2 research outputs found
Kondratāeva Ligation: DielsāAlder-Based Irreversible Reaction for Bioconjugation
Diversification of existing chemoselective
ligations is required
to efficiently access complex and well-defined biomolecular assemblies
with unique and valuable properties. The development and bioconjugation
applications of a novel DielsāAlder-based irreversible site-specific
ligation are reported. The strategy is based on a Kondratāeva
cycloaddition between bioinert and readily functionalizable 5-alkoxyoxazoles
and maleimides that readily react together under mild and easily tunable
reaction conditions to afford a fully stable pyridine scaffold. The
potential of this novel bioconjugation is demonstrated through the
preparation of fluorescent conjugates of biomolecules and a novel
FoĢrster resonance energy transfer (FRET)-based probe suitable
for the in vivo detection and imaging of urokinase-like plasminogen
activator (uPA), which is a key protease involved in cancer invasion
and metastasis
Synthesis, Biological Evaluation, and <i>in Vivo</i> Imaging of the first CamptothecināFluorescein Conjugate
The first synthesis and photophysical
properties of a fluorecently
labeled camptothecin derivative, namely, camptothecin-FI (CPT-FI),
an antitumoral agent that targets topoisomerase I, are reported. The
preparation of this fluorescent conjugate is based on a highly convergent
and flexible approach which enables the rapid chemical modification
of the AB ring system of this fragile pentacyclic alkaloid, aimed
at introducing an anchoring point to graft the fluorophore. The selection
of a fluorescein analogue as the reporter group has enabled us to
get the first green-emitting CPT conjugate exhibiting valuable spectral
properties and retaining biological properties of native CPT. Indeed,
in biological models, i.e., glioma cell lines U87 and/or T98, the
kinetics of cell endocytosis, as well as the efficacy of CPT-FI were
compared to those of CPT. CPT-FI fluorescence was measured in the
cytosolic compartment of T98 glioma cells from 5 min treatment and
remained detectable until 48 h. As CPT, CPT-FI drastically inhibited
glioma growth and cell cycle but exhibited a reduced affinity as compared
to the native CPT. <i>In vivo</i> and <i>ex vivo</i> imaging studies of CPT-FI intratumoraly injected into a model of
NIH-3T3 murine tumor xenografts in nude mice, showed accumulation
around the injected site area, which is very promising to target tumors
and follow biodistribution <i>in vivo</i>