Extracts Obtained from Pterocarpus angolensis DC and Ziziphus mucronata Exhibit Antiplasmodial Activity and Inhibit Heat Shock Protein 70 (Hsp70) Function

Proteostasis is a key driver of the pathogenesis in Apicomplexa

Proteostasis, including protein folding mediated by molecular chaperones, protein degradation, and stress response pathways in organelles like ER (unfolded protein response: UPR), are responsible for cellular protein quality control. This is essential for cell survival as it regulates and reprograms cellular processes. Here, we underscore the role of the proteostasis pathway in Apicomplexan parasites with respect to their well-characterized roles as well as potential roles in many parasite functions, including survival, multiplication, persistence, and emerging drug resistance. In addition to the diverse physiological importance of proteostasis in Apicomplexa, we assess the potential of the pathway's components as chemotherapeutic targets.

Phytochemicals from Pterocarpus angolensis DC and Their Cytotoxic Activities against Breast Cancer Cells

Pterocarpus anglonesis DC is an indigenous medicinal plant belonging to the Pterocarpus genus of the Fabaceae family. It is used to treat stomach problems, headaches, mouth ulcers, malaria, blackwater fever, gonorrhea, ringworm, diarrhea, heavy menstruation, and breast milk stimulation. Column chromatography of the stem bark extracts resulted in the isolation of eight compounds, which included friedelan-3-one (1), 3α-hydroxyfriedel-2-one (2), 3-hydroxyfriedel-3-en-2-one (3), lup-20(29)-en-3-ol (4), Stigmasta-5-22-dien-3-ol (5), 4-O-methylangolensis (6), (3β)-3-acetoxyolean-12-en-28-oic acid (7), and tetradecyl (E)-ferulate (8). The structures were established based on NMR, IR, and MS spectroscopic analyses. Triple-negative breast cancer (HCC70), hormone receptor-positive breast cancer (MCF-7), and non-cancerous mammary epithelial cell lines (MCF-12A) were used to test the compounds' cytotoxicity. Overall, the compounds showed either no toxicity or very low toxicity to all three cell lines tested, except for the moderate toxicity displayed by lupeol (4) towards the non-cancerous MCF-12A cells, with an IC50 value of 36.60 μM. Compound (3β)-3-acetoxyolean-12-en-28-oic acid (7) was more toxic towards hormone-responsive (MCF-7) breast cancer cells than either triple-negative breast cancer (HCC70) or non-cancerous breast epithelial (MCF-12A) cells (IC50 values of 83.06 vs. 146.80 and 143.00 μM, respectively).

Genus Pterocarpus: A review of ethnopharmacology, phytochemistry, biological activities, and clinical evidence

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Pterocarpus (Fabaceae) has about 46 species that are distributed over Asia, especially Indonesia, Africa, and several countries in America. Particularly, P. indicus and P. santalinus have been recorded as ancestor recipe in the old Indonesian book (Cabe puyang warisan nenek moyang). These plants have found application in traditional medicine, such as in the treatment of inflammatory diseases, gonorrhoea, infection, coughs, mouth ulcers, boils, diarrhoea, as well as in the management of pain (as an analgesic).

AIM OF THE REVIEW

The present review aimed to comprehensively summarise the current researches on the traditional and scientific applications of the genus Pterocarpus with regard to the phytochemical content, in vivo and in vitro bioactivities, as well as clinical evidence that may be useful for future drug development.

MATERIALS AND METHODS

Information about the Pterocarpus genus were obtained from local classic herbal literature and electronic databases, such as PubMed, Scopus, and Google Scholar. The scientific name of the species and its synonyms were checked with the information of The Plant List. Additionally, clinical trial results were obtained from the Cochrane library.

RESULTS

Several phytochemical constituents of the plants, e.g., flavonoids, isoflavonoids, terpenoids, phenolic acids, and fatty acids have been reported. There are about 11 species of Pterocarpus that have been scientifically studied for their biological activities, including anti-inflammatory, anti-microbial, analgesic, and anti-hyperglycemic. Of which, the anti-hyperglycemic activity of the extracts and phytochemicals of P. indicus and P. marsupium is particularly remarkable, allowing them to be further studied under clinical trial.

CONCLUSION

The present review has provided an insight into the traditional applications of the plants and some of them have been validated by scientific evidence, particularly their applications as anti-inflammatory and anti-microbial agents. In addition, the genus has demonstrated notable anti-diabetic activity in various clinical trials.

