Efficacy of Artemisia afra phytotherapy in experimental tuberculosis

Antitubercular drugs: possible role of natural products acting as antituberculosis medication in overcoming drug resistance and drug-induced hepatotoxicity

Mycobacterium tuberculosis (Mtb) is a pathogenic bacterium which causes tuberculosis (TB). TB control programmes are facing threats from drug resistance. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains need longer and more expensive treatment with many medications resulting in more adverse effects and decreased chances of treatment outcomes. The World Health Organization (WHO) has emphasised the development of not just new individual anti-TB drugs, but also novel medication regimens as an alternative treatment option for the drug-resistant Mtb strains. Many plants, as well as marine creatures (sponge; Haliclona sp.) and fungi, have been continuously used to treat TB in various traditional treatment systems around the world, providing an almost limitless supply of active components. Natural products, in addition to their anti-mycobacterial action, can be used as adjuvant therapy to increase the efficacy of conventional anti-mycobacterial medications, reduce their side effects, and reverse MDR Mtb strain due to Mycobacterium's genetic flexibility and environmental adaptation. Several natural compounds such as quercetin, ursolic acid, berberine, thymoquinone, curcumin, phloretin, and propolis have shown potential anti-mycobacterial efficacy and are still being explored in preclinical and clinical investigations for confirmation of their efficacy and safety as anti-TB medication. However, more high-level randomized clinical trials are desperately required. The current review provides an overview of drug-resistant TB along with the latest anti-TB medications, drug-induced hepatotoxicity and oxidative stress. Further, the role and mechanisms of action of first and second-line anti-TB drugs and new drugs have been highlighted. Finally, the role of natural compounds as anti-TB medication and hepatoprotectants have been described and their mechanisms discussed.

Integrated Network Pharmacology Approach to Evaluate Bioactive Phytochemicals of Acalypha indica and Their Mechanistic Actions to Suppress Target Genes of Tuberculosis

Mycobacterium tuberculosis is responsible for tuberculosis (TB) all over the world. Despite tremendous advancements in biomedical research, new treatment approaches, and preventive measures, TB incidence rates continue to ascend. The herbaceous plant Acalypha indica, also known as Indian Nettle, belongs to the Euphorbiaceae family and is known as one of the most important sources of medicines and pharmaceuticals for the medical therapy for a range of ailments. However, the precise molecular mechanism of its therapeutic action is still unknown. In this study, an integrated network pharmacology approach was employed to explore the potential mechanism of A. indica phytochemicals against TB. The active chemical components of A. indica were collected from two independent databases and published sources, whereas SwissTargetPrediction was used to identify the target genes of these phytochemicals. GeneCards and DisGeNET databases were employed to retrieve tuberculosis-related genes and variants. Following the evaluation of overlapped genes, gene enrichment analysis and PPI network analysis were performed using the DAVID and STRING databases, respectively. Later, to identify the potential target(s) for the disease, molecular docking was performed. A. indica revealed 9 active components with 259 potential therapeutic targets; TB attributed 694 intersecting genes from the two data sets; and both TB and A. indica overlapped 44 potential targets. The in-depth analysis based on the degree revealed that AKT1 and EGFR formed the foundation of the PPI network. Moreover, docking analysis followed by molecular dynamics simulations revealed that phytosterol and stigmasterol have higher binding affinities to AKT1 and EGFR to suppress tuberculosis. This study provides a convincing proof that A. indica can be exploited to target TB after experimental endorsement; further, it lays the framework for more experimental research on A. indica's anti-TB activity.

