Antibacterial activities of extracts from Nigerian chewing sticks

Anogeissus leiocarpus (DC.) Guill. & Perr. (Combretaceae): A review of the traditional uses, phytochemistry and pharmacology of African birch

Anogeissus leiocarpus (DC.) Guill. & Perr. belongs to the family Combretaceae and is used both by African traditional medical practitioners and livestock rearers to treat diseases such as African trypanosomiasis, animal diarrhoea, asthma, cancer, cough, diabetes, dysentery, erectile dysfunction, fever, giardiasis, helminthiases, meningitis, menstrual disorders, monkeypox, oral infections, poliomyelitis, sickle cell anaemia, snake bites, toothache, urinary schistosomiasis, and yellow fever. Some of these activities have been associated with the presence of polyphenols in the plant which include ellagic acid derivatives, flavonoids, stilbenes, tannins, and triterpenes. Several bioactive molecules have been identified from A. leiocarpus. These include the main active constituents, ellagitannins, ellagic acid derivates, flavonoids and triterpenes. Pharmacological studies have confirmed its antibacterial, antifungal, antihyperglycemic, antihypertensive, antimalarial, antioxidative, antiparasitic, antitumour and anti-ulcer effects. The stem bark has been investigated mainly for biological activities and phytochemistry, and it is the most mentioned plant part highlighted by the traditional users in ethnomedicinal surveys. In vitro and in vivo models, which revealed a wide range of pharmacological actions against parasites causing helminthiasis, leishmaniasis, malaria and trypanosomiasis, have been used to study compounds from A. leiocarpus. Because of its uses in African traditional medicine and veterinary practices, A. leiocarpus has received considerable attention from researchers. The current review provides a comprehensive overview and critical appraisal of scientific reports on A. leiocarpus, covering its traditional uses, pharmacological activities and phytochemistry.

Invasive alien plants and weeds in South Africa: A review of their applications in traditional medicine and potential pharmaceutical properties

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional pharmacopoeias are constantly evolving and adapting, hence the assimilation of alien plants and weeds into traditional systems of healing. Invasive plants are detrimental to the ecosystem, however they are also potential sources of secondary metabolites with useful biological activities.

AIM OF THE REVIEW

The aim of this review was to investigate published reports of traditional use and biological activity of declared invasive alien plants and other weeds in South Africa.

MATERIALS AND METHODS

Information was retrieved from scientific databases including Scopus, Web of Science, ScienceDirect, Google Scholar, PubMed, Chemical Abstracts Services and books, theses, dissertations and technical reports. Keywords used for the search engines were "South Africa" or "southern Africa" in conjunction with "(native weeds OR alien invasive)" AND "medicinal". Separate searches were conducted on the individual invasive plant species recorded as having been used in ethnobotanical surveys to determine their known biological activities and chemical components.

RESULTS

A total of 89 plant species regarded as invasive species or weeds in South Africa were identified as being used in traditional medicine. The most commonly mentioned plant family was the Asteraceae with a total of 15 species followed by the Fabaceae and Solanaceae with 6 species each. Of the 89 species recorded, 68% were reported to have traditional usage with both phytochemical and biological data available. A history of traditional usage coupled with biological data was available for 12% of species. Records of traditional usage alone were linked to 11% of species. Invasive alien species comprised 61% of recorded species, while native and non-invasive alien weeds formed the remaining 39%.

CONCLUSIONS

The exploration of alternative uses for weeds and particularly invasive plants, whether native or alien, as medicines for possible commercialisation may lead to innovative mechanisms for putting such species to good use.

Physicochemical Evaluation and Antibacterial Activity of Massularia acuminata Herbal Toothpaste

Objectives

Oral hygiene, an integral part of the body's general well-being, should be maintained to prevent dental problems. This study was conducted to incorporate the ethanol extract of Massularia acuminata twigs in a formulation of herbal toothpaste and evaluate its antibacterial activity compared with a commercially available herbal toothpaste against two dental pathogens, namely, Staphylococcus aureus and Streptococcus mutans.

Materials and Methods

The content of dried M. acuminata twig was extracted using ethanol and used in the formulation of toothpaste containing 1%, 2%, 3%, 4%, and 5% M. acuminata extract. The sensory and physicochemical properties of the toothpaste were evaluated. The agar well diffusion method was used to evaluate the antibacterial susceptibility of the toothpaste against S. aureus and S. mutans. Data were analyzed using One-Way analysis of variance and Student's t-test.

Results

All toothpastes were smooth and sweet and smelled pleasant. They all had good retention ability on the bristles of toothbrush and had a pH range of 7.18-7.83. The toothpastes of the extracts of different concentration demonstrated antibacterial activities against the test organisms. The antibacterial activity of the formulated toothpastes increased significantly with an increase in the extract concentration. F5 that contained 5% extract showed the highest activity, with an inhibition zone of 19.30±0.17 mm and 12.60±0.52 mm against S. aureus and S. mutans, respectively, even when compared with the commercially available herbal toothpaste.

Conclusion

The incorporation of the M. acuminata extract in the formulation of herbal toothpaste prevented the growth of S. aureus and S. mutans. Incorporating this extract in toothpaste formulation will satisfactorily maintain oral hygiene, which is desirable to prevent dental caries and periodontal diseases.

Possible health benefits of polyphenols in neurological disorders associated with COVID-19

Novel Coronavirus disease 2019 (COVID-19) represents an emergent global health burden that has challenged the health systems worldwide. Since its sudden upsurge in 2019, many COVID-19 patients have exhibited neurological symptoms and complications. Till now, there is no known effective established drug against the highly contagious COVID-19 infection despite the frightening associated mortality rate. This article aims to present the mechanism of action of coronavirus-2 (SARS-CoV-2), the clinical neurological manifestations displayed by COVID-19 patients, and present polyphenols with neuroprotective ability that can offer beneficial effects against COVID-19-mediated neuropathology. Reports from COVID-19 clinical studies, case reports, and other related literature were evaluated for this review. Neurological complications of COVID-19 include anosmia, acute cerebrovascular disease, acute disseminated post-infectious encephalomyelitis, encephalitis, etc. Also, SARS-CoV-2 sould be a neurotropic vіruѕ due to its iѕolatіon from serebroѕrіnal fluіd. Multіrle neurologіsal damages displayed by COVID-19 patients might be due to hyperinflammation associated with SARS-CoV-2 infections. Resveratrol, kolaviron, quercetin and apigenin are polyphenols with proven anti-inflammatory and therapeutic properties that can extenuate the adverse effects of COVID-19. These polyphenols have been documented to suppress c-Jun N-terminal kinase (JNK), phosphoinositide-3-kinase (PI3-K), extrasellularѕіgnal-regulated kinase (ERK), nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-kB) and mіtogen-astіvated protein kіnaѕe (MAPK) pathways which are essential in the pathogenesis of COVID-19. They also showed significant inhibitory activities against SARS-CoV-2 proteins. Taken together, these polyphenols may offer neuroprotective benefits against COVID-19 mediated neuropathology via modulation of the pathogenic pathways.

