Antimalarial activity and safety assessment of Flueggea virosa leaves and its major constituent with special emphasis on their mode of action

A comprehensive review of antimalarial medicinal plants used by Tanzanians

CONTEXT

Tanzania has rich medicinal plant (MP) resources, and most rural inhabitants rely on traditional healing practices for their primary healthcare needs. However, available research evidence on antimalarial MPs is highly fragmented in the country.

OBJECTIVE

This systematic review compiles ethnomedicinal research evidence on MPs used by Tanzanians as antimalarials.

MATERIALS AND METHODS

A systematic web search was conducted using various electronic databases and grey materials to gather relevant information on antimalarial MPs utilized by Tanzanians. The review was per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The data were collected from 25 articles, and MS Excel software was used to analyse relevant ethnobotanical information using descriptive statistics.

RESULTS

A total of 227 MPs belonging to 67 botanical families and 180 genera were identified. Fabaceae (15.9%) is the most frequently utilized family. The ethnobotanical recipes analysis indicated leaves (40%) and trees (44%) are the preferred MPs part and life form, respectively. Decoctions (67%) are the dominant preparation method of remedies. Of the recorded MPs, 25.9% have been scientifically investigated for antimalarial activities with positive results. However, 74.1% of MPs have no scientific records on antimalarial activities, but they could be potential sources of remedies.

CONCLUSIONS

The study discloses a wealth of antimalarial MPs possessed by Tanzanians and suggests a need for research to authenticate the healing potential of antimalarial compounds from the unstudied MPs. Additionally, it indicates that some of the presented MPs are potential sources for developing safe, effective and affordable antimalarial drugs.

In-vitro Cytotoxicity Investigations for Phytoconstituents of Saudi Medicinal Plants With Putative Ocular Effects

BACKGROUND

Metastatic secondary ocular tumors spread from systemic malignancies, including breast cancer. This study aimed to evaluate the cytotoxicity of extracts from 5 medicinal plants native to Saudi Arabia.

METHODS

For preliminary activity screening, cytotoxicity using the MTT assay and selectivity index determinations were made for medicinal plant extracts against various cancer cell-lines. The most promising extract was subjected to GC-MS analysis to determine the phytochemical composition. Clonogenic assays were performed using the most promising extract to confirm the initial results. Finally, western blot analysis was used to determine the modulation in expression of survivin and P27 suppressor genes in the human breast adenocarcinoma (MCF7) cell-line to understand the potential mechanistic properties of the active plant extract.

RESULTS

The 5 plant extracts showed various cytotoxic activity levels using IC50. The most active extract was found to be the leaves of Capparis spinosa L. (BEP-07 extract) against the MCF7 breast cancer cell-line (IC50 = 3.61 ± 0.99 μg/ml) and selectivity index of 1.17 compared to the normal human fetal lung fibroblast (MRC5) cells. BEP-07 extract showed a dose dependent clonogenic effect against the MCF7 colonies which was comparable with the effect of doxorubicin. BEP-07 extract caused a significant decrease of survivin and increase in P27 expression compared to control GAPDH at its highest dose (14 µg/ml). The GC-MS chromatogram of Capparis spinosa L. (BEP-07 extract) revealed the existence of 145 compounds, belonging to the diverse classes of phytoconstituents. Fatty acids and their derivatives represent 15.4%, whilst octadecanoic acid, 2,3-dihydroxypropyl ester was the principal component (7.9%) detected.

CONCLUSION

Leaves of Capparis spinosa L. (BEP-07 extract) exhibited a significant cytotoxic effect particularly against breast cancer cells. It exhibited this effect through survivin inhibition and via P27 upregulation. The detected phytoconstituents in the plant extract might be involved in tested cytotoxic activity, while further investigations are required to complete the drug candidate profile.

Antimalarial activity of Toona ciliata MJ Roem aqueous methanolic leaf extract and its antioxidant and phytochemical properties

Background and aim

Malaria is a global health issue causing substantial morbidity and mortality. Screening of various traditionally important medicinal plants is a key source for the discovery of new antimalarials. We evaluated the antimalarial and antioxidant activities, and performed detailed phytochemical analyses of Toona ciliata MJ Roem aqueous methanolic leaf extract (TcMLE).

Experimental procedures

In vitro antiplasmodial studies in Plasmodium falciparum (Pf) 3D7 and PfCam3.IR539T strains were performed by [3H]-hypoxanthine uptake assays. In vitro cytotoxicity in HeLa and HEK293T cell lines was evaluated using MTT assays. Hemolysis assay was performed using RBCs. Phytochemical analysis by GC-MS and in vitro antioxidant studies by DPPH and ABTS assays were performed. In vivo antimalarial studies in Pb-infected mice were carried out using Rane's test and Peters' 4-day test.

