Antiprotozoal activities of traditional medicinal plants from the Garhwal region of North West Himalaya, India

Ethnopharmacological relevance

In a search for new plant-derived biologically active compounds against protozoan parasites, an ethnopharmacological study was carried out to evaluate extracts from selected 17 traditional medicinal plants which were used by healers from the Garhwal region of North West Himalaya for the treatment of protozoal infections and fever including malaria.

Materials and methods

In vitro activity against erythrocytic stages of Plasmodium falciparum was determined using a modified [3H]-hypoxanthine incorporation assay with the chloroquine- and pyrimethamine-resistant K1 strain. Activity against Trypanosoma brucei rhodesiense was performed on the STIB 900 strain and activity against Trypanosoma cruzi on infected rat skeletal myoblasts (L6 cells) seeded in 96-well microtitre plates while amastigotes of Leishmania donovani strain MHOM/ET/67/L82 were used to assess activity against Leishmania donovani. Cytotoxicity assays were performed against rat skeletal myoblasts (L6-cells).

Results and conclusions

Extracts of Artemisia roxburghiana, Roylea cinerea, Leucas cephalotes, Nepeta hindostana and Viola canescens showed good antiplasmodial activity (IC50 < 5 μg/ml). The chloroform extract of Artemisia roxburghiana was the most active (IC50 value of 0.42 μg/ml) and the most selective (SI = 78) extract for Plasmodium falciparum among all plants extracts examined. The chloroform extract of Leucas cephalotes and the petroleum ether extract of Viola canescens exhibited substantial activities against Leishmania donovani with IC50 values of 3.61 μg/ml (SI = 8) and 0.40 μg/ml (SI = 30), respectively. The petroleum ether extract of Viola canescens exhibited activity against Trypanosoma cruzi with an IC50 value of 1.86 μg/ml (SI = 7). Methanol and water extracts from all plants under investigation were found inactive against all parasites tested. These results support investigation of components of traditional medicines as potential new antiprotozoal agents. On the other hand since herbalism has become the main stream throughout the world, investigation demonstrates that these non-polar plant extracts of six of the plants examined in this study could play an important role in herbal formulations for the treatment of vector borne protozoal diseases.     

Antiprotozoal activity of Khaya anthotheca, (Welv.) C.D.C. a plant used by chimpanzees for self-medication

Ethnopharmacological relevance

Khaya species, endemic to Africa and Madagascar, continues to be valuable in indigenous traditional medicine. Their bitter tasting barks are decocted to treat fevers, several febrile conditions, microbial infections and worm infestations. In the Budongo rain forest of Western Uganda, non-human primates, especially chimpanzees and baboons, have been observed to eat the bitter non-nutritious bark and occasionally the seed.

Materials and methods

Extracts were prepared by sequential fractionation with solvents of increasing polarities and assayed using standard procedures. Bioassay guided purification of the petroleum ether extract by column chromatography yielded three pure limonoids, Grandifolione (1), 7-deacetylkhivorin (2) and 1,3-deacetyldeoxyhavenensin (3). The antitrypanosomal, antileishmanial and antiplasmodial activities of pure compounds (1) and (2) were evaluated in vitro against Plasmodium falciparum K1, Trypanosoma brucei rhodesiense STIB 900, Trypanosoma cruzi trypomastigotes (Tulahuen C4), and axenic Leishmania donovani MHOMET-67/L82 and for cytotoxicity against L6 rat skeletal myoblast cells, in parallel with standard drugs.

Results

Of the four extracts tested, the petroleum ether extract showed activity against Plasmodium falciparum (IC₅₀ 0.955 μg/ml) and Trypanosoma brucei rhodesiense (IC₅₀ 5.72 μg/ml). The pure compounds (1) and (2) demonstrated activity against Plasmodium falciparum (KI strain) and marginal activities against Trypanosoma brucei brucei, Trypanosoma brucei rhodesiense, Trypanosoma cruzi and Leishmania donovani.

Conclusion

The present study provides evidence justifying the use of Khaya preparations in traditional medicine to treat fevers and microbial infections. The observed antiprotozoal activity of grandifolione and 7-deacetylkhivorin from the seed of Khaya anthotheca further confirms the ethnomedicinal potential of this plant and supports the hypothesis that non-human hominids (chimpanzees and baboons) too, eat the bitter bark and seeds for self-medication and in general, the use of Khaya plant material for medication by humans in disease endemic tropical areas. The antiprotozoal activity of gradifolione, and, the antitrypanosomal and antileishmanial activities of 7-deacetylkhivorin are reported here for the first time.     

