Metabolomic Investigation of Natural Antiplasmodial Agents

Malaria is one of the deadliest parasitic diseases that still plagues humanity in recent times. Despite being target of several eradication campaigns, the widespread presence of the multiple agents that cause this parasitosis, along with its increased adaptability into developing resistance to treatments, make this old ailment a challenge to modern medicine. Natural products with potential antiplasmodial activity are valuable to discover new therapeutic targets and shed light on new scaffolds that can be optimized into revolutionary treatments. In this thesis, metabolomics, a sensitive and robust approach that can describe the metabolites of the malaria parasite maintained in culture, was used to profile the effects of natural products on the parasite and hypothesize their mode of action. Before this could be done, workflow investigation and protocol optimization were carried out, including a study on metabolic extraction methods with state-of-the-art statistical algorithms. Further exploration revealed that time and complexity are detrimental to repeatability and robustness of the results, so a method with a single washing step followed by methanolic 90% extraction was used and analyzed through 1HNMR and/or LC-MS, depending on sample availability. Five individual cases were studied in collaboration with the Department of Biochemistry and Molecular Biology and the Huck Center for Malaria Research at Penn State (The Pennsylvania State University), which allowed the use of their inhouse MS system and database for targeted metabolite annotation. First, an exploration of plant extracts and fractions were studied in parallel to the known active antiplasmodial compounds present in those plants to assess how early in plant screening a potential mode of action can be hypothesized. Results show that extract effects can already be distinguished from a control, though fractions with active compounds separate more clearly. The more purified the fraction, the bigger the correlation in mode of action with the isolated natural compounds, possibly due to the lack of matrix effects and interactions, which shows that metabolomics can be introduced early in bioassay-guided fractionation in plant studies. Second, two of the most important plants in traditional medicine against malaria were studied, Artemisia afra and A. annua, to investigate their phenolic content, presence or absence of artemisinin and correlate the composition with the metabolomic results on a synchronized malaria culture. Results indicate a correlation between activity and artemisinin abundance in these extracts, with A. annua presenting a similar parasitic profile to artemisinin whereas A. afra, despite trace amounts of this compound, differs significantly. A. afra affects various unspecific metabolites but significantly changes myo-inositol distinctly from A. annua and artemisinin, which clearly target redox mechanisms. Lastly, three independent studies aimed to investigate three natural scaffolds for their mode of action: alkyl cyclohexenones compounds named poupartones, ellagic acid and derivatives, and a mixture of triterpene esters. Poupartones showed to interfere with hemoglobin metabolism, DNA and RNA synthesis and redox management systems which correlated to their potential to participate in nucleophilic additions that establish covalent bonds with proteins and generate radical oxygen species, an effective yet not specific type of activity. Our studies on ellagic acid and derivatives support literature data and point to the parasite’s digestive vacuole as the site of action of these compounds. Changes in hemoglobin metabolism and redox metabolites suggest possible effects on plasmepsins, enzymes that act early in hemoglobin breakdown, and on glutathione metabolism, essential to maintaining a balanced organelle. Lastly, a mixture of 8 triterpenic esters seems to affect pyrimidine synthesis and amino acid metabolism through N-carbamoyl-L-aspartate, though it is unclear exactly how. Metabolomics is a hypothesis generating approach that gives a snapshot of the effects of innovative natural compounds on the malaria parasite in order to accurately guide antimalarial drug discovery.METNATPA

Recent metabolomic developments for antimalarial drug discovery.

peer reviewedMalaria is a parasitic disease that remains a global health issue, responsible for a significant death and morbidity toll. Various factors have impacted the use and delayed the development of antimalarial therapies, such as the associated financial cost and parasitic resistance. In order to discover new drugs and validate parasitic targets, a powerful omics tool, metabolomics, emerged as a reliable approach. However, as a fairly recent method in malaria, new findings are timely and original practices emerge frequently. This review aims to discuss recent research towards the development of new metabolomic methods in the context of uncovering antiplasmodial mechanisms of action in vitro and to point out innovative metabolic pathways that can revitalize the antimalarial pipeline

