Tag Archives: malaria

Natural Products for the Control of Malaria

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Natural products for the control of malaria

Malar J. 2011 Mar 15;10 Suppl 1:S1
BioMed Central

PubMed recently posted several articles from a 2011 supplement to Malaria Journal devoted to natural products for the control of malaria, so I’ve taken the opportunity to look at the entire issue.

Edited by Hagai Ginsburg of The Hebrew University of Jerusalem, and funded with contributions from the African Network for Drugs & Diagnostics Innovation, Department of Primary Health Care at University of Oxford, Institut de Recherche pour le Développement, MMV – Medicines for Malaria Venture and University of Cape Town, the supplement surveys a number of topics related to the use of natural compounds in the development of antimalarial treatments.

I’ll address the articles one at a time, starting with the editor’s introduction.

I. A call for using natural compounds in the development of new antimalarial treatments – an introduction

Ginsburg H, Deharo E
Malar J. 2011 Mar 15;10 Suppl 1:S1
PubMed Central PMCID: PMC3059457

In this introduction, supplement editor Hagai Ginsburg and Eric Deharo of the Université de Toulouse and the Institut de Recherche pour le Développement argue for a revisiting of old approaches to the development of antimalarial drugs.

From the abstract:

“Natural compounds, mostly from plants, have been the mainstay of traditional medicine for thousands of years. They have also been the source of lead compounds for modern medicine, but the extent of mining of natural compounds for such leads decreased during the second half of the 20th century. The advantage of natural compounds for the development of drugs derives from their innate affinity for biological receptors. Natural compounds have provided the best anti-malarials known to date. Recent surveys have identified many extracts of various organisms (mostly plants) as having antiplasmodial activity. Huge libraries of fractionated natural compounds have been screened with impressive hit rates. Importantly, many cases are known where the crude biological extract is more efficient pharmacologically than the most active purified compound from this extract. This could be due to synergism with other compounds present in the extract, that as such have no pharmacological activity. Indeed, such compounds are best screened by cell-based assay where all potential targets in the cell are probed and possible synergies identified. Traditional medicine uses crude extracts. These have often been shown to provide many concoctions that deal better with the overall disease condition than with the causative agent itself. Traditional medicines are used by ~80 % of Africans as a first response to ailment. Many of the traditional medicines have demonstrable anti-plasmodial activities. It is suggested that rigorous evaluation of traditional medicines involving controlled clinical trials in parallel with agronomical development for more reproducible levels of active compounds could improve the availability of drugs at an acceptable cost and a source of income in malaria endemic countries.”

For malaria research, Ginsburg and Deharo propose a shift in the drug discovery paradigm from ‘finding new-entity drugs’ to ‘combining existing agents’. Reviewing the current literature on drug leads for novel plant-based antimalarials, they note a bias against studying the biological activity of crude extracts and favoring the screening of purified compounds – potentially missing the effect of synergistic combinations that might have arisen over the natural history of the plant-based therapy. They also address significant limitations of the prevailing model of rational drug development, in which a thorough understanding of a disease’s pathogenesis and the mechanism of a therapy’s action is the primary, if not exclusive, driver of discovery:

“Testing the effects of extracts usually doesn’t divulge the drug target or its mode of action. But if the extract is working well is it really important as to know the precise mode of action? In the context of anti-malarials, it is relevant to underscore the fact that till this very day, the mechanism of action of two of the most efficient drugs derived from traditional medicine, artemisinin and quinine, is still debatable.”

In their conclusion, Ginsburg and Deharo introduce a third key theme for this supplement, a review of scientific and pharmacological evidence to provide a “basis for further development of ethnic/traditional medicine as a valid, cheap and locally-available means to treat malaria.”

Read the complete article at PubMed Central.

The information on my blog is not intended as a substitute for medical professional help or advice but is to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition.

Madagascar Periwinkle – A Potential Eco-Friendly Mosquito Pesticide

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Larvicidal efficacy of Catharanthus roseus Linn. (Family: Apocynaceae) leaf extract and bacterial insecticide Bacillus thuringiensis against Anopheles stephensi Liston

Panneerselvam C, Murugan K, Kovendan K et al
Asian Pac J Trop Med
2013 Nov;6(11):847-53
PubMed PMID: 24083578

Investigators at Bharathiar University (Tamil Nadu) and National Taiwan Ocean University investigated the larvicidal activity of Catharanthus roseus leaf extract and Bacillus thuringiensis against the mosquito Anopheles stephensi, an important vector of malaria in Indian cities.

