A Doxorubicin Prodrug Activated by the Staudinger Reaction

Abstract

Much effort has been devoted to prodrug systems that effect drug release at the tumor through enzymatic action. To widen the scope of prodrug therapy, the use of the selective Staudinger reaction as prodrug activator, instead of relying on enzymatic action, was investigated. Doxorubicin was conjugated to a p-azidobenzyl trigger that is cleaved after reacting with the chemical activator, triphenylphosphine. The prodrug activation was confirmed in water, cell growth medium, and serum, using HPLC and LCMS. Next, this approach was tested in a cell proliferation assay with A431 human vulvar skin squamous carcinoma cells. The doxorubicin prodrug was shown to exhibit a 176-fold higher IC50 of 15.1 microM vs 0.086 microM for the parent drug, doxorubicin. Addition of triphenylphosphine (5 x 60 microM in 72 h) to the prodrug in cell culture effected the complete recovery of the activity of the parent drug as evidenced by an IC50 value of 0.074 microM. Furthermore, high levels of triphenylphosphine were tolerated well by the cells. The demonstrated usefulness of the Staudinger reaction in cell culture and its in vivo potential opens up new avenues for prodrug therapy.

Aminopeptidase P Mediated Targeting for Breast Tissue Specific Conjugate Delivery

“…It had been previously shown that the Tat peptide does not induce membrane leakage up to a concentrations of 20 uM, suggesting that the peptide building blocks and conjugate showed no toxicity to cells. 18,33 …”

Click Chemistry in Complex Mixtures: Bioorthogonal Bioconjugation

“…An example is the use of abiotic bioorthgonal reactions to provoke drug activation (Figure 10A), in contrast to the traditional reliance on endogeneous processes such as hydrolysis or enzymatic cleavage (Figure 10B). In a relatively simple example, the reduction of an azide by phosphine (Brakel et al, 2008) has been used as the prodrug activator in vivo , producing the corresponding aromatic amine that releases the cytotoxic cargo by 1,6-benzylic fragmentation (Figure 10C). The Staudinger ligation was also used to trigger drug liberation by virtue of a similar process triggered by O-to-N acyl migration to the iminophosphorane intermediate in the Staudinger process (Figure 10D) (Azoulay et al, 2006).…”

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2007–2008

“…Aminocoumarin antibiotics TOF (sinapinic) Chemoenzymatic formation of novel aminocoumarin antibiotics by the enzymes CouN1 and CouN7 (Fridman, et al, 2007) Chloramphenicol-neomycin conjugate TOF Bacteriophage links to neomycin to carry chloramphenicol to target (Yacoby, et al, 2007) TOF Doxorubicin prodrug Drug activated by Staudinger reaction (triphenylphosphine not toxic as used) (van Brakel, et al, 2008) Enzymatic attachment of GalNAc to peptide array on gold surface (Laurent, et al, 2008c) Mannose-decorated thioacetates TOF (norharmane)…”