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 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.     

Anti-plasmodial activity of the extracts of some Kenyan medicinal plants

Ethnopharmacological relevance

The spread of drug resistant Plasmodium falciparum strains necessitates search for alternative newer drugs for use against malaria. Medicinal plants used traditionally in preparation of herbal medicines for malaria are potential source of new anti-malarial drugs.

Aim of the Study

To identify the anti-plasmodial potential of twelve plants used in preparing herbal remedies for malaria in Kilifi and Tharaka districts of Kenya.

Materials and Methods

Twelve plants used traditionally for anti-malarial therapy in Kilifi and Tharaka districts were extracted with water/methanol yielding twenty-three extracts. The extracts were tested against chloroquine sensitive (NF54) and resistant (ENT30) P. falciparum strains in vitro using ³Hypoxanthine assay.

Results

Seven (30%) extracts showed activity against P. falciparum with IC₅₀ values below 20 μg/ml. The remaining 16 extracts showed low or no activity. The most active extracts were from Zanthoxylum chalybeum (Rutaceae) with an IC₅₀ value of 3.65 μg/ml, Cyperus articulatus (Cyperaceae) with 4.84 μg/ml, and Cissampelos pareira (Menispermaceae) with 5.85 μg/ml.

Conclusions

This study revealed plants, that are potential sources of anti-malarial compounds. Anti-plasmodial activities of extracts of T. simplicifolia, C. pareira, and C. articulatus are reported for the first time.     

Prophylactic and curative activities of extracts from Warburgia ugandensis Sprague (Canellaceae) and Zanthoxylum usambarense (Engl.) Kokwaro (Rutaceae) against Plasmodium knowlesi and Plasmodium berghei

Ethnopharmacological relevance

This work reports the anti-plasmodial activities of Warburgia ugandensis and Zanthoxylum usambarense commonly used as phytomedicines against malaria by some Kenyan communities.

Aim of study

To determine the anti-plasmodial activities of extracts from Warburgia ugandensis and Zanthoxylum usambarense against Plasmodium knowlesi and Plasmodium berghei.

Materials and methods

Eight plant extracts were screened for in vitro anti-plasmodial activity against Plasmodium knowlesi, in a 96-well plate incubated at 37 °C on a RPMI culture medium supplemented with baboon serum. Of the eight, three were investigated for prophylactic and curative activities in BALB/c mice against drug-sensitive Plasmodium berghei in a 4-day test at a dose rate of 200 mg/kg/day.

Results

Inhibitory concentrations (IC₅₀) values of between 3.14 and 75 μg/ml, up to 69% chemosuppression of parasites growth and over 80% survivorship of treated mice were observed.

Conclusion

The two medicinal plants, Warburgia ugandensis and Zanthoxylum usambarense possess bioactive compounds against malaria parasites and could be exploited for further development into malaria therapy.     

Antimicrobial activity of plants used as medicinals on an indigenous reserve in Rio das Cobras, Paraná, Brazil

Ethnopharmacological relevance

A considerable percentage of global biodiversity is located in Brazil, a country that also has rich cultural and ethnic diversity. In the community of Rio das Cobras, Paraná, plants are still widely used in the health care not only by indigenous people but also by the non-indigenous population that inhabits the region. The investigation of the efficacy and safety of these plants in the treatment of infectious diseases provides insights for future studies of these species allowing the appropriated use by the indigenous people, since few or none study has been conducted so far.

Aim of the study

Evaluate the antimicrobial activity and cytotoxicity of some plants used as medicinal on an indigenous reserve in Rio das Cobras, Paraná, Brazil.

Materials and methods

The aqueous extracts were obtained by decoction and the 50% and 70% hydroalcoholic extracts by turbo extraction. The extracts were tested against strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, Candida parapsilosis, Candida tropicalis, Leishmania amazonensis, Poliovirus and HSV-1. Cytotoxicity assay using VERO cells were also performed.