Artemisinin as a therapeutic vs. its more complex Artemisia source material

Covering: up to 2017-2022Many small molecule drugs are first discovered in nature, commonly the result of long ethnopharmacological use by people, and then characterized and purified from their biological sources. Traditional medicines are often more sustainable, but issues related to source consistency and efficacy present challenges. Modern medicine has focused solely on purified molecules, but evidence is mounting to support some of the more traditional uses of medicinal biologics. When is a more traditional delivery of a therapeutic appropriate and warranted? What studies are required to establish validity of a traditional medicine approach? Artemisia annua and A. afra are two related but unique medicinal plant species with long histories of ethnopharmacological use. A. annua produces the sesquiterpene lactone antimalarial drug, artemisinin, while A. afra produces at most, trace amounts of the compound. Both species also have an increasing repertoire of modern scientific and pharmacological data that make them ideal candidates for a case study. Here accumulated recent data on A. annua and A. afra are reviewed as a basis for establishing a decision tree for querying their therapeutic use, as well as that of other medicinal plant species.

Anti-Salmonella activity of plant species in the Benin republic: Artemisia afra and Detarium senegalense with promising in vitro and in vivo activities

Non-typhoidal invasive Salmonella (NTiS) diseases are one of the most important zoonoses in the world. This study explored the antipathogenic potential of twenty-four plants used in Benin folk medicine against NTiS diseases. The in vitro antibacterial and antibiofilm activities of ethanolic plant extracts were screened against clinical resistant isolates and ATCC reference strains of Salmonella. Salmonella enterica serovar Typhimurium-infected rat model was used to examine the in vivo antibacterial potential of plant extracts. Of the 24 plants, 18 plants exhibited antibacterial activity against Salmonella enterica strains with minimum inhibitory concentrations (MICs) ranging from 0.156 to 1.25 mg/mL. Anacardium occidentale, Artemisia afra, Detarium microcarpum, Detarium senegalense, and Leucaena leucocephala were the most active plant species. Extracts from A. afra, D. microcarpum, and D. senegalense showed biofilm inhibition greater than 50% against Salmonella clinical isolates. In the rat model of infection, A. afra and D. senegalense extracts were found to have an effective dose of less than 100 mg/kg and to stop the salmonellosis after 10 days of treatment. Additionally, these extracts did not produce any toxic effects in the treated animals. These results indicate clear evidence supporting the anti-Salmonella activity of A. afra and D. senegalense. Further studies are now needed to isolate bioactive compounds and to ensure the safety of these plant species.

Artemisia afra and Artemisia annua Extracts Have Bactericidal Activity against Mycobacterium tuberculosis in Physiologically Relevant Carbon Sources and Hypoxia

Mycobacterium tuberculosis (Mtb) is a deadly pathogen and causative agent of human tuberculosis, causing ~1.5 million deaths every year. The increasing drug resistance of this pathogen necessitates novel and improved treatment strategies. A crucial aspect of the host-pathogen interaction is bacterial nutrition. In this study, Artemisia annua and Artemisia afra dichloromethane extracts were tested for bactericidal activity against Mtb strain mc26230 under hypoxia and various infection-associated carbon sources (glycerol, glucose, and cholesterol). Both extracts showed significant bactericidal activity against Mtb, regardless of carbon source. Based on killing curves, A. afra showed the most consistent bactericidal activity against Mtb for all tested carbon sources, whereas A. annua showed the highest bactericidal activity in 7H9 minimal media with glycerol. Both extracts retained their bactericidal activity against Mtb under hypoxic conditions. Further investigations are required to determine the mechanism of action of these extracts and identify their active constituent compounds.

Antimycobacterial, cytotoxic, and anti-inflammatory activities of Artemisialudoviciana

ETHNOPHARMACOLOGICAL RELEVANCE

A third part of the world population has been exposed to the pathogen Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB). TB is a deadly disease, and its treatment has been hampered because of the lack of new antibiotics or the development of new antimycobacterial agents against this pathogen. The situation is aggravated because of the appearance of multidrug-resistant strains. In Mexican traditional medicine, records showed Artemisia ludoviciana for the treatment of TB. Thus, the combination of antibiotics and plant extracts might represent new antimycobacterial agents as an attractive alternative.

MATERIALS AND METHODS

The biological activities of ethanol extract obtained from A. ludoviciana were evaluated for its antimycobacterial activities using an M. tuberculosis clinical isolate. Also, the toxicity of the extracts was assessed ex vivo and in vivo using the human-derived macrophages cell line (THP-1) and the Artemia spp. model, respectively. Lastly, the inflammatory response of macrophages exposed to the extracts was also evaluated.

