Thirty-eight compounds were evaluated against T. cruzi and six were found to be more potent against trypomastigotes than benznidazole.

Thirty four halogen and selenium-containing quinones, synthesized by rhodium-catalyzed C-H bond activation and palladium-catalyzed cross-coupling reactions, were evaluated against bloodstream trypomastigotes of T. cruzi. We have identified fifteen compounds with IC/24 h values of less than 2 μM. Electrochemical studies on A-ring functionalized naphthoquinones were also performed aiming to correlate redox properties with trypanocidal activity. For instance, (E)-5-styryl-1,4-naphthoquinone 59 and 5,8-diiodo-1,4-naphthoquinone 3, which are around fifty fold more active than the standard drug benznidazole, are potential derivatives for further investigation. These compounds represent powerful new agents useful in Chagas disease therapy.

This review discusses the state of the art, challenges and perspectives in recent applications of electrochemistry in the life sciences. It deals mainly with the elucidation of molecular mechanisms of drug action, drug design and development, involving electron transfer, pharmaco-electrochemistry (the combination of electrochemical and pharmacological assays), and electrochemical studies of membrane models and drug delivery. It aims to shed light on the question: does electrochemistry really contribute to this area? It includes a general introduction for the use of electrochemistry in the life sciences, with a focus on how electrochemistry can uniquely provide both kinetic and thermodynamic information. A number of studies are reported in the literature and from the authors' laboratories, including the investigation of biooxidative/bioreductive activation of pro-drugs, DNA alkylation, electrochemically- based release of reactive oxygen and nitrogen species, with a particular emphasis on quinones, ferrocifens and compounds with mixed-functionality. Within the context of drug delivery and bioavailability, the electrochemical investigation of supramolecular interactions of the chosen classes of compounds with cyclodextrins and lipid bilayers, in relation to their solubilization and vectorization was also carried out. The updated examples herein illustrate how relevant and challenging the integration of electrochemistry, supramolecular and materials chemistry, biochemistry and medical knowledge for the design and development of redox-selective molecular approaches is. Many questions related to these fields are still unclear and the search for selectivity toward redox therapeutic agents remains of expanding interest. This review hopes to stimulate researchers to become more involved in this fruitful interface between electrochemistry and the life sciences.

Background: Natural naphthoquinones have shown diversified biological activities including antibacterial, antifungal, antimalarial, and cytotoxic activities. However, they are also compounds with acute cytotoxicity, immunotoxicity, carcinogenesis, and cardio- and hepatotoxicity, then the modification at their redox center is an interesting strategy to overcome such harmful activity. Objective: In this study, four novel semisynthetic hydrazones, derived from the isomers α- and β-lapachones (α and β, respectively) and coupled with the drugs hydralazine (HDZ) and isoniazid (ACIL), were prepared, evaluated by electrochemical methods and assayed for anticancer activity. Method: The semisynthetic hydrazones were obtained and had their molecular structures established by NMR, IR, and MS. Anticancer activity was evaluated by cell viability determined by reduction of 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyl-2H-tetrazolium bromide (MTT). The electrochemical studies, mainly cyclic voltammetry, were performed, in aprotic and protic media. Result: The study showed that the compounds 2, 3, and 4 were active against at least one of the cancer cell lines evaluated, being compounds 3 and 4 the most cytotoxic. Toward HL-60 cells, compound 3 was 20x more active than β-lapachone, and 3x more cytotoxic than doxorubicin. Furthermore, 3 showed an SI value of 39.62 for HL-60 cells. Compound 4 was active against all cancer cells tested, with IC50 values in the range 2.90–12.40 μM. Electrochemical studies revealed a profile typical of self-protonation and reductive cleavage, dependent on the supporting electrolyte. Conclusion: These results therefore indicate that compounds 3 and 4 are strong candidates as prototypes of new antineoplastic drugs.

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We report a sequential C-H iodination/organoyl-thiolation of naphthoquinones and their relevant trypanocidal activity. Under a combination of AgSR with a copper source, sulfur-substituted benzenoid quinones were prepared in high yields (generally >90%). This provides an efficient and general method for preparing A-ring modified naphthoquinoidal systems, recognized as a challenge in quinone chemistry.

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For the first time, a fluorescent lapachone-based BODIPY was synthesised and characterised by NMR and mass spectrometry. Computational and electrochemical aspects, as well as cytotoxic activity and subcellular localisation, were studied. Confocal microscopy experiments indicated that the probe was a specific mitochondria-staining agent. These in-detail analyses were useful in understanding the cytotoxic effects and mechanism of action of this novel hybrid compound. This molecule constitutes a promising prototype owing to its potential biological activities and the new strategies aimed at mechanistic investigations in cells and in vivo, and opens up an interesting avenue of research.