Results

None of the extracts had a selectivity index (SI)>1 for any of the tested bacteria. Only Campomanesia eugenioides and Schinus terebinthifolius had an SI>1.0 for all of the tested Candida species. The best anti-Leishmania activity was obtained with Zanthoxylum rhoifolium and Schinus terebinthifolius. Extracts of Cordia americana were the most effective against herpes simplex virus type 1. Zanthoxylum rhoifolium was the most effective against Poliovirus, and Ocimum gratissimum was effective against both Poliovirus and Herpes Simplex virus. Among the plants investigated in the present study, Zanthoxylum rhoifolium had the fewest cytotoxic effect.

Conclusions

The plants investigated in the present study exhibited potential for future pharmacological uses, but additional studies, especially with regard to in vivo toxicity, must be conducted. The results of this preliminary survey are important for the Rio das Cobras Reserve community for the safe and effective use of plants in the treatment of some infectious diseases.     

In vitro antigonococcal activity of Coscinium fenestratum stem extract

Ethnopharmacological relevance

Gonorrhea is a sexually transmitted disease (STD), which originates from bacteria, Neisseria gonorrhoeae. It is still one of the major health problems worldwide in both men and women. Many medicinal plants have been recorded in Thai folk medicine for relieving STD but there is no scientific report of these plants for antigonococcal activity.

Aim of the study

This study was conducted to evaluate antigonococcal activity of 22 Thai medicinal plants selected from the plants popularly used in Thai folk medicine for treatment of gonorrhea.

Materials and methods

This study was performed by disc diffusion and agar dilution methods against Neisseria gonorrhoeae. Active compound was investigated by bioautographic assay.

Results

Among the selected plants, Coscinium fenestratum (Gaertn.) Colebr. extract showed the most effective activity against Neisseria gonorrhoeae ATCC 49226 with MIC value of 47.39 μg/ml. Bioautographic assay revealed that berberine was the active compound of Coscinium fenestratum against Neisseria gonorrhoeae. The average MIC values of purified berberine against Neisseria gonorrhoeae ATCC 49226 and 11 clinical isolates were 13.51 and 17.66 μg/ml, respectively while average MIC value of the crude extract of Coscinium fenestratum against all clinical isolates was about 56.39 μg/ml. There was no acute toxicity detected at the dose of 5 g of Coscinium fenestratum crude extract per kilogram.

Conclusions

These results provide theoretical support for ethnopharmacological relevance of antigonococcal activity of Coscinium fenestratum and its active compound.     

Hepatoprotective activity of ethanolic extracts of bark of Zanthoxylum armatum DC in CCl4 induced hepatic damage in rats

Aim of the study

Zanthoxylum armatum DC is described as a hepatoprotective in Ayurveda, the Indian system of medicine. However, there is no scientific basis or reports in the modern literature regarding its usefulness as a hepatoprotective agent. The present study was carried out to evaluate the hepatoprotective activity of ethanolic extract of bark of Zanthoxylum armatum DC in CCl₄ induced hepatotoxicity in male Wistar rats.

Materials and methods

Ethanolic extracts at doses of 100, 200, and 400 mg/kg were administered orally once daily for 7 days. The hepatoprotective activity was assessed using various biochemical parameters like alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, serum bilirubin, total protein and serum antioxidant enzymes along with histopathological studies of liver tissue.

Results

The substantially elevated serum enzymatic levels of serum transaminases, alkaline phosphatase and total bilirubin were significantly restored towards normalization by the extracts. Bark extracts significantly increased the levels of antioxidant enzymes: superoxide dismutase, catalase and glutathione. Phytochemical analysis revealed presence of isoquinoline alkaloid, berberine, as well as flavonoids and phenolic compounds, which have been known for their hepatoprotective activities.

Conclusions

Zanthoxylum armatum DC possesses significant protective effect against hepatotoxicity induced by CCl₄ which may be attributed to the individual or combined action of phytoconstituents present in it.     