RESULTS

The ethanol extract of A. ludoviciana showed antimycobacterial activity with a MIC of 250 μg/mL against a clinical strain of M. tuberculosis. Ex vivo cytotoxicity using the THP-1 cell line incubated with the ethanol extract showed an IC₅₀ of 20 μg/mL. On the other hand, the Artemia model's toxicity test showed moderate toxicity when the A. ludoviciana extract was tested with LC₅₀ of 195.64 μg/mL. Analysis of the inflammatory response of THP-1 cells exposed to the same extract showed no increase in secreted interleukine-6 and -10. Also, no effect was observed in the pro-inflammatory tumor necrosis factor-α cytokine level. Moreover, a chemical profile of the extracts identified achillin as the major component in the ethanol extract, along with other minor components such as thujone and stigmasterol.

CONCLUSIONS

We showed that the ethanol extract of A. ludoviciana possessed antimycobacterial activity and could potentially be used to supplement the antibiotic treatment of TB.

Polymeric Microparticles: Synthesis, Characterization and In Vitro Evaluation for Pulmonary Delivery of Rifampicin

Rifampicin, a potent broad-spectrum antibiotic, remains the backbone of anti-tubercular therapy. However, it can cause severe hepatotoxicity when given orally. To overcome the limitations of the current oral therapy, this study designed inhalable spray-dried, rifampicin-loaded microparticles using aloe vera powder as an immune modulator, with varying concentrations of alginate and L-leucine. The microparticles were assessed for their physicochemical properties, in vitro drug release and aerodynamic behavior. The spray-dried powders were 2 to 4 µm in size with a percentage yield of 45 to 65%. The particles were nearly spherical with the tendency of agglomeration as depicted from Carr’s index (37 to 65) and Hausner’s ratios (>1.50). The drug content ranged from 0.24 to 0.39 mg/mg, with an association efficiency of 39.28 to 96.15%. The dissolution data depicts that the in vitro release of rifampicin from microparticles was significantly retarded with a higher L-leucine concentration in comparison to those formulations containing a higher sodium alginate concentration due to its hydrophobic nature. The aerodynamic data depicts that 60 to 70% of the aerosol mass was emitted from an inhaler with MMAD values of 1.44 to 1.60 µm and FPF of 43.22 to 55.70%. The higher FPF values with retarded in vitro release could allow sufficient time for the phagocytosis of synthesized microparticles by alveolar macrophages, thereby leading to the eradication of M. tuberculosis from these cells.

Artemisia annua and Artemisia afra extracts exhibit strong bactericidal activity against Mycobacterium tuberculosis

ETHNOPHARMACOLOGICAL RELEVANCE

Emergence of drug-resistant and multidrug-resistant Mycobacterium tuberculosis (Mtb) strains is a major barrier to tuberculosis (TB) eradication, as it leads to longer treatment regimens and in many cases treatment failure. Thus, there is an urgent need to explore new TB drugs and combinations, in order to shorten TB treatment and improve outcomes. Here, we evaluated the potential of two Asian and African traditional medicinal plants, Artemisia annua, a natural source of artemisinin (AN), and Artemisia afra, as sources of novel antitubercular agents.

AIM OF THE STUDY

Our goal was to measure the activity of A. annua and A. afra extracts against Mtb as potential natural and inexpensive therapies for TB treatment, or as sources of compounds that could be further developed into effective treatments.

MATERIALS AND METHODS

The minimum inhibitory concentrations (MICs) of A. annua and A. afra dichloromethane extracts were determined, and concentrations above the MICs were used to evaluate their ability to kill Mtb and Mycobacterium abscessus in vitro.