Methanol extracts of Fagara zanthoxyloides leaves possess antimalarial effects and normalizes haematological and biochemical status of Plasmodium berghei-passaged mice

Context: The resistance of Plasmodium species to many available antimalarials calls for a continuous search for newer antimalarial agents. One possible source of new antimalarials is from natural sources such as Fagara zanthoxyloides Lam (Rutaceae), a medicinal plant used traditionally for treating malaria in South-Eastern Nigeria, Uganda and Asia. Objectives: To investigate the application of methanol extracts of F. zanthoxyloides in combating malaria infection and its associated disorders. Materials and methods: Methanol extracts of F. zanthoxyloides leaves (MEFZ) were evaluated for in vivo antimalarial activity. MEFZ at doses of 200, 400, and 600 mg/kg/d were administered orally for 4 consecutive days (days 0-4) to P. berghei-infected mice. The possible ameliorative effects of MEFZ on malaria-associated organ malfunctions were also assessed. Results: At 200, 400 and 600 mg/kg b.w., respectively, MEFZ produced 82.37% and 68.39%, 84.84%, and 90.75%, 95.95% and 92.67% chemosuppression and inhibition of P. berghei, respectively, comparable to 98.67% and 97.29% by combisunate, a standard antimalarial. The IC₅₀ of MEFZ was estimated to be 235.23 mg/kg b.w. Similarly, treatment of parasitized mice with MEFZ significantly restored the malaria-modified haematological and biochemical status of the parasitized-MEFZ-treated mice compared with parasitized-untreated mice. MEFZ was tolerable up to 5000 mg/kg b.w dose; hence, the LD₅₀ is above 5000 mg/kg b.w. Discussion and conclusions: The results of this curative assay demonstrated that MEFZ has antimalarial effects and normalized haematological and biochemical aberrations generated by malaria. The isolation of the antimalarial principles in MEFZ is warranted; they could be lead molecules for the development of new antimalarials.

Termiglaucescin, a new polyhydroxy triterpene glucoside from Terminalia glaucescens with antioxidant and anti-inflammatory potential

Termiglaucescin (1), a new triterpene glucoside, has been isolated from the ethyl acetate extract of the root bark of Terminalia glaucescens Planch. ex Benth, together with 11 known compounds, β-D-glucopyranosyl 2α,3β,6β-trihydroxy-23-galloylolean-12-en-28-oate (2), arjunglucoside I (3), sericoside (4), arjungenin (5), sericic acid (6), arjunetin (7), chebuloside II (8), 3,3',4-tri-O-methylelagic acid (9), 3,3'-di-O-methylelagic acid (10), β-sitosterol (11) and stigmasterol (12). Compounds 2, 3, 7, 8 and 9 are reported from the plant for the first time. The structures of the isolated compounds were characterized by spectroscopic data interpretations, especially 1D and 2D NMR. The triterpenic isolates showed potent antioxidant and anti-inflammatory activities.

Strategies for Oral Health Research in Africa and the Middle Eastern Region

The highest burden of diseases worldwide is in low- and middle-income countries, but due to lack of capacity and inadequate infrastructure, research output from these countries is unable to address existing and emerging challenges in health care. Oral health research has particularly been hampered by low prioritization, resulting in insufficient development of this sector. There is an urgent need for research correlating oral health to upstream social and environmental determinants and promoting the common risk factor approach for prevention of noncommunicable diseases. Population-wide preventive measures for oral health care are more effective than purely curative approaches, especially for vulnerable groups who have limited access to information and appropriate health care. This article identifies priorities and proposes strategies for researchers, stakeholders, and policy makers for the initiation and sustenance of appropriate oral health care research. The proposed interventions are intended to promote collaboration, capacity building, and health advocacy. Local ownership in multinational research projects in low- and middle-income countries, complemented by skills transfer from high-income countries, is encouraged to ensure that regional health needs are addressed. Emphasis is placed on a shift toward translational research that has a direct impact on oral health care systems.

Antimicrobial activity of Nigerian medicinal plants

Antimicrobial resistance (AMR) is currently one of the major threats facing mankind. The emergence and rapid spread of multi- and pan-drug-resistant organisms (such as vancomycin-, methicillin-, extended-spectrum β-lactam-, carbapenem- and colistin-resistant organisms) has put the world in a dilemma. The health and economic burden associated with AMR on a global scale are dreadful. Available antimicrobials have been misused and are almost ineffective with some of these drugs associated with dangerous side effects in some individuals. Development of new, effective, and safe antimicrobials is one of the ways by which AMR burden can be reduced. The rate at which microorganisms develop AMR mechanisms outpaces the rate at which new antimicrobials are being developed. Medicinal plants are potential sources of new antimicrobial molecules. There is renewed interest in antimicrobial activities of phytochemicals. Nigeria boasts of a huge heritage of medicinal plants and there is avalanche of researches that have been undertaken to screen antimicrobial activities of these plants. Scientific compilation of these studies could provide useful information on the antimicrobial properties of the plants. This information can be useful in the development of new antimicrobial drugs. This paper reviews antimicrobial researches that have been undertaken on Nigerian medicinal plants.

The genus Anogeissus: A review on ethnopharmacology, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Anogeissus (axlewood tree, ghatti tree, button tree and chewing stick tree) belongs to Combretaceae, includes eight species that are distributed in Asia and Africa. Plants are used as an ethnomedicine in Asia and Africa to treat various ailments like diabetes, fever, diarrhoea, dysentery, tuberculosis, wound healing, skin diseases (eczema, psoriasis), snake and scorpion venom. Based on the traditional knowledge, different phytochemical and pharmacological activities have been at the focus of research. The aim of this review is to provide updated, comprehensive and categorized information on the ethnobotany, phytochemistry, pharmacological research and toxicity of Anogeissus species in order to identify their therapeutic potential and directs future research opportunities.