Antimicrobial activity of Schinus lentiscifolius (Anacardiaceae)

Ethnopharmacological relevance

Schinus lentiscifolius Marchand (syn. Schinus weinmannifolius Engl) is a plant native to Rio Grande do Sul (Southern Brazil) and has been used in Brazilian traditional medicine as antiseptic and antimicrobial for the treatment of many different health problems as well as to treat leucorrhea and to assist in ulcer and wound healing. Although it is a plant widely used by the population, there are no studies proving this popular use.

Material and methods

The crude aqueous extract, the crude neutral methanol extract, fractions prepared from this extract (n-hexane, ethyl acetate, and n-butanol), pure compounds isolated from these fractions, and derivatives were investigated in vitro for antimicrobial activities against five Gram positive bacteria: Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Streptococcus pyogenes, three Gram negative bacteria: Escherichia coli, Pseudomonas aeruginosa, and Shigella sonnei, and four yeasts: Candida albicans, Candida tropicalis, Cryptococcus neoformans, and Saccharomyces cerevisiae. The isolated compound moronic acid, which is the most active, was tested against a range of other bacteria such as two Gram positive bacteria, namely, Bacillus cereus, Enterococcus spp, and six Gram negative bacteria, namely, Burkholderia cepacia, Providencia stuartii, Morganella morganii, Enterobacter cloacae, Enterobacter aerogenes, and Proteus mirabilis.

Results

The leaf aqueous extract (decoction) of Schinus lentiscifolius showed a broad spectrum of antibacterial activity, ranging from 125 to 250 μg/ml (MIC) against the tested bacteria and fungi. The n-hexane extract, despite being very little active against bacteria, showed an excellent antifungal activity, especially against Candida albicans (MIC=25 μg/ml), Candida tropicalis (MIC=15.5 μg/ml), and Cryptococcus neoformans, (MIC=15.5 μg/ml). From the acetate fraction (the most active against bacteria), compounds 1–6 were isolated: nonadecanol (1), moronic acid (2), gallic acid methyl ester (3), gallic acid (4), quercetin (5) and quercitrin (6). The minimal inhibitory concentration (MIC) of moronic acid between 1.5 and 3 μg/ml against most of the tested bacteria shows that it is one of the metabolites responsible for the antibacterial activity of Schinus lentiscifolius.

Conclusion

The antimicrobial activity and some constituents of Schinus lentiscifolius are reported for the first time. The results of the present study provide scientific basis for the popular use of Schinus lentiscifolius for a number of different health problems.     

Conservation strategy for Pelargonium sidoides DC: Phenolic profile and pharmacological activity of acclimatized plants derived from tissue culture

Ethnopharmacological relevance

Pelargonium sidoides DC (Geraniaceae), a popular medicinal plant used in folk medicine in the treatment of respiratory-related infections has gained international prominence due to its usage in several herbal formulations. This has led to high demand and the subsequent decimation of wild populations.

Aim of the study

Using plant tissue culture techniques, Pelargonium sidoides plants were cloned in vitro, acclimatized under greenhouse conditions and evaluated for their phytochemical content and pharmacological activity.

Methods

Phenolic content in extracts of in vitro-derived, greenhouse-acclimatized and wild Pelargonium sidoides plants were analyzed using UPLC-MS/MS. The oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity and minimum inhibitory concentration (MIC) of the extracts against bacterial and fungal strains were evaluated.

Results

Similarities in phenolic profiles were identified confirming the chemical signatures that characterize Pelargonium sidoides plants. Extracts of greenhouse-acclimatized and wild plants exhibited comparable antimicrobial and antioxidant properties.

Conclusions

Overall, the study highlights the potential of integrating plant tissue culture technologies in conservation strategies of medicinal plants. In particular, the results strongly suggest the feasibility of both large-scale cultivation and plant part substitution as alternative solutions to the current destructive overharvesting practices of wild Pelargonium sidoides populations.     

