Anticancer Triazenes: from Bioprecursors to Hybrid Molecules

Rational design and synthesis of triazene-amonafide derivatives as novel potential antitumor agents causing oxidative damage towards DNA through intercalation mode

In this work, we rationally designed and synthesized two novel triazene-amonafide derivatives 2-(2-(diisopropylamino)ethyl)-5-(3,3-dimethyltriaz-1-en-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (D-11) and 5-(3,3-diethyltriaz-1-en-1-yl)-2-(2-(diisopropylamino)ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (D-12) as potential antitumor agents. The DNA damage induced by the intercalation mode of D-11 (D-12) towards DNA was electrochemically detected through the construction of efficient biosensors. The consecutive processes of reversible redox of naphthylimide ring and irreversible oxidation of triazene moiety were elucidated on the surface of glassy carbon electrode (GCE) by CV, SWV, and DPV methods. Electrochemical biosensors were obtained through the immobilization of ctDNA, G-quadruplexes, poly(dG), and poly(dA), respectively, on the clean surface of GCE. After the incubation of biosensors with D-11 or D-12, the peaks of dGuo and dAdo decreased prominently, and the peak of 8-oxoGua appeared at +0.50 V, suggesting that the interaction between D-11 (D-12) and DNA could result in the oxidative damage of guanine. Unexpected, the as-prepared DNA biosensor possessed satisfactory anti-interference property and good practicability in real samples. UV-vis and fluorescence spectra, and gel electrophoresis assays were employed to further confirm the intercalation mode of D-11 (D-12) towards DNA base pairs. Moreover, D-11 was proved to exhibit stronger anti-proliferation activity than mitionafide and amonafide against both A549 and HeLa cell lines.

A step forward on the in vitro and in vivo assessment of a novel nanomedicine against melanoma

Melanoma is the most aggressive form of skin cancer, with increasing incidence and mortality rates. To overcome current treatment limitations, a hybrid molecule (HM) combining a triazene and a ʟ-tyrosine analogue, was recently synthesized, incorporated in long blood circulating liposomes (LIP HM) and validated in an immunocompetent melanoma model. The present work constitutes a step forward in the therapeutic assessment of HM formulations. Here, human melanoma cells, A375 and MNT-1, were used and dacarbazine (DTIC), a triazene drug clinically available as first-line treatment for melanoma, constituted the positive control. In cell cycle analysis, A375 cells, after 24-h incubation with HM (60 μM) and DTIC (70 μM), resulted in a 1.2 fold increase (related to control) in the percentage of cells in G0/G1 phase. The therapeutic activity was evaluated in a human murine melanoma model (subcutaneously injected with A375 cells) to most closely resemble the human pathology. Animals treated with LIP HM exhibited the highest antimelanoma effect resulting in a 6-, 5- and 4-fold reduction on tumor volume compared to negative control, Free HM and DTIC groups, respectively. No toxic side effects were detected. Overall, these results constitute another step forward in the validation of the antimelanoma activity of LIP HM, using a murine model that more accurately simulates the pathology that occurs in human patients.

Preclinical validation of a new hybrid molecule loaded in liposomes for melanoma management

The aggressiveness of melanoma and lack of effective therapies incite the discovery of novel strategies. Recently, a new dual acting hybrid molecule (HM), combining a triazene and a ʟ-tyrosine analogue, was synthesized. HM was designed to specifically be activated by tyrosinase, the enzyme involved in melanin biosynthesis and overexpressed in melanoma. HM displayed remarkable superior antiproliferative activity towards various cancer cell lines compared with temozolomide (TMZ), a triazene drug in clinical use, that acts through DNA alkylation. In B16-F10 cells, HM induced a cell cycle arrest at phase G0/G1 with a 2.8-fold decrease in cell proliferation index. Also, compared to control cells, HM led to a concentration-dependent reduction in tyrosinase activity and increase in caspase 3/7 activity. To maximize the therapeutic performance of HM in vivo, its incorporation in long blood circulating liposomes, containing poly(ethylene glycol) (PEG) at their surface, was performed for passively targeting tumour sites. HM liposomes (LIP HM) exhibited high stability in biological fluids. Preclinical studies demonstrated its safety for systemic administration and in a subcutaneous murine melanoma model, significantly reduced tumour progression. In a metastatic murine melanoma model, a superior antitumour effect was also observed for mice receiving LIP HM, with markedly reduction of lung metastases compared to positive control group (TMZ). Biodistribution studies using ¹¹¹In-labelled LIP HM demonstrated its ability for passively targeting tumour sites, thus correlating with the high therapeutic effect observed in the two experimental murine melanoma models. Overall, our proposed nanotherapeutic strategy was validated as an effective and safe alternative against melanoma.

