Anti-inflammatory and mutagenic evaluation of medicinal plants used by Venda people against venereal and related diseases

Ethnopharmacology relevance

Inflammation is a major risk factor for various human diseases including venereal diseases, often resulting in treatment complications. Plants have been traditionally used for treatment of many different diseases and have been successfully proven to be an alternative source in treatment of infectious diseases.

Aim of the study

This study was aimed at evaluating the anti-inflammatory activities and the mutagenic properties of 12 medicinal plants used by the Venda people against venereal and related diseases.

Materials and methods

The plants were evaluated for their anti-inflammatory activity against the cyclooxygenase (COX-1 and -2) enzymes and genotoxicity using the Ames test, with and without S9 (metabolic activation) against Salmonella typhimurium tester strain TA98.

Results

DCM and PE extracts of Adansonia digitata bark, Bolusanthus speciosus bark, Pterocarpus angolensis bark and Pappea capensis leaves and EtOH and water extracts of Bolusanthus speciosus stem and Ekebergia capensis bark showed the best anti-inflammatory activity in both COX-1 and -2 assays at 250 μg/ml. These were further evaluated at three other concentrations (31.25, 62.5, and 125 μg/ml) to determine IC₅₀ values. Water extracts of Ekebergia capensis bark showed the best IC₅₀ value towards COX-1. The Ames test revealed that all plant extracts were non-mutagenic towards Salmonella typhimurium strain TA98 except for Elephantorrhiza burkei and Ekebergia capensis that showed weak mutagenicity.

Conclusion

The active plants may offer a new source of chemicals for the effective treatment of anti-inflammatory conditions related to venereal diseases.     

Pharmacological screening of Malian medicinal plants used against epilepsy and convulsions

Ethnopharmacological relevance

Several medicinal plants are used in Mali to treat epilepsy and convulsions. So far, no studies have investigated the pharmacological effect of these plants.

Aims

The aim of this study was to investigate the in vitro and in vivo antiepileptic potential of the ethanolic extracts of 11 Malian medicinal plants.

Materials and methods

The extracts were screened for antiepileptic properties in the mouse cortical wedge preparation and in the [³H]-flumazenil binding assay. Two of the plant extracts were investigated for anticonvulsive properties in the pentylenetetrazol (PTZ) kindling model in mice. Possible side effects on motor impairment were evaluated using the rota-rod test.

Results

Extracts of 10 of the 11 medicinal plants showed affinity to the benzodiazepine binding site on the GABA_A receptor. Seven of the 11 extracts inhibited the spontaneous discharges (SEDs) in the mouse cortical wedge preparation, with the extracts of Flueggea virosa and Psorospermum senegalense being the most potent. However, when tested for in vivo anticonvulsive properties these two extracts failed to show any effect on PTZ-induced seizures in mice.

Conclusions

The pharmacological screening of the ethanolic extracts of 11 Malian medicinal plants in vitro lead to the identification of several extracts with potential anticonvulsant properties.     

In vitro antimicrobial synergism within plant extract combinations from three South African medicinal bulbs

Ethnopharmacological relevance

Tulbaghia violacea, Hypoxis hemerocallidea and Merwilla plumbea are used in South African traditional medicine for the treatment of some infectious diseases and other ailments.

Aim of the study

The study aimed at investigating the antimicrobial efficacies of independent and various within-plant extract combinations of three medicinal bulbs to understand the possible pharmacological interactions.

Materials and methods

Bulb and leaf extracts of the three medicinal plants, independently and in combinations, were comparatively assessed for antimicrobial activity against two Gram-positive and two Gram-negative bacteria and Candida albicans using the microdilution method. The fractional inhibitory concentration indices (FIC) for two extract combinations were determined.

Results

At least one extract combination in each plant sample demonstrated good antimicrobial activity against all the test organisms. The efficacies of the various extract combinations in each plant sample varied, with the strongest synergistic effect exhibited by the proportional extract yield combination of PE and DCM extracts in Merwilla plumbea bulb sample against Staphylococcus aureus (FIC index of 0.1). Most extract combinations demonstrated either a synergistic, additive or indifferent interaction effect against the test bacteria with only a few exhibiting antagonistic effects.

Conclusion

The observed antimicrobial efficacy and synergistic interactions indicate the beneficial aspects of combination chemotherapy of medicinal plant extracts in the treatment of infectious diseases.     