Heat Shock Proteins as Targets for Novel Antimalarial Drug Discovery

Plasmodium falciparum, the parasitic agent that is responsible for a severe and dangerous form of human malaria, has a history of long years of cohabitation with human beings with attendant negative consequences. While there have been some gains in the fight against malaria through the application of various control measures and the use of chemotherapeutic agents, and despite the global decline in malaria cases and associated deaths, the continual search for new and effective therapeutic agents is key to achieving sustainable development goals. An important parasite survival strategy, which is also of serious concern to the scientific community, is the rate at which the parasites continually develop resistance to drugs. Among the key players in the parasite's ability to develop resistance, maintain cellular integrity, and survives within an unusual environment of the red blood cells are the molecular chaperones of the heat shock proteins (HSP) family. HSPs constitute a novel avenue for antimalarial drug discovery and by exploring their ubiquitous nature and multifunctional activities, they may be suitable targets for the discovery of multi-targets antimalarial drugs, needed to fight incessant drug resistance. In this chapter, features of selected families of plasmodial HSPs that can be exploited in drug discovery are presented. Also, known applications of HSPs in small molecule screening, their potential usefulness in high throughput drug screening, as well as possible challenges are highlighted.

The Role of Hsp70s in the Development and Pathogenicity of Plasmodium falciparum

The main agent of human malaria, the protozoa, Plasmodium falciparum is known to infect liver cells, subsequently invading the host erythrocyte, leading to the manifestation of clinical outcomes of the disease. As part of its survival in the human host, P. falciparum employs several heat shock protein (Hsp) families whose primary purpose is to ensure cytoprotection through their molecular chaperone role. The parasite expresses six Hsp70s that localise to various subcellular organelles of the parasite, with one, PfHsp70-x, being exported to the infected human erythrocyte. The role of these Hsp70s in the survival and pathogenicity of malaria has received immense research attention. Several studies have reported on their structure-function features, network partnerships, and elucidation of their potential substrates. Apart from their role in cytoprotection and pathogenicity, Hsp70s are implicated in antimalarial drug resistance. As such, they are deemed potential antimalarial drug candidates, especially suited for co-targeting in combination therapies. In addition, Hsp70 is implicated in host immune modulation. The current report highlights the various structure-function features of these proteins, their roles in the development of malaria, current and prospective efforts being employed towards targeting them in malaria intervention efforts.

Heat Shock Proteins of Malaria: Highlights and Future Prospects

The deadliest malaria parasite of humans, Plasmodium falciparum, is an obligate parasite that has had to develop mechanisms for survival under the unfavourable conditions it confronts within host cells. The chapters in the book "Heat Shock Proteins of Malaria" provide a critique of the evidence that heat shock proteins (Hsps) play a key role in the survival of P. falciparum in host cells. The role of the plasmodial Hsp arsenal is not limited to the protection of the parasite cell (largely through their role as molecular chaperones), as some of these proteins also promote the pathological development of malaria. This is largely due to the export of a large number of these proteins into the infected erythrocyte cytosol. Although P. falciparum erythrocyte membrane protein 1 (PfEMP1) is the main virulence factor for the malaria parasite, some of the exported plasmodial Hsps appear to augment parasite virulence. While this book largely delves into experimentally validated information on the role of Hsps in the development and pathogenicity of malaria, some of the information is based on hypotheses yet to be fully tested. Therefore, here we highlight what we know to be definite roles of plasmodial Hsps. Furthermore, we distill information that could provide practical insights on the options available for future research directions, including interventions against malaria that may target the role of Hsps in the development of the disease.

Ethnobotanical study of plants used by the traditional healers to treat malaria in Mogovolas district, northern Mozambique

INTRODUCTION

Malaria is an important parasitic disease that affects mostly the African continent. Traditional medicine is very important in Mozambique and traditional healers play a key role in the primary health care services, particularly in rural areas. We aim to report the results of an ethnobotanical survey undertaken in Mogovolas district, northern region of Mozambique. We recorded and identified the medicinal plants used by traditional healers for treatment of malaria, as well as the mode of preparation and administration.

METHODS

The study was conducted in 14 villages from Mogovolas between June and August 2015. Sixteen traditional healers were interviewed using semi-structured questionnaires. Under their guidance, we collected medicinal plants and prepared herbarium specimens that were sent and kept at Eduardo Mondlane University Herbarium for scientific identification. We searched for information on the in vitro and in vivo studies of the cited plants for antiplasmodial activity.