From the Introduction:

“In India, malaria is transmitted by six vector species, in which Anopheles stephensi (An. stephensi) is responsible in urban areas. Mosquitoes in the larval stage are attractive targets for pesticides because they breed in water; thus, it is easy to deal with them in this habitat. Management of disease vector using synthetic chemicals has failed because of resistance, effect on non-target organisms and environmental pollution. On the other hand, the recent public perception against the vector control using synthetic chemicals has shifted the research effort towards the development of environmentally sound and biodegradable agents. In that way, plant extracts including essential oils have attracted much attention to control the vector transmitted diseases.”

Madagascar Periwinkle (Catharanthus roseus)
Madagascar Periwinkle (Catharanthus roseus) [Source: Wikimedia Commons user: Biswarup Gangulyb]
C. roseus (Madagascar periwinkle) is an important medicinal plant; for example, it is the source of two anti-cancer drugs, vincristine and vinblastine. It contains alkaloids known to have hypotensive and antispasmodic properties.

The team found that C. roseus extract and B. thuringiensis both have potential to be used as eco-friendly agents for the control of An. stephensi in vector control programs, and that the combined treatment with the plant extract and bacterial toxin has better larvicidal efficacy against An. stephensi than either agent alone:

“In conclusion, the larvicidal potentiality of the crude extracts of C. roseus and B. thuringiensis was studied in the laboratory as well as field conditions. The C. roseus leaf extract and B. thuringiensis have been shown to be effective mosquito control agents. These results show that these two biological agents could reduce the malarial incidence. It also divulges the presence of active metabolites which are causes of larval mortality. Therefore, the botanicals are one of the best alternatives for chemical insecticides and are also ecofriendly bio-pesticides which create a healthy environment.”

Read the complete article at PubMed.

The information on my blog is not intended as a substitute for medical professional help or advice but is to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition.

Anti-Malaria Activity of Three Zulu Medicinal Plants

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Anti-plasmodial activity of some Zulu medicinal plants and of some triterpenes isolated from them

Mthokozisi B. C. Simelane, Addmore Shonhai, Francis O. Shode, Peter Smith, Mogie Singh and Andy R. Opoku
Molecules
2013 Oct 8;18(10):12313-23
PubMed PMID: 24108397
Mimusops caffra
Mimusops caffra (Source: Wikimedia Commons User Michaelwild)

Researchers at the University of Zululand, University of Cape Town, and University of KwaZulu-Natal analyzed crude extracts and specific isolates of three medicinal plants used by the Zulu people as treatments for malaria, for activity against Plasmodium falciparum (one of the parasites that causes malaria in humans): Mimusops caffra, Mimusops obtusifolia, and Hypoxis colchicifolia.

The team verified anti-malaria activity of M. caffra in particular, which though not as high as that reported for the standards (chloroquine and artesunate), was found to be dose dependent, and with low toxicity levels, and encouraged continued exploration of M. caffra in managing malaria in traditional medicine.

From the Introduction:

“Malaria is one of the major health problems in tropical Africa, South-east Asia, Central South America and Oceania. Despite the various efforts by governmental and non-governmental organizations aimed at eradicating the disease, malaria is said to kill a child every 30 s. Malaria cases have been reported in other areas of the World that were previously considered eradicated of malaria. In Africa, herbal medicines are an important part of the culture and traditions of its people.
“Traditional healers use different concoctions prepared from medicinal plants to treat malaria. Given the remarkable anti-malarial properties of Cinchona bark that have been known for more than 300 years, resulting in the discovery of quinine and the more recent development of artemisinin derivatives, the potential of plant species to provide effective drugs for the treatment of malaria cannot be overemphasized. Furthermore, the drug resistance of the malaria parasite to chloroquine and sulfadoxine–pyrimethamine, and also the toxicity of the currently available drugs have stimulated the search for alternative medicines which are naturally derived. In addition, modern health care to the rural people is still a far-reaching goal, due to economic constraints and many vulnerable groups depend on plant-based traditional healing. The anti-malarial activity of many plants has been reported. An ethonobotanical survey revealed the extensive utilization of M. caffra, M. obtusifolia and H. colchicifolia for the management of malaria in Zulu traditional medicine.”

Read the complete article at PubMed.

The information on my blog is not intended as a substitute for medical professional help or advice but is to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition.