A comparative study of the antimicrobial and phytochemical properties between outdoor grown and micropropagated Tulbaghia violacea Harv. plants

Aim of the study

The study aimed to compare the antimicrobial and phytochemical properties of in vitro cultured and outdoor grown Tulbaghia violacea plants in the quest to validate the use of micropropagated plants as alternatives to outdoor grown plants in traditional medicine. Tulbaghia violacea is used extensively in South African traditional medicine for HIV/AIDS patients and in the treatment of gastrointestinal ailments, asthma, fever and tuberculosis.

Materials and methods

Extracts of micropropagated and outdoor grown Tulbaghia violacea plants were evaluated for their antibacterial and antifungal activities against Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and a fungus Candida albicans using microdilution methods. Saponins and phenolic compounds including condensed tannins, gallotannins and flavonoids were quantitatively determined using spectrophotometric methods. A qualitative test for saponins was also carried out.

Results

The petroleum ether (PE) extracts of micropropagated plants and dichloromethane (DCM) extracts of outdoor grown plants showed good antibacterial activity, each against two bacterial test strains. PE extracts of micropropagated plants showed the best antibacterial activity with a minimum inhibitory concentration (MIC) of 0.39 mg/ml against Bacillus subtilis. Good MIC (<1 mg/ml) and minimum fungicidal concentration (MFC) values of 0.78 mg/ml were only obtained in DCM extracts of outdoor grown plants. MIC and MFC values for water and ethanol extracts of both micropropagated and outdoor grown plants were similar and in the range 3.125-12.5 mg/ml. Total phenolics, gallotannins, flavonoids and saponins were significantly higher in micropropagated plants than in outdoor grown ones. In all cases, the amounts of phytochemical compounds in micropropagated plants were more than twice that of outdoor grown plants except for condensed tannins.

Conclusion

The results form a good basis for the use of Tulbaghia violacea micropropagated plants as a complement to the outdoor grown plants in traditional medicine.     

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.     

Antimicrobial and acetylcholinesterase inhibitory activities of Buddleja salviifolia (L.) Lam. leaf extracts and isolated compounds

Ethnopharmacological relevance

Buddleja salviifolia leaves are used for the treatment of eye infections and neurodegenerative conditions by various tribes in South Africa.

Aim of study

This study was designed to isolate the phenolic constituents from the leaf extracts of Buddleja salviifolia and evaluate their antimicrobial and acetylcholinesterase (AChE) activities.

Material and methods

Three phenolic compounds were isolated from the ethyl acetate fraction of a 20% aqueous methanol leaf extract of Buddleja salviifolia using Sephadex LH-20 and silica gel columns. Structure elucidation of the isolated compounds was carried out using spectroscopic techniques: mass spectrometry (ESI-TOF-MS) and NMR (1D and 2D). The extracts and isolated compounds were evaluated for antimicrobial and acetylcholinesterase activities using the microdilution technique. The bacteria used for the antimicrobial assays were Gram-positive Bacillus subtilis and Staphylococcus aureus and Gram-negative Escherichia coli and Klebsiella pneumoniae.

Results

The isolated compounds were characterized as: 4′-hydroxyphenyl ethyl vanillate (1) a new natural product, acteoside (2) and quercetin (3). The crude extract, fractions and the isolated compounds from the leaves of the plant exhibited a broad spectrum of antibacterial activity. The EtOAc fraction exhibited good activity against Bacillus subtilis and Staphylococcus aureus with MIC values ranging from 780.0 to 390.0 µg/mL. Isolated compound 2 exhibited good activity against Staphylococcus aureus with an MIC value of 62.5 µg/mL. The hexane and DCM fractions of leaves showed the best activity against Candida albicans with MIC and MFC values of 390.0 µg/mL. In the AChE inhibitory test, among the tested extracts, the hexane fraction was the most potent with an IC₅₀ value of 107.4 µg/mL, whereas for the isolated compounds, it was compound (3) (quercetin) with an IC₅₀ value of 66.8 µg/mL.

Conclusions

Activities demonstrated by the extracts and isolated compounds support the ethnopharmacological use of Buddleja salviifolia against eye infections and neurodegenerative diseases.     