Synthesis and Reactivity of a Terminal 1-Alkynyl Triazene

1-Alkynyl triazenes are versatile reagents in synthetic organic chemistry, but the structural diversity of this compound class has so far been limited. Herein, we describe the synthesis of a terminal 1-alkynyl triazene. Subsequent functionalization allows the preparation of 1-alkynyl triazenes with a range of functional groups including esters, alcohols, cyanides, phosphonates, and amides. Furthermore, the terminal 1-alkynyl triazene can be used for the synthesis of di- and triynes and for the preparation of (hetero)aromatic triazenes in metal-catalyzed cyclization reactions.

Discovery of spirooxindole-derived small-molecule compounds as novel HDAC/MDM2 dual inhibitors and investigation of their anticancer activity

Simultaneous inhibition of more than one target is considered to be a novel strategy in cancer therapy. Owing to the importance of histone deacetylases (HDACs) and p53-murine double minute 2 (MDM2) interaction in tumor development and their synergistic effects, a series of MDM2/HDAC bifunctional small-molecule inhibitors were rationally designed and synthesized by incorporating an HDAC pharmacophore into spirooxindole skeletons. These compounds exhibited good inhibitory activities against both targets. In particular, compound 11b was demonstrated to be most potent for MDM2 and HDAC, reaching the enzyme inhibition of 68% and 79%, respectively. Compound 11b also showed efficient antiproliferative activity towards MCF-7 cells with better potency than the reference drug SAHA and Nutlin-3. Furthermore, western blot analysis revealed that compound 11b increased the expression of p53 and Ac-H4 in MCF-7 cells in a dose-dependent manner. Our results indicate that dual inhibition of HDAC and MDM2 may provide a novel and efficient strategy for the discovery of antitumor drug in the future.

Chemo- and regio-divergent access to fluorinated 1-alkyl and 1-acyl triazenes from alkynyl triazenes

The 1,1,2,2-tetrafluoroethylene unit is a prevalent pattern in bioactive molecules and functional materials. Despite being in principle a straightforward strategy to access this motif, the direct tetrafluorination of alkynes involves...

Discovery of novel tubulin/HDAC dual-targeting inhibitors with strong antitumor and antiangiogenic potency

A novel series of cis-diphenylethene and benzophenone derivatives as tubulin/HDAC dual-targeting inhibitors were designed and synthesized. Among them, compound 28g exhibited the most potent antiproliferative activities against six different human cancer cell lines, 28g could not only inhibited tubulin polymerization, disrupted cellular microtubule networks but also selectively inhibited class IIa HDACs, especially HDAC7 activity. Further molecular docking demonstrated 28g could occupy the binding pockets of tubulin and HDAC7 meanwhile. Cellular mechanism studies revealed that 28g could induce G2/M phase arrest by down-regulated expression of p-cdc2 and cell apoptosis by regulating mitochondrial membrane potential, reactive oxygen species (ROS) levels and apoptosis-related proteins (PARP, Caspase families) in a dose-dependent manner. Importantly, 28g significantly inhibited HUVEC tube formation, proliferation, migration and invasion. The inhibitory effect against angiogenesis in vivo was confirmed by zebrafish xenograft. Furthermore, 28g could effectively suppress the proliferation and metastasis of MGC-803 cells in vitro and in zebrafish xenograft. All above results indicated that 28g can act as a promising antitumor and antiangiogenic agent via targeting tubulin and class IIa HDACs.