Results and conclusions

TcMLE showed significant in vitro antioxidant activity and had phytochemicals reported for antimalarial activity. In vitro studies showed prominent antiplasmodial activity against Pf3D7 strain (IC50 ∼22 μg/ml) and PfCam3. IR539Tstrain (IC50 value ∼43 μg/ml). In vitro cytotoxicity studies, in vitro hemolytic assays, and in vivo acute toxicity studies further suggested that TcMLE is nontoxic. In vivo antimalarial studies using Rane's test showed a significant decrease in parasitemia by ∼70% at 1200 mg/kg doses and delayed the mortality of mice by ∼10-14 days. Peters' 4-day test also showed a similar pattern. The present study demonstrated the antimalarial potential of TcMLE. These findings deliver a platform for further studies to identify the active components of TcMLE and discover new antimalarials.

Chemistry and Pharmacology of Bergenin or Its Derivatives: A Promising Molecule

Bergenin is a glycosidic derivative of trihydroxybenzoic acid that was discovered in 1880 by Garreau and Machelart from the rhizomes of the medicinal plant Bergenia crassifolia (currently: Saxifraga crassifolia—Saxifragaceae), though was later isolated from several other plant sources. Since its first report, it has aroused interest because it has several pharmacological activities, mainly antioxidant and anti-inflammatory. In addition to this, bergenin has shown potential antimalarial, antileishmanial, trypanocidal, antiviral, antibacterial, antifungal, antinociceptive, antiarthritic, antiulcerogenic, antidiabetic/antiobesity, antiarrhythmic, anticancer, hepatoprotective, neuroprotective and cardioprotective activities. Thus, this review aimed to describe the sources of isolation of bergenin and its in vitro and in vivo biological and pharmacological activities. Bergenin is distributed in many plant species (at least 112 species belonging to 34 families). Both its derivatives (natural and semisynthetic) and extracts with phytochemical proof of its highest concentration are well studied, and none of the studies showed cytotoxicity for healthy cells.

Inhibition of heme detoxification pathway in malaria parasite by 3-hydroxy-11-keto-β-boswellic acid isolated from Boswellia serrata

Malaria eradication is still a major global health problem in developing countries, which has been of more concern ever since the malaria parasite has developed resistance against frontline antimalarial drugs. Historical evidence proves that the plants possess a major resource for the development of novel anti-malarial drugs. In the present study, the bioactivity guided fractionation of the oleogum-resin of Boswellia serrata Roxb. yielded the optimum activity in the ethyl acetate fraction with an IC₅₀ of 22 ± 3.9 μg/mL and 26.5 ± 4.5 μg/mL against chloroquine sensitive (NF54) and resistant (K1) strains of Plasmodium falciparum respectively. Further, upon fractionation, the ethyl acetate fraction yielded four major compounds, of which 3-Hydroxy-11-keto-β-boswellic acid (KBA) was found to be the most potent with IC₅₀ values 4.5 ± 0.60 µg/mL and 6.25 ± 1.02 μg/mL against sensitive and resistant strains respectively. KBA was found to inhibit heme detoxification pathways, one of the most common therapeutic targets, which probably lead to an increase in reactive oxygen species (ROS) and nitric oxide (NO) detrimental to P. falciparum. Further, the induced intracellular oxidative stress affected the macromolecules in terms of DNA damage, increased lipid peroxidation, protein carbonylation as well as loss of mitochondrial membrane potential. However, it did not exhibit any cytotoxic effect in VERO cells. Under in vivo conditions, KBA exhibited a significant reduction in parasitemia, retarding the development of anaemia, resulting in an enhancement of the mean survival time in Plasmodium yoelii nigeriensis (chloroquine-resistant) infected mice. Further, KBA did not exhibit any abnormality in serum biochemistry of animals that underwent acute oral toxicity studies at 2000 mg/kg body weight.

Bergenin - a biologically active scaffold: Nanotechnological perspectives

Bergenin, 4-O-methyl gallic acid glucoside, is a bioactive compound present in various plants belonging to different families. The present work compiles scattered information on pharmacology, structure activity relationship and nanotechnological aspects of bergenin, collected from various electronic databases such as Sci Finder, PubMed, Google scholar, etc. Bergenin has been reported to exhibit hepatoprotective, anti-inflammatory, anticancer, neuroprotective, antiviral and antimicrobial activities. Molecular docking studies have shown that isocoumarin pharmacophore of bergenin is essential for its bioactivities. Bergenin holds a great potential to be used as lead molecule and also as a therapeutic agent for development of more efficacious and safer semisynthetic derivatives. Nanotechnological concepts can be employed to overcome poor bioavailability of bergenin. Finally, it is concluded that bergenin can be emerged as clinically potential medicine in modern therapeutics.

