Oligomers of Cyclic Oligochalcogenides for Enhanced Cellular Uptake

Abstract

Monomeric cyclic oligochalcogenides (COCs) are emerging as attractive transporters to deliver substrates of interest into the cytosol through thiol-mediated uptake. The objective of this study was to explore COC oligomers. We report a systematic evaluation of monomers, dimers, and trimers of asparagusic, lipoic, and diselenolipoic acid as well as their supramolecular monomers, dimers, trimers, and tetramers. COC dimers were more than twice as active as the monomers on both the covalent and noncovalent levels, whereas COC trimers were not much better than dimers. These trends might suggest that thiol-mediated uptake of COCs is synergistic over both short and long distances, that is, it involves more than two COCs and more than one membrane protein, although other interpretations cannot be excluded at this level of complexity. These results thus provide attractive perspectives for structural evolution as well as imminent use in practice. Moreover, they validate automated HC-CAPA as an invaluable method to collect comprehensive data on cytosolic delivery within a reasonable time at a level of confidence that is otherwise inconceivable.

Dithiolane quartets: thiol-mediated uptake enables cytosolic delivery in deep tissue

“…28 The dithiolane quartet hypothesis was in full agreement with introductory studies focusing on EU peptide length and complex stoichiometry. 50 With regard to peptide stereochemistry covered in this study, the high activity of all-D eueueu 15 was consistent with the dithiolane quartet hypothesis and the absence of important enantioselectivity (Fig. 2).…”

“…AspA was selected as the COC because its activity was the highest of the series in our introductory studies, and dynamic covalent exchange with TfRs and transit through endosomes together with TfRs have been demonstrated. 29,32,50,51 Peptides 5-14 were designed, synthesized, and then complexed with streptavidin 3 to produce a collection of transporters 15-26 that covers wide functional space with minimal structural change (Schemes S1-S10, † Fig. 2 and Table 1).…”

“…Dynamic covalent disulfide exchange of transporters such as 1 (ref. 50 ) with thiols C556 and C558 of the TfR and tether the transporters through at least one disulfide bond to the membrane protein. 29 Then, direct translocation occurs by thiolate-disulfide exchange cascades along the TfR or other protein partners to deliver COCs like 1 into the cytosol ( Fig.…”

Thiol-Mediated Uptake

“…Peptide-based oligomers of COCs, together with the introduction of cell-penetrating streptavidin, also showed that multivalency of COCs strongly increases uptake. 106 The complementary AspA 33 for automated peptide synthesis has been introduced as well, and already one AspA per peptide was confirmed to suffice for efficient delivery. 107 1,2-Dithiolane probes, such as 34 , that turn on fluorescence (or release drugs) upon reductive opening as outlined in 35 , have been quite extensively explored by Fang and co-workers.…”

Genetically Encoded Supramolecular Targeting of Fluorescent Membrane Tension Probes within Live Cells: Precisely Localized Controlled Release by External Chemical Stimulation

“…Wild-type Sav 5 does not penetrate cells. 85 To ensure the efficient delivery of 18 to the HaloTagged MOI inside the cell, cyclic oligochalcogenides (COCs) 85 were attached along the trifunctional peptide 19 . Not only the best COC oligomers 19 and 20 containing two and three asparagusic acids, 86 respectively, but also their counterparts with diselenolipoic acid 87 instead of asparagusic acid were tested ( Figure S11 ).…”