We describe herein a synthetic strategy for the synthesis of new fluorescent imidazole and phenazine derivatives synthesized from lapachol, a naturally occurring naphthoquinone isolated from Tabebuia species (ipê tree). The photophysical properties and computational details of these compounds have been studied, aiming at gaining a complete understanding of the potential of these derivatives as probes capable of staining mitochondria selectively. Cell imaging experiments proved the capacity of the imidazole derivatives as selective fluorescent mitochondrial imaging probes. These heterocycles present the same staining patterns as MitoTracker Red, corroborating the potential of these compounds as new mitochondria markers permeable to the cell membrane.
Leishmaniasis is a group of infectious diseases caused by protozoan parasites that belong to the genus Leishmania. Currently, there is no human vaccine, and the available treatments are associated with toxicity, high cost, and the emergence of resistant strains. These factors highlight the need to identify new antileishmanial candidates. In this study, we synthesized twenty-four methoxylated cinnamides containing 1,2,3-triazole fragments and evaluated their antileishmanial activity against the Leishmania braziliensis species, which is the main etiological agent responsible for American Tegumentary Leishmaniasis (ATL). The cinnamides were synthetically prepared using nucleophilic acyl substitution and copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reactions. The compounds were characterized using infrared, nuclear magnetic resonance, and high-resolution mass spectrometry techniques. We performed preliminary studies to evaluate the biological activity of these compounds against L. braziliensis promastigotes and axenic amastigotes. Compound 28, N-((1-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)-1H-1,2,3-triazole-4-yl) methyl)-3,4-dimethoxy cinnamide, demonstrated relevant antileishmanial activity with low toxicity in murine cells. The selectivity index values for this compound were superior compared with data obtained using amphotericin B. Furthermore, this cinnamide derivative reduced the infection percentage and number of recovered amastigotes in L. braziliensis-infected macrophages. It also induced an increase in reactive oxygen species production, depolarization of the mitochondrial potential, and disruption of the parasite membrane. Taken together, these findings suggest that this synthetic compound holds potential as an antileishmanial candidate and should be considered for future studies in the treatment of ATL.
The cover picture shows a synthetic strategy based on the redox center modification of naturally occurring naphthoquinones for the synthesis of new fluorescent imidazole and phenazine derivatives. Cell imaging experiments proved the capacity of imidazole derivatives as selective fluorescent mitochondrial imaging probes. These heterocycles present the same staining patterns as MitoTracker red, corroborating the potential of these compounds as new mitochondria markers permeable to the cell membrane. The strategy employed is efficient and innovative, enabling the preparation of cellular probes in a single synthetic step. Details are discussed in the Full Paper by E. N. da Silva Júnior et al. on page 3763 ff (https://doi.org/10.1002/ejoc.201700227).
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