Evaluation of an ethnopharmacologically selected Bhutanese medicinal plants for their major classes of phytochemicals and biological activities

Ethnopharmacological relevance

As many as 229 medicinal plants have been currently used in the Bhutanese Traditional Medicine (BTM) as a chief ingredient of polyherbal formulations and these plants have been individually indicated for treating various types of infections including malaria, tumor, and microbial. We have focused our study only on seven species of these plants.

Aim of the study

We aim to evaluate the antiplasmodial, antimicrobial, anti-Trypanosoma brucei rhodesiense and cytotoxicity activities of the seven medicinal plants of Bhutan selected using an ethno-directed bio-rational approach. This study creates a scientific basis for their use in the BTM and gives foundation for further phytochemical and biological evaluations which can result in the discovery of new drug lead compounds.

Materials and methods

A three stage process was conducted which consisted of: (1) an assessment of a pharmacopoeia and a formulary book of the BTM for their mode of plant uses; (2) selecting 25 anti-infective medicinal plants based on the five established criteria, collecting them, and screening for their major classes of phytochemicals using appropriate test protocols; and (3) finally analyzing the crude extracts of the seven medicinal plants, using the standard test protocols, for their antiplasmodial, antimicrobial, anti-Trypanosoma brucei rhodesiense and cytotoxicity activities as directed by the ethnopharmacological uses of each plant.

Results

Out of 25 medicinal plants screened for their major classes of phytochemicals, the majority contained tannins, alkaloids and flavonoids. Out of the seven plant species investigated for their biological activities, all seven of them exhibited mild antimicrobial properties, five plants gave significant in vitro antiplasmodial activities, two plants gave moderate anti-Trypanosoma brucei rhodesiense activity, and one plant showed mild cytotoxicity. Meconopsis simplicifolia showed the highest antiplasmodial activity with IC₅₀ values of 0.40 μg/ml against TM4/8.2 strain (a wild type chloroquine and antifolate sensitive strain) and 6.39 μg/ml against K1CB1 (multidrug resistant strain) strain. Significantly the extracts from this plant did not show any cytotoxicity.

Conclusions

These findings provide the scientific basis for the use of seven medicinal plants in the BTM for the treatment of malaria, microbial infections, infectious fevers, and the Trypanosoma brucei rhodesiense infection. The results also form a good preliminary basis for the prioritization of candidate plant species for further in-depth phytochemical and pharmacological investigations toward our quest to unearth lead antiparasitic, anticancer and antimicrobial compounds.     

Antioxidant, antimicrobial and cytotoxic activities of selected medicinal plants from Yemen

Ninety crude extracts, including dichloromethane, methanol and aqueous extracts from 30 medicinal plants used in the Yemeni ethnomedicine to treat common infections, were screened in vitro for antimicrobial activities against three Gram-positive bacteria and two Gram-negative bacteria, Candida maltosa and five opportunistic human fungal pathogens (two yeasts, three hyphomycetes). Most of the plants showed antibacterial activities. Extracts from Tamarindus indica flowers and Ficus vasta fruits have been the most active. Of the 30 plants tested, 13 showed antifungal activity (40%) against one ore more human pathogenic fungi. The strongest inhibition was exhibited by Azima tetracantha (fruits), Sansevieria ehrenbergii (fruits) and Solanum incanum (fruits). Ten methanol extracts, especially those of Acacia asak barks and Solanum nigrum fruits, showed effective free radical scavenging activities in the DPPH assay. Remarkable cytotoxic activity against FL-cells was shown only for five plants, among them Plicosepalus curviflorus (stems).     

In vivo antimalarial activity,toxicity and phytochemical screening of selected antimalarial plants

Ethnopharmacological relevance

Malaria continues to kill over a million people each year and in many populations affected by malaria, conventional drugs are often unaffordable or inaccessible. Historically, plants have been a prominent source of antimalarial drugs. Those plants currently used by indigenous people to treat malaria should be documented and investigated as potential sources of new antimalarial drugs.