Antimalarial and Erythrocyte Membrane Stability Properties of Globimetula braunii (Engle Van Tiegh) Growing on Cocoa in Plasmodium berghei-Infected Mice

Introduction

Resistant malaria is a fatal disease. Globimetula braunii (African Mistletoe) is traditionally used for malarial treatment but this fact has not been scientifically reported.

Methods

Plasmodium berghei (NK65)-infected male Swiss mice (20±2 g) were treated orally and once daily with 100, 200, and 400 mg/kg BW of methanol extract and its respective hexane, dichloromethane and ethyl acetate fractions for 9 days. P-alaxin was used as control drug P. berghei (ANKA)-infected mice were then treated with the most potent fraction for 5 days. Parasitemia and parasite clearance were determined by microscopy, while hematological parameters, heme, hemozoin, and mouse erythrocyte membrane stabilisation were assayed. The phytochemicals in the most potent fraction were identified using gas chromatography-mass spectrometry.

Results

Hexane fraction (HF)-treated mice (400 mg/kg BW) had the least mean parasite load (0.00 ± 0.00; 0.14 ± 0.05%) and highest clearance (100 ± 0.00; 75.50 ± 4.95%) compared with infected control (9.81 ± 0.09; 6.84 ± 0.09%) in susceptible and resistant models, respectively. Hexane fraction modulated hematological indices, minimised erythrocyte membrane damage in heat-induced (2.18 ± 0.94%) and hypotonic solution-induced (7.93 ± 0.93%) compared to artequin (5.05 ± 2.18; 6.38 ± 0.33%) and P-alaxin (67.45 ± 5.15; 56.78 ± 1.10%) in both models of membrane stabilisation, respectively. Hexane fraction (P<0.01) increased heme and decreased hemozoin contents. Friedelan-3-one was identified as the most abundant triterpene.

Conclusion

The results indicated that G. braunii has anti-plasmodial properties and minimally dis-stabilised erythrocyte membrane. The major findings in this study are that n-hexane fraction of G. braunii possess excellent and moderate antiplasmodial activity against susceptible and resistant P. berghei, respectively. This was reflected via decreased parasite load, improved hematological parameters, increased heme and decreased hemozoin contents. Friedelan-3-one, a major constituent of the n-hexane fraction, may be responsible for this activity.

Medicinal plants as a fight against murine blood-stage malaria

OBJECTIVE

Malaria is an infectious parasitic disease affecting most of countries worldwide. Due to antimalarial drug resistance, researchers are seeking to find another safe efficient source for treatment of malaria. Since many years ago, medicinal plants were widely used for the treatment of several diseases. In general, most application is done first on experimental animals then human. In this article, medicinal plants as antimalarial agents in experimental animals were reviewed from January 2000 until November 2020.

MATERIALS AND METHODS

In this systematic review published articles were reviewed using the electronic databases NCBI, ISI Web of knowledge, ScienceDirect and Saudi digital library to check articles and theses for M.Sc/Ph.D. The name of the medicinal plant with its taxon ID and family, the used Plasmodium species, plant part used and its extract type and the country of harvest were described.

RESULTS AND CONCLUSION

The reviewed plants belonged to 83 families. Medicinal plants of families Asteraceae, Meliaceae Fabaceae and Lamiaceae are the most abundant for use in laboratory animal antimalarial studies. According to region, published articles from 33 different countries were reviewed. Most of malaria published articles are from Africa especially Nigeria and Ethiopia. Leaves were the most common plant part used for the experimental malaria research. In many regions, research using medicinal plants to eliminate parasites and as a defensive tool is popular.

Toxic Prediction of Pyrrolizidine Alkaloids and Structure-Dependent Induction of Apoptosis in HepaRG Cells