Antiplasmodial and cytotoxic activities of medicinal plants traditionally used in the village of Kiohima, Uganda

Aim of the study

In Uganda, malaria is the most common disease and Ugandan people largely rely on traditional medicine. In this context, we carried out an ethnobotanical study on the Kiohima village, located close to the Kibale National Park in South-Western Uganda and investigated in vitro the antiplasmodial and cytotoxic activities of selected medicinal plants.

Materials and methods

Seventy-five plants-using adults (men and women) were interviewed to find out their plant use. From these information, 48 plants used in traditional medicine were identified and according to their reported uses and to bibliographic data, several parts of 28 plants (leaves, barks, roots), were selected and collected for biological evaluations. These samples were dried, extracted with ethyl acetate and the crude extracts were assayed for in vitro antiplasmodial and cytotoxic activities at 10 μg/mL.

Results

One third of the screened plants showed a significant antiplasmodial activity with inhibition greater than 50% at 10 μg/mL.

Conclusion

These results may indicate a possible explanation of the use of some medicinal plant against malaria in the village of Kiohima and have also allowed to highlight a plant with potent antimalarial activity: Citropsis articulata root barks.     

Encecalol angelate, an unstable chromene from Ageratum conyzoides L.: total synthesis and investigation of its antiprotozoal activity

Ethnopharmacological relevance

In agreement with ethnomedicinal reports, the dichloromethane extract of Ageratum conyzoides L. (Asteraceae) was recently shown to be of considerable activity against Trypanosoma brucei rhodesiense, the etiologic agent of East African Human Trypanosomiasis (East African Sleeping Sickness). Isolated compounds, namely, methoxylated flavonoids as well as the chromene derivative encecalol methyl ether, were less active than the crude extract. The activity of the extract was found to decrease considerably while stored in solution. An unstable compound was detected in the fresh extract by HPLC, which was converted rapidly into the encecalol methyl ether while stored in methanolic solution. This compound, deemed to represent a constituent with antitrypanosomal activity, could not be isolated from the extract in intact form.

Aim of the study

To elucidate the structure of this unstable compound and to investigate its potential role in the antitrypanosomal activity of the total extract.

Materials and Methods

UHPLC/ESI-qQTOF MSMS and NMR data of the degraded product indicated its chemical identity as encecalol angelate (1) which was therefore prepared by total synthesis via a linear six steps synthesis, starting from resorcinol and 2-methylbut-3-en-2-ol.

Results

Total synthesis, in an overall yield of 15%, led to pure 1, which was chromatographically and spectroscopically identical with the natural product. The compound degraded in methanol with a half-life of approximately 6 h to yield encecalol methyl ether (2). The antiprotozoal activity of synthetic encecalol angelate against T. brucei rhodesiense as well as T. cruzi, Leishmania donovani and Plasmodium falciparum was investigated and found to be quite low.

Conclusions

The synthetic approach applied here for the first time also provides access to the related bioactive chromenes encecalin (7) and encecalol (8) with improved yields compared with reported methods. Encecalol angelate, however, is most likely not responsible for the high antitrypanosomal activity of the freshly prepared dichloromethane extract of A. conyzoides.     

Ethnomedicinal study of plants used by Sheko ethnic group of Ethiopia

Aim of the study

This study was conducted to document and evaluate knowledge on medicinal plant use by Sheko ethnic group in Southwest Ethiopia.

Materials and methods

Interviews and ranking exercises were the main methods employed to collect the ethnobotanical data. Fidelity level (FL) values were calculated for claimed Sheko medicinal plants to estimate their healing potentials.

Results

Seventy-one Sheko medicinal plants were reported, the majority of which were used to treat skin and gastro-intestinal ailments. Ocimum lamiifolium, Phytolacca dodecandra, Amaranthus dubius and Amaranthus graecizans were the medicinal plants assigned with the highest FL values, a possible indication of their better healing potential. The majority of Sheko medicinal plants were found to be herbs, and leaf was the most preferred plant part in remedy preparations. The study indicated that men, older people and illiterate ones had better knowledge of medicinal plants use as compared to women, younger people and literate ones, respectively.

Conclusions

The study showed that the Sheko people have rich knowledge of medicinal plant use. This knowledge is however, currently threatened mainly due to acculturation. Awareness should thus be created among Sheko community by concerned bodies regarding the usefulness of their medical practice. The efficacy and safety of the claimed medicinal plants need to be evaluated before recommending them for a wider use with priority given to those with high fidelity level values.     