Plant composition, pharmacological properties and mutagenic evaluation of a commercial Zulu herbal mixture: Imbiza ephuzwato

Ethnopharmacology relevance

Imbiza ephuzwato is a traditional herbal tonic made from a mixture of extracts of roots, bulbs, rhizomes and leaves of 21 medicinal plants and is used in traditional medicine as a multipurpose remedy.

Aim of the study

To compile and investigate the bioactivity and mutagenic effects of extracts of the 21 plant species used in the preparation of Imbiza ephuzwato herbal tonic.

Materials and methods

The 21 plant species used to make Imbiza ephuzwato herbal mixture were each investigated for their pharmacological properties. Petroleum ether (PE), dichloromethane (DCM), 80% ethanol (EtOH) and water extracts of the 21 plants were evaluated against two gram-positive, two gram-negative bacteria and a fungus Candida albicans. The extracts were also evaluated for their inhibitory effects against cyclooxygenase (COX-1 and -2) and acetylcholinesterase AChE enzymes. Mutagenic effects of the water extracts were evaluated using the Ames test.

Results

Gunnera perpensa and Rubia cordifolia were the only plant species used to manufacture Imbiza ephuzwato that had water extracts which showed good antibacterial activity. The extracts of G. perpensa (EtOH), Hypericum aethiopicum (DCM) and Urginea physodes (EtOH) showed the best antifungal activity. The water extracts of H. aethiopicum, G. perpensa, Drimia robusta, Vitellariopsis marginata, Scadoxus puniceus and Momordica balsamina showed percentage inhibition of COX-1 that was over 70%. For COX-2 enzyme, the water extracts of G. perpensa, Cyrtanthus obliquus, M. balsamina and Tetradenia riparia exhibited inhibitory activity above 70%. Water extracts of G. perpensa, C. obliquus, V. marginata, Asclepias fruticosa and Watsonia densiflora showed good AChE inhibitory activity (>80%). The Ames test results revealed that all the water extracts of the 21 plant species used to make Imbiza ephuzwato were non-mutagenic towards the Salmonella typhimurium TA98 strain for the assay with and without S9 metabolic activation. In contrast, Imbiza ephuzwato showed mutagenic effects after exposure to S9 enzyme mixture.

Conclusion

The observed activities of some plant extracts, if supported by other confirmatory tests, may justify their inclusion in the makeup of Imbiza ephuzwato herbal mixture as well as their use in traditional medicine. Further studies aimed at investigating possible synergistic effects as a result of mixing plant extracts are necessary. The reported mutagenicity in Imbiza ephuzwato could be as a result of interaction of biomolecules in the heterogeneous mixture, yielding compounds that are converted to mutagenic agents by xenobiotic metabolizing enzymes. It is therefore important to carry out further studies aimed at identifying and eliminating the sources of the mutagenic compounds in the heterogeneous mixture.     

Cytotoxicity and inhibition of P-glycoprotein by selected medicinal plants from Thailand

Ethnopharmacological relevance

Thai medicine has a long tradition of tonifying medicinal plants. In the present investigation, we studied the flower extracts of Jasminum sambac, Mammea siamensis, Mesua ferrea, Michelia alba, Mimusops elengi, and Nelumbo nucifera and speculated that these plants might influence metabolism and substance flow in the body.

Materials and methods

Isolation of porcine brain capillary endothelial cells (PBCECs) as well as multidrug-resistance CEM/ADR5000 leukemia cells, MDA-M;B-231 breast cancer, U-251 brain tumor, and HCT-116 colon cancer cells were used. The calcein-acetoxymethylester (AM) assay was used to measure inhibition of P-glycoprotein transport. XTT and resazurin assays served for measuring cytotoxicity.

Results

The extracts revealed cytotoxicity towards CCRF-CEM leukemia cells to a different extent. The strongest growth inhibition was found for the n-hexane extracts of Mammea siamensis and Mesua ferrea, and the dichloromethane extracts of Mesua ferrea and Michelia alba. The flower extracts also inhibited P-glycoprotein function in porcine brain capillary endothelial cells and CEM/ADR5000 leukemia cells, indicating modulation of the blood–brain barrier and multidrug resistance of tumors. Bioactivity-guided isolation of coumarins from Mammea siamensis flowers revealed considerable cytotoxicity of mammea A/AA, deacetylmammea E/BA and deacetylmammea E/BB towards human MDA-MB-231 breast cancer, U-251 brain tumor, HCT-116 colon cancer, and CCRF-CEM leukemia cells.