Antimicrobial activity of the extracts of Craniotome furcata (Lamiaceae)

Ethnopharmacological relevance

Craniotome furcata (Link.) O. Kuntze (Lamiaceae) is used in the traditional medicine for the treatment of cuts and wounds indicating antimicrobial activity.

Aim of the study

To validate the traditional medicinal claim, in vitro antimicrobial activity of the extracts was screened against eleven human pathogenic bacteria and fungi.

Materials and methods

The ethyl acetate (CE) and n-butanol (CB) extracts of the aerial parts of Craniotome furcata were tested against four Gram-positive bacteria, four Gram-negative bacteria and three fungi species. Antimicrobial activity was determined by the tube-dilution method.

Results

The CE and CB extracts showed antimicrobial activity against all of the tested microorganisms, with minimum inhibitory concentration (MIC) values in the range of 0.41–4.58 mg/ml.

Conclusions

The tested microbes Micrococcus flavus and Escherichia coli were highly susceptible to extract CE and antimicrobial activity of CB is comparable to that of extract CE against Escherichia coli and Staphylococcus faecalis while it is better than that of extract CE, against Klebsiella pneumoniae. Both the extracts were found less susceptible against tested fungi.     

Zanthoxylum capense constituents with antimycobacterial activity against Mycobacterium tuberculosis in vitro and ex vivo within human macrophages

Ethnopharmacological relevance

Zanthoxylum capense Thunb. (Rutaceae) is a medicinal plant traditionally used in Mozambique to treat tuberculosis.

Aims of the study

The main aim of the study was to find antimycobacterial lead compounds from Zanthoxylum capense. Another goal was to provide scientific validation for the use of this plant in traditional medicine.

Methods and materials

By bioassay-guided fractionation, 16 compounds were isolated and screened for their in vitro antimycobacterial activity against two different strains of Mycobacterium tuberculosis. Their in vitro cytotoxicity to human THP-1 macrophages was also assessed. The compounds with favourable selectivity index values (SI>10) were further investigated for their ability to inhibit the growth of Mycobacterium tuberculosis H37Rv in an intracellular macrophage model of infection.

Results

The best results were obtained for a benzophenanthridine alkaloid, decarine (1), and an N-isobutylamide, N-isobutyl-(2E,4E)-2,4-tetradecadienamide (15), which showed high activity against Mycobacterium tuberculosis H37Rv (MIC of 1.6 μg/ml), and a low macrophage cytotoxicity (IC₅₀>60 μg/ml), indicating considerable selective activity. The benzophenanthridine alkaloid 6-acetonyldihydronitidine (6) revealed cytotoxicity (IC₅₀ 1.7 μg/ml), despite the determined MIC of 6.2–12.5 μg/ml. In infected macrophages, decarine (1) was able to reduce bacterial survival by almost two log units at a concentration of 6.2 μg/ml 5 days post-drug exposure. Compound 15 exhibited an intermediate activity at drug concentrations ranging from 6.2 to 25 μg/ml.

Conclusions

The high antimycobacterial activity of decarine found, both in vitro and ex vivo against mycobacteria, and the low cytotoxicity towards human macrophages indicate that it may be valuable as a lead scaffold for the development of anti-TB drugs.     

Antibacterial,cytotoxic activities and chemical composition of fruits of two Cameroonian Zanthoxylum species

Ethnopharmacological relevance

Zanthoxylum leprieurii (Syn. Fagara leprieurii) is a plant extensively used by traditional healers in Cameroon for the treatment of stomach disorders, gonorrhea, intestinal parasites and sterility. The infusion from the fruit is taken in Cameroon for the treatment of sickle cell anemia, as well. Similarly, the roots of Zanthoxylum zanthoxyloides (Syn. Fagara zanthoxyloides) are also used for wound dressing, sickle cell anemia and as pain reliever, in addition to the uses mentioned for Zanthoxylum leprieurii.