Plants used by native Amazonian groups from the Nanay River (Peru) for the treatment of malaria

Aim of the study

In order to evaluate the antimalarial potential of traditional remedies used in Peru, Indigenous and Mestizo populations from the river Nanay in Loreto were interviewed about traditional medication for the treatment of malaria.

Materials and methods

The survey took place on six villages and led to the collection of 59 plants. 35 hydro-alcoholic extractions were performed on the 21 most cited plants. The extracts were then tested for antiplasmodial activity in vitro on Plasmodium falciparum chloroquine resistant strain (FCR-3), and ferriprotoporphyrin inhibition test was also performed in order to assume pharmacological properties.

Results

Extracts from 9 plants on twenty-one tested (Abuta rufescens, Ayapana lanceolata, Capsiandra angustifolia, Citrus limon, Citrus paradise, Minquartia guianensis, Potalia resinífera, Scoparia dulcis, and Physalis angulata) displayed an interesting antiplasmodial activity (IC₅₀ < 10 μg/ml) and 16 remedies were active on the ferriprotoporphyrin inhibition test.

Conclusions

The results give scientific validation to the traditional medical knowledge of the Amerindian and Mestizo populations from Loreto and exhibit a source of potentially active plants.     

Inhibition of TNF-α production in LPS-activated THP-1 monocytic cells by the crude extracts of seven Bhutanese medicinal plants

Ethnopharmacological relevance

Seven studied medicinal plants; Aconitum laciniatum, Ajania nubigena, Codonopsis bhutanica, Corydalis crispa, Corydalis dubia, Meconopsis simplicifolia and Pleurospermum amabile, are currently used in the Bhutanese Traditional Medicine (BTM) for the management of different types of disorders including the diseases that bore relevance to various inflammatory conditions.

Aims of the study

This study aimed to evaluate the inhibition of TNF-α production in LPS-activated THP-1 monocytic cells by the crude extracts of seven selected Bhutanese medicinal plants. It is expected to; (a) generate a scientific basis for their use in the BTM and (b) form a basis for prioritization of the seven plants for further phytochemical and anti-inflammatory studies.

Materials and methods

Seven plants were selected using an ethno-directed bio-rational approach and their crude extracts were prepared using four different solvents (methanol, hexane, dichloromethane and chloroform). The TNF-α inhibitory activity of these extracts was determined by cytokine-specific sandwich quantitative enzyme-linked immunosorbent assays (ELISAs). The results were quantified statistically and the statistical significance were evaluated by GraphPad Prism version 5.01 using Student's t-test with one-tailed distribution. A p-value ≤0.05 was considered statistically significant.

Results

Of the seven plants studied, the crude extracts of six of them inhibited the production of pro-inflammatory cytokine, TNF-α in LPS-activated THP-1 monocytic cells. Amongst the six plants, Corydalis crispa gave the best inhibitory activity followed by Pleurospermum amabile, Ajania nubigena, Corydalis dubia, Meconopsis simplicifolia and Codonopsis bhutanica. Of the 13 extracts that exhibited statistically significant TNF-α inhibitory activity (p<0.05; p<0.01), five of them showed very strong inhibition when compared to the DMSO control and RPMI media.

Conclusions

Six medicinal plants studied here showed promising TNF-α inhibitory activity. These findings rationalize the traditional use of these selected medicinal plants in the BTM as an individual plant or in combination with other ingredients for the treatment of disorders bearing relevance to the inflammatory conditions. The results forms a good preliminary basis for the prioritization of candidate plant species for an in-depth phytochemical study and anti-inflammatory activity screening of the pure compounds contained within those seven plants.     

Assessment of anti-protozoal activity of plants traditionally used in Ecuador in the treatment of leishmaniasis

Aim of the Study

For the assessment of the in vitro anti-protozoal potential of plants traditionally used in Ecuador in the treatment of leishmaniasis, a combined approach based on interviews with healers as well as a literature search was carried out.

Materials and Methods

From three regions of Ecuador, 256 local healers called “Agents of Traditional Medicine” (ATMs) were interviewed about their knowledge of the use of plants to treat and heal the illness recognized by the ATMs as leishmaniasis. From literature sources, 14 plants were identified as being used in the treatment of leishmaniasis. Subsequently, plant material was collected from a representative selection of 39 species. A total of 140 extracts were screened in vitro against Leishmania donovani, Plasmodium falciparum, Trypanosoma brucei rhodesiense and Trypanosoma cruzi. Additionally, these extracts were evaluated for their anti-microbial activities using five gram-positive and -negative bacteria as well as Candida albicans.

