Amidate Prodrugs of 9-[2-(Phosphonomethoxy)Ethyl]Adenine as Inhibitors of Adenylate Cyclase Toxin from Bordetella pertussis

Abstract

Adenylate cyclase toxin (ACT) is the key virulence factor of Bordetella pertussis that facilitates its invasion into the mammalian body. 9-[2-(Phosphonomethoxy)ethyl]adenine diphosphate (PMEApp), the active metabolite of the antiviral drug bis(POM)PMEA (adefovir dipivoxil), has been shown to inhibit ACT. The objective of this study was to evaluate six novel amidate prodrugs of PMEA, both phenyloxy phosphonamidates and phosphonodiamidates, for their ability to inhibit ACT activity in the J774A.1 macrophage cell line. The two phenyloxy phosphonamidate prodrugs exhibited greater inhibitory activity (50% inhibitory concentration [IC 50 ] ‫؍‬ 22 and 46 nM) than the phosphonodiamidates (IC 50 ‫؍‬ 84 to 3,960 nM). The inhibitory activity of the prodrugs correlated with their lipophilicity and the degree of their hydrolysis into free PMEA in J774A.1 cells. Although the prodrugs did not inhibit ACT as effectively as bis(POM)PMEA (IC 50 ‫؍‬ 6 nM), they were significantly less cytotoxic. Moreover, they all reduced apoptotic effects of ACT and prevented an ACT-induced elevation of intracellular [Ca 2؉ ]i. The amidate prodrugs were less susceptible to degradation in Caco-2 cells compared to bis(POM)PMEA, while they exerted good transepithelial permeability in this assay. As a consequence, a large amount of intact amidate prodrug is expected to be available to target macrophages in vivo. This feature makes nontoxic amidate prodrugs attractive candidates for further investigation as novel antimicrobial agents.

Nucleobase Modified Adefovir (PMEA) Analogues as Potent and Selective Inhibitors of Adenylate Cyclases from Bordetella pertussis and Bacillus anthracis

“…Bisamidate prodrugs with L-phenylalanine isopropyl ester were used based on their significantly improved stability in plasma and decreased cytotoxicity compared to the original adefovir dipivoxil (bis(POM)PMEA). 43 …”

“…1), with enhanced plasma stability profile and low toxicity were evaluated as potentially more suitable drug candidates for antitoxin therapy despite their somewhat lower efficacy to inhibit ACT compared with bis(POM)PMEA ( I ). 43 Based on these results, 43 and taking into account various aspects of the prodrug strategy (stability, cytotoxicity, cell membrane permeability, ease of synthesis and handling), L-phenylalanine isopropyl ester moiety (as in compound III , Fig. 1) has been selected as a representative type of bisamidate prodrug for the evaluation of any other novel nucleotide analogues.…”

Synthesis of α‐Branched Acyclic Nucleoside Phosphonates as Potential Inhibitors of Bacterial Adenylate Cyclases

“…Later, it was found that PMEApp is also a potent inhibitor of bacterial ACs, and crystal structures of EF–calmodulin and ACT–calmodulin with PMEApp were resolved. Recently, Česnek et al . studied a series of amidate prodrugs of PMEA and selected the corresponding isopropyl ester l ‐phenylalanyl derivative III (Figure ) as a promising type of prodrug considering its in vitro activity, bioavailability and synthetic accessibility.…”

Synthesis and evaluation of symmetric acyclic nucleoside bisphosphonates as inhibitors of the Plasmodium falciparum, Plasmodium vivax and human 6-oxopurine phosphoribosyltransferases and the antimalarial activity of their prodrugs

“…12 In general, ANPs have ability to target various metabolic pathways where they exhibit a wide range of biological activities, e.g. antibacterial, immunomodulatory and antineoplastic 13,14,15,16,17 and can serve as monomers for oligonucleotide synthesis. 18 Figure 2.…”