Medicinal plants of Babile Wereda, Eastern Ethiopia

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Medicinal plants potential and use by pastoral and agro-pastoral communities in Erer Valley of Babile Wereda, Eastern Ethiopia

Belayneh A, Asfaw Z, Demissew S, Bussa NF
J Ethnobiol Ethnomed
2012 Oct 22;8:42
PubMed Central PMCID: PMC3549935

Researchers at Haramaya University and Addis Ababa University undertook an ethnobotanical study centered around the potential and use of traditional medicinal plants by pastoral and agro-pastoral communities in the Babile Wereda district of eastern Ethiopia, with a goal of setting up of conservation priorities, and preservation of local biocultural knowledge with sustainable use and development of the resource.

Azadirachta indica
Azadirachta indica (Source: Wikimedia Commons User J.M. Garg)

Working with traditional herbalists, the authors identified 51 medicinal plant species used for 54 human ailments, in addition to some used in vector control. Aloe pirottae, Azadirachta indica and Hydnora johannis were the most cited and preferred species.

A high percentage (71%) of the preparations are made for the most common human health problems of the area, including internal parasites, diarrhea, malaria, pneumonia, abdominal pain, dermal infections, eye diseases, and infections of the skin and subcutaneous tissues.

The authors note that many of the region’s ethnomedicinal plants, and the associated knowledge about them, are endangered:

“…like else where in the country, nowadays the natural stands of the Erer Valley are becoming negatively impacted as a result of agricultural expansion, livestock population pressure and human settlement. Medicinal plant species of the woodland (for example Hydnora johannis) are highly threatened and that might be related to the decline in the population of host trees such as Acacia nilotica and Acacia tortilis. Visual inspection shows that woodland trees including Balanites eagyptiaca and B. glabra are locally threatened due to selective cutting of the mother trees for charcoal making. The riverine tree species, Acacia robusta and Tamarindus indica, are locally threatened due to selective cutting for charcoal making and house construction given the increasing population in the Erer Valley. Along with the loss of the natural vegetation of the valley we are bound to loose the huge potential of the medicinal plants and the associated knowledge. Therefore, the study area calls for urgent measures to be taken to rehabilitate and conserve the remaining vegetation with special regard to the key medicinal plants and preserve the indigenous knowledge.”

Read the complete article at PubMed Central.

The information on my blog is not intended as a substitute for medical professional help or advice but is to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition.

Endangered Ethnomedicinal Plant Demonstrates Anti-Mosquito Properties

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Screening of selected ethnomedicinal plants from South Africa for larvicidal activity against the mosquito Anopheles arabiensis

Rajendra Maharaj, Vinesh Maharaj, Neil R Crouch, Niresh Bhagwandin, Peter I Folb, Pamisha Pillay, and Reshma Gayaram
Malar J
2012 Sep 10;11:320
PubMed Central PMCID: PMC3472289

Investigators from the South African Medical Research Council, CSIR and University of KwaZulu-Natal undertook a study to establish whether any South African ethnomedicinal plants used traditionally to repel or kill mosquitoes demonstrate effective mosquito larvicidal properties.

Toddalia asiatica
Deforestation is making the ethnomedicinal plant Toddalia asiatica vulnerable to extinction (Nabwami J et al, African Crop Science Conference Proceedings 8: 2057-2061, 2007). (Photo source: Wikimedia Commons User Vinayaraj)

The authors tested 381 crude plant extracts, consisting of plants found native or naturalized in southern Africa, for their larvicidal effect on Anopheles arabiensis. They successfully identified one plant, Toddalia asiatica, that demonstrated superior larvicidal activity and that is now being further studied with the goal to isolate the active compound and develop a malaria vector control tool.

Read the complete article at PubMed Central.

The information on my blog is not intended as a substitute for medical professional help or advice but is to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition.

Essential Oils Against Malaria

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Anti-plasmodial and insecticidal activities of the essential oils of aromatic plants growing in the Mediterranean area

Mario Dell’Agli, Cinzia Sanna, Patrizia Rubiolo, Nicoletta Basilico, Elisa Colombo, Maria M Scaltrito, Mamadou Ousmane Ndiath, Luca Maccarone, Donatella Taramelli, Carlo Bicchi, Mauro Ballero, Enrica Bosisio
Malar J
2012 Jul 2;11:219
PubMed Central PMCID: PMC3441327
Sardinia
Sardinia (Source: Wikimedia Commons User: TUBS)

Researchers at Università degli Studi di Milano, Università degli Studi di Cagliari, Università degli Studi di Torino and Laboratoire de Biologie Moléculaire undertook a screening study to evaluate the anti-plasmodial activity of aromatic plants traditionally used in Sardinia against malaria: Myrtus communis (myrtle, Myrtaceae), Satureja thymbra (savory, Lamiaceae), and Thymus herba-barona (caraway thyme, Lamiaceae).