Aim of the study

To investigate in vivo antimalarial activity, toxicity and carry out phytochemical screening of selected plants which have been used in traditional medicine for the treatment of malaria.

Materials and methods

Organic and water extracts of four medicinal plants used for the treatment of malaria in traditional health systems of Msambweni people in Kenya were tested for antimalarial activity against Plasmodium berghei and brine shrimp lethality. They were also screened for their major phytochemical constituents.

Results

Aqueous extract of the stem bark of Adansonia digitata exhibited highest chemosuppression of parasitaemia, >60% in a murine model of Plasmodium berghei infected mice. Aqueous and organic extracts of Launaea cornuta and Zanthoxylum chalybeum were toxic to the brine shrimp (LD₅₀<1000 μg/ml) while aqueous and organic extracts of Adansonia digitata and aqueous extracts of Canthium glaucum were not toxic to brine shrimp (LD₅₀>1000 μg/ml). Phytochemical screening revealed the presence of alkaloids and flavonoids in all the crude extracts of the selected plant species studied. Sesquiterpene lactones and saponis were present in organic extracts but absent in the aqueous extracts of Adansonia digitata, Canthium glaucum, Launaea cornuta and Zanthoxylum chalybeum.

Conclusion

The results showed that the crude extracts of Adansonia digitata and Canthium glaucum demonstrated promising antimalarial activity and there is potential for isolation of lead compounds from their extracts.     

Evaluation of antiplasmodial properties in 15 selected traditional medicinal plants from India

ObjectiveThe objective of this study was to evaluate the in vitro antiplasmodial properties against malaria parasite in 15 plants mentioned in Indian traditional medicine texts.MethodsIn vitro antiplasmodial activity of methanolic extracts obtained from Indian traditional medicinal plants was evaluated on Plasmodium falciparum of FCK2 and INDO strains using schizont maturation inhibition assay and parasite lactate dehydrogenase inhibition assay.ResultsMethanolic extracts of Adhatoda zeylanica, Embelia ribes, Piper nigrum and Plumbago zeylanica exhibited more than 50% inhibition in both the stains in schizont maturation inhibition assay. Methanolic extracts of seven medicinal plants exhibited antiplasmodial activity at half maximal inhibitory concentration (IC₅₀) < 100 µg/mL, and methanolic extracts of five medicinal plants exhibited antiplasmodial activity at IC₅₀ < 50 µg/mL in P. falciparum lactate dehydrogenase (PfLDH) inhibition assay. A. zeylanica, E. ribes and P. nigrum exhibited promising antiplasmodial activity in PfLDH inhibition assay. A. zeylanica and E. ribes exhibited improved activity against resistant in comparison to sensitive strain.ConclusionA. zeylanica and E. ribes were the most promising extracts from this study and deserve further investigation of their antiplasmodial properties.     

Screening of Brazilian medicinal plants for antiviral activity against rotavirus

Ethnopharmacological relevance

Brazilian medicinal plants traditionally used for the treatment of diarrhoea were investigated for their in vitro antiviral activity against the simian rotavirus SA11.

Materials and methods

The ethanolic crude extracts of plants collected in the cerrado of Minas Gerais, Brazil were submitted to phytochemical screening. The cytotoxicity of the extracts was inferred by cellular morphologic alterations. Antiviral activity was assessed by the ability of the extracts to inhibit the cytopathic effect (CPE) of rotavirus on the treated cells. RT-PCR was performed to confirm and/or confront antiviral assay data.

Results

The maximum non-toxic concentration ranged from 50 to 500 μg/mL. All extracts were toxic at a concentration of 5000 μg/mL but no extract showed cytotoxicity at 50 μg/mL. The species Byrsonima verbascifolia, Myracrodruon urundeuva, Eugenia dysenterica and Hymenaea courbaril exhibited the strongest in vitro activity against rotavirus. Their extracts prevented the formation of CPE, and RT-PCR analysis detected no amplification of genetic material from rotavirus. Tannins, flavonoids, saponins, coumarins and terpenes were the major classes of natural products found in the leaf extracts that showed antiviral activity.

