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Quinones represent an important class of biological compounds, but are also involved with toxicological intermediates and among their hazardous effects include cytotoxicity, immunotoxicity, and carcinogenesis. The structure-toxicity relationship for quinone derivatives has been used to cytotoxicity or cytoprotective effects by redox mechanism is determined using quantum chemical calculations through the density functional theory (DFT). According to our DFT study, the electron acceptance is related with LUMO, electron affinity, and stabilization energy values. The highest spin density distribution in the heteroatoms is more favored for the more cytotoxic compounds. The electrophilic capacities of these compounds have been related with LUMO values. The cytotoxic properties of quinones are related to the stabilization energy after electron accepting by redox mechanism. Electron affinity is the most relevant parameter related to toxicity mechanism. Regioisomers has different electrophilic capacity. The electrophilicity increases on molecules containing electron-withdrawing groups (EWG) and reduces on molecules containing electron-donating groups (EDG). These results explain the toxic difference between natural and synthetic quinone derivatives and can be used in the design and study of new drugs.

Leishmaniasis is a neglected infectious disease caused by different species of the Leishmania parasite and is one of the major public health problems in developing countries. Despite the progress in fundamental knowledge about the Leishmania parasite, current therapy against leishmaniasis is still unsatisfactory due to limited efficacy, prolonged treatment, high cost and undesirable adverse effects. Thus, the research for new prototypes compounds of antileishmaniasis drugs remains a matter of current importance. The objective of this study was to evaluate the leishmanicidal activity of cytochalasin B, a natural compound isolated by our group in a previous study, against L. amazonensis, using experimental tests and computational simulation methodologies. The results of the biological evaluation showed that cytochalasin B has antileishmanial activity against the promastigote form of Leishmania amazonensis. These results are corroborated by the docking and molecular dynamics that showed that the activity occurs due to the inactivation of the trypanothione reductase enzyme (TryR).

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