Chiral analysis of anti‐acquired immunodeficiency syndrome drug, 9‐(R)‐[2‐(phosphonomethoxy)propyl]adenine (tenofovir), and related antiviral acyclic nucleoside phosphonates by CE using β‐CD as chiral selector

Abstract

A new CZE method has been developed for chiral analysis of an important anti-acquired immunodeficiency syndrome drug, 9-(R)-[2-(phosphonomethoxy)propyl]adenine ((R)-PMPA, tenofovir), and six related antiviral acyclic nucleoside phosphonates using beta-CD as a chiral selector. The influence of the composition, concentration and pH of the BGE and the type and concentration of chiral selector on enantiomer resolution was investigated. Complete separations of (R,S)-enantiomers of PMPA with very good resolution (R(s)=1.50-3.64) were achieved within a short time (4-15 min) in 20-50 mM sodium borate or sodium tetraborate BGEs, pH 10.0, at 20 mg/mL concentration of beta-CD. (R,S)-enantiomers of five similar PMPA analogs containing purine bases (adenine, diaminopurine or guanine) and hydroxyl or fluor substituents at C3 carbon atom of propyl chain were baseline separated within 10-17 min in 35 mM sodium tetraborate BGE, pH 10.0, at 20 mg/mL beta-CD concentration. Another important antiviral used by acquired immunodeficiency syndrome patients, derived from pyrimidine base cytosine, 1-(S)-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (cidofovir), and the (R)-enantiomer of this drug were successfully separated in 50 mM sodium tetraborate BGE, pH 10.5, at 20 mg/mL beta-CD concentration within 45 min. Using the UV-absorption detection at 206 nm, the concentration detection limits of the analyzed acyclic nucleoside phosphonates were determined in the submicromolar to micromolar range (0.15-2.51 microg/mL level).

Amphiphilic macromolecule nanoassemblies suppress smooth muscle cell proliferation and platelet adhesion

“…As previous studies have established that negatively charged functional groups provide enhanced binding to oxLDL receptors on macrophages, it was important to compare these end-groups to determine the effects of the singly charged carboxylic acid relative to the doubly charged phosphonic acid [42]. In comparing the end-group chemistries, the 1pM micelles had an increased ζ-potential due to the higher net negative charge (−2 net charge for 1pM compared to −1 net charge for 1cM) on the anionic end group (Figure 1D), yet the ζ-potential of phosphonate-and carboxylate-terminated AM micelles and NPs were indistinguishable, likely due to the negative AM termini being shielded by the PEG corona to varying extents.…”

“…At the higher concentrations, the phosphonate-AM micelles may provide enhanced binding to the cationic MSR1 and CD36 residues, thereby inhibiting oxLDL internalization and moderating scavenger receptor expression [36, 42]. In previous work, anionic AMs with a greater net negative charge were more efficacious in counteracting macrophage oxLDL uptake in silico and in vitro due to their favorable binding energies [25–27].…”

Sodium Acetate Coated Tenofovir-Loaded Chitosan Nanoparticles for Improved Physico-Chemical Properties

“…Concomitantly, during the freeze drying, the intrinsic surface active and efflorescent properties of SA constraint TFV to remain entrapped in chitosan NPs core during the self-assembly of the NPs shell as explained above This enhanced EE% is not due to the charge of TFV at the final working pH 4.76 condition. Indeed, at this pH, the EE% of uncoated NPs is only 5.5–11.7% because the drug water solubility outweigh its charge-charge interaction with the polymeric matrix and the drug is mainly lost by mass transfer in the supernatant even though the two basic amino groups are positively charged and the phosphonic acid group of TFV has a charge of −1 at pH 4.76 (10, 11)…”

“…The phosphonic acid group of TFV has two pKa values of 2 and 6.8, respectively (10). Below pH = 5, the two basic amino groups are protonated and thus positively charged and the phosphonic acid group has a charge of −2 above pH = 7 (11). …”

Differential Binding of Tenofovir and Adefovir to Reverse Transcriptase of Hepatitis B Virus

“…With respect to tenofovir, diesterification of the homochiral 9-[2-(R)-phosphonomethoxypropyl]adenine (PMPA) is a non-stereoselective synthetic route, yielding a 1∶1 mixture of diastereoisomeric pro-drugs due to the asymmetric center at the phosphorus atom. Synthesis and enantiomeric purification of these pro-drugs have been developed into a practical kilo-scale process [13]–[15]. The disoproxil derivative of PMPA (tenofovir) is administered to patients and requires in vivo cleavage by diesterases and subsequent phosphorylation by cellular kinases, rendering the biologically active triphosphate compound.…”