RESULTS

Traditional healers from Mogovolas district reported the use of 37 plants to treat malaria, belonging to 22 families. The most used species are Ochna kirkii Oliv. (5 citations), Ehretia amoena Klotzsch and Pteleopsis myrtifolia (M.A.Lawson) Engl. & Diels (both with 3 citations). These plants belong to Ochnaceae, Boraginaceae and Combretaceae families, respectively. The herbal remedies are prepared using leaves (22/37), roots (18/37), stem barks (16/37) and stems (3/37). The administration of the herbal remedies was made essentially by oral route and bathing.

CONCLUSION

The ethnobotanical data resulted from this study can be the starting point for further chemical and pharmacological studies aiming to identify medicinal species with antimalarial activity, thus, open the insights for the discovery of new antimalarial substances, as well as better integration of the traditional medicine into the national health systems, particularly in developing countries, as the health system coverage is limited.

Medicinal plants used by 'root doctors', local traditional healers in Bié province, Angola

ETHNOPHARMACOLOGICAL RELEVANCE

This study is one of the first post-civil war efforts to document traditional botanical knowledge in Bié province, central Angola, in a first step to bring more studies on the use of medicinal plant resources in this area so as to bring new insights into Angolan bio-cultural diversity.

AIM OF THE STUDY

Examine the variety of plant species used for medical purposes, as well as characterize their social and cultural values. Also, it is aimed to compare their uses in the studied region with those in Sub-Saharan Africa and report new ethnomedicinal uses.

MATERIALS AND METHODS

We documented traditional medicinal plant knowledge among professional herbalists in two areas in Bié province through participatory observation, semi-structured interviews and transect walks. Ethnobotanical information was quantified based on Use Reports to (1) rate traditional knowledge; and (2) determine most useful taxa.

RESULTS

In total, 10 traditional healers shared information on their knowledge. A total of 87 plant species distributed among 57 genera and 36 botanical families were documented with Fabaceae being the best-represented family with 18 species, followed by Phyllanthaceae (6), Apocynaceae (5), Asteraceae (5), Rubiaceae (5), Lamiaceae (4), and Ochnaceae (3). Most medicinal plants are usually gathered at a distance from human settlements because of the belief in the higher efficacy of 'wild' plants shared by all herbalists. Roots are the most common plant part used (79%), explaining why the consulted herbalists call themselves 'root doctors'.

CONCLUSIONS

The culturally most important medicinal species identified in this study, i.e. Securidaca longepedunculata, Garcinia huillensis, Annona stenophylla, Afzelia quanzensis and Strychnos cocculoides, were previously reported for the same use in neighbouring countries and elsewhere in Africa. Our study also indicates that there are several locally valuable species that have not yet been studied for their medical potential, to name a few: Alvesia rosmarinifolia, Diplorhynchus condylocarpon, Eriosema affine, Paropsia brazzaeana, Rhus squalida, Sclerocroton cornutus or Xylopia tomentosa. Moreover, the ethnomedicinal use of 26 species was reported for the first time to sub-Saharan Africa.

CLASSIFICATION

Ethnopharmacological field studies.

Julbernardia paniculata and Pterocarpus angolensis: From Ethnobotanical Surveys to Phytochemical Characterization and Bioactivities Evaluation

Julbernardia paniculata and Pterocarpus angolensis are two plant species with important application in African traditional medicine, particularly in Angola, in the treatment of several diseases. However, scientific studies concerning these species are scarce. The goal of this work was to know better which medicinal approaches are used by the Huíla population in Angola by means of ethnobotanical surveys. Furthermore, extracts of both plants were phytochemically characterized. Antioxidant, anti-inflammatory, wound-healing activities, and potential cytotoxicity were also studied. With this study it was possible to verify that 67% of the individuals that use medicinal plants are women, and their main therapeutic uses are the treatment of problems of the digestive system and skin disorders. Barks of J. paniculata and leaves of P. angolensis are the most often used plant parts. Through high-performance liquid chromatography coupled to diode-array detector (HPLC-DAD) and GC-MS it was possible to characterize the chemical composition of the two species, which are rich in phenolic compounds, terpenes, terpenoids, sesquiterpenoids and fatty acids. Both plants showed to possess antioxidant, anti-inflammatory proprieties, and wound-healing activity. To the best of our knowledge, this is the most comprehensive study of these two species and the first ethnobotanical and ethnopharmacological study of medicinal plants from this region of Angola.