MATERIALS AND METHODS

The relevant data was searched by using the keyword "Anogeissus" in "Scopus", "Google Scholar", "Web of Science", "PubMed", and "ScienceDirect" databases. Plant taxonomy was validated by the databases "The Plant List" and A.J. Scott, 1979.

RESULTS

This review discusses the current knowledge of the ethnobotany, phytochemistry and in vitro as well as in vivo pharmacological evaluations carried out on the extracts and isolated main active constituents of Anogeissus genus. Among eight species, most of the phytochemical and pharmacological studies were performed on four species. About 55 secondary metabolites are isolated from the genus. Stem bark, leaf, seed, fruit, root of the plants are used for the treatment of several health disorders such as diabetes, fever, diarrhoea, dysentery, tuberculosis, wound healing, skin diseases (eczema, psoriasis), snake and scorpion venom. Gum ghatti obtained from Anogeissus latifolia is used after delivery as tonic and in spermatorrhoea. Many phytochemical investigations on this genus confirmed that it is rich in phenolic compounds. Modern pharmacology research has confirmed that the crude extracts or the isolated active compounds of the genus Anogeissus possess antioxidant, antimicrobial, wound healing, antiulcer, anti-inflammation, anti-diabetics, hepatoprotective, hypolipidemic, antiparasitic and neuroprotective effects.

CONCLUSIONS

This review confirms that some Anogeissus species have emerged as a good source of the traditional medicine for wound healing, inflammation, skin diseases, microbial infection and diabetes. Many traditional uses of Anogeissus species have now been validated by modern pharmacology research. Intensive investigations of all the species of Anogeissus regarding phytochemical and pharmacological properties, especially their mechanism of action, safety and efficacy could be the future research interests before starting clinical trials.

Chemical Diversity and Antimicrobial Activity of Volatile Compounds from Zanthoxylum zanthoxyloides Lam. according to Compound Classes, Plant Organs and Senegalese Sample Locations

The chemical diversity of Zanthoxylum zanthoxyloides growing wild in Senegal was studied according to volatile compound classes, plant organs and sample locations. The composition of fruit essential oil was investigated using an original targeted approach based on the combination of gas chromatography (GC) and liquid chromatography (LC) both coupled with mass spectrometry (MS). The volatile composition of Z. zanthoxyloides fruits exhibited relative high amounts of hydrocarbon monoterpenes (24.3 - 55.8%) and non-terpenic oxygenated compounds (34.5 - 63.1%). The main components were (E)-β-ocimene (12.1 - 39%), octyl acetate (11.6 - 21.8%) and decanol (9.7 - 15.4%). The GC and GC/MS profiling of fruit essential oils showed a chemical variability according to geographical locations of plant material. The LC/MS/MS analysis of fruit oils allowed the detection of seven coumarins in trace content. The chemical composition of fruit essential oils was compared with volatile fractions of leaves and barks (root and trunk) from the same plant station. Hexadecanoic acid, germacrene D and decanal were identified as the major constituents of leaves whereas the barks (root and trunk) were dominated by pellitorine (85.8% and 57%, respectively), an atypic linear compound with amide group. The fruit essential oil exhibited interesting antimicrobial activities against Staphylococcus aureus and Candida albicans, particularly the alcohol fraction of the oil.

Safety evaluation of Bon-santé cleanser® polyherbal in male Wistar rats

BACKGROUND

The potential harm of medicinal herbs has been recently observed following herbal toxicity studies after ingestion of polyherbal remedies. This was the rationale for the food and drug regulatory agency decision for thorough safety evaluation of herbal medicines. Androgenic, antipyretic, analgesic and anti-inflammatory potentials as well as chemical compositions of extracts of massularia acuminata, terminalia ivorensis, anogeissus leiocarpus and macuna pruriens respectively have been documented. Thus, Bon-santé cleanser® (BSC) is formulated from these medicinal plants with the intention to boost body hormones and energizes the body. Considering the wide usage of BSC, we investigated on its safety in male Wistar rats.

METHODS

Thirty-two male Wistar rats weighing 201.9 ± 7.5 g were grouped into four treatment groups of eight per group. Group I, (control) received distilled water (10 ml/kg). Groups II-IV received 250 mg/kg, 500 mg/kg and 1000 mg/kg of BSC per oral respectively. Each group was treated for sixty days.

RESULTS

Acute toxicity test, in male Wistar albino mice, showed that LD50 was 600 mg/kg via i.p. while 4 g/kg was nonlethal after oral administration in mice. Hepatic and renal biomarker enzymes were unaltered in all rats. Increased in PCV (p <0.05) was observed at 500 mg/kg. BSC modulates antioxidants biomarkers following sub-chronic administration and increased serum Na(+) (p >0.05). BSC at 1000 mg/kg caused mild inflammation of the liver and heart but not kidneys histologically.

CONCLUSIONS

BSC has been found to be relatively safe in Wistar rats. Although, our findings indicate that herbal therapy with BSC should be done with caution as a mild alteration in the liver and heart architectures were observed.

Nauclea latifolia: biological activity and alkaloid phytochemistry of a West African tree

Covering up to 2016Nauclea latifolia (syn. Sarcocephalus latifolius, Rubiaceae), commonly called the African pincushion tree, is a plant widely used in folk medicine in different regions of Africa for treating a variety of illnesses, including malaria, epilepsy and pain. N. latifolia has not only drawn the interest of traditional healers but also of phytochemists, who have identified a range of bioactive indole alkaloids in its tissue. More recently, following up on the traditional use of extracts in pain management, a bio-guided purification from the roots of the tree led to the identification of the active ingredient as tramadol, available as a synthetic analgesic since the 1970s. The discovery of this compound as a natural phytochemical was highlighted worldwide. This review focuses on the correlation between extracted compounds and pharmacological activities, paying special attention to infectious diseases and neurologically-related disorders. A critical analysis of the data reported so far on the natural origin of tramadol and its proposed biosynthesis is also presented.

Some Nigerian anti-tuberculosis ethnomedicines: a preliminary efficacy assessment

ETHNOPHARMACOLOGICAL SIGNIFICANCE

Nigerian herbalists possess indigenous ethnomedicinal recipes for the management of tuberculosis and related ailments. A collaborative preliminary modern scientific evaluation of the efficacy of some Nigerian ethnomedicines used by traditional medicine practitioners (TMPs) in the management of tuberculosis and related ailments has been carried out.

MATERIALS AND METHODS

Ethnomedicinal recipes (ETMs) were collected from TMPs from locations in various ecological zones of Nigeria under a collaborative understanding. The aqueous methanolic extracts of the ETMs were screened against Mycobacterium bovis, BCG and Mycobacterium tuberculosis strain H37Rv using the broth microdilution method.