Conclusion

Among the species studied, Byrsonima verbascifolia, Eugenia dysenterica, Hymenaea courbaril and Myracrodruon urundeuva showed potential activity against rotavirus and are worthy of further study. The present study corroborates ethnopharmacological data as a valuable source in the selection of plants with antiviral activity and to some extent validates their traditional uses.     

Antiplasmodial and cytotoxic activities of Rwandan medicinal plants used in the treatment of malaria

Aim of the study

In our study, methanol, dichloromethane and aqueous extracts of 13 Rwandan medicinal plants used in the treatment of malaria were tested for in vitro antiplasmodial activity.

Materials and methods

The growth inhibition of chloroquine-sensitive Plasmodium falciparum strain (3D7) was evaluated using the measurement of lactate dehydrogenase activity. The active extracts were also tested against the chloroquine-resistant Plasmodium falciparum strain (W2) and for cytotoxicity assay using human normal foetal lung fibroblasts (WI-38).

Results

The majority of the plants tested showed an antiplasmodial activity and the best results were observed with dichloromethane leaf and flower extracts of Tithonia diversifolia, leaf extract of Microglossa pyrifolia and root extract of Rumex abyssinicus, methanol leaf extract of Fuerstia africana, root bark extracts of Zanthoxylum chalybeum and methanol bark extract of Terminalia mollis. Those extracts were active (IC₅₀ < 15 μg/ml) on both chloroquine-sensitive and resistant strains of Plasmodium falciparum. Zanthoxylum chalybeum, Solanecio mannii and Terminalia mollis presented the best selectivity index.

Conclusions

The traditional use of most of the plant evaluated was confirmed by the antiplasmodial test. This study revealed for the first time the antiplasmodial activity of two plants: Terminalia mollis and Rumex abyssinicus.     

In vitro antiplasmodial activity of selected Luo and Kuria medicinal plants

Ethnopharmacological relevance

Drug resistance in malaria is a recurring subject that threatens public health globally. There is an urgent need to seek new antimalarial agents. This study seeking new antimalarials from medicinal plants is guided by ethnobotany.

Materials and methods

Medicinal plants of the Luo and Kuria ethnic groups of Kenya with high usage reports were screened in vitro for their antiplasmodial activity using the SYBR Green I fluorescence assay (MSF assay).

Results

The IC50's for drugs and total plant extracts ranged from 0.01217 to 10.679 mg/ml. Extracts were more active on chloroquine sensitive than resistant Plasmodium falciparum strains. Tylosema fassoglense, Ageratum conyzoides and Ocimum kilimandscharicum exhibited promising results. Plectranthus barbatus did not show activity.

Conclusion

Ethnobotanical knowledge was sufficiently reliable for identifying plant extracts with antiplasmodial activity.     

Nigerian antimalarial plants and their anticancer potential: A review

Cancer is a leading cause of death globally, while malaria is the leading cause of death from parasitic diseases in Nigeria. Historically, plant remedies have been used to manage both cancer and malaria. Interestingly, the possibility of treating cancer with antimalarial remedies has long been reported, even though the two diseases appear to have little in common. However, a body of research has indicated the potential anticancer activity of both synthetic and nature-derived antimalarials. In Nigeria, over 100 plants are used for the management of malaria, but little is known for their potential role in combatting cancer. Therefore, this review is to highlight the documented anticancer activities of plants used to treat malaria in Nigeria, with the goal of supporting anticancer drug discovery. Scientific databases were used to search for antimalarial plants using selected keywords. Of over 100 plants used to treat malaria in Nigeria, 56 have documented anticancer properties, containing alkaloids, flavonoids, tannins, terpenes, terpenoids, quinones, anthraquinones, saponins, steroids, sterols, organosulfur compounds and other polyphenols as the major bioactive components. The major mechanisms of anticancer activity include induction of apoptosis and autophagy, arrest of cell growth, generation of reactive oxygen species and inhibition of angiogenesis. However, mechanistic and clinical investigations of the anticancer properties of most of these plants are still lacking. Notwithstanding, the huge anticancer potential uncovered by the in vitro or in vivo studies and a few clinical studies, Nigerian antimalarial plants may provide a valuable resource, ready to be harnessed for anticancer drug development.     