Secondary Metabolites Isolated from Artemisia afra and Artemisia annua and Their Anti-Malarial, Anti-Inflammatory and Immunomodulating Properties—Pharmacokinetics and Pharmacodynamics: A Review

peer reviewedThere are over 500 species of the genus Artemisia in the Asteraceae family distributed over the globe, with varying potentials to treat different ailments. Following the isolation of artemisinin (a potent anti-malarial compound with a sesquiterpene backbone) from Artemisia annua, the phytochemical composition of this species has been of interest over recent decades. Additionally, the number of phytochemical investigations of other species, including those of Artemisia afra in a search for new molecules with pharmacological potentials, has increased in recent years. This has led to the isolation of several compounds from both species, including a majority of monoterpenes, sesquiterpenes, and polyphenols with varying pharmacological activities. This review aims to discuss the most important compounds present in both plant species with anti-malarial properties, anti-inflammatory potentials, and immunomodulating properties, with an emphasis on their pharmacokinetics and pharmacodynamics properties. Additionally, the toxicity of both plants and their anti-malaria properties, including those of other species in the genus Artemisia, is discussed. As such, data were collected via a thorough literature search in web databases, such as ResearchGate, ScienceDirect, Google scholar, PubMed, Phytochemical and Ethnobotanical databases, up to 2022. A distinction was made between compounds involved in a direct anti-plasmodial activity and those expressing anti-inflammatory and immunomodulating activities or anti-fever properties. For pharmacokinetics activities, a distinction was made between compounds influencing bioavailability (CYP effect or P-Glycoprotein effect) and those affecting the stability of pharmacodynamic active components

Trypanosoma brucei: Metabolomics for analysis of cellular metabolism and drug discovery.

[en] BACKGROUND: Trypanosoma brucei is the causative agent of Human African Trypanosomiasis (also known as sleeping sickness), a disease causing serious neurological disorders and fatal if left untreated. Due to its lethal pathogenicity, a variety of treatments have been developed over the years, but which have some important limitations such as acute toxicity and parasite resistance. Metabolomics is an innovative tool used to better understand the parasite's cellular metabolism, and identify new potential targets, modes of action and resistance mechanisms. The metabolomic approach is mainly associated with robust analytical techniques, such as NMR and Mass Spectrometry. Applying these tools to the trypanosome parasite is, thus, useful for providing new insights into the sleeping sickness pathology and guidance towards innovative treatments. AIM OF REVIEW: The present review aims to comprehensively describe the T. brucei biology and identify targets for new or commercialized antitrypanosomal drugs. Recent metabolomic applications to provide a deeper knowledge about the mechanisms of action of drugs or potential drugs against T. brucei are highlighted. Additionally, the advantages of metabolomics, alone or combined with other methods, are discussed. KEY SCIENTIFIC CONCEPTS OF REVIEW: Compared to other parasites, only few studies employing metabolomics have to date been reported on Trypanosoma brucei. Published metabolic studies, treatments and modes of action are discussed. The main interest is to evaluate the metabolomics contribution to the understanding of T. brucei's metabolism

Antiplasmodial and cytotoxic activities of Catatia cordata Humbert (Asteraceae) and Symphonia eugenioides Baker (Clusiaceae), two endemic plants of Madagascar

peer reviewedMadagascar has an important diversity of endemic plants. However, this resource is little explored. Symphonia eugenioides and Catatia cordata are two endemic species of Madagascar which haven’t yet been subjected to any biological nor chemical studies. The present research aimed to evaluate the antiplasmodial activity of these species. The purpose is to find novel antimalarial compound within these species. The antiplasmodial activity of dichloromethane and methanol extracts of S. eugenioides (bark) and C. cordata (leaves) were evaluated against the chloroquine-resistant Plasmodium falciparum strain (W2). The cytotoxicity was also tested on human melanoma A2058 and human breast cancer MDA-MB-231 cell lines. The dichloromethane extracts of S. eugenioides and C. cordata showed the best antiplasmodial activity, with IC50 values of 7.70±0.62 and 9.23±1.77 µg/mL, respectively. The dichloromethane extract of S. eugenioides had also a significant cytotoxic activity against A2058 and MDA-MB-231 cell lines with IC50 values of 17.17±2.80 and 14.48±4.94 µg/mL, respectively. The different chromatographic analysis (LC-DAD and TLC) indicated the presence of ursolic acid and oleanolic acid in dichloromethane extract and chlorogenic acid in methanolic extract in methanolic extract of C. cordata. This is the first report on antiplasmodial, cytotoxic activities and chemical content for S. eugenioides and the first findings on species belonging Catatia genus. The results have indicated that these two plants can potentially be used to treat malaria. S. eugenioides may also contain some potent active compounds for developing anticancer agent.3. Good health and well-bein