DNA-Based Electrodes and Computational Approaches on the Intercalation Study of Antitumoral Drugs

The binding between anticancer drugs and double-stranded DNA (dsDNA) is a key issue to understand their mechanism of action, and many chemical methods have been explored on this task. Molecular docking techniques successfully predict the affinity of small molecules into the DNA binding sites. In turn, various DNA-targeted drugs are electroactive; in this regard, their electrochemical behavior may change according to the nature and strength of interaction with DNA. A carbon paste electrode (CPE) modified with calf thymus ds-DNA (CPDE) and computational methods were used to evaluate the drug–DNA intercalation of doxorubicin (DOX), daunorubicin (DAU), idarubicin (IDA), dacarbazine (DAR), mitoxantrone (MIT), and methotrexate (MTX), aiming to evaluate eventual correlations. CPE and CPDE were immersed in pH 7 0.1 mM solutions of each drug with different incubation times. As expected, the CPDE response for all DNA-targeted drugs was higher than that of CPE, evidencing the drug–DNA interaction. A peak current increase of up to 10-fold was observed; the lowest increase was seen for MTX, and the highest increase for MIT. Although this increase in the sensitivity is certainly tied to preconcentration effects of DNA, the data did not agree entirely with docking studies, evidencing the participation of other factors, such as viscosity, interfacial electrostatic interactions, and coefficient of diffusion.

S16020 pyridocarbazole derivatives display high activity to lung cancer cells

Background: Despite the dynamic development of medicine, globally cancer diseases remain the second leading cause of death. Therefore, there is a strong necessity to improve chemotherapy regimens and search for new anticancer agents. Pyridocarbazoles are compounds with confirmed antitumor properties based on multimodal mechanisms, i.a. DNA intercalation and topoisomerase II-DNA complex inhibition. One of them, S16020, displayed a wide spectrum of activity. Objective: The aim of the study was to investigate the antitumor potency of six S16020 derivatives, synthesized according to the SAR (structure-activity relationship) method. Methods: The biological evaluation included influence on cancer cell viability, proliferation, and migration, as well as P-glycoprotein activity. NHDF, A549, MCF-7, LoVo, and LoVo/DX cell lines were used in the study. Results: All derivatives displayed low toxicity to normal (NHDF) cells at 1 and 2 µM (≤ 20% of cell growth inhibition). The highest reduction in cell viability was noted in A549 cells which was accompanied by significant disruption of cells proliferation and motility. Compound 1 exhibited the strongest cytotoxic, antiproliferative, and antimigratory effects, higher than the reference olivacine. A significant reduction in P-glycoprotein activity was found for derivatives 6 and 1. Conclusion: S16020 derivatives could be considered as potential candidates for new anticancer drugs.

Topoisomerase poisoning by the flavonoid nevadensin triggers DNA damage and apoptosis in human colon carcinoma HT29 cells

Nevadensin, an abundant polyphenol of basil, is reported to reduce alkenylbenzene DNA adduct formation. Furthermore, it has a wide spectrum of further pharmacological properties. The presented study focuses the impact of nevadensin on topoisomerases (TOPO) in vitro. Considering the DNA-intercalating properties of flavonoids, first, minor groove binding properties (IC50 = 31.63 µM), as well as DNA intercalation (IC50 = 296.91 µM) of nevadensin, was found. To determine potential in vitro effects on TOPO I and TOPO IIα, the relaxation and decatenation assay was performed in a concentration range of 1–500 µM nevadensin. A partial inhibition was detected for TOPO I at concentrations ≥ 100 µM, whereas TOPO IIα activity is only inhibited at concentrations ≥ 250 µM. To clarify the mode of action, the isolating in vivo complex of enzyme assay was carried out using human colon carcinoma HT29 cells. After 1 h of incubation, the amount of TOPO I linked to DNA was significantly increased by nevadensin (500 µM), why nevadensin was characterized as TOPO I poison. However, no effects on TOPO IIα were detected in the cellular test system. As a subsequent cellular response to TOPO I poisoning, a highly significant increase of DNA damage after 2 h and a decrease of cell viability after 48 h at the same concentration range were found. Furthermore, after 24 h of incubation a G2/M arrest was observed at concentrations ≥ 100 µM by flow cytometry. The analysis of cell death revealed that nevadensin induces the intrinsic apoptotic pathway via activation of caspase-9 and caspase-3. The results suggest that cell cycle disruption and apoptotic events play key roles in the cellular response to TOPO I poisoning caused by nevadensin in HT29 cells.