Results and Conclusions

The survey resulted in 431 use-records for 145 plant-taxa used for the treatment of leishmaniasis. The 10 most frequently reported taxa accounted for 37.7% of all records. In the case of leishmaniasis, activity was observed for Elephantopus mollis, Minquartia guianensis, Bocconia integrifolia, Gouania lupuloides, Scoparia dulcis, an as-yet-unidentified species of Piper and Brugmansia. For the leaves of M. guianensis and the twigs and bark of G. lupuloides a good selectivity index (SI) was found. IC₅₀ values and the SI of active plant extracts are presented.     

Traditional herbal antimalarial therapy in Kilifi district, Kenya

Aim of study

To identify plant species used by the traditional health practitioners (THPs) in treatment of malaria, carry out cytotoxicity and efficacy evaluation of the identified plants and to evaluate combination effects.

Materials and methods

Thirteen plants were selected through interviews with traditional healers. In vitro antiplasmodial testing was done by measuring ability of the test sample to inhibit the incorporation of radio-labelled hypoxanthine into the malaria parasite. The extracts were tested singly and then in combination using the standard fixed ratio analysis to evaluate synergism. In vivo bioassay was done in mice using Peter's 4-days suppressive test and cytotoxicity evaluated in vitro using Vero E6 cells.

Results

Of the plants tested in vitro, 25% were highly active (IC₅₀ < 10 μg/ml), 46% moderately active (IC₅₀ 10-50 μg/ml), 16% had weak activity of 50-100 μg/ml while 13% were not active IC₅₀ >100 μg/ml. Methanolic extracts of Azadirachta indica, Premna chrysoclada and Uvaria acuminata were the most active (IC₅₀ < 10 μg/ml) against both the chloroquine (CQ) sensitive (D6) and the CQ resistant (W2) Plasmodium falciparum clones. When tested in vivo in a mouse model, Azadirachta indica, Rhus natalensis and Grewia plagiophylla depicted the highest percent parasite clearance and chemo suppression of 89%, 82% and 78%, respectively. Evaluating effect of combining some of these extracts with one another against a multi-drug resistant Plasmodium falciparum (W2) clone revealed synergism among some combinations. The highest synergy was between Uvaria acuminata and Premna chrysoclada. The interaction between Grewia plagiophylla and Combretum illairii was largely antagonistic. Impressive cytotoxicity results were obtained with most of the plants tested revealing high selectivity indices an indication of enabling achievement of therapeutic doses at safe concentrations. Uvaria acuminata was, however, toxic to the cultured cells. Mild cytotoxicity was also observed in Hoslundia opposita and Lannea schweinfurthii (CC₅₀ 37 and 76 μg/ml, respectively).

Conclusions

This study identified plants with low IC₅₀ values, high percent chemo suppression and low cytotoxicity thus potential sources for novel antiplasmodial agents. The findings remotely justify use of combined medicinal plants in traditional medicine practices as synergy among some plant species was demonstrated.     

Anti-ulcer polysaccharides from Cola cordifolia bark and leaves

Ethnopharmacological relevance

The study documented medicinal plants that are traditionally used for treatment of malaria in Shinile District, eastern Ethiopia, and evaluated selected medicinal plants for their antiplasmodial activities against Plasmodium berghei.

Materials and methods

The study was conducted in four kebeles of Shinile District, Somali Region, Ethiopia. A total of 15 traditional healers were sampled based on recommendations of local elders and administrators. Specimens of the reported antimalarial plants were collected and stored at the Mini Herbarium of the Aklilu Lemma Institute of Pathobiology, Addis Ababa University, following identification. Crude aqueous and ethanol extracts of Aloe sp., Azadirachta indica and Tamarindus indica were tested in vivo against Plasmodium berghei. The three plants were selected based on the frequency antimalarial use report by healers.

Results

The study revealed 27 antimalarial plants, the majority of which were harvested from the wild. Root was the most frequently sought plant part. Most of the remedies were used in decoction form. Aloe sp., Azadirachta indica and Tamarindus indica were the most commonly reported plants for their antimalarial use. For the in vivo test, all the plant extracts were given to mice orally. Ethanol and aqueous leaf extracts of Aloe sp. caused 73.94% and 58.10% parasitaemia suppression, respectively at dose of 650 mg/kg. Ethanol extract of Azadirachta indica leaves induced 54.79% parasitaemia suppression at the dose of 650 mg/kg and its water extract induced 21.47% parasite suppression at a similar dose. Water extract of the fruits of Tamarindus indica showed the highest parasitaemia suppression (81.09%) at the dose of 650 mg/kg. Most Plasmodium berghei infected mice treated with high dose of plant extracts survived relatively longer compared to their respective controls although the difference was not significant.