RESULTS

Previous studies showed that A. annua and A. afra inhibit Mtb growth. Here, we show for the first time that Artemisia extracts have a strong bactericidal activity against Mtb. The killing effect of A. annua was much stronger than equivalent concentrations of pure AN, suggesting that A. annua extracts kill Mtb through a combination of AN and additional compounds. A. afra, which produces very little AN, displayed bactericidal activity against Mtb that was substantial but weaker than that of A. annua. In addition, we measured the activity of Artemisia extracts against Mycobacterium abscessus. Interestingly, we observed that while A. annua is not bactericidal, it inhibits growth of M. abscessus, highlighting the potential of this plant in combinatory therapies to treat M. abscessus infections.

CONCLUSION

Our results indicate that Artemisia extracts have an enormous potential for treatment of TB and M. abscessus infections, and that these plants contain bactericidal compounds in addition to AN. Combination of extracts with existing antibiotics may not only improve treatment outcomes but also reduce the emergence of resistance to other drugs.

Artemisia afra, a controversial herbal remedy or a treasure trove of new drugs?

ETHNOPARMACOLOGICAL RELEVANCE

Artemisia afra is one of the most widely used herbal remedies in South Africa. This highly aromatic shrub is used to treat various disorders including coughs, colds, influenza, and malaria. Due to the long tradition of use and popularity of A. afra, it has been successfully commercialised and can currently be bought from various internet stores and pharmacies. The most notable indication is for the prophylaxis and treatment of Plasmodium falciparum infections. In 2013, the Medicine Control Council (MCC) of South Africa banned the sale of A. afra for the treatment of malaria because it lacks scientific evidence of efficacy. This resulted in a lawsuit being filed in 2017 against the MCC by an herbal company which claimed that artemisinin was responsible for A. afra's antiplasmodial activity. At the time, no scientific literature reported that A. afra contained artemisinin.

MATERIALS AND METHODS

This review aims to collate all available scientific literature regarding the phytochemistry and biological activity, focusing on antimalarial activity, of A. afra published from 2009 to 2019 and follows on our earlier review, which covered all literature until 2009. All scientific literature in English published between 2009 and June 2019 were retrieved from scientific databases (Scifinder scholar, Web of Science, Scopus, PubMed, Google scholar) and a number of books regarding medicinal plants in South Africa were also consulted.

RESULTS

In the last decade very few compounds have been identified in A. afra, none of which were novel compounds. Based on all the tests that have been conducted using extracts and compounds of A. afra in a disparate variety of in vitro and in vivo bioassays, the results indicate only weak biological activity. The activity of extracts, and in some cases pure compounds, exhibited IC₅₀ or MIC values of 1000-10 000 fold less active than the positive controls. In contrast, and quite surprisingly, two randomised controlled trials were recently conducted (Schistosoma mansoni and Plasmodium falciparum infected patients) and although criticised based on design, execution, statistical analysis and ethical concerns, showed remarkably positive results.

CONCLUSIONS

Pre-clinical in vitro and in vivo animal experiments failed to yield any promising drug leads. However, if the recent randomised controlled trials can be independently replicated in well-designed and executed clinical trials it might indicate that A. afra contain powerful 'prodrugs'. Future research on A. afra should therefore focus on reproducing the randomised controlled trials and on artificially metabolising A. afra extracts/compounds in order to identify the presence of any 'prodrugs'.

Medicinal plants: Adjunct treatment to tuberculosis chemotherapy to prevent hepatic damage

The effectiveness of herbs for the management of chemically induced hepatotoxicity has been discussed by many researchers. However, there is a paucity of compressive literature on the significance of hepatoprotective plants for the management of anti-TB drug induced toxicity. Anti-TB drugs have been reported to causes hepatic damage, due to which, many patients across the globe discontinued the treatment. Medicinal plants have multiple therapeutic effects. The assessment of biological activity of plants against Mycobacterium and its use for hepatic recovery provides an effective treatment approach. Traditionally used medicinal plants are the rich source of phytochemicals and secondary metabolites. These compounds can restore normal function, enzymatic activity and structure of hepatic cells against anti-TB drug induced hepatotoxicity. The present review covers comprehensive details on different hepatoprotective and antimycobacterial plants studied during past few decades so that potential adjuvants can be studied for Tuberculosis chemotherapy.