Aim of the study

To scientifically validate their traditional use, the in vitro antimicrobial and anticancer assays were performed. In addition, chemical compositions of their fruit extracts and essential oils were also studied.

Material and methods

The chemical compositions of their essential oils and methanol extracts were studied. GC and GC–MS were used for analyzing the essential oils while various chromatographic methods were used to isolate the pure compounds from methanol extracts. MTT assay was used for the cytotoxic studies of methanol extracts, their fractions and some pure compounds. Antimicrobial activity of methanol extracts, some isolated compounds as well as essential oils was tested against a panel of human pathogenic bacteria by diffusion and dilution methods.

Results

The principal constituents of the essential oil of Zanthoxylum zanthoxyloides were identified as citronellol and geraniol whereas Zanthoxylum leprieurii was rich in E-β-ocimene. Furthermore, we report for the first time, the presence of 7,8-dimethoxycoumarin and sinapic acid in the methanol extract of Zanthoxylum leprieurii. In vitro bioassays reveal that the methanol extracts, essential oil and some of the isolated compounds from fruits of both the plants exhibit moderate anticancer and antimicrobial activities.

Conclusion

Altogether, the present findings justify the traditional use of Zanthoxylum zanthoxyloides and Zanthoxylum leprieurii in the treatment of stomach disorders and cancer disease. The antimicrobial properties in the essential oil of Zanthoxylum zanthoxyloides are of additional significance.     

Investigations of antimicrobial activity of some Cameroonian medicinal plant extracts against bacteria and yeast with gastrointestinal relevance

Ethnopharmacological relevance

Resistance against antibiotics of many bacteria is accumulating. Therefore, searches for new substances with antimicrobial activity have become an urgent necessity. Medicinal plants are frequently used in popular medicine as remedies for many infectious diseases (intestinal infection, malaria, tuberculosis, etc.).

Aim of the study

This study aimed to determine the in vitro antimicrobial activity of hexane, ethyl acetate and methanol extracts from different parts (leaves, stem bark, entire plant) of five different plant species against bacteria and yeast of gastrointestinal relevance.

Material and methods

Twenty-one extracts from all the following plants (Albizia gummifera (leaf), Ficus exasperata (leaf and stem bark), Nauclea latifolia (leaf and stem bark), Ricinodendron heudelotii (stem bark), Senna hirsuta (entire plant) have been screened for their antimicrobial activity against eight bacteria species including Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus), Gram-negative bacteria (Escherichia coli, Shigella dysenteriae, Shigella flexneri, Salmonella typhi, Pseudomonas aeruginosa, and Klebsiella pneumoniae) and one yeast species (Candida albicans) using agar disc-diffusion, and microbroth dilution assays.

Results

Results demonstrated that F. exasperata and N. latifolia were active against the whole set of tested microorganisms. The methanol extract of N. latifolia (leaf and stem bark) was the most active against against C. albicans, E. coli, S. aureus, P. aeruginosa with a minimum inhibitory concentration (MIC) of 2, 32, 64 and 64 μg/ml, respectively. The methanol extract of leaf of F. exasperata was also most active with significant inhibitory activity against E. coli, S. dysenteriae, S. Typhi and P. aeruginosa with MIC values of 128 μg/ml. Only the extract of N. latifolia (stem bark and leaf) showed anticandidal property.

Conclusion

The results show that these plant extracts exhibit antimicrobial activity and N. latifolia proved to be most effective as an antibacterial and antifungal.     

Anti-Helicobacter pylori activity of plants used in Mexican traditional medicine for gastrointestinal disorders

Aim of the study

Helicobacter pylori is the major etiological agent of chronic active gastritis and peptic ulcer disease and is linked to gastric carcinoma. Treatment to eradicate the bacteria failed in many cases, mainly due to antibiotic resistance, hence the necessity of developing better therapeutic regimens. Mexico has an enormous unexplored potential of medicinal plants. This work evaluates the in vitro anti-H. pylori activity of 53 plants used in Mexican traditional medicine for gastrointestinal disorders.