Conclusions

The result of this study may support the traditional use of Aloe sp., Azadirachta indica and Tamarindus indica in the study area against malaria. Results of this study can be used as a basis for further phytochemical and pharmacological investigations in the effort for search of new and locally affordable antimalarial agents.     

Identification of medicinal plants used as Tibetan Traditional Medicine Jie-Ji

Aim of the study

Based on the authors’ collection of specimens used as Jie-Ji in local Tibetan areas, China, and taxonomic determination, this paper aims to give a list of medicinal plants as Jie-Ji, formally identify the ones recognized as Jie-Ji Ga-Bao or Jie-Ji Na-Bao and to offer basic data for further studies on these Tibetan herbs.

Materials and methods

Local herbalists were visited in Tibetan areas, China to observe which plants were being used as Jie-Ji. Samples of the indigenous plants were collected at the same time. Also, the medicinal plants as Jie-Ji were taxonomically identified.

Results

A list of medicinal plants including 10 species of Jie-Ji in local Tibetan areas is given, including their morphological pictures used for identification.

Conclusions

The origin of Jie-Ji is from 10 species of the Section Cruciata, Genus Gentiana (Gentianaceae). five species with dark blue flowers are used as Jie-Ji Na-Bao, the other five with white flowers are used as Jie-Ji Ga-Bao. Also, Gentiana macrophylla Pall. with dark blue flowers in the Section Cruciata, Genus Gentiana is not the original plant of Jie-Ji Na-Bao. The species endemic to the province are used as the original plants of Jie-Ji only in local Tibetan area of the province. Finally, the drug use of Jie-Ji in Traditional Tibetan Medicine is reasonable and it is efficacious.     

Bactericidal activity of medicinal plants,employed for the treatment of gastrointestinal ailments,against Helicobacter pylori

Aim of the study

Helicobacter pylori infection plays a crucial role in the pathogenesis of peptic ulcer, and gastric cancer. The current PPI-based triple regimens for the eradication of Helicobacter pylori faces uprising resistance problem demanding for the search of novel candidates. Medicinal plants have always been a source of lead compounds for drug discovery.In the present study, we evaluated the anti-Helicobacter pylori activity of 50 commonly used Unani (traditional) medicine plants from Pakistan that are extensively utilized for the cure of gastrointestinal disorders to explore the natural source for pilot compounds against Helicobacter pylori.

Materials and methods

Total seven clinical isolates and one standard strain were employed to examine the bactericidal effects of medicinal plants. Helicobacter pylori was isolated from the antral biopsy specimens and confirmed through the standard microbiology procedures. Minimum bactericidal concentration (MBC) of the active plants was determined at the concentration range from 7.8 to 500 μg/ml.

Results

Among the herbs evaluated, more than 50% inhibited the growth of eight strains at the concentration of 500 μg/ml. The 70% aqueous-ethanol extracts of Curcuma amada Roxb., Mallotus phillipinesis (Lam) Muell., Myrisctica fragrans Houtt., and Psoralea corylifolia L. demonstrated strong anti-Helicobacter pylori activity with MBC value ranged from 15.6 to 62.5 μg/ml. The most potent bactericidal activity was exhibited by Mallotus phillipinesis (Lam) Muell. which completely killed the bacteria at the concentration of 15.6–31.2 μg/ml.

Conclusion

The results revealed significant anti-Helicobacter pylori activity of medicinal plants which could be the potential source of new bactericidal agents.     

Potent antiplasmodial extracts from Cameroonian Annonaceae

Aim of the study

In a search for new antimalarial leads, we have carried out a preliminary ethnopharmacological study with the aim of evaluating the in vitro antiplasmodial activity of extracts from thirteen Annonaceae species growing in Cameroon, and of assessing the acute toxicity of promising fractions in Swiss albino mice.

Materials and methods

Plants were selected on the basis of an ethnobotanical survey carried out in four sites in centre and south regions of Cameroon (Yaoundé neighbourhoods, Kon-Yambetta, Ngobayang and Mbalmayo) on Annonaceae plants locally used to treat malaria and related symptoms. The choice of the sites was mainly based on environmental factors enabling mosquito breeding, cosmopolitan areas regrouping people from different cultural origins, areas with limited access to health centers, and areas with people relying exclusively on traditional medical practices. Collected materials were extracted by maceration in 95% ethanol. The crude extract was partitioned using organic solvents and the fractions afforded were evaluated for antiplasmodial activity in culture against the W2 strain of Plasmodium falciparum. Promising fractions (methanol fractions) were assessed for their acute toxicity in Swiss albino mice.

