Chagas disease (CD) still represents a serious public health problem in Latin America, even after more than 100 years of its discovery. Clinical treatments (nifurtimox and benznidazole) are considered inadequate, especially because of undesirable side effects and low efficacy in the chronic stages of the disease, highlighting the urgency for discovering new effective and safe drugs. A small library of compounds (1a–i and 2a–j) was designed based on the structural optimization of a Hit compound derived from 1,4-naphthoquinones (C2) previously identified. The biological activity, structure-activity relationship (SAR), and the in silico physicochemical profiles of the naphthoquinone derivatives were analyzed. Most modifications resulted in increased trypanocidal activity but some substitutions also increased toxicity. The data reinforce the importance of the chlorine atom in the thiophenol benzene ring for trypanocidal activity, highlighting 1g, which exhibit a drug-likeness profile, as a promising compound against Trypanosoma cruzi. SAR analysis also revealed 1g as cliff generator in the structure-activity similarity map (SAS maps). However, compounds C2 and 1g were unable to reduce parasite load, and did not prevent mouse mortality in T. cruzi acute infection. Phenotypic screening and computational analysis have provided relevant information to advance the optimization and design of new 1,4-naphthoquinone derivatives with a better pharmacological profile.

: Juglone is a metabolite produced by several species of plants, in particular Juglans nigra. Additionally, juglone is a 1,4-naphthoquinone that has several biological actions. Antimicrobial, antifungal, sedative, oxidizing, antihypertensive, and especially anti-proliferative actions have been described for juglone. This justifies that 1,4-naphthoquinone is a privileged structure for Medicinal Chemistry, and it is useful for the development of new prototypes with varied actions. In this work, we make a profound review of juglone synthesis methodology, the biological actions of juglone, and mainly the synthesis and pharmacological actions of juglone derivatives. We hope that the potent biological actions described for these derivatives in this review will stimulate the continuous design, synthesis, and pharmacological evaluation of new juglone derivatives.

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New sulfonyl-lapachones were efficiently obtained through the catalytic oxidation of arylthio- and cyclohexylthio-lapachone derivatives with hydrogen peroxide in the presence of a Mn(III) porphyrin complex. The antibacterial activities of the non-oxidized and oxidized lapachone derivatives against the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus were evaluated after their incorporation into polyvinylpyrrolidone (PVP) micelles. The obtained results show that the PVP-formulations of the lapachones 4b–g and of the sulfonyl-lapachones 7e and 7g reduced the growth of S. aureus.

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