Materials and methods

To test the in vitro antibacterial activity, agar dilution and broth dilution methods were used for aqueous and methanolic extracts, respectively.

Results

Aqueous extracts of Artemisia ludoviciana subsp. mexicana, Cuphea aequipetala, Ludwigia repens,and Mentha × piperita (MIC 125 to <250 μg/ml) as well as methanolic extracts of Persea americana, Annona cherimola, Guaiacum coulteri, and Moussonia deppeana (MIC <7.5 to 15.6 μg/ml) showed the highest inhibitory effect.

Conclusions

The results contribute to understanding the mode of action of the studied medicinal plants and for detecting plants with high anti-Helicobacter pylori activity.     

Ethnopharmacological study of plants from Pondoland used against diarrhoea

Ethnopharmacological relevance

Waterborne diseases such as diarrhoea are common world wide, including in Bizana, South Africa where the majority of rural dwellers depend largely on water from unprotected sources. The people from Bizana use medicinal plants as their first line of health care to cure and prevent diarrhoea.

Aim of the study

To record and document plants used for the treatment of diarrhoea in Bizana, to evaluate antibacterial and anti-inflammatory activities of selected plant extracts as well as to perform genotoxicity testing of evaluated plants.

Materials and methods

An ethnobotanical approach was used to select plants used for treating diarrhoea in Bizana for pharmacological assays using questionnaires. Nine plants were selected for bioassays based on their frequency index and the fact that they have never been evaluated against diarrhoea causing-microorganisms. The petroleum ether (PE), dichloromethane (DCM), 70% ethanol (EtOH), and water extracts were evaluated for antibacterial (Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli and Shigella flexneri) activity using the microdilution technique, their ability to inhibit COX-1 and COX-2 enzymes. Genotoxicity was evaluated using the Salmonella microsome assay.

Results

This study revealed that 34 plant species belonging to 27 families are used for the treatment of diarrhoea in Bizana. The extracts showed good inhibitory activity with MIC values ranging from 0.39 to 12.5 mg/ml. The best activity was exhibited by DCM extracts of Rapanea melanophloeos, and EtOH extracts of Ficus craterostoma and Maesa lanceolata with MIC values of 0.098 mg/ml. The inhibitory activity against COX-1 enzyme was higher than COX-2, with 19 plant extracts for the former and 7 for the latter. All the tested plant extracts were not mutagenic at all concentrations tested against all tester strains of bacteria.

Conclusion

In view of the fact that the plants were selected based on their ethnobotanical usage for treating diarrhoea, the activities reported here goes a long way in validating the plants for traditional use.     

Antibacterial and cytotoxic activity of isoprenylated coumarin mammea A/AA isolated from Mammea africana

Ethnopharmacological relevance

The stem bark of Mammea africana is widely distributed in tropical Africa and commonly used in traditional medicine. This study aims to identify the active compound in Mammea africana and to evaluate its antimicrobial and antiproliferative activity.

Materials and methods

Methanol extract from the bark of the Mammea africana was separated by liquid–liquid extraction, followed by open column chromatography. A principal antimicrobial compound was purified by high performance liquid chromatography (HPLC) and its structure was elucidated by nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). The antibacterial activity of the purified compound was determined using the broth microdilution method against 7 common pathogenic bacteria. The compound was also evaluated for cytotoxicity by cell proliferation assay (MTS) using the mouse embryonic fibroblast cell line NIH 3T3 and the non-small cell lung cancer cell line A549.

Results

The purified active compound was determined to be mammea A/AA and was found to be highly active against Campylobacter jejuni (MIC=0.5 μg/ml), Streptococcus pneumoniae (MIC=0.25 μg/ml), and Clostridium difficile (MIC=0.25 μg/ml). The compound exhibited significant antiproliferative activities against both NIH 3T3 and A549 cell lines.