RESULTS

Extracts of ETMs screened against BCG showed 69% activity against the organism. The activities varied from weak, ≤2500 µg/mL to highly active, 33 µg/mL 64% of the extracts were active against Mycobacterium tuberculosis The activities of the extracts against Mycobacterium tuberculosis varied from weak, ≤2500 µg/mL to highly active, 128 µg/mL. There was 77% agreement in results obtained using BCG or Mycobacterium tuberculosis as test organisms.

CONCLUSION

The results show clear evidence for the efficacy of the majority of indigenous Nigerian herbal recipes in the ethnomedicinal management of tuberculosis and related ailments. BCG may be effectively used, to a great extent, as the organism for screening for potential anti-Mycobacterium tuberculosis agents. A set of prioritization criteria for the selection of plants for initial further studies for the purpose of antituberculosis drug discovery research is proposed.

A new bioactive thiophenolic glycoside from the leaf of Massularia acuminata (g. Don Bullock) ex Hoyle (Rubiaceae)

BACKGROUND

Massularia acuminata is a small tree or shrub of tropical rainforest. The leaves are used in Nigerian ethno-medicine for the treatment of microbial infections and pharmacological report suggested the leaf extract as possessing antioxidant activity. This study was therefore carried out to determine the most antioxidant and antimicrobial active fraction(s) of Massularia acuminata leaf and the constituent(s) responsible for the activities.

MATHERIALS AND METHODS

The leaf of Massularia acuminata was investigated for in vitro antioxidant and antimicrobial activities, using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and agar dilution method respectively.

RESULTS

The ethyl acetate fraction demonstrated the best activities among the partitioned fractions tested. Bioassay guided purification of the most active ethyl acetate fraction led to isolation of a new thiophenolic glycoside, characterized as 4-(3',3'-dihydroxy-1-mercaptopropyl)phenyl glycosylpyranoside.

CONCLUSION

The isolated compound from the leaf of Massularia acuminata demonstrated antioxidant and antimicrobial activities and may be responsible for the activities of leaf extract and its ethyl acetate fraction, hence this may justify its ethnomedicinal use.

Isolation and characterization of an antibacterial biflavonoid from an African chewing stick Garcinia kola Heckel (Clusiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The use of African chewing sticks in maintaining oral health is widely practiced in African countries. It has been reported that chewing stick users have a lower rate of dental caries and a better general oral health than non-users. It is generally thought that the beneficial effect of chewing stick is attributed to the mechanical cleansing effect and antimicrobial substances present in the stick. However, the active antimicrobial substances remain uncharacterized.

AIM OF THE STUDY

To provide a scientific basis for the anti-caries effect of African chewing sticks, the authors purify an active antibacterial compound from Garcinia kola Heckel, a Nigerian chewing stick and examined the antibacterial activity of this compound against the cariogenic bacterium Streptococcus mutans.

MATERIALS AND METHODS

Methanol extract was prepared from Garcinia kola and was further fractionated by solvent extractions. Silica gel chromatography was used to purify the antibacterial compound from the active fraction. The identity of the purified compound was determined by NMR analysis. The antibacterial activity of the purified compound was examined by standard microbiological assays.

RESULTS

The antibacterial activity was found in the ether fraction and the active compound was isolated and determined to be a biflavonoid named GB1. GB1 was active against Streptococcus mutans and other oral bacteria with minimum inhibitory concentration (MIC) values of 32-64μg/ml. The basis for the antibacterial effect of GB1 was investigated using Streptococcus mutans as the target. At 256μg/ml, GB1 exhibited some bacteriocidal activity against Streptococcus mutans and induced the aggregation of Streptococcus mutans. GB1 has no apparent effects on protein synthesis and DNA synthesis but inhibited glucose uptake and utilization by Streptococcus mutans suggesting that GB1 exerts its antibacterial effect by inhibiting metabolism. GB1 also inhibited the formation of water-insoluble glucan by the extracellular glucosyltransferases from Streptococcus mutans in a dose-dependent manner. Streptococcus mutans did not develop resistance to GB1 upon subculturing in the presence of sub-MIC level of the biflavonoid.

CONCLUSION

The antibacterial effect and glucan synthesis-inhibition property of this biflavonoid may account for some of the beneficial effects reported in the chewing stick users.

A review of the medicinal potentials of plants of the genus Vernonia (Asteraceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The Vernonia genus has about one thousand species and members of the genus are widely used as food and medicine. The aim of this review is to analyze published data on the ethnomedicinal, ethnoveterinary and zoopharmacognostic uses of plants of the Vernonia genus. This will help to identify the state of ethnopharmacological knowledge in regard to this genus and to propose future research priorities.

MATERIALS AND METHODS

The major scientific databases including SciFinder, Sciencedirect, Medline and Google Scholar were queried for information on Vernonia genus using various keyword combinations. The International Plant Name Index was also used to verify the names of species and authors.

RESULTS

A total of 109 Vernonia species were reported in the literature to have medicinal properties. One hundred and five (105) plants were linked to the treatment or management of 44 human diseases or health conditions. Plants of the genus also feature in ethnoveterinary and zoopharmacognostic practices. A total of 12 vernonia species were identified to be used in ethnoveterinary medicine while 2 species are used in self medication practices by chimpanzees and gorillas. In vitro and in vivo research studies reporting the validation of the medicinal properties of some species were also reviewed. One hundred and three bioactive compounds isolated from various Vernonia species were also identified. Vernonia amygdalina was identified as the most frequently used member of the Vernonia genus. The Vernolides, a class of sesquiterpene lactone were identified as the most studied compounds from the genus and show interesting bioactivity in antiplasmodial, antileishmanial, antischistosomial, cytotoxicity, antimicrobial and anti-inflammatory assays.

CONCLUSION

On the basis of results from a combination of in vitro and in vivo efficacy and toxicity studies reported, Vernonia amygdalina holds the most promise for development into a nutraceutical against diabetes and malaria while Vernonia cinerea has potential against cancer and inflammatory conditions. Vernolide A is so far the most promising single agent from a Vernonia species that has potential for development into an anticancer agent. The other Vernonia species and isolated compounds require further studies to ascertain their medicinal potentials.