EPAC1 Inhibition Protects the Heart from Doxorubicin-Induced Toxicity

Rationale: The widely used chemotherapeutic agent Doxorubicin (Dox) induces cardiotoxicity leading to dilated cardiomyopathy and heart failure. This cardiotoxicity has been related to ROS generation, DNA intercalation, bioenergetic distress and cell death. However, alternative mechanisms are emerging, focusing on signaling pathways. Objective: We investigated the role of Exchange Protein directly Activated by cAMP (EPAC), key factor in cAMP signaling, in Dox-induced cardiotoxicity. Methods and Results: Dox was administrated in vivo (10 +/- 2 mg/kg, i.v.; with analysis at 2, 6 and 15 weeks post injection) in WT and EPAC1 KO C57BL6 mice. Cardiac function was analyzed by echocardiography and intracellular Ca2+ homeostasis by confocal microscopy in isolated ventricular cardiomyocytes. 15 weeks post-injections, Dox-treated WT mice, developed a dilated cardiomyopathy with decreased ejection fraction, increased telediastolic volume and impaired Ca2+ homeostasis, which were totally prevented in the EPAC1 KO mice. The underlying mechanisms were investigated in neonatal and adult rat cardiac myocytes under Dox treatment (1-10 uM). Flow cytometry, Western blot, BRET sensor assay, and RT-qPCR analysis showed that Dox induced DNA damage and cardiomyocyte cell death with apoptotic features rather than necrosis, including Ca2+-CaMKKβ-dependent opening of the Mitochondrial Permeability Transition Pore, dissipation of the Mitochondrial membrane potential, caspase activation, cell size reduction, and DNA fragmentation. Dox also led to an increase in both cAMP concentration and EPAC1 protein level and activity. The pharmacological inhibition of EPAC1 (CE3F4) but not EPAC2 alleviated the whole Dox-induced pattern of alterations including DNA damage, Mitochondrial membrane potential, apoptosis, mitochondrial biogenesis, dynamic, and fission/fusion balance, and respiratory chain activity, suggesting a crucial role of EPAC1 in these processes. Importantly, while preserving cardiomyocyte integrity, EPAC1 inhibition potentiated Dox-induced cell death in several human cancer cell lines. Conclusion: Thus, EPAC1 inhibition could be a valuable therapeutic strategy to limit Dox-induced cardiomyopathy without interfering with its antitumoral activity.

Domino Suzuki-Miyaura Cross-Coupling and Oxidative Condensation Reaction: An Approach Towards Synthesis of Phenanthridine and Its Analogues

Phenanthridines belong to a very important class of nitrogen containing heterocylic compounds and constitute core structure of many natural alkaloids such as trisphaeridine and nitidine. Quarternarybenzo[c]phenanthridine alkaloids (QBA) represented by sanguinarine(SA), chelerythrine (CHE), and fagaronine (FA) exhibit antifungal and nematocidal properties and also serve as the core structure of broad range of medicinally active molecules showing anti-tumor activity, anti-viral property, anti-neoplastic or mutagenic activity through DNA-intercalation. Phenanthridines are also utilized for the synthesis of compounds of therapeutic interests such as anticancer platinum complex typified by phenanthriplatin antibacterial, anti-infectives, antprotozoal, antituberculosis, antitrypanosomiasis compounds. Although conventional synthetic methods towards their development showed their own advantages, they generally involved either multistep processes with low yield, or starting materials which are not readily available or requirement of prefunctionalization. Hence herein we present the development of an efficient and convenient synthetic methodology towards these versatile compounds. <br>

Domino Suzuki-Miyaura Cross-Coupling and Oxidative Condensation Reaction: An Approach Towards Synthesis of Phenanthridine and Its Analogues

Phenanthridines belong to a very important class of nitrogen containing heterocylic compounds and constitute core structure of many natural alkaloids such as trisphaeridine and nitidine. Quarternarybenzo[c]phenanthridine alkaloids (QBA) represented by sanguinarine(SA), chelerythrine (CHE), and fagaronine (FA) exhibit antifungal and nematocidal properties and also serve as the core structure of broad range of medicinally active molecules showing anti-tumor activity, anti-viral property, anti-neoplastic or mutagenic activity through DNA-intercalation. Phenanthridines are also utilized for the synthesis of compounds of therapeutic interests such as anticancer platinum complex typified by phenanthriplatin antibacterial, anti-infectives, antprotozoal, antituberculosis, antitrypanosomiasis compounds. Although conventional synthetic methods towards their development showed their own advantages, they generally involved either multistep processes with low yield, or starting materials which are not readily available or requirement of prefunctionalization. Hence herein we present the development of an efficient and convenient synthetic methodology towards these versatile compounds. <br>

Spectroscopic, computational and molecular docking study of Cu(II) complexes with flavonoids: From cupric ion binding to DNA intercalation.

Polyphenolic compounds such as flavonoids are closely linked with therapeutical approaches in oxidative stress related diseases mainly because of their antioxidant and metal binding properties. The formation of metal ion...