This review article summarizes recent applications of electrochemical techniques to redox-active drug development and mechanistic studies. It includes a general introduction to the use of electrochemistry in biology, with a focus on how electrochemistry can uniquely provide both kinetic and thermodynamic information. A number of studies are reported from the literature and the authors' laboratories, including the investigation of reactive oxygen species, biooxidative/bioreductive activation of pro-drugs, and DNA alkylation, with a particular emphasis on quinones and related compounds. Data from techniques ranging from traditional cyclic voltammetry to sophisticated single cell studies are presented. The examples herein presented illustrate how electrochemical, biochemical and medical knowledge can be integrated to develop strategies for the design and development of redox-selective therapeutics.

Essa revisão resume alguns dos aspectos mais relevantes na correlação entre processos e parâmetros eletroquímicos e atividades biológicas, relacionadas, principalmente, a doenças tropicais e câncer. Apesar da gama de possibilidades e da complexidade da química celular/tecidual/extracelular, é possível racionalizar o papel da eletroquímica em poucas bases teóricas, principalmente: transferência eletrônica -estresse oxidativo, geração eletroquímica in situ de agentes tóxicos diferentes das espécies oxigenadas reativas, interação com endobióticos, com ênfase particular em alquilação biorredutiva e substituição de endobióticos com função em reações de oxi-redução biológicas. O uso de métodos eletroquímicos para a obtenção de mecanismos de ação de drogas e na análise de eventos celulares é também apresentado. Nessas correlações, métodos e/ou parâmetros eletroquímicos exercem papel relevante, porém, não absoluto.This review summarises some of the more relevant achievements in the correlation between electrochemical processes and parameters and bioactive properties, mainly related to cancer and tropical diseases. Despite the broad range of possibilities and the complexity of cell/tissue/extracell chemistry, it is possible to rationalise the role of electrochemistry in few basic theoretical frameworks, mainly, the one based on electron transfer-oxidative stress and in situ generation of toxic species, other than the reactive oxygen species; interaction with endobiotics, with emphasis on bioreductive alkylation and replacement of endobiotics with function in biological redox reactions. The use of electrochemical methods to obtain relevant informations about drugs' mechanism of action and analysis of cellular events is also presented. Electrochemical methods and/or parameters play essential but not absolute roles.

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Niclosamide is the only commercially available molluscicide recommended by the WHO for large-scale use in schistosomiasis control programs. The electrochemical reduction and oxidation mechanism of niclosamide was studied using cyclic, differential and square wave voltammetry, at a glassy carbon electrode. An indirect procedure for in situ quantification of niclosamide using batch injection analysis with electrochemical detection, possible to be used for in situ determinations in river streams and effluents, was developed. It enabled a detection limit of 8 )/10 (7 M. The investigation of the niclosamide Á/DNA interaction using an electrochemical DNA-biosensor showed for the first time clear evidence of interaction with DNA and suggested that niclosamide toxicity can be caused by this interaction, after reductive activation. #