Obtaining raw material: plants as tool sources for Nigerian chimpanzees

We investigated the acquisition of plant materials from which Nigerian chimpanzees manufacture wooden tools to harvest insects and honey from nests of army ants, honey bees and stingless bees. Slender trunks of juvenile trees and branches are most commonly used, and bendable vines rarely, probably reflecting the need to work with relatively sturdy tools to extract resources. While several tools are sometimes sourced from the same plant, there is also evidence for a depletion effect, as multiple tool sources at the same site are often spaced several metres apart. Identified tool sources belong to 27 species of at least 13 families. Honey-gathering implements are often chewed upon by chimpanzees. Interestingly, twigs of the most commonly used honey-gathering species possess antibacterial propensities and are favoured by Nigerians as chewing sticks. This suggests that extractive tools might possess associated medicinal or stimulatory properties. We do not know if chimpanzees actively select specific plant parts or species as we cannot compare observed with expected frequencies. Nevertheless, about three quarters of tools are picked from plants more than 6 m away from the extraction site, potentially indicating some degree of forward planning.

Reflections on cultural diversity in oral health promotion and prevention

Dental caries is an extremely debilitating disease with lifelong consequences. In most developed countries significant oral health inequalities exist in disadvantaged communities, including refugee and migrant populations. Addressing these inequalities is becoming increasingly challenging as communities become more culturally diverse. An awareness of traditional oral health practices would enable the dental and broader health professions, to understand these differences and consequently better meet the needs of disadvantaged communities. The use of miswak is a common traditional oral hygiene practice used by a number of culturally diverse groups. Further research is required into the use and effectiveness of traditional oral health practices within developed countries. Such practices need to be understood, respected and incorporated within oral health care, policies and practices in order to reduce significant inequalities experienced in our communities. This commentary describes the current literature on miswak, its effectiveness and the implications for promoting oral health.

In vitro anti-listerial activities of crude n-hexane and aqueous extracts of Garcinia kola (heckel) seeds

We assessed the anti-Listerial activities of crude n-hexane and aqueous extracts of Garcinia kola seeds against a panel of 42 Listeria isolates previously isolated from wastewater effluents in the Eastern Cape Province of South Africa and belonging to Listeria monocytogenes, Listeria grayi and Listeria ivanovii species. The n-hexane fraction was active against 45% of the test bacteria with zones of inhibition ranging between 8-17 mm, while the aqueous fraction was active against 29% with zones of inhibition ranging between 8-11 mm. The minimum inhibitory concentrations (MIC) were within the ranges of 0.079-0.625 mg/mL for the n-hexane extract and 10 to >10 mg/mL for the aqueous extract. The rate of kill experiment carried out for the n-hexane extract only, revealed complete elimination of the initial bacterial population for L. grayi (LAL 15) at 3× and 4× MIC after 90 and 60 min; L. monocytogenes (LAL 8) at 3× and 4× MIC after 60 and 15 min; L. ivanovii (LEL 18) at 3× and 4× MIC after 120 and 15 min; L. ivanovii (LEL 30) at 2, 3 and 4× MIC values after 105, 90 and 15 min exposure time respectively. The rate of kill activities were time- and concentration-dependant and the extract proved to be bactericidal as it achieved a more than 3log(10) decrease in viable cell counts after 2 h exposure time for all of the four test organisms at 3× and 4× MIC values. The results therefore show the potential presence of anti-Listerial compounds in Garcinia kola seeds that can be exploited in effective anti-Listerial chemotherapy.

Antioxidative and chemopreventive properties of Vernonia amygdalina and Garcinia biflavonoid

Recently, considerable attention has been focused on dietary and medicinal phytochemicals that inhibit, reverse or retard diseases caused by oxidative and inflammatory processes. Vernonia amygdalina is a perennial herb belonging to the Asteraceae family. Extracts of the plant have been used in various folk medicines as remedies against helminthic, protozoal and bacterial infections with scientific support for these claims. Phytochemicals such as saponins and alkaloids, terpenes, steroids, coumarins, flavonoids, phenolic acids, lignans, xanthones, anthraquinones, edotides and sesquiterpenes have been extracted and isolated from Vernonia amygdalina. These compounds elicit various biological effects including cancer chemoprevention. Garcinia kola (Guttiferae) seed, known as "bitter kola", plays an important role in African ethnomedicine and traditional hospitality. It is used locally to treat illnesses like colds, bronchitis, bacterial and viral infections and liver diseases. A number of useful phytochemicals have been isolated from the seed and the most prominent of them is the Garcinia bioflavonoids mixture called kolaviron. It has well-defined structure and an array of biological activities including antioxidant, antidiabetic, antigenotoxic and hepatoprotective properties. The chemopreventive properties of Vernonia amygdalina and Garcinia biflavonoids have been attributed to their abilities to scavenge free radicals, induce detoxification, inhibit stress response proteins and interfere with DNA binding activities of some transcription factors.

In-vitro antagonistic characteristics of crude aqueous and methanolic extracts of Garcinia kola (Heckel) seeds against some Vibrio bacteria

The methanolic and aqueous extracts of Garcinia kola seeds were screened for their anti-Vibrio activities against 50 Vibrio isolates obtained from wastewater final effluents in the Eastern Cape Province, South Africa. The crude extracts at 10 mg/mL exhibited appreciable inhibitory activities against most of the test Vibrio isolates, with zones of inhibition ranging from 10-19 mm for methanol extract and 8-15 mm for the aqueous extracts. The minimum inhibitory concentrations (MIC) of the methanol extract varied from 0.313 to 2.5 mg/mL while that for the aqueous extract was 10 mg/mL for all the susceptible Vibrio isolates. Rate of kill assay of the methanolic extracts against three selected Vibrio species showed bacteriostatic activities against all of them achieving 58% and 60% (Vibrio vulnificus AL042); 68% and 69% (Vibrio parahaemolyticus AL049); and 70% and 78% (Vibrio fluvialis AL040) killing of the test bacteria at 3× and 4 ×MIC values, respectively, after 2 h exposure time. We conclude that Garcinia kola seeds hold promise as a potential source of therapeutic compounds of relevance in Vibrio infections management.

Pentacyclic triterpenoids and ceramide mediate the vasorelaxant activity of Vitex cienkowskii via involvement of NO/cGMP pathway in isolated rat aortic rings

ETHNOPHARMACOLOGICAL RELEVANCE

Vitex cienkowskii Kotschy & Peyritsch is a deciduous tree, prescribed by Cameroonian traditional healers as one of the most popular plant widely used in many disorders including cardiovascular diseases. The preliminary pharmacological studies carried out on Vitex cienkowskii showed its vasorelaxant activities on guinea-pig aortic rings.