Fractions and isolated compounds from Oxyanthus speciosus subsp. stenocarpus (Rubiaceae) have promising antimycobacterial and intracellular activity

BACKGROUND

Tuberculosis is a deadly disease caused by Mycobacterium species. The use of medicinal plants is an ancient global practice for the treatment and prevention of diverse ailments including tuberculosis. The aim of this study was to isolate and characterize antimycobacterial compounds by bioassay-guided fractionation of the acetone leaf extract of Oxyanthus speciosus.

METHODS

A two-fold serial microdilution method was used to determine the minimum inhibitory concentration (MIC) against mycobacteria. Cytotoxicity and nitric oxide inhibitory activity of the isolated compounds was determined to evaluate in vitro safety and potential anti-inflammatory activity. Intracellular efficacy of the crude extract against Mycobacterium-infected macrophages was also determined.

RESULTS

Two compounds were isolated and identified as lutein (1) and rotundic acid (2). These had good antimycobacterial activity against the four mycobacteria tested with MIC values ranging from 0.013 to 0.1 mg/mL. Rotundic acid had some cytotoxicity against C3A human liver cells. Lutein was not cytotoxic at the highest tested concentration (200 μg/mL) and inhibited nitric oxide production in RAW 264.7 macrophages by 94% at a concentration of 25 μg/mL. The acetone crude extract (120 μg/mL) of O. speciosus had intracellular antimycobacterial activity, reducing colony forming units by more than 90%, displaying bactericidal efficacy in a dose and time-dependent manner.

CONCLUSION

This study provides good proof of the presence of synergism between different compounds in extracts and fractions. It is also the first report of the antimycobacterial activity of lutein and rotundic acid isolated from Oxyanthus speciosus. The promising activity of the crude extract of O. speciosus both in vitro and intracellularly in an in vitro macrophage model suggests its potential for development as an anti- tuberculosis (TB) herbal medicine.

The Anti-leishmanial Efficacy of Artemisia dracunculus Ethanolic Extract in Vitro and Its Effects on IFN-γ and IL-4 Response

BACKGROUND

Leishmaniasis is a parasitic disease that appears with a range of symptoms including cutaneous, mucocutaneous, and visceral leishmaniasis. The present study sought to determine the antileishmanial effect of the extract of Artemisia dracunculus (Tarragon) compared to control treatment with pentavalent antimony (meglumine).

METHODS

This experimental study was performed in 2014-2015. A. dracunculus were collected from West Azerbaijan Province, Iran and dried; then the ethanolic extract of the plant was prepared. The effect of different concentrations of Artemisia's extract was compared with Glucantime ® in the stationary phase by MTT colorimetric assay and Trypan blue staining. Human peripheral blood mononuclear cells (HPBMCs) treated with L. major and production of IFN-γ and IL-4 cytokines measured at concentrations of 25, 20, 10 and 5μg/ml A. dracunculus.

RESULTS

Treatment with the extract did not affect the survival of the parasites during the first 48 h; however, on the third day (72 h), all concentrations significantly reduced the number of parasites with an efficacy of more than 50% at 10 μg/ml (P<0.01), 20μg/ml (P<0.001), and 25 μg/ml (P<0.0001). Moreover, IFN-γ and IL-4 secretion from the HPBMCs was significantly affected in a dose-dependent manner, compared to the control (no extract). The IFN-γ/IL-4 ratio further confirmed this notion.

CONCLUSION

A. dracunculus extract cannot only exert potent antileishmanial activity but may also enhance cellular immunity to this parasite. Further studies are required to determine the main compound(s) responsible for these effects of the plant.

