Epidithiodiketopiperazines: Strain-Promoted Thiol-Mediated Cellular Uptake at the Highest Tension

Abstract

The disulfide dihedral angle in epidithiodiketopiperazines (ETPs) is near 0°. Application of this highest possible ring tension to strain-promoted thiol-mediated uptake results in efficient delivery to the cytosol and nucleus. Compared to the previous best asparagusic acid (AspA), ring-opening disulfide exchange with ETPs occurs more efficiently even with nonactivated thiols, and the resulting thiols exchange rapidly with nonactivated disulfides. ETP-mediated cellular uptake is more than 20 times more efficient compared to AspA, occurs without endosomal capture, depends on temperature, and is “unstoppable” by inhibitors of endocytosis and conventional thiol-mediated uptake, including siRNA against the transferrin receptor. These results suggest that ETP-mediated uptake not only maximizes delivery to the cytosol and nucleus but also opens the door to a new multitarget hopping mode of action.

Cell‐Penetrating Dynamic‐Covalent Benzopolysulfane Networks

“…The position of the compound numbers reflects the approximate fluorescence intensities after correction using quenching factors (QFs) of reduced COCs (note the log scale). [12] Independent of any corrections applied, the uptake of BPS 5 1 exceeded all other COCs.W ith correction, BPS 5 1 was approximately 10-times more active than the previous best in the sulfur series,E TP 2 5, [11] and approximately 140-times more active than the best explored asparagusic acid (AspA) derivative 7. [10,11] Biotinylated and TEGylated BPS 5 2 and 3 were prepared correspondingly.E TP 4 4 was prepared from ethylamine 12, which was converted into heterocycle 13 as described.…”

“…[5] Benzopolysulfane rings are not very strained (XSSX dihedral angles ! [1][2][3][4][5][6][7] This extreme sulfur chemistry attracted our attention in our search for new ways to enter cells.F rom cell-penetrating peptides (CPPs) [8] to cell-penetrating poly(disulfide)s (CPDs) [9] and COCs, [10][11][12][13] the cellular uptake via dynamic covalent dichalcogenide exchange chemistry has come to prominence,o ften referred to as thiol-mediated uptake,w ith exofacial thiols as initial targets and continuing on the way into the cell. [1][2][3][4][5][6][7] This extreme sulfur chemistry attracted our attention in our search for new ways to enter cells.F rom cell-penetrating peptides (CPPs) [8] to cell-penetrating poly(disulfide)s (CPDs) [9] and COCs, [10][11][12][13] the cellular uptake via dynamic covalent dichalcogenide exchange chemistry has come to prominence,o ften referred to as thiol-mediated uptake,w ith exofacial thiols as initial targets and continuing on the way into the cell.…”

“…728 8), [6] but excel with unique,complex chemistry. [10][11][12][13][14][15] Promising results with strained cyclic disulfides [10,11] and diselenides [12,13] called for as hift of attention to the extreme sulfur chemistry of higher oligochalcogenides. [10][11][12][13][14][15] Promising results with strained cyclic disulfides [10,11] and diselenides [12,13] called for as hift of attention to the extreme sulfur chemistry of higher oligochalcogenides.…”

“…BPS 5 1 was prepared from catechol 9 following the Greer procedure. [10,11] Biotinylated and TEGylated BPS 5 2 and 3 were prepared correspondingly.E TP 4 4 was prepared from ethylamine 12, which was converted into heterocycle 13 as described. (20 mm,45min,Leibovitz's medium).…”

“…[3] Dithiastannole 10, obtained in six steps from 9,w as treated with S 2 Cl 2 to give 11, [3] which in turn was condensed with an amine equipped with fluorescein (FL-NH 2 )t oy ield BPS 5 1. [11] Methanolysis of thioesters followed by treatment with S 2 Cl 2 , [18] removal of the tert-butyl ester in 14, and reaction with FL-NH 2 yielded ETP 4 4.Aclose congener of ETP 2 5, [11] ETP 2 6 was newly prepared from amine 15,also to explore the advantages of aphenyl group during synthesis. The position of the compound numbers reflects the approximate fluorescence intensities after correction using quenching factors (QFs) of reduced COCs (note the log scale).…”