AIM OF THE STUDY

The present work evaluated the vasorelaxant activity of extract and isolated compounds from Vitex cienkowskii.

MATERIALS AND METHODS

Rat aortic rings were used to evaluate the in vitro vascular effect of the extract. The antioxidant activity was determined by measuring the reduction of the free radical 1,1-diphenyl-1-picryl-hydrazyl (DPPH).

RESULTS

Vitex cienkowskii induced significant relaxation in a concentration- and endothelium-dependent manner (EC(50)=12.12 μg/ml, CH(2)Cl(2)-MeOH, 1:1) and did not produce a vasorelaxant effect on contraction evoked by KCl (60 mM). In order to determine its mode of action, Vitex cienkowskii-induced relaxant effect was evaluated in the presence of indomethacin (10 μM), L-NAME (100 μM), ODQ (1 μM) and SQ22356 (100 μM). Relaxation was significantly blocked by L-NAME and ODQ. These results indicate that Vitex cienkowskii-mediated relaxation is endothelium dependent, probably due to NO release, and the consequent activation of vascular smooth muscle soluble guanylate cyclase (sGC), a signal transduction enzyme that forms the second messenger cGMP. Bio-guided study of Vitex cienkowskii allowed the isolation of the known pentacyclic triterpenoids and a ceramide. It is the first report of salvin A, maslinic acid and a ceramide from Vitex cienkowskii. The activity induced by these compounds indicated that they may be partly responsible for the vasorelaxant effect of the plant extract. A dose of 40 mg/kg of CH(2)Cl(2)-MeOH (1:1) extract administered intravenously induced a decrease of mean arterial pressure but did not affect the heart rate. Moreover the plant extracts were found to be highly active in the DPPH radical scavenging assay.

CONCLUSION

Vitex cienkowskii extract possesses antioxidant property, vasorelaxing, and hypotensive effect linked to the endothelium related factors, where nitric oxide is involved.

The analgesic and antiplasmodial activities and toxicology of Vernonia amygdalina

Vernonia amygdalina possesses several bioactive compounds and is used in traditional medicines of southwestern Uganda, along with other regions. Its analgesic potential has not been investigated thus far. The present study examines the antinociceptive potential of the aqueous leaf extract (50-200 mg/kg) using three models of nociception (acetic acid-induced writhing, formalin test, and tail-flick test), antiplasmodial activity, and toxicology of the extract. The results show the extract significantly inhibits acetic acid-induced writhing and the formalin test in mice but did not give a potent effect in the tail-flick test, suggesting that the extract may have peripheral and central analgesic properties. The extract also exhibited significant antiplasmodial activity in mice against Plasmodium berghei with 73% inhibition in the group that received a dose of 200 mg/kg i.p. daily for 4 days. Toxicology results show no clinical signs of toxicity or adverse toxicological effects in the treated groups, except for a significant decrease in red blood cell count and a dose-dependent increase in serum bilirubin. These changes were within control values based on historical reference ranges at doses of 500-2,000 mg/kg/day for 14 consecutive days as compared to the control. This study supports the traditional use of V. amygdalina as an alternative therapy for malaria and the symptomatic relief of pain usually associated with malaria.

Phytochemistry and in vitro pharmacological activities of South African Vitex (Verbenaceae) species

AIM OF THE STUDY

The in vitro phytochemical and pharmacological investigation of the non-volatile extracts of five South African Vitex species (Verbenaceae); V. obovata ssp. obovata, V. obovata ssp. wilmsii, V. pooara, V. rehmannii and V. zeyheri were investigated in order to validate their traditional use to treat a wide range of ailments such as malaria, wounds, skin diseases and body pains.

MATERIAL AND METHODS

The antimicrobial activity was assessed using the minimum inhibitory concentration assay. Through bioactivity-guided fractionation, the fraction responsible for the antimicrobial activity was determined. The toxicity profile, anti-oxidant and anti-inflammatory activity was evaluated using the tetrazolium cellular viability, 2,2-diphenyl-1-picrylhydrazyl and 5-lipoxygenase assays respectively. The antimalarial activity of the extracts and isolated compound from V. rehmannii was also investigated on the chloroquine-resistant Gambian FCR-3 strain of Plasmodium falciparum using the tritiated hypoxanthine incorporation assay.

RESULTS

Mostly good antimicrobial inhibition was evident against Gram-positive bacteria (0.02-8.00 mg/ml) and lower activity against the Gram-negative bacteria and the yeast (0.50-8.00 mg/ml). The fraction responsible for antimicrobial activity of V. rehmannii was purified to give a labdane diterpene as an inseparable epimeric mixture of 12S,16S/R-dihydroxy-ent-labda-7,13-dien-15,16-olide. Cirsimaritin was also isolated and identified from V. rehmannii. All the species, apart from V. zeyheri, exhibited scavenging activity (IC50: 22.14+/-1.74 to 33.06+/-1.68 microg/ml) in the anti-oxidant assay. None of the species displayed any anti-inflammatory activity at 100 microg/ml. All the extracts and the labdane diterpene exhibited good antimalarial activity, with the labdane diterpene being the most active (IC50: 2.39+/-0.64 microg/ml). The test extracts were shown to be highly toxic, displaying safety index values ranging from 0.53 to 2.59.

CONCLUSION

Of all the pharmacological investigations, the antimalarial and antimicrobial activity exhibited greatest activity and may provide a scientific basis for the ethnomedical use of Vitex species.

Use of phytotherapy in dentistry

Over the past decade, interest in drugs derived from medicinal plants has markedly increased. This study was aimed at a literature review focusing on studies investigating herbal drugs and other natural products, as well as their therapeutic application, side effects and possible drug interactions. Few studies were found to support their rational use in dentistry. Since there is an increasing use of phytotherapeutic agents in dentistry, further studies are needed to evaluate their safety and effectiveness for clinical use.

Stimulation of gastric acid secretion and intestinal motility by Vernonia amygdalina extract

Aqueous extract of Vernonia amygdalina infused intragastrically at a dose of 10 mg/ml to rats induced a significant increase in acid output which was reduced by, ranitidine (5 mg/kg b.w.) or atropine (1.2 microMol/kg b.w.). Moreover the extract evoked a dose-dependent contraction of the guinea pig ileum at a dose range of 0.6 mg/ml to 66 mg/ml which was inhibited by atropine (2.4 x 10(-8)-2.4 x 10(-6) M).