Results

From the results achieved, 37 (31.3%) out of 118 extracts tested exhibited antiplasmodial activity, with IC₅₀ values ranging from 1.07 μg/ml to 9.03 μg/ml. Of the active extracts, 29 (78.4%) were methanol fractions, 21 (72.4%) of which inhibited the parasites with IC₅₀ < 5 μg/ml. The promising fractions proved to be safe through oral administration in mice.

Conclusions

The activities and toxicity profiles of methanol fractions indicate that they deserve to be further investigated in detail for antimalarial lead discovery.     

HPLC-based activity profiling for antiplasmodial compounds in the traditional Indonesian medicinal plant Carica papaya L

Ethnopharmacological relevance

Leaf decoctions of Carica papaya have been traditionally used in some parts of Indonesia to treat and prevent malaria. Leaf extracts and fraction have been previously shown to possess antiplasmodial activity in vitro and in vivo.

Materials and methods

Antiplasmodial activity of extracts was confirmed and the active fractions in the extract were identified by HPLC-based activity profiling, a gradient HPLC fractionation of a single injection of the extract, followed by offline bioassay of the obtained microfractions. For preparative isolation of compounds, an alkaloidal fraction was obtained via adsorption on cationic ion exchange resin. Active compounds were purified by HPLC–MS and MPLC–ELSD. Structures were established by HR-ESI-MS and NMR spectroscopy. For compounds 5 and 7 absolute configuration was confirmed by comparison of experimental and calculated electronic circular dichroism (ECD) spectroscopy data, and by X-ray crystallography. Compounds were tested for bioactivity in vitro against four parasites (Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum), and in the Plasmodium berghei mouse model.

Results

Profiling indicated flavonoids and alkaloids in the active time windows. A total of nine compounds were isolated. Four were known flavonols – manghaslin, clitorin, rutin, and nicotiflorin. Five compounds isolated from the alkaloidal fraction were piperidine alkaloids. Compounds 5 and 6 were inactive carpamic acid and methyl carpamate, while three alkaloids 7–9 showed high antiplasmodial activity and low cytotoxicity. When tested in the Plasmodium berghei mouse model, carpaine (7) did not increase the survival time of animals.

Conclusions

The antiplasmodial activity of papaya leaves could be linked to alkaloids. Among these, carpaine was highly active and selective in vitro. The high in vitro activity could not be substantiated with the in vivo murine model. Further investigations are needed to clarify the divergence between our negative in vivo results for carpaine, and previous reports of in vivo activity with papaya leaf extracts.     

In vitro antiplasmodial activity of indole alkaloids from the stem bark of Geissospermum vellosii

Ethnopharmacological relevance

The stem bark of Geissospermum vellosii has been traditionally used by the native population of northern South America to treat malaria. Indole alkaloids have been previously isolated from this plant, but the antiplasmodial constituents have not yet been described. As part of our ongoing investigations of new bioactive compounds with activity against malaria parasites, we tested the in vitro antiplasmodial activity of isolated fractions and purified alkaloids from Geissospermum vellosii.

Materials and methods

Indole alkaloids were isolated and identified from a methanolic crude extract of Geissospermum vellosii bark using a combination of high performance counter current chromatography, mass spectrometry and nuclear magnetic resonance technologies. The methanolic extract, the crude alkaloid fractions and the purified compounds were tested for in vitro antiplasmodial activity against the chloroquine-sensitive strain of Plasmodium falciparum (D10).

Results

An indole alkaloid (4) along with four known indole alkaloids, geissolosimine (1), geissospermine (2), geissoschizoline (3), and vellosiminol (5) were isolated and structure elucidated. The antiplasmodial activity (IC₅₀) of the methanolic crude extract was 2.22 μg/mL, while for the isolated compounds it ranged from 0.96 μM to 13.96 μM except for (5) which showed a low activity (157 μM). Geissolosimine (1) showed the highest antiplasmodial activity (0.96 μM).

Conclusions

This study provides evidence to support the use of Geissospermum vellosii as an antimalarial agent, as used by the native populations. Geissolosimine (1) is a lead molecular structure for possible antimalarial drug development.     