The authors found evidence for the use of essential oils for treating malaria and fighting the vector at both the larval and adult stages, opening the possibility for further investigation aimed at the isolation of natural products with anti-parasitic properties.

From the discussion:

“Among the three plants, S. thymbra showed the highest in vitro anti-plasmodial activity, especially against the [Chloroquine]-resistant strain. Moreover, the time of collection (before, during, and after flowering) did not influence the anti-plasmodial effect, which appeared to be mainly associated with thymol, one of the components of the [Essential oil]. These results are in agreement with a recent report that the [Essential oil] of Oreganum compactum, rich in thymol, shows anti-plasmodial activity in vitro. Such a conclusion is corroborated by the data obtained with the [Essential oils] of M. communis and T. herba-barona since the latter, which does not contain thymol, possesses lower activity against P. falciparum. Moreover, the activity of thymol was selective against the parasites with low cytotoxicity against human dermal fibroblasts.”

Read the complete article at PubMed Central.

The information on my blog is not intended as a substitute for medical professional help or advice but is to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition.

Antimalarial Plants Used in Portuguese-Speaking Countries

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A review of antimalarial plants used in traditional medicine in communities in Portuguese-speaking countries: Brazil, Mozambique, Cape Verde, Guinea-Bissau, São Tomé and Príncipe and Angola

Jefferson Rocha de A Silva; Aline de S Ramos; Marta Machado; Dominique F de Moura; Zoraima Neto; Marilene M Canto-Cavalheiro; Paula Figueiredo; Virgilio E do Rosário; Ana Claudia F Amaral; Dinora Lopes
Mem Inst Oswaldo Cruz
2011 Aug;106 Suppl 1:142-58
PubMed PMID: 21881769
Chromolaena odorata
Chromolaena odorata (Source: Wikimedia Commons user Ashasathees)

Researchers from the Universidade Federal do Amazonas (Brazil), Farmanguinhos (Brazil), Universidade Nova de Lisboa (Portugal) and Instituto Oswaldo Cruz-Fiocruz (Brazil) compiled an extensive catalog of phytochemical studies of medicinal plants used to treat malaria in traditional medicine from the Comunidade dos Países de Língua Portuguesa: Angola, Brazil, Cape Verde, Guinea-Bissau, Mozambique and São Tomé and Príncipe.

Their analysis indicates that seven families (Apocynaceae, Asteraceae, Cucurbitaceae, Fabaceae, Meliaceae, Myristicaceae and Pi-peraceae) have species commonly used in these countries to treat malaria. “The Euphorbiaceae, Rubiaceae and Solanaceae families are represented by botanical species used primarily within African countries. Further, there are reports of other families of plants restricted to some countries: Angola (Annonaceae and Cochlospermaceae), Guinea-Bissau (Combretaceae and Hypencaceae) and Brazil have the most references to species belonging to the seven botanical families.”

A detailed table lists the studied species, tested parts and scientific data from vitro and in vivo research.

Read the complete article at PubMed.

The information on my blog is not intended as a substitute for medical professional help or advice but is to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition.

Folk Medicines Used to Treat Malaria in Calabria

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Tagarelli G, Tagarelli A, Piro A.
Folk medicine used to heal malaria in Calabria (southern Italy).
J Ethnobiol Ethnomed. 2010 Sep 18;6:27.
PubMed PMID: 20849654; PubMed Central PMCID: PMC2949813. [Free full text via PubMed Central.]

Researchers at Istituto di Scienze Neurologiche-CNR identified folk medical cures that were used by the Calabrian people for the treatment of malaria, as evidenced in writings produced between the 19th and 20th centuries.

The authors identify 53 plants used by Calabrian people to treat malaria, and note that some of these plants are still currently used in Calabrian folk medicine to treat various diseases.

From the Discussion:

“The methodology based on the analysis of historical sources regarding Calabrian folk medicine remedies for the prophylaxis and treatment of malaria, if not compared with similar studies, can be considered a case study where the ordinary methodologies of ethno-medical-biological research are combined with the methodologies pertaining to historical-anthropological sciences. In addition, this is part of a debate regarding the association between ethnobotany and ethnopharmacology and other disciplines, to improve our understanding of the human usage of plants.”

Free full text is available via PubMed Central.

The information on my blog is not intended as a substitute for medical professional help or advice but is to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition.