The Functioning of Na+-ATPases from Protozoan Parasites: Are These Pumps Targets for Antiparasitic Drugs?

Anti-Infection of Oral Microorganisms from Herbal Medicine of Piper crocatum Ruiz & Pav

The WHO Global Status Report on Oral Health 2022 reveals that oral diseases caused by infection with oral pathogenic microorganisms affect nearly 3.5 billion people worldwide. Oral health problems are caused by the presence of S. mutans, S. sanguinis, E. faecalis and C. albicans in the oral cavity. Synthetic anti-infective drugs have been widely used to treat oral infections, but have been reported to cause side effects and resistance. Various strategies have been implemented to overcome this problem. Synthetic anti-infective drugs have been widely used to treat oral infections, but they have been reported to cause side effects and resistance. Therefore, it is important to look for safe anti-infective alternatives. Ethnobotanical and ethnopharmacological studies suggest that Red Betel leaf (Piper crocatum Ruiz & Pav) could be a potential source of oral anti-infectives. This review aims to discuss the pathogenesis mechanism of several microorganisms that play an important role in causing health problems, the mechanism of action of synthetic oral anti-infective drugs in inhibiting microbial growth in the oral cavity, and the potential of red betel leaf (Piper crocatum Ruiz & Pav) as an herbal oral anti-infective drug. This study emphasises the importance of researching natural components as an alternative treatment for oral infections that is more effective and can meet global needs.

Identification of the ATPase alpha subunit of Trypanosoma cruzi as a potential biomarker for the diagnosis of Chagas disease

BACKGROUND

Chagas disease (CD) is considered by the World Health Organisation (WHO) a neglected disease endemic to the Americas, but it has spread throughout the world due to migrations. The disease is almost 100% curable if detected in time. Still, the lack of rapid diagnostic tests with sufficient sensitivity and specificity leads to a chronic phase with a mortality of about 50,000 people worldwide per year.

METHODS

Using the total proteins extracted from serum samples of patients confirmed with chronic phase CD; we performed the Bio-SELEX strategy. The best aptamers were selected using next-generation sequencing (NGS) based on their most abundant sequences (reads and rpm). Then, selected aptamers were used to isolate potential biomarkers directly from serum samples of patients with chronic phase CD using pull-down and mass spectrometry experiments.

RESULTS

CH1 aptamer was the aptamer selected after the NGS results analysis. The pull-down and mass spectrometry experiments identified the presence of the ATPase alpha subunit of T. cruzi circulating in serum samples of patients with chronic phase CD.

CONCLUSIONS

We report the ATPase alpha subunit of T. cruzi as a potential biomarker for chronic phase CD and CH1 aptamer as a potential tool for diagnosing CD.

The Na+,K+-ATPase and its stoichiometric ratio: some thermodynamic speculations

 Almost seventy years after its discovery, the sodium-potassium adenosine triphosphatase (the sodium pump) located in the cell plasma membrane remains a source of novel mechanistic and physiologic findings. A noteworthy feature of this enzyme/transporter is its robust stoichiometric ratio under physiological conditions: it sequentially counter-transports three sodium ions and two potassium ions against their electrochemical potential gradients per each hydrolyzed ATP molecule. Here we summarize some present knowledge about the sodium pump and its physiological roles, and speculate whether energetic constraints may have played a role in the evolutionary selection of its characteristic stoichiometric ratio.

Genome sequence of Ophryocystis elektroscirrha, an apicomplexan parasite of monarch butterflies: cryptic diversity and response to host-sequestered plant chemicals

Apicomplexa are ancient and diverse organisms which have been poorly characterized by modern genomics. To better understand the evolution and diversity of these single-celled eukaryotes, we sequenced the genome of Ophryocystis elektroscirrha, a parasite of monarch butterflies, Danaus plexippus. We contextualize our newly generated resources within apicomplexan genomics before answering longstanding questions specific to this host-parasite system. To start, the genome is miniscule, totaling only 9 million bases and containing fewer than 3,000 genes, half the gene content of two other sequenced invertebrate-infecting apicomplexans, Porospora gigantea and Gregarina niphandrodes. We found that O. elektroscirrha shares different orthologs with each sequenced relative, suggesting the true set of universally conserved apicomplexan genes is very small indeed. Next, we show that sequencing data from other potential host butterflies can be used to diagnose infection status as well as to study diversity of parasite sequences. We recovered a similarly sized parasite genome from another butterfly, Danaus chrysippus, that was highly diverged from the O. elektroscirrha reference, possibly representing a distinct species. Using these two new genomes, we investigated potential evolutionary response by parasites to toxic phytochemicals their hosts ingest and sequester. Monarch butterflies are well-known to tolerate toxic cardenolides thanks to changes in the sequence of their Type II ATPase sodium pumps. We show that Ophryocystis completely lacks Type II or Type 4 sodium pumps, and related proteins PMCA calcium pumps show extreme sequence divergence compared to other Apicomplexa, demonstrating new avenues of research opened by genome sequencing of non-model Apicomplexa.