Antimycobacterial evaluation and preliminary phytochemical investigation of selected medicinal plants traditionally used in Mozambique

Ethnopharmacological relevance

Several medicinal plants are traditionally used in Mozambique to treat tuberculosis and related symptoms.

Aims of the study

It was aimed to assess the in vitro antimycobacterial activity of crude extracts from fifteen medicinal plants and to reveal main classes of compounds which may account for the activity of extracts.

Methods and materials

The plant materials were sequentially extracted by n-hexane, dichloromethane, ethyl acetate, and 70% ethanol. Decoction of each plant material was also prepared according to traditional use. Broth microdilution method was employed to screen extracts against two mycobacterial species: Mycobacterium smegmatis ATCC 607 and Mycobacterium tuberculosis H37Rv. The extracts with minimum inhibitory concentration(s) (MIC) below 125 μg/mL were considered active and further tested against different mycobacterial species and strains, namely Mycobacterium tuberculosis H37Ra, Mycobacterium bovis BCG ATCC 35734, Mycobacterium smegmatis mc² 155, Mycobacterium avium DSM 44156 and DSM 44157. Cytotoxic effect was evaluated against human macrophages from the monocytic THP-1 cells. Main classes of compounds in these active extracts were proposed from their ¹H NMR spectroscopic characterizations.

Results

n-Hexane extracts of Maerua edulis and Securidaca longepedunculata, ethyl acetate extract of Tabernaemontana elegans and dichloromethane extract of Zanthoxylum capense were found to possess considerable activity against Mycobacterium bovis BCG and Mycobacterium tuberculosis H37Ra with MIC 15.6-62.5 μg/mL. Tabernaemontana elegans ethyl acetate extract displayed strong activity against Mycobacterium tuberculosis H37Rv (MIC 15.6 μg/mL). Except for Tabernaemontana elegans ethyl acetate extract which presented potent cytotoxic effects in THP-1 cells (IC₅₀ < 4 μg/mL), the other three plant extracts showed moderate to none toxicity. Based on ¹H NMR spectroscopic analysis, major components in both Maerua edulis and Securidaca longepedunculata n-hexane extracts were linear chain unsaturated fatty acids. Zanthoxylum capense dichloromethane extract contained more complex constituents (mostly phenolic compounds). In the most potent extract, Tabernaemontana elegans ethyl acetate extract, the prominent compounds were identified as indole alkaloids.

Conclusions

The pronounced antimycobacterial activity of the medicinal plants Maerua edulis, Securidaca longepedunculata, Zanthoxylum capense, and Tabernaemontana elegans suggested that they might provide compounds which could be potential anti-TB drug leads.     

Antiprotozoal and cytotoxic screening of 45 plant extracts from Democratic Republic of Congo