Pyrrolizidine alkaloids (PAs) are common phytotoxins and could cause liver genotoxicity/carcinogenicity following metabolic activation. However, the toxicity of different structures remains unclear due to the wide variety of PAs. In this study, the absorption, distribution, metabolism, excretion, and toxicity (ADMET) of 40 PAs were analyzed, and their toxicity was predicted by Komputer Assisted Technology (TOPKAT) using Discovery Studio software. The in silico results showed that all PAs except retronecine had good intestinal absorption, and all PAs were predicted to have different toxicity ranges. To verify the predictive results, 4 PAs were selected to investigate cell injury and possible mechanisms of the differentiation in HepaRG cells, including retronecine type of twelve-membered cyclic diester (retrorsine), eleven-membered cyclic diester (monocrotaline), noncyclic diester (retronecine), and platynecine type (platyphylline). After 24 h exposure, retronecine-type PAs exhibited concentration-dependent cytotoxicity. The high-content screening assay showed that cell oxidative stress, mitochondrial damage, endoplasmic reticulum stress, and the concentration of calcium ions increased, and neutral lipid metabolism was changed notably in HepaRG cells. Induced apoptosis by PAs was indicated by cell cycle arrest in the G2/M phase, disrupting the mitochondrial membrane potential. Overall, our study revealed structure-dependent cytotoxicity and apoptosis after PA exposure, suggesting that the prediction results of in silico have certain reference values for compound toxicity. A 1,2-membered cyclic diester seems to be a more potent apoptosis inducer than other PAs.

Antimalarial Plants Used across Kenyan Communities

Malaria is one of the serious health problems in Africa, Asia, and Latin America. Its treatment has been met with chronic failure due to pathogenic resistance to the currently available drugs. This review attempts to compile phytotherapeutical information on antimalarial plants in Kenya based on electronic data. A comprehensive web search was conducted in multidisciplinary databases, and a total of 286 plant species from 75 families, distributed among 192 genera, were retrieved. Globally, about 139 (48.6%) of the species have been investigated for antiplasmodial (18%) or antimalarial activities (97.1%) with promising results. However, there is no record on the antimalarial activity of about 51.4% of the species used although they could be potential sources of antimalarial remedies. Analysis of ethnomedicinal recipes indicated that mainly leaves (27.7%) and roots (19.4%) of shrubs (33.2%), trees (30.1%), and herbs (29.7%) are used for preparation of antimalarial decoctions (70.5%) and infusions (5.4%) in Kenya. The study highlighted a rich diversity of indigenous antimalarial plants with equally divergent herbal remedy preparation and use pattern. Further research is required to validate the therapeutic potential of antimalarial compounds from the unstudied claimed species. Although some species were investigated for their antimalarial efficacies, their toxicity and safety aspects need to be further investigated.

Antiplasmodial natural products: an update

Background

Malaria remains a significant public health challenge in regions of the world where it is endemic. An unprecedented decline in malaria incidences was recorded during the last decade due to the availability of effective control interventions, such as the deployment of artemisinin-based combination therapy and insecticide-treated nets. However, according to the World Health Organization, malaria is staging a comeback, in part due to the development of drug resistance. Therefore, there is an urgent need to discover new anti-malarial drugs. This article reviews the literature on natural products with antiplasmodial activity that was reported between 2010 and 2017.

Methods

Relevant literature was sourced by searching the major scientific databases, including Web of Science, ScienceDirect, Scopus, SciFinder, Pubmed, and Google Scholar, using appropriate keyword combinations.

Results and Discussion

A total of 1524 compounds from 397 relevant references, assayed against at least one strain of Plasmodium, were reported in the period under review. Out of these, 39% were described as new natural products, and 29% of the compounds had IC₅₀ ≤ 3.0 µM against at least one strain of Plasmodium. Several of these compounds have the potential to be developed into viable anti-malarial drugs. Also, some of these compounds could play a role in malaria eradication by targeting gametocytes. However, the research into natural products with potential for blocking the transmission of malaria is still in its infancy stage and needs to be vigorously pursued.

Exploring Antimalarial Herbal Plants across Communities in Uganda Based on Electronic Data

Malaria is one of the most rampant diseases today not only in Uganda but also throughout Africa. Hence, it needs very close attention as it can be severe, causing many deaths, especially due to the rising prevalence of pathogenic resistance to current antimalarial drugs. The majority of the Ugandan population relies on traditional herbal medicines for various health issues. Thus, herein, we review various plant resources used to treat malaria across communities in Uganda so as to provide comprehensive and valuable ethnobotanical data about these plants. Approximately 182 plant species from 63 different plant families are used for malaria treatment across several communities in Uganda, of which 112 plant species have been investigated for antimalarial activities and 96% of the plant species showing positive results. Some plants showed very strong antimalarial activities and could be investigated further for the identification and validation of potentially therapeutic antimalarial compounds. There is no record of an investigation of antimalarial activity for approximately 39% of the plant species used for malaria treatment, yet these plants could be potential sources for potent antimalarial remedies. Thus, the review provides guidance for areas of further research on potential plant resources that could be sources of compounds with therapeutic properties for the treatment of malaria. Some of the plants were investigated for antimalarial activities, and their efficacy, toxicity, and safety aspects still need to be studied.