Synthesis and Structure−Activity Relationships of Phenylenebis(methylene)- Linked Bis-azamacrocycles That Inhibit HIV-1 and HIV-2 Replication by Antagonism of the Chemokine Receptor CXCR4

Abstract

Bis-tetraazamacrocycles such as the bicyclam AMD3100 are a class of potent and selective anti-HIV-1 and HIV-2 agents that inhibit virus replication by binding to the chemokine receptor CXCR4, the co-receptor for entry of X4 viruses. With the aim of optimizing the anti-HIV-1 and HIV-2 activity of bis-azamacrocycles, a series of analogues were synthesized which contain neutral heteroatom (oxygen, sulfur) or heteroaromatic (of lower pK(a) than a secondary amine) replacements for the amino groups of AMD3100. The introduction of one or more heteroatoms such as oxygen or sulfur into the macrocyclic ring of p-phenylenebis(methylene)-linked dimers (to give N(3)X or N(2)X(2) bis-macrocycles) gave analogues with substantially reduced anti-HIV-1 (III(B)) and anti-HIV-2 (ROD) potency. In addition, the bis-sulfur analogue was also markedly more cytotoxic to MT-4 cells. However, bis-tetraazamacrocycles featuring a single pyridine group incorporated within the macrocyclic framework exhibited anti-HIV-1 and HIV-2 potency comparable to that of their saturated, aliphatic counterparts. The p-phenylenebis(methylene)-linked dimer of the py[14]aneN(4) macrocycle inhibited HIV-1 replication at a 50% effective concentration (EC(50)) of 0.5 microM while remaining nontoxic to MT-4 cells at concentrations approaching 200 microM. A series of analogues containing macrocyclic heteroaromatic groups of varying pK(a) were also synthesized, and their ability to inhibit HIV replication was evaluated. Replacing the pyridine moiety of the py[14]aneN(4) macrocyclic ring with pyrazine or pyridine groups substituted in the 4-position (with electron-withdrawing or -donating groups) either reduced antiviral potency or increased cytotoxicity to MT-4 cells. Finally, we synthesized a series of analogues in which the ring size of the bis-pyridyl macrocycles was varied between 12 and 16 members per ring including the py[iso-14]aneN(4) ring system, an isomer of the py[14]aneN(4) macrocycle. The p-phenylenebis(methylene)-linked dimer of the py[iso-14]aneN(4) (AMD3329) displayed the highest antiviral activity of the bis-azamacrocyclic analogues reported to date, exhibiting EC(50)'s against the cytopathic effects of HIV-1 and HIV-2 replication of 0.8 and 1.6 nM, respectively, that is, about 3-5-fold lower than the EC(50) of AMD3100. AMD3329 also inhibited the binding of a specific CXCR4 mAb and the Ca(2+) flux induced by SDF-1alpha, the natural ligand for CXCR4, more potently than AMD3100. Furthermore, AMD3329 also interfered with virus-induced syncytium formation at an EC(50) of 12 nM.

Inhibition of Human Immunodeficiency Virus Replication by a Dual CCR5/CXCR4 Antagonist

“…Here, a close correlation between anti-HIV activity and inhibition of MAb 12G5 binding was found for more than 20 different bicyclam derivatives (29). Compounds with the highest MAb 12G5 binding inhibitory capacity exhibited the most potent anti-HIV activity (10,29). The second extracellu-…”

Molecular Mechanism of Action of Monocyclam Versus Bicyclam Non-peptide Antagonists in the CXCR4 Chemokine Receptor

“…However, this was not the case for the first high affinity, but low potency monocyclam compound AMD3389, that in contrast, potentiates the binding of 12G5 with high potency and display a very low ability to inhibit HIV-1 cell entry (10). In contrast to the low potency (IC 50 ϳ 1 M) in respect of HIV cell entry blockade previously observed for AMD3389 (10,25), we observed a high potency in the nanomolar range for AMD3465 (Table 3) for three different X4 viral strains (IC 50 of 2.7, 4.7, and 36 nM for the NDK, CI number 10, and NL3.3, respectively). Similar inhibitory potencies were obtained for AMD3100 (Table 3).…”

Blocking CXCR4-Mediated Cyclic AMP Suppression Inhibits Brain Tumor GrowthIn vivo

“…Previously, we evaluated the in vitro and in vivo antitumor activity of the bicyclam antagonist of CXCR4 activation, AMD 3100 (12). This drug, which functions as a competitive antagonist of CXCL12 binding (28,29) with partial agonist properties (30,31), exhibited significant antitumor activity both in vitro and in vivo. In the present study, we evaluated a newer generation competitive antagonist, AMD 3465.…”