AIM OF THE STUDY: To evaluate in vitro the antiprotozoal and cytotoxic activities of 80% methanol extract from 45 medicinal plants collected in Sankuru (Democratic Republic of Congo) against Trypanosoma brucei brucei, Trypanosoma cruzi and the chloroquine-sensitive Ghanaian strain of Plasmodium falciparum, and MRC-5 cell lines respectively. MATERIAL AND METHODS: Different extracts were obtained by maceration of each plant part used with 80% methanol for 24h. The mixture was filtered and evaporated in vacuo to give corresponding dried extract. The activity against Trypanosoma brucei brucei and Trypanosoma cruzi were performed in 96 well tissue plates each containing 10 microl aqueous plant extract dilutions (100 to 0.01 microg/ml) with 10 microl of the parasite suspension cultured in Hirumi medium supplemented with 10% foetal calf serum, a solution of 2% penicillin/streptomycin (2% P/S) After 4 days incubation with Almar bluea solution, fluorescence was measured at 500 nm emission and 530 nm excitation and results expressed as percentage reduction in parasite compared to control wells. The antiplasmodial activity of was assessed in vitro against the chloroquine-sensitive Ghanaian strain of Plasmodium falciparum cultured in RPMI-1640 medium by the lactate deshydrogenase assay in the presence of plant extracts (50 to 0.01 microg/ml). Cell-lines MRC-5 were cultured in MEM medium supplemented with 20mM l-glutamine, 16.5mM NaHCO(3), 5% foetal calf serum and 2% P/S solution. After 4h incubation, cell proliferation/viability was spectrophotomecally assessed at 540 nm after addition of MTT. In each assay, the IC50 value for each sample was derived by the drug concentration-response curves. RESULTS: The extracts from Alcornea cordifolia leaves, Momordica charantia whole plant, Omphalocarpum glomerata, root bark and Piptadia africanum stem bark showed good antiprotozoal activity against Trypanosoma brucei brucei with IC50 values from 0.7 to 7 microg/ml. Only Piptadenia africanum extract showed a pronounced antiprotozoal activity against Trypanosoma cruzi (IC50=4.0+/-06 microg/ml). The extracts from Alchornea cordifolia, Polyathia swaveleons stem bark, Sapium cornutum stem bark and Triclisia giletii stem bark exhibited a pronounced antiplasmodial activity against P. falciparum Ghanaian strain with IC50 values ranging from 0.5 to 3.0 microg/ml. Piptadenia africanum extract was the most cytotoxic sample (CC50=0.25 microg/ml) with poor selectivity against all selected protozoa (SI<10) while other active extracts did not show a significant cytotoxic effect against MCR-5 cell-lines with good selectivity according to the case. CONCLUSION: These active plant extracts are selected for extensive studies leading to the isolation of active constituents.     

Ethnopharmacological survey of medicinal plants in Nor-Yauyos, a part of the Landscape Reserve Nor-Yauyos-Cochas, Peru

Aim of the study

To collect, analyze and evaluate the ethnopharmacologic knowledge in Nor-Yauyos in order to protect it. This paper reports the results of an ethnopharmacological survey on the uses of medicinal plants by inhabitants of the Andean region Nor-Yauyos, Peru. In this region one surviving ethnic group, the Jaqaru-Quichuas, has been identified.

Methodology

Field work was concluded between October 1999 and March 2000, using semi-structured questionnaire and participant observation as well as transects walks in wild herbal plant collection. Interviews with 68 informants (mean age: 54; 100% men, 0% women) were performed in 12 farmers’ communities: Huancaya, Vilca, Vitis, Miraflores, Piños, Carania, San Lorenzo De Alis, Santa Rosa De Tinco, Tomás, Huancachi, Laraos and Huantán.

Results

63 species of plants belonging to 29 families were reported. More than a half of reported plants were native, endemic of the studied area. Leaves and their mixtures were the most (67.26%) commonly used plant part. Most of the remedies were prepared in infusion, and 90.08% were administered orally. Most treated disorders were the gastrointestinal (18.59%) and respiratory ones (18.22%).

Conclusions

6 species (9.52%) without pharmacological references in international scientific literature, 21 species (33.33%) with 1-2 references, 16 species (25.40%) with 3-6 references, and 20 species (31.75%) that have been already widely studied were found.     

Ethnopharmacological application of medicinal plants to cure skin diseases and in folk cosmetics among the tribal communities of North-West Frontier Province,Pakistan

Aim of the study

The present investigation is an attempt to find out ethnopharmacological application of medicinal plants to cure skin diseases and in folk cosmetics.

Method

We interviewed respondents in 30 remote sites of North-West Frontier Province by a structured interview form in the local language and respondents were queried for the type of herbal cure known to him.