The use of microfluorometric method for activity-guided isolation of antiplasmodial compound from plant extracts

In vitro antiplasmodial activity of methanolic extracts of 16 medicinal plants was evaluated by fluorometric assay using PicoGreen. The IC50s, as determined by parasite DNA concentration, ranged from <11 to >200 and <13 to >200 microg/ml for Plasmodium falciparum 3D7 and K1, respectively; and the most active extracts were those from Anogeissus leiocarpus and Terminalia avicennoides (<11-> or =14 microg/ml). Aqueous, butanolic, ethyl acetate, and methanolic fractions of these two extracts revealed butanolic fraction to have a relatively better activity (IC50, 10-12 microg/ml). Activity-guided chromatographic separation of the butanolic fraction on Sephadex LH-20 followed by nuclear magnetic resonance and correlation high-performance liquid chromatography revealed the presence of known hydrolysable tannins and some related compounds-castalagin, ellagic acid, flavogallonic acid, punicalagin, terchebulin, and two other fractions. The IC50s of all these compounds ranged between 8-21 microg/ml (8-40 microM) against both the strains. Toxicity assay with mouse fibroblasts showed all the extracts and isolated compounds to have IC50 > or = 1500 microg/ml, except for Momordica balsamina with <1500 microg/l. All the extracts and isolated compounds did not affect the integrity of human erythrocyte membrane at the observed IC50s. However, adverse effects manifest in a concentration-dependent fashion (from IC50 > or = 500 microg/ml).

Reduced reproductive function in wild baboons (Papio hamadryas anubis) related to natural consumption of the African black plum (Vitex doniana)

Several authors have suggested that the consumption of plant compounds may have direct effects on wild primate reproductive biology, but no studies have presented physiological evidence of such effects. Here, for two troops of olive baboons (Papio hamadryas anubis) at Gashaka-Gumti National Park, Nigeria, we show major seasonal increases in levels of fecal progesterone metabolites in females, and provide evidence that this is linked to the consumption of natural plant compounds. Increases in fecal progestogen excretion occurred seasonally in all females, in all reproductive states, including lactation. Detailed feeding data on the study animals showed that only one food species is consumed by both troops at the time of observed progestogen peaks, and at no other times of the year: the African black plum, Vitex doniana. Laboratory tests demonstrated the presence of high concentrations of progestogen-like compounds in V. doniana. Together with published findings linking the consumption of a related Vitex species (Vitex agnus castus) to increased progestogen levels in humans, our data suggest that natural consumption of V. doniana was a likely cause of the observed increases in progestogens. Levels of progestogen excretion in the study baboons during periods of V. doniana consumption are higher than those found during pregnancy, and prevent the expression of the sexual swelling, which is associated with ovulatory activity. As consortship and copulatory activity in baboons occur almost exclusively in the presence of a sexual swelling, V. doniana appears to act on cycling females as both a physiological contraceptive (simulating pregnancy in a similar way to some forms of the human contraceptive pill) and a social contraceptive (preventing sexual swelling, thus reducing association and copulation with males). The negative effects of V. doniana on reproduction may be counter-balanced by the wide-range of medicinal properties attributed to plants in this genus. This is the first time that physiological evidence has been presented of direct effects of plant consumption on the reproductive biology of wild primates.

Ethnoveterinary medicinal plants at Bale Mountains National Park, Ethiopia

An ethnobotanical study on veterinary medicinal plants of Bale Mountains National Park and adjacent areas was conducted from July 2003 to June 2004. Semi-structured interviews and observations were used to generate ethnoveterinary data from traditional healers residing in the park and buffer zones. A total of 25 animal ailments were reported, of which blackleg, Darissaa and hepatitis were the most frequently reported ailments. Seventy four veterinary medicinal plant species that were distributed among 64 genera and 37 families were recorded. The most utilized growth forms were herbs (35 species, 47.3%) followed by shrubs (28 species, 37.84%). Roots (54 species, 41.54%) followed by leaves (47 species, 36.15%) were the most frequently used plant parts for ethnoveterinary medicine. Usually, fresh materials (53 species, 43.44%) were preferred for medicine preparations. The most frequently used route of drug administration was oral (65 species, 42.76%) followed by dermal (55 species, 36.18%). Indigenous knowledge was mostly transferred to an elect of a family member in word of mouth indicating that it was prone to fragmentation or loss.

Cytotoxic Prenylated Phenolic Compounds from the Twig Bark ofGarcinia xanthochymus

Three new hydroxylated xanthones with prenyl or geranyl substituents, compounds 1-3, were isolated from the twig bark of Garcinia xanthochymus, along with the four known compounds 1,4,5,6-tetrahydroxy-7,8-diprenylxanthone (4), 1,3,5,6-tetrahydroxy-4,7,8-triprenylxanthone (5), garciniaxanthone E (6), and 6-prenylapigenin (7). Their structures were elucidated by extensive spectroscopic analysis, including 1D- and 2D-NMR as well as HR-MS experiments. All compounds showed moderate cytotoxicities against breast cancer (MDA-MB-435S) and lung adenocarcinoma (A549) cell lines, but lacked antifungal activity against Candida albicans.

PIXE analysis of some medicinal plants used in cleaning teeth in southwestern Nigeria

Sixteen medicinal plants used for cleaning teeth in southwestern Nigeria were analyzed using the particle-induced X-ray emission (PIXE) technique. These medicinal plants have other therapeutic uses, but the emphasis and main focus were on their beneficial effects on human teeth. PIXE measurements were carried out using 1.8 MeV collimated proton beam from the 2.5 MV AN 2000 Van de Graaff accelerator at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Padova Italy. The results showed the presence of 18 different elements at different concentrations, 2 plants had traces of gold, and none of the plants contained any toxic heavy metals. The metabolic roles of the detected elements were discussed especially as they affected the formation, growth, development, and protection of human teeth. The results of this study are presented and discussed.

Sesquiterpene lactones are potent and irreversible inhibitors of the antibacterial target enzyme MurA

We report the identification of the sesquiterpene lactones cnicin and cynaropicrin as potent, irreversible inhibitors of the bacterial enzyme MurA. They covalently bind to the thiol group of Cys115. Judging from the structure-activity relationships, we conclude that the unsaturated ester side chain of cynaropicrin and cnicin is of particular importance for the inhibition of MurA. These results provide evidence that MurA is a target protein of SLs with a probably high relevance for their known antibacterial effect.