Conclusion

Mammea A/AA isolated from Mammea africana exerts specific inhibitory activity against Campylobacter jejuni, Streptococcus pneumoniae, and Campylobacter difficile. Mammea A/AA was also found to exhibit significant cytotoxicity against both cancer and normal cell lines.     

Inhibitory properties of selected South African medicinal plants against Mycobacterium tuberculosis

Ethnopharmacological relevance

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) is the most commonly notified disease and the fifth largest cause of mortality. One in 10 cases is resistant to treatment in some areas. Several plants are used locally to treat TB-related disease.

Aims of the study

The aim was to screen selected South African medicinal plants used to treat TB and related symptoms by traditional healers for antimycobacterial activity.

Materials and methods

Ethnobotanical information on these plants was obtained. Crude acetone, methanol, hexane and ethanol extracts of 21 selected medicinal plants obtained in Venda, South Africa were screened for their ability to inhibit MTB H₃₇Ra and a clinical strain resistant to first-line drugs and one second-line drug using tetrazolium microplate assay to determine the minimum inhibitory concentration (MIC). Results were analyzed using Microsoft Excel 2007 and One way ANOVA; p < 0.05 was considered for statistical significance.

Results

Few acetone extracts were active against MTB with MIC under 100 μg/mL. Four plants showed lower MIC values; Berchemia discolor Klotzsch Hemsl 12, 5 μg/mL on H₃₇Ra and 10.5 μg/mL on the clinical isolate, Bridelia micrantha Hochst. Baill (25 μg/mL), Warbugia salutaris Bertol. F Chiov (25 μg/mL), and Terminalia sericea Burch ex D. F (25 μg/mL) on both H₃₇Ra and clinical isolate. However, the roots of Ximenia caffra Sond. Var. caffra, barks of Sclerocarya birrea (A Rich) Hochst, Asclepias fruticosa L, tubers of Allium sativum L, leaves of Carica papaya L, Solanum panduriforme E. Mey C, and roots of Securidaca longepedunculata Fresen gave MIC greater than 100 μg/mL.

Conclusion

The acetone extracts of Berchemiadiscolor, Bridelia micrantha, Terminalia sericea and Warbugia salutaris could be important sources of mycobactericidal compounds against multidrug-resistant MTB.     

Antibacterial activities of plants from Central Africa used traditionally by the Bakola pygmies for treating respiratory and tuberculosis-related symptoms

Ethnopharmacological relevance

The antibacterial activities of 18 plants from 10 different families were investigated for their antimicrobial efficacy, based on the traditional uses of these species by Bakola pygmies living in Central Africa, especially along the Ngoyang area in Cameroon for the treatment of respiratory and tuberculosis-related symptoms. The aim of the study is to test the antimicrobial efficacy of these plants against some pathogens associated with respiratory disease and to determine if there is any validation for the traditional use against Mycobacterium species.

Materials and methods

Medium polar extracts were prepared in MeOH/DCM (1:1, v/v) from the plant parts of each species used traditionally and were assayed against pathogens associated with respiratory tract ailments [Staphylococcus aureus (ATCC 25923), Klebsiella pneumoniae (ATCC 13883) and Morexella cattarhalis (ATCC 14468)] using the minimum inhibitory concentration (MIC) method. Two additional faster growing Mycobacterium strains [Mycobacterium smegmatis (ATCC 23246) and Mycobacterium aurum (NCTC 10437)] were included in the assay as predictive test organisms for the more pathogenic strain Mycobacterium tuberculosis.