Conclusion

The plants analyzed may be valuable in developing novel treatment strategies to overcome the blood–brain barrier and multidrug-resistance in tumor cells mediated by P-glycoprotein.     

Screening of selected Indian medicinal plants for acetylcholinesterase inhibitory activity

Seventy-six plant extracts including methanolic and successive water extracts from 37 Indian medicinal plants were investigated for acetylcholinesterase (AChE) inhibitory activity (in vitro). Results indicated that methanolic extracts to be more active than water extracts. The potent AChE inhibiting methanolic plant extracts included Withania somnifera (root), Semecarpus anacardium (stem bark), Embelia ribes (Root), Tinospora cordifolia (stem), Ficus religiosa (stem bark) and Nardostachys jatamansi (rhizome). The IC(50) values obtained for these extracts were 33.38, 16.74, 23.04, 38.36, 73.69 and 47.21mug/ml, respectively. These results partly substantiate the traditional use of these herbs for improvement of cognition.     

Antimicrobial,anti-inflammatory and mutagenic investigation of the South African tree aloe (Aloe barberae)

Ethnopharmacology relevance

In recent times, many products ranging from aloe drinks to aloe gels, powders, capsules, and creams have appeared on the commercial market prepared from different aloe species including Aloe barberae. These products are used in ethnomedicine to treat various conditions including gastrointestinal disorders, insect bites, skin burns and other skin injuries by traditional communities.

Aim of the study

This study was aimed at evaluating the antibacterial, antifungal and anti-inflammatory activities as well as genotoxic effects of different extracts of Aloe barberae.

Materials and methods

Organic and water extracts of the upper stem, young bark, mature bark, leaves and roots of the South African tree aloe (Aloe barberae) were evaluated for their antimicrobial [Gram-positive (Bacillus subtilis and Staphylococcus aureus), Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria as well as the fungus Candida albicans], anti-inflammatory (COX-1 and COX-2) and mutagenic properties (Ames test). Thin layer chromatography (TLC) was used to compare the phytochemical profiles of different extracts of Aloe barberae.

Results

The petroleum ether (PE) and dichloromethane (DCM) extracts of the mature bark, leaves and roots exhibited good activity against all the bacteria and fungus Candida albicans with minimum inhibitory concentrations (MIC) ranging from 0.195 to 1.56 mg/ml. All the PE extracts evaluated showed a high activity (>70%) in both COX-1 and COX-2 assays. Apart from the organic extracts of the root with consistently good activity (>70%), all the remaining extracts showed moderate activity (40–69%) in COX-1 assay. The PE extracts also showed a dose dependent increase in activity. Ultraviolet (UV) spectrum of the leaves and root EtOH extracts indicated the presence of compounds that could absorb UV light (wavelength: 190–820 nm). None of the extracts had a mutagenic effect in the Salmonella/microsome assay against a tester strain, TA98.

Conclusion

Activity observed in the bark, leaves and roots of Aloe barberae validates its use in commercial herbal products, ethnobotany and ethnoveterinary medicine by South African communities and small scale farmers to treat various conditions.     

Pharmacological and phytochemical study on a Sisymbrium officinale Scop. extract

Ethnopharmacological relevance

The aerial parts of Sisymbrium officinale Scop. are commonly used to treat airway ailments, moreover in antiquity the herbal drug was reputed to possess anticancer properties. The results obtained in present work support the traditional use and the properties ascribed to Sisymbrium officinale.

Aim of the study

In order to give a scientific basis to the traditional uses of Sisymbrium officinale, this study was aimed to evaluate in vitro the myorelaxant activity, the antimicrobial properties and the antimutagenic effect of an aqueous dry extract of the aerial parts of the plant. A phytochemical characterization of the extract was also performed.

Materials and methods

The myorelaxant activity was studied against the contractions induced by carbachol, histamine and leukotriene C₄, in isolated guinea-pig trachea. The antimicrobial activity was tested against six bacteria and one yeast. The Ames test, performed by the preincubation method, was used to study the antimutagenic activity of the extract by its capability to inhibit the mutagenic effect of 2-nitrofluorene, sodium azide, methyl methanesulfonate and 2-aminoanthracene, in Salmonella typhimurium TA98, Salmonella typhimurium TA100 and Escherichia coli WP2uvrA strains. The chemical composition of the extract was analyzed by TLC and HPLC.