In vitro antiplasmodial activity and cytotoxicity of nine plants traditionally used in Gabon

Aim of the study

As part of a project to identify new compounds active on malarial parasites, we tested the in vitro antiplasmodial activity of nine plants traditionally used to treat malaria symptoms in Haut-Ogooué Province, South-East Gabon.

Materials and methods

Dichloromethane and methanolic extracts of each plant were tested for their antiplasmodial activity on two chloroquine-resistant strains of Plasmodium falciparum (FCB and W2), based on lactate dehydrogenase activity. Cytotoxicity was assessed with the MTT test on MRC-5 human diploid embryonic lung cells.

Results

The methanolic extract of Staudtia gabonensis and the dichloromethane extract of Adhatoda latibracteata showed high antiplasmodial activity (IC₅₀ < 1 μg/ml) and low cytotoxicity, with selectivity indexes of about 58.25 and 16.43, respectively. The methanolic extract of Monodora myristica and the dichloromethane extract of Afromomum giganteum also showed promising activity (1 < IC₅₀ < 10 μg/ml) and low cytotoxicity, with selectivity indexes about 15.70 and 12.48, respectively. Dichloromethane extracts of Monodora myristica and Leonotis Africana showed moderate activity (10 < IC₅₀ < 40 μg/ml), with selectivity indexes about 6.07 and 28.89, respectively. Both extracts of Culcasia lancifolia had IC₅₀ values of 10-40 μg/ml but high cytotoxicity (selectivity indexes <2.77). The methanolic extract of Dorstenia klaineana had moderate antiplasmodial activity (IC₅₀ around 17 μg/ml) but strong cytotoxicity (0.43 μg/ml), giving a selectivity index of about 0.03.

Conclusions

Most extracts of nine selected plants traditionally used to treat malaria in Gabon had interesting antiplasmodial activity in vitro. This supports continued investigations of traditional medicines in the search for new antimalarial agents. The compounds responsible for the observed antiplasmodial effects are under investigation.     

Phyllanthus amarus: ethnomedicinal uses, phytochemistry and pharmacology: a review

Ethnopharmacological relevance

Phyllanthus amarus Schum. &; Thonn. belongs to the family Euphorbiaceae is a small herb well known for its medicinal properties and widely used worldwide. P. amarus is an important plant of Indian Ayurvedic system of medicine which is used in the problems of stomach, genitourinary system, liver, kidney and spleen. It is bitter, astringent, stomachic, diuretic, febrifuge and antiseptic. The whole plant is used in gonorrhea, menorrhagia and other genital affections. It is useful in gastropathy, diarrhoea, dysentery, intermittent fevers, ophthalmopathy, scabies, ulcers and wounds.

Materials and methods

The present review covers a literature across from 1980 to 2011. Some information collected from traditional Ayurvedic texts and published literature on ethanomedicinal uses of Phyllanthus amarus in different countries worldwide.

Results

Phytochemical studies have shown the presence of many valuable compounds such as lignans, flavonoids, hydrolysable tannins (ellagitannins), polyphenols, triterpenes, sterols and alkaloids. The extracts and the compounds isolated from P. amarus show a wide spectrum of pharmacological activities including antiviral, antibacterial, antiplasmodial, anti-inflammatory, antimalarial, antimicrobial, anticancer, antidiabetic, hypolipidemic, antioxidant, hepatoprotective nephroprotective and diurectic properties.

Conclusion

The present review summarizes information concerning the morphology, ecology, ethnopharmacology, phytochemistry, biological activities, clinical applications and toxicological reports of P. amarus. This review aims at gathering the research work undertaken till date on this plant in order to provide sufficient baseline information for future works and commercial exploitation.     

Pharmacological, genotoxic and phytochemical properties of selected South African medicinal plants used in treating stomach-related ailments

Ethnopharmacological relevance

The evaluated medicinal plants are used in South African traditional medicine in treating stomach-related ailments.

Aims of the study

The study aimed at evaluating the pharmacological, genotoxic and phytochemical properties of the seven selected medicinal plants used for treating stomach-related ailments.

Materials and methods

: Ethyl acetate (EtOAc), ethanol (EtOH) 70% and water extracts of the selected plant parts were evaluated for their antimicrobial and anthelmintic activities using microdilution assays. Gram-positive bacteria (Enterococcus faecalis and Staphylococcus aureus), Gram-negative bacterium (Escherichia coli) and Candida albicans were used for antimicrobial assays. Caenorhabditis elegans was used for the anthelmintic assay. Plant extracts were also assayed for their cyclooxygenase-inhibitory activity against cyclooxygenase-1 and -2 enzymes. The Ames test was used to evaluate the genotoxicity of the plant extracts. A spectrophotometric method was used to determine the total phenolics, gallotannins, flavonoids and saponins.