Results

Some plant species, such as Alchornea floribunda, Musanga cecropioides (both leaves and stem bark), Tetracera potatoria and Xylopia aethiopica (stem bark), were effective in inhibiting Morexella cattarhalis, having MIC values between 65 and 250 μg/mL. Some noteworthy antimycobacterial inhibition (MIC≤200 μg/mL and as low as MIC 6.5 µg/mL) for 54% of the extracts were observed.

Conclusion

While moderate activity was shown for pathogens causing respiratory tract infections, these plant species seems to be selectively targeting Mycobacteria spp. suggesting that the traditional use for treating tuberculosis related symptoms may be indeed be accurate.     

Antimicrobial and antimalarial activity of Cussonia species (Araliaceae)

Ethnopharmacological relevance

Cussonia species are used in African traditional medicine mainly against pain, inflammation, gastro-intestinal problems, malaria and sexually transmitted diseases.

Aim of the study

To summarise ethnomedicinal uses of Cussonia and to find scientific evidence in support of selected main uses.

Materials and methods

Using the minimum inhibitory concentration (MIC) method, leaves of 13 Cussonia species, Schefflera umbellifera and Seemannaralia gerrardii were tested against pathogens associated with diarrhoea (Enterococcus faecalis and Escherichia coli), sexually transmitted infections (Neisseria gonorrhoeae and Trichomonas vaginalis) and general infectious diseases (Staphylococcus aureus and Pseudomonas aeruginosa). Antimalarial sensitivity was studied using Plasmodium falciparum and the [³H]-hypoxanthine incorporation assay. Cytotoxic effects on a T-cell leukaemia (Jurkat) cell line were determined using the tetrazolium-based cellular toxicity assay.

Results

Methanolic extracts were active against Pseudomonas aeruginosa (MIC of 1.0–1.5 mg/mL), Trichomonas vaginalis (MIC of 0.8–1.3 mg/mL) and Staphylococcus aureus (Cussonia arborea, 1.8 mg/mL). All samples were active against Neisseria gonorrhoeae (MIC of 0.02–0.7 mg/mL). The methanol extract of Cussonia arborea was the most active against Plasmodium falciparum (13.68 μg/mL) and showed anticancer properties (5.60 μg/mL).

Conclusions

The traditional use of Cussonia species to treat sexually transmitted diseases and Plasmodium infections appears to have a scientific basis.     

Simulated gastrointestinal tract metabolism and pharmacological activities of water extract of Scutellaria baicalensis roots

Ethnopharmacological relevance

.

Scutellaria baicalensis

Georgi (Labiatae) is a well-known traditional Chinese medicine to treat inflammation, cardiovascular diseases, respiratory and gastrointestinal infections, etc. The present study was to understand the metabolism of the root of Scutellaria baicalensis (a.k.a. Huangqin in Chinese) in the gastrointestinal tract and the correlation between the metabolites and their respective pharmacological activities.

Materials and methods

The water extract of the root of Scutellaria baicalensis (WESB) was incubated with simulated gastric and intestinal juices, and human fecal microflora for 24 h at 37 °C. The HPLC–DAD analysis was used to monitor the in vitro metabolic process and identify its metabolites by comparing their absorption spectrum and retention time with those of chemical references. The in vitro anticomplementary and antimicrobial activity was evaluated with hemolysis assay, agar disc-diffusion method and MIC value, respectively.

Results

Main constituents of WESB remain unchanged during the incubation with simulated gastric juice (pH=1.5) and intestinal juice (pH=6.8), whereas four flavones, baicalin, wogonoside, oroxyloside and norwogonoside were metabolized into their respective aglycons by human intestinal bacteria. All four metabolites were demonstrated to have higher anticomplementary and antimicrobial activity than those of WESB. The anticomplementary active metabolites were identified to be baicalein, oroxylin A and norwogonin, among them, norwogonin is the most active compound.

Conclusion

The presence of intestinal bacteria is demonstrated to play an important role in the gastrointestinal metabolism of WESB, and the pharmacological effects of Scutellaria baicalensis may be dependent on the intestinal bacteria metabolism.