Abstract
BackgroundPlasmodium falciparum has shown multidrug resistance, leading to the necessity for the development of new drugs with novel targets, such as the synthesis of isoprenic precursors, which are excellent targets because the pathway is different in several steps when compared with the human host. Naphthoquinone derivatives have been described as potentially promising for the development of anti-malarial leader molecules. In view of that, the focus in this work is twofold: first, evaluate the in vitro naphthoquinone antiplasmodial activity and cytotoxicity; secondly, investigate one possible action mechanism of two derivatives of hydroxy-naphthoquinones.ResultsThe two hydroxy-naphthoquinones derivatives have been tested against P. falciparum in vitro, using strains of parasites chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2), causing 50% inhibition of parasite growth with concentrations that varied from 7 to 44.5 μM. The cell viability in vitro against RAW Cell Line displayed IC50 = 483.5 and 714.9 μM, whereas, in primary culture tests using murine macrophages, IC50 were 315.8 and 532.6 μM for the two selected compounds, causing no haemolysis at the doses tested. The in vivo acute toxicity assays exhibited a significant safety margin indicated by a lack of systemic and behavioural toxicity up to 300 mg/kg. It is suggested that this drug seems to inhibit the biosynthesis of isoprenic compounds, particularly the menaquinone and tocopherol.ConclusionsThese derivatives have a high potential for the development of new anti-malarial drugs since they showed low toxicity associated to a satisfactory antiplasmodial activity and possible inhibition of a metabolic pathway distinct from the pathways found in the mammalian host.
Highlights
Plasmodium falciparum has shown multidrug resistance, leading to the necessity for the development of new drugs with novel targets, such as the synthesis of isoprenic precursors, which are excellent targets because the pathway is different in several steps when compared with the human host
Several anti-malarials drugs are available, their efficacies are limited by the existence of drug-resistant parasites worldwide, especially in the case of Plasmodium falciparum [2, 3]
Compounds The tested hydroxy-naphthoquinone derivatives were setting in the School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Brazil [9], namely: 2-aniline-3-hydroxy-1,4-naphthoquinone, 2-chloro-aniline-3hydroxy-1,4-naphthoquinone, 4-methoxy-aniline-3-hydroxy-1,4-naphthoquinone and 2.6-dimethyl-aniline-3hydroxy-1.4-naphthoquinone, on designated as 4a–4d, respectively
Summary
Plasmodium falciparum has shown multidrug resistance, leading to the necessity for the development of new drugs with novel targets, such as the synthesis of isoprenic precursors, which are excellent targets because the pathway is different in several steps when compared with the human host. The focus in this work is twofold: first, evaluate the in vitro naphthoquinone antiplasmodial activity and cytotoxicity; secondly, investigate one possible action mechanism of two derivatives of hydroxy-naphthoquinones. Several anti-malarials drugs are available, their efficacies are limited by the existence of drug-resistant parasites worldwide (including Brazil), especially in the case of Plasmodium falciparum [2, 3]. In this context, it is needed either the discovery of new drugs associated with new targets or to improve determined anti-malarial drug class. Its mechanism of action was already proposed by means of the inhibition of the mitochondrial electron carrier chain [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