Results

Twelve extracts exhibited minimum inhibitory concentration (MIC) <1 mg/mL against the bacterial test strains, and five extracts exhibited MIC <1 mg/mL against Candida albicans. The EtOAc extract of Tetradenia riparia had the best minimum lethal concentration (MLC) value (0.004 mg/mL) against Caenorhabditis elegans. All the EtOAc extracts exhibited percentage inhibition in the range of 50.7-94.7% against COX-1 and -2 enzymes at 250 μg/mL. All the plant extracts were non-mutagenic towards Salmonella typhimurium tester strains TA98, TA100 and TA1537 without metabolic activation. Phytochemical analysis revealed relatively high amounts of total phenolics, gallotannins and flavonoids in the evaluated plant extracts.

Conclusions

The general pharmacological activities exhibited by some of the plant extracts in this study support the traditional uses of the selected plants in treating stomach-related ailments. The Ames test showed that all the plant extracts were non-mutagenic but cytotoxicity tests are needed to ascertain the safety for long-term consumption.     

Comparative ethnobotany and in-the-field antibacterial testing of medicinal plants used by the Bulu and inland Kaulong of Papua New Guinea

Ethnopharmacological relevance

The island of New Britain in Papua New Guinea is an area of great floristic and cultural diversity that has received little attention from ethnobotanists. Here we present the results of a comparative medicinal ethnobotanical survey of the Bulu and inland Kaulong; two distinct people groups inhabiting lowland rainforest on different sides of the island. A high proportion of species are used in the treatment of bacterial infections and plants with antibacterial activity were identified in the field using a specially developed antibacterial assay kit. Follow up testing with human pathogens was used to evaluate active plant material in more detail.

Materials and methods

Rapid appraisal techniques were used to survey both people groups with all data corroborated by three or more separate sources. Plants from both groups were tested in-the-field with a portable antibacterial test kit based on the agar diffusion assay, using a pressure cooker to sterilise glassware and media. Follow up laboratory based tests were carried out using standardised agar dilution protocols for drug resistant and drug sensitive strains of Staphylococcus aureus and Streptococcus pneumoniae.

Results

We find surprisingly little overlap in the plant species used by the two people groups with only 1 out of 70 species used for the same purpose. There is also a difference in emphasis in the conditions treated with 53% of Kaulong medicinal plants dedicated to treating tropical ulcers compared with only 8% of in the Bulu group. In-the-field testing identified Garcinia dulcis bark (a Kaulong tropical ulcer treatment) to have antibacterial activity and follow up tests against a drug resistant strain of Staphylococcus aureus (a pathogen implicated in tropical ulcer pathogenesis) revealed the crude bark extract to be potently active with an MIC of just 1 mg/ml.

Conclusions

The results demonstrate extreme differences in medicinal plant use between two people groups living a mere 100 km apart and suggests the two medicinal plant systems have developed in isolation from one another. In-the-field antibacterial testing of plant extracts was found to be a valuable technique that enabled early identification of active plant material.     

An inventory of the ethnobotanicals used as anti-diabetic by a rural community of Dhemaji district of Assam, Northeast India

Ethnopharmacological relevance

Traditional remedies used for treating diabetic ailments are very important in the primary health care of the people living in rural Dhemaji district of Assam, north-east India. Novel information gathered from the current survey is important in preserving folk indigenous knowledge.

Materials and methods

Interviews were conducted amongst 80 households comprising of 240 individuals using semi-structured questionnaires. The focus was on plants used in treating diabetes mellitus.

Results

The current survey documented 21 plant species (20 families) which are reportedly used to treat diabetes mellitus by the rural people in the study area. To the best of our knowledge, Amomum linguiforme, Cinnamomum impressinervium, Colocasia esculenta, Dillenia indica, Euphorbia ligularia, Garcinia pedunculata, Solanum indicum, Sterculia villosa and Tabernaemontana divaricata are recorded for the first time based on globally published literature as medicinal plants used for treating diabetes mellitus and related symptoms.

Conclusions

The wide variety of plants that are used to treat diabetes mellitus in this area supports the traditional value that medicinal plants have in the primary health care system of the rural people of Dhemaji district of Assam. The finding of new plant uses in the current study reveals the importance of the documentation of such ethnobotanical knowledge.