Azide vs Alkyne Functionalization in Pt(II) Complexes for Post-treatment Click Modification: Solid-State Structure, Fluorescent Labeling, and Cellular Fate

Abstract

Tracking of Pt(II) complexes is of crucial importance toward understanding Pt interactions with cellular biomolecules. Post-treatment fluorescent labeling of functionalized Pt(II)-based agents using the bioorthogonal Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has recently been reported as a promising approach. Here we describe an azide-functionalized Pt(II) complex, cis-[Pt(2-azidobutyl)amido-1,3-propanediamine)Cl2] (1), containing the cis geometry and difunctional reactivity of cisplatin, and present a comparative study with its previously described alkyne-functionalized congener. Single-crystal X-ray diffraction reveals a dramatic change in the solid-state arrangement with exchange of the alkyne for an azide moiety wherein 1 is dominated by a pseudo-chain of Pt-Pt dimers and antiparallel alignment of the azide substituents, in comparison with a circular arrangement supported by CH/π(C≡C) interactions in the alkyne version. In vitro studies indicate similar DNA binding and click reactivity of both congeners observed by fluorescent labeling. Interestingly, complex 1 shows in vitro enhanced click reactivity in comparison to a previously reported azide-appended Pt(II) complex. Despite their similar behavior in vitro, preliminary in cellulo HeLa studies indicate a superior imaging potential of azide-functionalized 1. Post-treatment fluorescent labeling of 1 observed by confocal fluorescence microscopy shows nuclear and intense nucleolar localization. These results demonstrate the potential of 1 in different cell line localization studies and for future isolation and purification of Pt-bound targets.

Cisplatin Primary Complex with l‐Histidine Target Revealed by IR Multiple Photon Dissociation (IRMPD) Spectroscopy

“…[1][2][3] Whereas the mechanism of action, involving entry into the cell anda quation steps ultimately leading to nucleobase binding and DNA distortion, is known well enough, [4,5] fewer details are availableo nt he interaction of cisplatin with other molecules in the biological medium. Indeed, cisplatin has been found to bind to av ariety of biological targets, [6] notably amino acid residues in peptidesa nd proteins. [7,8] Some data indicate that cisplatin interaction with proteins, which is held responsible for an umber of toxic side effects, maya lso account for antitumor activity.…”

Superresolution imaging of individual replication forks reveals unexpected prodrug resistance mechanism

“…Drug metabolism can then be characterized by adding a fluorescent probe containing a complementary bioorthogonal functional group to the treated cells or animals. This type of "bioorthogonal chemical reporter strategy" has been used to study the metabolism of carbohydrates (24), proteins (25,26), lipids (27), nucleic acids (28)(29)(30)(31), new drug candidates (32,33) and their binding reactions in cells (34)(35)(36)(37), but no bioorthogonal reporter of prodrug anabolism has been previously reported. To evaluate this possibility, we synthesized a mimic of ara-C called "AzC" by replacing the 2′(S) hydroxyl group of ara-C with azide ( Fig.…”

Photoactivated Colibactin Probes Induce Cellular DNA Damage

“…Only cells treated with 9 (+ hv ) showed intense fluorescence, which localized with the γ‐H2AX signal within the nuclei (DAPI) (Figure ). Accumulation in the nucleoli and minor cytoplasmic staining was also observed, which has also been observed during studies of platinum‐based DNA targeting probes …”