Sulfur Analogues of Tyrosine in the Development of Triazene Hybrid Compounds: A New Strategy against Melanoma

Malignant melanoma is the major cause of death from skin cancer. Treatment of metastatic melanoma remains an enormous challenge. In this study we developed hybrid compounds and studied their potential use in malignant melanoma chemotherapy. They were designed to act by a double mechanism of action, being composed of two pharmacophores: the tyrosine sulfur analogue 4-S-cysteaminylphenol (4-S-CAP, 10), with immunomodulatory properties and specific melanocytotoxic activity, and triazene 4, with DNA alkylating properties. The design of these compounds aims to achieve selective activation by the enzyme tyrosinase overexpressed in melanoma cells. Compounds 11a-e, 13a, and 13b were found to be excellent tyrosinase substrates (0.5 min ≤ t _1/2 ≤ 3.7 min). Furthermore, derivatives 11 and 13 were evaluated for their molecular properties, hepatotoxicity, in vivo toxicity profile, and assessment of cytotoxic activity in melanoma and non-melanoma cell lines. The results were compared with those obtained for temozolomide, a triazene used in melanoma therapy. It was discovered that the hybrids are selective and effective drugs, representing a valuable model for the development of new multitarget melanoma therapy. In particular, compound 10 may be an important component for these strategies that use a metabolic pathway of melanin synthesis. Molecular hybridization of 10 with triazenes 4 renders the hybrids (11 and 13) unexpectedly devoid of hepatotoxicity while maintaining cytotoxic activity in malignant cells.

Chelation-Assisted Interrupted Copper(I)-Catalyzed Azide-Alkyne-Azide Domino Reactions: Synthesis of Fully Substituted 5-Triazenyl-1,2,3-triazoles

We describe the synthesis of 1,4-(disubstituted)-5-triazenyl-1,2,3-triazoles through a ligand-free domino copper(I)-catalyzed azide-alkyne-azide process of chelating aryl azides bearing N-P═O, P═O, and SO₃H groups at the ortho position with a wide variety of acetylenes. DFT calculations reveal that Cu-chelation is a crucial factor in the interception of the CuAAC intermediate by the azide. The crystal structure of the catalytic species has been determined by X-ray diffraction.

Vinyl and Alkynyl Triazenes: Synthesis, Reactivity, and Applications

Aromatic compounds containing triazenyl groups (N₃ RR') have a profound impact on synthetic organic and medicinal chemistry. In contrast, the chemistry of vinyl and alkynyl triazenes was a largely uncharted territory until recently. The situation has changed over the last five years, and it has become apparent that vinyl and alkynyl triazenes are highly interesting compounds with a unique reactivity. The electron-donating properties of the triazenyl group provide alkynyl triazenes with an ynamide-like reactivity, which can be exploited in reactions of the triple bond. Vinyl triazenes, on the other hand, can be used for electrophilic vinylation reactions. The foundation for this new triazene chemistry are synthetic pathways which allow preparing vinyl and alkynyl triazenes in few steps from readily available starting materials. In this Minireview, we summarize recent developments in this area.

Brønsted and Lewis acid adducts of triazenes

Spectroscopy and crystallographic data show that triazenes are protonated at N1 position.

Novel sulphonamides incorporating triazene moieties show powerful carbonic anhydrase I and II inhibitory properties

A series of compounds incorporating 3-(3-(2/3/4-substituted phenyl)triaz-1-en-1-yl) benzenesulfonamide moieties were synthesised and their chemical structure was confirmed by physico-chemical methods. Carbonic anhydrase (CA, EC 4.2.1.1) inhibitory effects of the compounds were evaluated against human isoforms hCA I and II. K_I values of these sulphonamides were in the range of 21 ± 4–72 ± 2 nM towards hCA I and in the range of 16 ± 6–40 ± 2 nM against hCA II. The 4-fluoro substituted derivative might be considered as an interesting lead due to its effective inhibitory action against both hCA I and hCA II (K_Is of 21 nM), a profile rarely seen among other sulphonamide CA inhibitors, making it of interest in systems where the activity of the two cytosolic isoforms is dysregulated.