Tuberculosis and nature's pharmacy of putative anti-tuberculosis agents

Due to the growing problem of drug resistant Mycobacterium tuberculosis strains, coupled with the twinning of tuberculosis (TB) to human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), the burden of TB is now difficult to manage. Therefore, new antimycobacterial agents are being sought from natural sources. This review focuses on natural antimycobacterial agents from endophytes and medicinal plants of Africa, Europe, Asia, South America and Canada. In the countries mentioned in this review, numerous plant species display putative anti-TB activity. Several antimycobacterial chemical compounds have also been isolated, including: ellagitannin punicalagin, allicin, anthraquinone glycosides, iridoids, phenylpropanoids, beta-sitosterol, galanthimine, crinine, friedelin, gallic acid, ellagic acids, anthocyanidin, taraxerol, termilignan B, arjunic acid, glucopyranosides, 1-epicatechol, leucopelargonidol, hydroxybenzoic acids, benzophenanthridine alkaloids, neolignans, and decarine. These compounds may provide leads to novel and more efficacious drugs to lessen the global burden of TB and drug-resistant M. tuberculosis strains. If there is a long-term remedy for TB, it must lie in nature's pharmacy of putative antimycobacterial agents.

Host-parasite relationship between colonial terns and bacteria is modified by a mutualism with a plant with antibacterial defenses

Predator-prey and host-parasite interactions and mutualisms are common and may have profound effects on ecosystems. Here we analyze the parasitic and mutualistic associations between three groups of organisms: the plant Artemisia maritima, bacteria, and a colonial seabird (the sandwich tern Sterna sandvicensis) that breeds in dense colonies covered in feces produced by both adults and chicks. A disproportionately large fraction of colonies of the sandwich tern in Denmark were located in patches covered by A. maritima. This association was specific for the densely colonial sandwich tern, but was not present for four other sympatric species of terns that breed in much less dense colonies. A. maritima reduced the abundance of pathogenic Staphylococcus on chicken eggshells in a field experiment. Recruitment by sandwich terns breeding in patches of A. maritima was 18 % higher than for sandwich terns breeding in the absence of A. maritima. A. maritima benefitted from the association with sandwich terns due to the supply of nutrients from feces and uneaten food lost by young. These findings are consistent with sandwich terns exploiting the association with A. maritima and its antimicrobial properties to improve their reproductive success, while sandwich terns and A. maritima are involved in a mutualistic interaction.

Antimicrobial and cytotoxic activities of medicinal plants of the Brazilian cerrado, using Brazilian cachaça as extractor liquid

ETHNOPHARMACOLOGICAL IMPORTANCE

Many species of plants in the Brazilian cerrado (savanna) are widely used in ethnomedicine. However, the safety and effectiveness of medicinal plants used in communities with little or no access to manufactured drugs should be evaluated.

AIM OF THE STUDY

Evaluate the antimicrobial and cytotoxic activities of extracts from eight plant species, obtained using Brazilian cachaça as the extractor liquid.

MATERIALS AND METHODS

The extracts were tested against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, Candida parapsilosis, promastigote forms of Leishmania amazonensis, and poliovirus. In addition, cytotoxic activity was assayed in Vero cells and in human erythrocytes.

RESULTS

The plant species Curatella americana, Sclerolobium aureum, and Plathymenia reticulata showed the best activity against yeasts, especially the crude extract of C. americana and its ethyl-acetate fraction. Kielmeyera lathrophyton showed a minimum inhibitory concentration of 250 μg/ml against S. aureus, and was inactive against gram-negative bacteria. The extract obtained from Annona coriacea showed the best activity against the promastigote forms of Leishmania amazonensis (IC(50)=175 μg/ml). Only C. americana showed potential for antipoliovirus activity. The concentrations of the crude extracts that showed toxicity to VERO cells had CC(50) between 31 and 470 μg/ml, and the lyophilized Brazilian cachaça showed a CC(50) of 307 μg/ml. None of the extracts showed toxicity against human erythrocytes.

CONCLUSIONS

Among the plant species studied, C. americana proved to be effective against microorganisms, especially as an antifungal. The results will help in the search for alternative drugs to be used in pharmacotherapy, and will contribute to establish safe and effective use of phytomedicines in the treatment of infectious diseases.