Ziziphus mucronata Willd. (Rhamnaceae): it's botany, toxicity, phytochemistry and pharmacological activities

Ziziphus mucronata is an important multi-purpose plant species that has been used in African traditional medicine for ages in the treatment of various devastating human and animal infections. The current paper is aimed at providing an overview of uses, toxicology, pharmacological properties and phytochemistry of Z. mucronata. The information used in the current work was retrieved using various search engines, including Pubmed, Science Direct, Google Scholar, Scielo, SciFinder and Scopus. The key words used included Ziziphus mucronata, secondary metabolites, chemistry, biological activity and pharmacology, anti-inflammatory, antimicrobial, antifungal, antiviral, ethnobotanical survey, medicinal uses, safety, toxicology and other related words. Out of the 46 infections which the plant species is used to treat, the most common uses includes sexually transmitted infections, skin infections, diarrhoea and dysentery, respiratory and chest complaints and gynaecological complaints (citations ≥6). Pharmacologically, the plant species exhibited a potential antimicrobial activity yielding a minimum inhibitory concentration of <1 mg/ml against important pathogens which includes Mycobacterium tuberculosis, Moraxella catarrhalis, Staphylococcus aureus, Escherichia coli, Propionibacterium acnes, Candida albicans, Cryptoccoos neoformans amongst other microorganisms. Furthermore, the extracts and compounds from Z mucronata revealed potent antiviral, antioxidant, anti-inflammatory and other activities in vitro. Phytochemically, cyclo-peptide alkaloids (commonly called mucronines) dominates and in conjunction with triterpenes, flavonoids, phenolic acids and anthocyanins. Besides these compounds, the plant species exhibited the presence of important in minerals. These phytoconstituents may well explain the reported biological activities. Although the extracts revealed no cytotoxic effect to Vero cells, further toxicological characteristics of the plant species still needs to be explored. There is also a need to carry out the comprehensive safety profiles of the plant species, including heavy metal detection. Although the plant species revealed important biological activities, which includes antimicrobial, antiviral, anti-diabetic, anti-inflammatory, anti-oxidant, anti-plasmodial, anthelmintic, and anti-anaemic activity in vitro, further research is needed to explore the in vivo studies, other compounds responsible for such activities and the mechanisms of action thereof. Such activities validates the use of the plant species in traditional medicine. The data on the possible use of the plant species in the treatment of diarrhoea, sexually transmitted infections, skin related and gynaecological complaints are scant and still needs to be explored and validated both in vitro and in vivo. Furthermore, the anticancer and anthelmintic activity of the plant species also needs to be explored.

Partners in Mischief: Functional Networks of Heat Shock Proteins of Plasmodium falciparum and Their Influence on Parasite Virulence

The survival of the human malaria parasite Plasmodium falciparum under the physiologically distinct environments associated with their development in the cold-blooded invertebrate mosquito vectors and the warm-blooded vertebrate human host requires a genome that caters to adaptability. To this end, a robust stress response system coupled to an efficient protein quality control system are essential features of the parasite. Heat shock proteins constitute the main molecular chaperone system of the cell, accounting for approximately two percent of the malaria genome. Some heat shock proteins of parasites constitute a large part (5%) of the 'exportome' (parasite proteins that are exported to the infected host erythrocyte) that modify the host cell, promoting its cyto-adherence. In light of their importance in protein folding and refolding, and thus the survival of the parasite, heat shock proteins of P. falciparum have been a major subject of study. Emerging evidence points to their role not only being cyto-protection of the parasite, as they are also implicated in regulating parasite virulence. In undertaking their roles, heat shock proteins operate in networks that involve not only partners of parasite origin, but also potentially functionally associate with human proteins to facilitate parasite survival and pathogenicity. This review seeks to highlight these interplays and their roles in parasite pathogenicity. We further discuss the prospects of targeting the parasite heat shock protein network towards the developments of alternative antimalarial chemotherapies.

Proteomic analysis of Plasmodium falciparum histone deacetylase 1 complex proteins

Plasmodium falciparum histone deacetylases (PfHDACs) are an important class of epigenetic regulators that alter protein lysine acetylation, contributing to regulation of gene expression and normal parasite growth and development. PfHDACs are therefore under investigation as drug targets for malaria. Despite this, our understanding of the biological roles of these enzymes is only just beginning to emerge. In higher eukaryotes, HDACs function as part of multi-protein complexes and act on both histone and non-histone substrates. Here, we present a proteomics analysis of PfHDAC1 immunoprecipitates, identifying 26 putative P. falciparum complex proteins in trophozoite-stage asexual intraerythrocytic parasites. The co-migration of two of these (P. falciparum heat shock proteins 70-1 and 90) with PfHDAC1 was validated using Blue Native PAGE combined with Western blot. These data provide a snapshot of possible PfHDAC1 interactions and a starting point for future studies focused on elucidating the broader function of PfHDACs in Plasmodium parasites.