Aqueous Vernomia amygdalina extracts alter MCF-7 cell membrane permeability and efflux

Breast cancer is the second leading cause of cancer related deaths of women in the United States. Several treatment strategies have been developed over the past decade to reduce cancer morbidity and mortality rates. While mortality rates have declined in some ethnic populations, the overall cancer incidence continues to grow. Hence, chemotherapeutic agents are needed to improve cancer treatment outcome. Previous studies show that low concentrations (microgram/ml) of water-soluble leaf extracts of a Nigerian edible plant, V. amygdalina (VA), potently retard the proliferative activities of estrogen receptor positive (ER+) human breast cancerous cells (MCF-7) cells in vitro in a concentration-dependent fashion. The anti-proliferative activities of VA are extracellular signal-regulated kinases (1/2) (ERKs (1/2))-dependent. Cell culture and animal model studies, conducted by other investigators using other plant extracts, have also revealed that plant extract components called thionins may be responsible for their anticancer activities. These thionins are believed to interact with the cells in ways that compromise membrane potential/permeability resulting in the alteration of efflux, cytosolic activities, and subsequent cell death. Therefore, we hypothesized that VA exposure may compromise cell membrane as another mode of action to elicit its anticancer activities in MCF-7 cells. The exposure of cells to VA decreased [3H]thymidine uptake in a concentration-dependent (0, 30, and 100 mug/ml VA) manner (p < 0.05) but increased [3H]thymidine release, expressed as percent of [3H]thymidine incorporated, into the medium (p < 0.05). The amount of [3H]thymidine released into the medium was 1.7, 7.4, and 11.0 % for 0, 30, and 100 mug/ml VA respectively. Thus suggesting the membranes in VA-treated cells were compromised in a concentration-dependent fashion.

A survey of toxic plants on the market in the district of Bamako, Mali: traditional knowledge compared with a literature search of modern pharmacology and toxicology

In Mali, the empirical knowledge on plant medicine is held by traditional practioners. Scientific studies have been carried on some plants and they have confirmed their local uses, but few data are available on the toxicity of Malian medicinal plants. In the present work, we record the toxic plants used as medicines in the Bamako district, Mali, with the aim to evaluate the knowledge of traditional healers and herbalists on the toxicity of the plant used. A survey was carried out on the market places in the Bamako district and 106 healers and herbalists were interviewed. A survey of the scientific literature was conducted to verify or sustain the claimed toxicological data. Nineteen plants are arranged according to their frequency of quotation based on the questionnaire. The information includes the botanical name, literature survey on the pharmacology of the plants, the healers' knowledge on plant toxicity and its prevention by some of the healers.

The antibacterial principle of Caesalpina sappan

Using a bioassay-directed purification scheme, the active antibacterial principle from Caesalpina sappan was isolated and identified to be brasilin. This compound showed potent activity against antibiotic-resistant bacteria, notably methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), multi-drug resistant Burkholderia cepacia as well as a number of other bacteria. The minimal inhibitory concentrations ranged from 4 to 32 microg/mL. The results from time-kill studies showed that brasilin is bactericidal against MRSA. The addition of brasilin to growing MRSA cells resulted in a rapid inhibition of incorporation of [(3)H] thymidine or [(3)H] serine into DNA and proteins, respectively. Exposure of MRSA to a sub-MIC level of brasilin for ten consecutive subcultures did not induce resistance to the compound. The Trypan blue dye exclusion test showed that brasilin lacked cytotoxicity against Vero cells. In conclusion, brasilin is an antibacterial principle from C. sappan and it has the potential to be developed into an antibiotic.

In vitro antiplasmodial activity of extracts and fractions from seven medicinal plants used in the Democratic Republic of Congo

The in vitro antiplasmodial activity of seven EtOH extracts and twenty fractions from the partition of the initial ethanolic extracts from seven African medicinal plants used in the Democratic Republic of Congo (DR Congo) for the treatment of malaria was evaluated. The most active EtOH extracts (IC50 < 3 microg/ml) were those from Cassia occidentalis leaves, Euphorbia hirta whole plant, Garcinia kola stem bark and Phyllanthus niruri whole plant. Their respective petroleum ether soluble fractions also exhibited an antiplasmodial activity with IC50 < 3 microg/ml. EtOH extracts from Vernonia amygdalina leaves (5 < IC50 < 10 microg/ml), Tetracera poggei leaves (10 < IC50 < 50 microg/ml) and Morinda morindoides leaves (50 < IC50 < 100 microg/ml) were less active, but their petroleum ether fractions exhibited a pronounced antiplasmodial activity (IC50 < 3 microg/ml). The same observation could also be made for the petroleum ether fraction from Cassia occidentalis, Euphorbia hirta, Garcinia kola and Phyllanthus niruri. Isoamyl alcohol fractions from Euphorbia hirta, Phyllanthus niruri and Vernonia amygdalina showed IC50) values less than 3 microg/ml, and from Cassia occidentalis, Garcinia kola, Morinda morindoides and Tetracera poggei between 10 and 50 microg/ml. The observed antiplasmodial activity may be related to the presence of terpenes, steroids, coumarins, flavonoids, phenolic acids, lignans, xanthones and anthraquinones.

Antiplasmodial activity of plant extracts used in west African traditional medicine

Five plants originating from Ivory Coast were selected after an ethnobotanical survey, Alchornea cordifolia, Mitragyna inermis, Nauclea diderrichii, Pterocarpus santalinoides, and Terminalia glaucescens. Traditional healers for the treatment of malaria commonly used these plants. Extracts of these plants were tested on three strains of Plasmodium falciparum, FcB1-Colombia and FcM29-Cameroon (chloroquine-resistant strains) and a Nigerian chloroquine-sensitive strain. Extracts were obtained by preparing decoction in water of the powdered plant, the technique used by most of the traditional healers. A radioactive micromethod allowed the evaluation of the in vitro activity of the extracts on P. falciparum. Concentrations inhibiting 50% of the parasite growth (IC(50)) ranged from 2.34 to more than 500 microg/ml according to the plant. For the most active plants (A. cordifolia and T. glaucescens) ethanol and pentane extracts were made and tested. The IC(50) values obtained for these extracts ranged from 0.35 to 43.40 microg/ml. The stage specificity of the ethanol extracts of A. cordifolia and T. glaucescens and pentane extract of T. glaucescens on the parasite erythrocytic cycle were determined. The ethanol extract of T. glaucescens showed its highest activity at the transition from the trophozoite to the schizont stages. Cytotoxicity was estimated on human fibroblasts (HeLa) cells and a cytotoxicity/antiplasmodial index was calculated, it ranged between 5 and 21, and the best antiplasmodial extract (T. glaucescens ethanol extract) had the higher index (>20).