Results

A total of 66 plant species belonging to 45 families have been recorded. Seventy-five medications for 15 skin diseases and cosmetics were documented. The mode of application was topical as well as oral administration. Water, milk, ghee, oil, eggs, sulphur and butter are used during administration of herbal remedies. About 15 plant species are known for their use to cure multiple skin diseases. Among these Berberis lyceum, Bergenia ciliata, Melia azedarach, Otostegia limbata, Phyla nodiflora, Prunus persica and Zingiber officinale constitutes major plants. The herbal cosmetics products range from face freshness, removal of ugly spots, hair care, and colouring of palm, feet, gums, and teeth.

Conclusion

Most of the reported species are wild and rare; this demands an urgent attention to conserve such vital resources so as to optimize their use in the primary health care system. Since most of the skin diseases are caused by bacteria, viruses and fungi in this context, phytochemical screening for active constituents, biological activities and clinical studies is of global importance.     

Ethnopharmacological survey of medicinal plants used by traditional healers in Bangladesh for gastrointestinal disorders

Ethnopharmacological relevance

Gastrointestinal diseases are common worldwide, including Bangladesh where majority of the rural people depend on water from unprotected sources. The people from Bangladesh use medicinal plants as their first line of health care to cure and prevent different types of gastrointestinal disorders.

Aim of the study

To compile plants used for the treatment of different gastrointestinal disorders in Bangladesh.

Materials and methods

The field survey was carried out in a period of 18 months. Fieldwork was undertaken in total of eleven districts of Bangladesh. Open-ended and semi structured questionnaire were used to interview a total of 1280 people including traditional healers, Ayurvedic/Unani drug manufacturers and local people.

Results

A total of 250 plant species of 93 families were listed. Leaves were the most cited plant part used against gastrointestinal disorders. Most of the reported species were tree in nature and decoction is the mode of preparation of major portions of the plant species. Most of the plant species were very common and were cultivated or planted in homestead or roadsides. The doses of the plants for different treatments varied widely.

Conclusion

In view of the fact that the plants were selected based on their medicinal usage for treating different kinds of gastrointestinal diseases including diarrhoea, the activities reported here need more works for validation and could be rationalised by the presence of active compounds found in those plants. The documentation represents the preliminary information in need of future phytochemical investigation and is important for the conservation of these plants.     

In vitro cytotoxic, antileishmanial and antifungal activities of ethnopharmacologically selected Gabonese plants

Seventy-seven crude extracts from leaves and stem barks of 15 Gabonese plants used in traditional medicine were evaluated for their cytotoxic, antileishmanial and antifungal activities. Most of the extracts exhibited cytotoxic activities toward human monocytes, and most particularly the hydromethanolic 50% (v/v) fraction of Ganophyllum giganteum leaves (IC(50)=1.3 microg/ml) as well as the methanolic extracts of Polyalthia suaveolens, Dioscorea preussii, Augouardia letestui leaves and Cola lizae stem barks (IC(50)<5 microg/ml). The methanolic extract of Polyalthia suaveolens displayed a strong antiproliferative activity against the promastigote form of Leishmania infantum parasites and presented a good antifungal activity on all the tested strains (IC(50)<1mg/ml). This extract was divided into six fractions: fraction F6 demonstrated a cytotoxic activity stronger than those of the crude extract (IC(50)=0.6 microg/ml), fractions F4 and F5 were devoid of cytotoxicity (IC(50)>100 microg/ml) and displayed interesting antileishmanial activity against the intracellular amastigote form of the parasite (IC(50)=5.6 and 12.4 microg/ml), respectively. However, the antifungal activity observed for the crude extract could not be recovered in the corresponding fractions.     

In vitro antiprotozoal activities and cytotoxicity of some selected Cameroonian medicinal plants

