistry; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D020128:Inhibitory Concentration 50; D007364:Intercalating Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D013096:Spermine / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D059005:Topoisomerase II Inhibitors; D014407:Tumor Cells, Cultured
D000166:Acridines; D000873:Anthracenes; D000970:Antineoplastic Agents; D018105:DNA, Kinetoplast; D007364:Intercalating Agents; D059005:Topoisomerase II Inhibitors; D013096:Spermine