Prospecção in silico e in vitro de potenciais inibidores da enzima n-miristoiltransferase (NMT) em malaria e leishmaniose

Abstract

Neglected Tropical Diseases (NTDs) are a group of infectious diseases that primarily affect populations in tropical and subtropical areas, predominantly in low-income countries. These diseases receive little attention in terms of research, drug development, and public health investment, despite causing a significant burden in terms of morbidity, mortality, and socioeconomic impact. Among the most common NTDs are dengue, leishmaniasis, Chagas disease, schistosomiasis, lymphatic filariasis, among others. These diseases are often transmitted by vectors such as mosquitoes, flies, and ticks, and frequently affect underserved communities with limited access to basic sanitation, clean water, and healthcare services.The challenges in controlling NTDs include the lack of adequate healthcare infrastructure, limited access to effective treatments, drug resistance, insufficient investment in research and development of new therapies, as well as the complexity of interactions between parasites, their hosts, and the environment. Recent efforts to combat NTDs include prevention and control programs, access to medicines and treatments, investments in research and the development of vaccines and more effective therapies, as well as initiatives to improve health infrastructure and public health education. The effective fight against NTDs requires an integrated and collaborative approach among governments, non-governmental organizations, academic institutions, and the private sector. Malaria is an infectious disease caused by parasites of the Plasmodium genus, transmitted to humans through the bite of infected Anopheles mosquitoes. Although it is not classified as a neglected disease by the World Health Organization (WHO), it remains one of the most prevalent and deadly tropical diseases worldwide, particularly in tropical and subtropical regions, with a significant impact on low-income countries. Malaria symptoms include fever, chills, headaches, nausea, and vomiting, which can progress to severe complications such as anemia, brain dysfunction, kidney failure, and even death, especially in cases caused by Plasmodium falciparum, the most lethal strain. Malaria control relies on various strategies, including the use of insecticide-treated bed nets, residual insecticide spraying, early and effective treatment of diagnosed cases, and, when possible, the development of vaccines. However, resistance to antimalarial drugs and insecticides, along with socioeconomic challenges such as limited access to healthcare and poor infrastructure, remain significant obstacles in combating the disease. Despite these challenges, significant progress has been made in reducing malaria incidence and mortality over recent decades, thanks to global control initiatives and investments in research, diagnosis, and treatment. However, the complete eradication of malaria remains a challenging goal, requiring continuous and coordinated efforts at local, national, and international levels. Another important and complex disease among NTDs is leishmaniasis, a parasitic disease caused by protozoa of the Leishmania genus. The parasite is transmitted to humans through the bite of infected sandflies of the Phlebotomus genus (in the Old World) or Lutzomyia genus (in the New World). There are different forms of leishmaniasis, including cutaneous, mucocutaneous, and visceral leishmaniasis, the latter being the most severe and potentially fatal if not properly treated. Visceral leishmaniasis, also known as kala-azar, is characterized by prolonged fever, weight loss, enlargement of the spleen and liver, anemia, and immune system impairment. Cutaneous leishmaniasis causes skin ulcers, while mucocutaneous leishmaniasis can lead to the destruction of nasal and oral mucosa. The disease is endemic in many parts of the world, particularly in tropical and subtropical regions, mainly affecting impoverished populations with limited access to healthcare and inadequate sanitation conditions. Leishmaniasis control involves preventive measures against insect bites, early diagnosis, and effective treatment with antiparasitic drugs. Despite advances in diagnosis and treatment, leishmaniasis remains a public health problem in many developing countries, with challenges such as drug resistance, the lack of an effective vaccine, and socioeconomic barriers to healthcare access. Integrated control programs, continuous research, and collaborative efforts are essential to reducing the incidence and impact of this debilitating disease. One of the approaches to tackling the problem of NTDs is the search for new therapeutics, such as the development of inhibitors targeting specific biological pathways of parasites. One of the current biological targets in malaria and trypanosomatids is the N-myristoyltransferase (NMT) enzyme. NMT is an essential enzyme in many organisms and plays a crucial role in the post-translational modification of proteins. Its main function is to add a myristic acid chain to the N-terminal end of specific proteins, which can affect their cellular localization, activity, and interactions with other molecules. Myristoylation, catalyzed by NMT, is a key process for anchoring proteins to cellular membranes, commonly occurring in proteins associated with the plasma membrane and organelles such as the endoplasmic reticulum and the Golgi complex. This modification influences protein functions in various biological processes, including cell signaling, vesicular transport, and cytoskeleton regulation. Given the significant role of this enzyme in physiological processes, NMT inhibition has been investigated as a potential therapeutic target for the development of new drugs aimed at treating various diseases, including cancer, parasitic, and viral infections. In parasites such as Plasmodium falciparum and Trypanosoma brucei, NMT is a crucial target for new drug development, as inhibiting myristoylation of essential proteins can lead to parasite death. Additionally, recent studies have explored NMT as a potential target in cancer treatment due to its role in regulating signaling pathways associated with cell proliferation and metastasis. NMT inhibitors are currently being developed and tested as a novel approach to treating certain types of cancer, offering new hope in the fight against this devastating disease. Therefore, understanding the role of NMT in the biology of these parasites is crucial for developing new therapeutic strategies for leishmaniasis and malaria, two diseases that affect millions of people worldwide, particularly in low-income regions.To identify potential NMT inhibitors, computational methods are being employed in drug development. Currently, computational approaches play a significant role in drug discovery, providing powerful tools to predict and optimize the properties of candidate molecules. These methods encompass various techniques, including molecular modeling, molecular dynamics simulations, molecular docking, virtual screening, and structure-based drug design. In molecular modeling, the three-dimensional structures of biological molecules and candidate compounds are computationally constructed and optimized, allowing predictions of physicochemical properties, molecular interactions, and biological activities. Molecular dynamics simulations enable the study of atomic-scale molecular behavior over time, providing insights into dynamics, conformational changes, and interactions with the surrounding environment. Molecular docking predicts the binding geometry and affinity between a drug candidate and its biological target, facilitating the identification of compounds with potential pharmacological activity. Virtual screening is a computational approach that rapidly identifies promising compounds from large molecular databases, selecting those most likely to interact with a specific target. Structure-based drug design uses detailed structural information about biological targets and candidate compounds to design molecules with desirable pharmacological properties, such as high selectivity, affinity, and biological activity. These computational methods are often combined with laboratory experiments (in vitro and in vivo) to accelerate drug development, reduce costs, and increase the success rate in discovering new medicines. As a result, they play a crucial role in optimizing drug candidates, identifying new therapeutic targets, and understanding the molecular mechanisms underlying diseases. This study aimed to identify potential NMT inhibitors for developing new therapeutic molecules for diseases such as malaria and leishmaniasis. The research involves screening compounds to identify molecules capable of selectively disrupting NMT activity in the parasites responsible for these diseases. The goal is to provide a foundation for the development of more effective and less toxic treatments. This thesis is divided into three chapters. Chapter 1 presents the theoretical background, beginning with an introduction to neglected tropical diseases, with an emphasis on leishmaniasis, followed by a discussion on malaria. Next, it describes the NMT enzyme as a therapeutic target, including its function and importance in disease-causing parasites. Lastly, it covers computational methods used in drug development. Chapter 2, structured as a published article, discusses the identification of potential NMT inhibitors for malaria, detailing the screening methods and identification of compounds with inhibitory potential. Chapter 3 focuses on NMT inhibitors for leishmaniasis, providing a detailed report on research findings, in silico and in vitro assays, and the relevance of these results in advancing leishmaniasis treatment.