Eight extracts from seven selected Cameroonian medicinal plants, traditionally used to treat malaria and other protozoal diseases, were tested in vitro for their antiprotozoal activities against Plasmodium falciparum K1 chloroquine-resistant strain, Leishmania donovani, Trypanosoma cruzi and Trypanosoma brucei rhodesiense, protozoa responsible for malaria, visceral leishmaniasis, Chagas disease and African trypanosomiasis, respectively. The most active extract against Plasmodium falciparum K1 strain and Trypanosoma brucei rhodesiense was the methanolic extract of Albizia zygia (Fabaceae) stem bark with IC(50) values of 1.0 microg/ml and 0.2 microg/ml, respectively. Five extracts showed IC(50) values below 5mug/ml against Leishmania donovani, with the methanolic seed extract of Harungana madagascarensis showing the highest activity, but only the methanolic extract of Albizia zygia showed activity against Trypanosoma cruzi. Cytotoxicity and selectivity indexes were estimated for the most active extracts. The best ratio of cytotoxicity to antiplasmodial activity (SI(a)=14) was established for the methanolic leaf extract of Symphonia globulifera (Clusiaceae), while the methanolic stem bark extract of Albizia zygia showed the best ratio of cytotoxicity to antitrypanosomal activity (SI(b)=22.5).     

In vitro anti-Helicobacter pylori activity of extracts of selected medicinal plants from North West Cameroon

ETHNOPHARMACOLOGICAL RELEVANCE: Helicobacter pylori, a gram negative microaerophilic bacterium is a major etiological agent in duodenal, peptic and gastric ulcers. The growing problem of antibiotic resistance by the organism demands the search for novel compounds from plant based sources. AIM OF STUDY: The present study is aimed at evaluating the antimicrobial activity of some selected medicinal plants on clinical isolates of H. pylori circulating in Cameroon in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs. MATERIALS AND METHODS: Gastric biopsy samples were obtained from patients presenting with gastroduodenal complications. H. pylori was isolated from the specimens following standard microbiology procedures. The disk diffusion method was used to determine the susceptibility of 15 isolates to ten methanol plant extracts (Ageratum conyzoides, Scleria striatinux, Lycopodium cernua, Acanthus montanus, Eryngium foetidium, Aulutandria kamerunensis, Tapeinachilus ananassae, Euphorbia hirta, Emilia coccinea and Scleria verrucosa). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for the most active plant extracts were also determined by the agar dilution method. Results were analyzed statistically by the Fisher's exact test. RESULTS: All the plants tested demonstrated antimicrobial activity with zone diameters of inhibition ranging from 0-30mm. Of these, A. conyzoides, S. striatinux and L. cernua showed very potent antibacterial activity on the isolates. The lowest MIC and MBC recorded were 0.032mg/mL and 0.098mg/mL respectively. However, the MIC of the extracts ranged from 0.032-1.0mg/mL for S. striatinux; 0.063-0.5mg/mL for L. cernua and 0.063-1.0mg/mL for A. conyzoides. The MBC of the extracts ranged from 0.098-15.0mg/mL for S. striatinux; 0.098-12.5mg/mL for A. conyzoides, and 0.195-12.5mg/mL for L. cernua. The extracts had a wide spectrum of activity. The three most potent extracts possessed significant (P<0.05) inhibitory activities. CONCLUSION: The plant extracts may contain compounds with therapeutic activity.     

Ethnopharmacological survey of Annonaceae medicinal plants used to treat malaria in four areas of Cameroon

Ethnopharmacological relevance

Malaria endemic countries have vital resources that are medicinal plants on which their traditional medicines depend. In some Cameroonian settings, in addition to the commonly used potions from plants like Alstonia boonei, Zanthoxylum macrophylla and Mangifera indica, other herbal species are being increasingly used to treat malaria. So, specialized traditional healers have developed alternative reasonably priced therapies, relying on the signs and/or symptoms of malaria. Within this framework, Annonaceae plants were found to be increasingly utilized and therefore, highlighting the need to document this traditional knowledge for better malaria control.

Materials and methods

Interview approach was used to document indigenous knowledge, usage customs and practices of Annonaceae species in the treatment of malaria in four Cameroonian areas (Yaoundé and its surroundings, Ngoyang, Kon-Yambetta and Mbalmayo).

Results

A total of 19/30 users of plants accepted to share their experiences during a semi-structured survey. Twelve of the respondents were men and seven were women. Thirty recipes based on twenty-one plants were recorded.

