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103. Toxizität von Graphenoxid: Endoperoxide als Ursache.

Author

Pieper, Hanna, Chercheja, Serghei, Eigler, Siegfried, Halbig, Christian E., Filipovic, Milos R., and Mokhir, Andriy

Abstract

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2016
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116. Single-molecule chemical reactions on DNA origami

Author

Voigt, Niels V., primary, Tørring, Thomas, additional, Rotaru, Alexandru, additional, Jacobsen, Mikkel F., additional, Ravnsbæk, Jens B., additional, Subramani, Ramesh, additional, Mamdouh, Wael, additional, Kjems, Jørgen, additional, Mokhir, Andriy, additional, Besenbacher, Flemming, additional, and Gothelf, Kurt Vesterager, additional

Published
2010
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144. A prodrug of 3-(ferrocenylaminocarbonyloxymethyl)phenol activated by reactive oxygen species in cancer cells.

Author

Özkan, Hülya Gizem and Mokhir, Andriy

Abstract

Hybrid drugs containing ferrocene and phenol residues, whose π systems are not conjugated with each other, exhibit potent anticancer activity as previously reported. Few important open questions are remaining before practical application of these drugs becomes possible. First, their mode of action is not fully clarified. Second, it is not known whether these drugs exhibit cancer cell specificity. Third, due to the presence of the phenol moiety, these drugs can potentially be oxidatively deactivated and eliminated via phase II metabolism when applied in vivo. In this paper we report on synthesis of three prodrugs of aminoferrocene-phenol hybrids, where the phenolic OH group is masked as a boronic acid pinacol ester. We confirmed that the best prodrug in this small series p5 is activated in human ovarian cancer A2780 and Burkitt's lypmphoma BL-2 cells, but remains inactive in representative normal SBLF9 cells. Since p5 does not contain free phenolic OH groups, it will not be metabolized as phenols in vivo. We confirmed that the mechanism of anticancer activity of aminoferrocene-phenol prodrug p5 relies on generation of reactive oxygen species in cells. Prodrugs of ferrocene-phenol hybrid drugs, where π-systems of ferrocene and phenol moieties are not conjugated, were prepared. These prodrugs are activated in cancer cells in the presence of reactive oxygen species inducing oxidative stress, but remain inactive in normal cells. [Display omitted] • We prepared aminoferrocene-phenol (AFP) prodrugs responsive to reactive oxygen species (ROS). • In the presence of ROS the prodrugs generate stable AFP drugs. • AFP prodrugs generate ROS in cancer cells, but not in normal cells. • AFP prodrugs induce cancer cell death via apoptosis and necrosis. • The mechanism of action of AFP prodrugs relies on generation of intracellular ROS. [ABSTRACT FROM AUTHOR]

Published
2022
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147. Nucleic acid-specific photoactivation of oligodeoxyribonucleotides labeled with deuterated dihydro- N, N, N′, N′-tetramethylrhodamine using green light.

Author

Schikora, Margot, Dutta, Subrata, and Mokhir, Andriy

Subjects
DEOXYRIBONUCLEOTIDES, NUCLEIC acids, PHOTOACTIVATION, DEUTERATION, RHODAMINES, FLUOROPHORES, BIOCONJUGATES
Abstract

We developed a simple protocol for high-yielding synthesis of conjugates of a deuterated dihydro- N, N, N′, N′-tetramethylrhodamine (F*) with oligodeoxyribonucleotides and a 2′-OMe RNA (a representative nuclease-resistant, chemically modified oligonucleotide) using easily accessible starting materials including NaBD and conjugates of oligonucleotides with N, N, N′, N′-tetramethylrhodamine (F). These compounds were found to be stable in air and insensitive to light at 525, 635 and 650 nm, whereas slow activation occurs upon their exposure to 470 nm light. However, at the conditions of the templated reaction, in the presence of a target nucleic acid and a photocatalyst based on the eosin structure, the F* is oxidized forming fluorescent F. This reaction is >30-fold faster than the background reaction in the absence of the template. Moreover, the presence of a single mismatch in the target nucleic acid slows down the templated reaction by eightfold. These activatable dyes can potentially find applications as nucleic acid-specific probes for super-resolution imaging in live cells. [ABSTRACT FROM AUTHOR]

Published
2014
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149. Triggering RNA Interference by Photoreduction under Red Light Irradiation.

Author

Rühle, Jennifer, Klemt, Insa, and Mokhir, Andriy

Subjects
*RNA interference, *SMALL interfering RNA, *PHOTOREDUCTION, *REACTIVE oxygen species, *REDUCING agents
Abstract

RNA interference (RNAi) using small interfering RNAs (siRNAs) is a powerful tool to target any protein of interest and is becoming more suitable for in vivo applications due to recent developments in RNA delivery systems. To exploit RNAi for cancer treatment, it is desirable to increase its selectivity, e.g., by a prodrug approach to activate the siRNAs upon external triggering, e.g., by using light. Red light is especially well suited for in vivo applications due to its low toxicity and higher tissue penetration. Known molecular (not nanoparticle-based) red-light-activatable siRNA prodrugs rely on singlet oxygen (1O2)-mediated chemistry. 1O2 is highly cytotoxic. Additionally, one of the side products in the activation of the known siRNA prodrugs is anthraquinone, which is also toxic. We herein report on an improved redlight-activatable siRNA prodrug, which does not require 1O2 for its activation. In fact, the 5′ terminus of the antisense strand is protected with an electron-rich azobenzene promoiety. It is reduced and cleaved upon red light exposure in the presence of Sn(IV)(pyropheophorbide a)dichloride acting as a catalyst and ascorbate as a bulk reducing agent. We confirmed the prodrug activation upon red light irradiation both in cell-free settings and in human ovarian cancer A2780 cells. [ABSTRACT FROM AUTHOR]

Published
2023
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