Uncovering the antimalarial potential of toad venoms through a bioassay-guided fractionation process

Malaria remains to date one of the most devastating parasitic diseases worldwide. The fight against this disease is rendered more difficult by the emergence and spread of drug-resistant strains. The need for new therapeutic candidates is now greater than ever. In this study, we investigated the antiplasmodial potential of toad venoms. The wide array of bioactive compounds present in Bufonidae venoms has allowed researchers to consider many potential therapeutic applications, especially for cancers and infectious diseases. We focused on small molecules, namely bufadienolides, found in the venom of Rhinella marina (L.). The developed bio-guided fractionation process includes a four solvent-system extraction followed by fractionation using flash chromatography. Sub-fractions were obtained through preparative TLC. All samples were characterized using chromatographic and spectrometric techniques and then underwent testing on in vitro Plasmodium falciparum cultures. Two strains were considered: 3D7 (chloroquine-sensitive) and W2 (chloroquine-resistant). This strategy highlighted a promising activity for one compound named resibufogenin. With IC50 values of (29 ± 8) μg/mL and (23 ± 1) μg/mL for 3D7 and W2 respectively, this makes it an interesting candidate for further investigation. A molecular modelling approach proposed a potential binding mode of resibufogenin to Plasmodium falciparum adenine-triphosphate 4 pump as antimalarial drug target.

Cyclolauranes as plausible chemical scaffold against Naegleria fowleri

Primary amoebic meningoencephalitis (PAM) is a central nervous system (CNS) disease caused by Naegleria fowleri that mainly affects children and young adults with fatal consequences in most of the cases. Treatment protocols are based on the combination of different antimicrobial agents, nonetheless there is the need to develop new anti-Naegleria compounds with low toxicity and full effects compared to the currently used drug combination. The marine environment is a well-established source of bioactive natural products. In this work, we have focused on the structure of Laurencia cyclolaurane-type sesquiterpenes as potential chemical model against Naegleria species. The effects of debromolaurinterol (1) to induce PCD/apoptosis-like events in Naegleria fowleri have been evaluated, revealing that this compound induced reduction of ATP production showing a decrease of 99.98% in treated parasite cells. A SAR analysis have been supported with molecular modeling and analysis of the in silico ADME/Tox properties of the Laurencia sesquiterpenes debromolaurinterol (1), laurinterol (2) and allolaurinterol (3), which reinforce cyclolaurane metabolites as plausible molecular models to develop PAM treatments.

Candida albicans Potassium Transporters

Potassium is basic for life. All living organisms require high amounts of intracellular potassium, which fulfils multiple functions. To reach efficient potassium homeostasis, eukaryotic cells have developed a complex and tightly regulated system of transporters present both in the plasma membrane and in the membranes of internal organelles that allow correct intracellular potassium content and distribution. We review the information available on the pathogenic yeast Candida albicans. While some of the plasma membrane potassium transporters are relatively well known and experimental data about their nature, function or regulation have been published, in the case of most of the transporters present in intracellular membranes, their existence and even function have just been deduced because of their homology with those present in other yeasts, such as Saccharomyces cerevisiae. Finally, we analyse the possible links between pathogenicity and potassium homeostasis. We comment on the possibility of using some of these transporters as tentative targets in the search for new antifungal drugs.

Transporter-Mediated Solutes Uptake as Drug Target in Plasmodium falciparum

Malaria remains a public health problem with still more than half a million deaths annually. Despite ongoing efforts of many countries, malaria elimination has been difficult due to emerging resistances against most traditional drugs, including artemisinin compounds - the most potent antimalarials currently available. Therefore, the discovery and development of new drugs with novel mechanisms of action to circumvent resistances is urgently needed. In this sense, one of the most promising areas is the exploration of transport proteins. Transporters mediate solute uptake for intracellular parasite proliferation and survival. Targeting transporters can exploit these processes to eliminate the parasite. Here, we focus on transporters of the Plasmodium falciparum-infected red blood cell studied as potential biological targets and discuss published drugs directed at them.

New Acyl Derivatives of 3-Aminofurazanes and Their Antiplasmodial Activities

An N-acylated furazan-3-amine of a Medicines for Malaria Venture (MMV) project has shown activity against different strains of Plasmodium falciparum. Seventeen new derivatives were prepared and tested in vitro for their activities against blood stages of two strains of Plasmodium falciparum. Several structure-activity relationships were revealed. The activity strongly depended on the nature of the acyl moiety. Only benzamides showed promising activity. The substitution pattern of their phenyl ring affected the activity and the cytotoxicity of compounds. In addition, physicochemical parameters were calculated (log P, log D, ligand efficiency) or determined experimentally (permeability) via a PAMPA. The N-(4-(3,4-diethoxyphenyl)-1,2,5-oxadiazol-3-yl)-3-(trifluoromethyl)benzamide possessed good physicochemical properties and showed high antiplasmodial activity against a chloroquine-sensitive strain (IC₅₀(NF54) = 0.019 µM) and even higher antiplasmodial activity against a multiresistant strain (IC₅₀(K₁) = 0.007 µM). Compared to the MMV compound, the permeability and the activity against the multiresistant strain were improved.