Conclusion

Annickia chlorantha was the only plant commonly found in the four study sites. Seven species of Annonaceae were found to be used to treat malaria, while 14 were used to treat symptoms that might be related to malaria.     

Mutagenic and antimutagenic properties of extracts from South African traditional medicinal plants

Aim of the study

The aim of this paper was to summarize the results of our investigations on the in vitro genotoxic as well as antigenotoxic effects of a great number of selected South African traditional medicinal plants.

Materials and methods

Investigations of methanol and dichloromethane extracts of selected plants were conducted with the bacterial Ames, Umu-C and VITOTOX^® tests, and with the cytochalasin B micronucleus test and alkaline comet assay in human white blood cells.

Results

A number of extracts were found to have genotoxic properties. Amongst the genotoxic plant extracts, especially methanol extracts of Helichrysum simillimum DC. (Asteraceae) should be highlighted. On the other hand, some plant extracts also showed antimutagenic potential. Here Bauhinia galpinii N.E.Br. (Fabaceae) and especially Chlerodendrum myricoides (Hochst.) Vatke (=Rotheca myricoides (Hochst.) Steane &; Mabb.; Lamiaceae) appear to have antimutagenic properties.

Conclusion

The safe use of Helichrysum similimum should be questioned and further investigations on its mutagenicity and overall biological properties should be encouraged. Antimutagenic properties of especially Bauhinia galpinii and Rotheca myricoides are considered of particular interest as it may be assumed that these antimutagenic natural substances are able to lower the cancer risk from everyday exposures to environmental mutagens as well as to mutagenic pharmaceuticals.     

Antituberculosis potential of some ethnobotanically selected Malaysian plants

Aim of the study

Many local plants are used in Malaysian traditional medicine to treat respiratory diseases including symptoms of tuberculosis. The aim of the study was to screen 78 plant extracts from 70 Malaysian plant species used in traditional medicine to treat respiratory diseases including symptoms of tuberculosis for activity against Mycobacterium tuberculosis H37Rv using a colorimetric microplate-based assay.

Materials and methods

Plant extracts were prepared by maceration in methanol (80%) and antituberculosis screening was carried out using Tetrazolium bromide microplate assay (TEMA) method to determine the minimum inhibitory concentration (MIC).

Results

Thirty-eight plant extracts from 36 plant species exhibited antituberculosis activity with MICs in the range of 1600-400 μg/ml. The leaf extract of Angiopteris evecta exhibited the highest activity with MIC of 400 μg/ml. Five other extracts, namely, Costus speciosus (stem and flower), Piper sarmentosum (whole plant), Pluchea indica (leaf), Pluchea indica (flower), and Tabernaemontana coronaria (leaf) exhibited antituberculosis activity, each with MIC of 800 μg/ml. To the best of our knowledge, this is the first report of in vitro high throughput screening of Malaysian medicinal plants for antituberculosis activity.

Conclusions

Antituberculosis activity of extracts of some plants justifies, to a certain extent their ethnomedicinal uses as remedies for symptoms of tuberculosis. These results also support the general view that, selecting the plants based on ethnobotanical criteria would enhance the probability of finding species with antituberculosis activity.     

Antimicrobial activity of South African medicinal plants

This paper reviews the antimicrobial research undertaken on South African medicinal plants during the period 1997-2008. Antimicrobial methods (disc diffusion, minimum inhibitory concentration (MIC), bio-autography) are briefly discussed and an analysis of the publications reviewed indicates that the majority of papers use MIC assays for antimicrobial determination. Antimicrobial investigations on extracts are presented where the most active plants are identified from screening publications. A summary of some bioactive compounds are given with data restricted to papers reporting quantitative antimicrobial activity equivalent to or below 200 microg/ml. Antimicrobial activities on the essential oils of indigenous medicinal aromatic plants are also reviewed. An overview is given on what activities (extracts, compounds and oils) should be considered noteworthy for publication. Studies focusing on geographical ethnobotany, specific pathogenesis, formulation aspects and in vivo investigations are examined. Future recommendations to consider include pathogen selection, interactive studies and dosage administrations.