Lipophilic Triphosphate Prodrugs of Various Nucleoside Analogues

Abstract

The antiviral efficacy of many nucleoside analogues is strongly dependent on their intracellular activation by host cellular kinases to yield ultimately the bioactive nucleoside analogue triphosphates (NTP). The metabolic conversion of nucleoside analogues into their triphosphates often proceeds insufficiently. We developed a nucleoside triphosphate (NTP) delivery system (the TriPPPro approach), in which the γ-phosphate is covalently modified by two different biodegradable masking units, one is the acyloxybenzyl (AB) moiety and the other is the alkoxycarbonyloxybenzyl (ACB) group. Such compounds formed NTPs with high selectivity by an enzyme-triggered mechanism in human T-lymphocyte CEM cell extracts loosing first the AB moiety, followed by the ACB group. This enables the bypass of all steps of the intracellular phosphorylation. This approach was applied here to convert some modestly active or even inactive nucleoside analogues into powerful biologically active metabolites. Potent antiviral activity profiles were obtained depending on the lipophilicity of the TriPPPro-NTP prodrugs against HIV-1 and HIV-2 replication in cultures of infected wild-type CD4+ CEM T-cells and more importantly in thymidine kinase-deficient CD4+ T-cells (CEM/TK–). This TriPPPro strategy offers high potential for future antiviral and antitumoral chemotherapies.

Membrane Permeable, Bioreversibly Modified Prodrugs of Nucleoside Diphosphate-γ-Phosphonates

“…The TriPPPro-strategy was also used to convert so-far inactive nucleoside analogues into biologically active metabolites. 43,46 Both compounds 6 and 7 were rapidly hydrolyzed in cell extracts. However, it was very difficult to detect d4TTP 4 because of its relatively fast enzymatic dephosphorylation (t 1/2 = 38 min) by phosphorylases/kinases to form d4TDP 3 first and ultimately d4TMP 2.…”

“…We disclosed recently a unique pronucleotide approach based on partially masking the negative charges and improving the lipophilicity of nucleoside triphosphates, namely, the Tri PPP ro-approach 5 . − At first, Tri PPP ro-compounds 6 comprising two lipophilic and bioreversible acyloxybenzyl (AB) masking groups at the γ-phosphate and d4T 1 as a nucleoside analogue were disclosed . The successful formation of a nucleoside triphosphate inside cells was proven in a cell uptake study involving fluorescent nucleoside analogues .…”

Current Drugs to Treat Infections with Herpes Simplex Viruses-1 and -2

“…The first phosphorylation of antiviral nucleoside analogs typically occurs via a viral enzyme, thymidine kinase (TK); the subsequent di- and tri-phosphorylations are enacted through cellular kinases [ 6 ]. One benefit of this pathway is that host toxicity is limited because these drugs require the presence of said viral TK, which only appears during the early phase of an active, lytic HSV infection.…”

Metabolic Efficacy of Phosphate Prodrugs and the Remdesivir Paradigm

“… 54 , 55 Exciting recent studies have examined DiPPro and TriPPro approaches to generate prodrugs of di- and triphosphates that are plasma stable but are activated by cellular esterases ( Figure 3 E). 56 − 59 …”

“…Symmetrical amino acid bis-esters have been evaluated. Some of these compounds show increased potency, better selectivity, and more plasma stability relative to adefovir dipivoxil. , Likewise, some mixed aryl POM prodrugs have good plasma stability without loss in potency relative to bis-POM compounds. , Exciting recent studies have examined DiPPro and TriPPro approaches to generate prodrugs of di- and triphosphates that are plasma stable but are activated by cellular esterases (Figure E). − …”