Results

Sisymbrium officinale showed to reduce the chemically-induced contractions of isolated guinea-pig trachea with major potency against leukotriene C₄ and histamine. The extract did not show any antibacterial activity. The Ames test showed a strong antimutagenic activity against 2-aminoanthracene, in Escherichia coli WP2uvrA and in Salmonella typhimurium TA98 strains. The phytochemical study highlighted the presence of putranjivine, the glucosinolate marker of Sisymbrium officinale, and of proline.

Conclusions

The myorelaxant activity of Sisymbrium officinale offers a scientific basis to its use in traditional medicine. The strong antimutagenic effect suggests further studies to evaluate its possible chemopreventive activity.     

Phytosynergy in some Hypoxis species and pharmacological properties of a Hypoxis-based phytopharmaceutical formula

Ethnopharmacology relevance

Hypoxis species are used extensively in traditional medicine in southern Africa for several ailments including tuberculosis, chest infections, and nervous and urinary disorders. Several other claims have been made for extracts emanating from Hypoxis species and have led to the production of several commercial products used as immunostimulants mostly for people living with HIV/AIDS and cancer. This study was aimed at investigating the biological activity of four Hypoxis species and a commercial herbal product, ‘African potato extract’ (APE).

Materials and methods

Antibacterial, antifungal, cyclooxygenase (COX) and acetylcholineasterase (AChE) inhibitory activities of four Hypoxis species (H. acuminata, H. colchicifolia, H. hemerocallidea and H. rigidula) and a popular Hypoxis-based herbal preparation, APE were tested. The phytoconstituents of the mixture were also profiled using TLC methods. Several combinations of the Hypoxis species were prepared and their synergism, additive, autonomic and antagonism effects investigated. As a quality control measure, batch to batch comparison in the phytoconstituents and biological activity of APE was carried out.

Results

The results confirmed H. colchicifolia and H. hemerocallidea as the phytoconstituents of APE. The extracts showed a broad spectrum of activities against the bacterial and fungal strains used. Of particular interest were the activities exhibited by the APE and combinations of H. colchicifolia and H. hemerocallidea. The APE mixture exhibited good antibacterial activity (MIC values of 0.78 mg/ml each) in all the tested batches against the bacterial strains used. The water extracts of all four Hypoxis species, three batches of APE and the combination (water extracts) of H. colchicifolia and H. hemerocallidea exhibited high COX-1 and moderate COX-2 inhibitory activity except for H. acuminata which showed low activity against COX-2. All the extract, batches of APE and combinations showed low to moderate AChE inhibitory activity. These results provided some evidence of phytosynergy in some extracts of H. hemerocallidea and H. colchicifolia except for a few extracts which act as additive, autonomous and antagonistic when used to inhibit some bacterial and fungal strains. However, this was not the case for COX and AChE inhibition, as only acetone extracts acted in a synergistic way to reduce the activity of the enzyme.

Conclusion

Even though the results give an indication of a positive interaction between some extracts of H. hemerocallidea and H. colchicifolia, the study was carried out on 1:1 v/v combinations only. It is therefore important to carry out isobologram studies, which considers more than one ratio of the combinations.     

Antibacterial, antioxidant and fibroblast growth stimulation activity of crude extracts of Bridelia ferruginea leaf, a wound-healing plant of Nigeria

Aim of the study

Determination of pharmacological activity relevant to wound healing of Bridelia ferruginea leaf, a traditional medicine used to treat wounds in rural Nigeria.

Materials and methods

Aqueous and ethanolic leaf extracts were tested against bacterial species of relevance to wound infections: Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The ethanolic extracts were assessed for their ability to stimulate the growth of human dermal fibroblasts (FS5) and protect against damage induced by hydrogen peroxide. Antioxidant activity was also assessed using the DPPH assay.

Results

Both aqueous and ethanolic extracts had weak antibacterial activity (MIC > 470 μg/ml). A significant effect (p < 0.001) on the growth of FS5 fibroblasts was observed only at a concentration of 5 μg/ml (28% increase), above which the extracts appeared toxic to the cells. The ethanolic extract offered the highest protection against H₂O₂ damage to FS5 cells, comparable with catalase (82% at 250 μg/ml). The DPPH assay revealed antioxidant activity of the ethanolic leaf extract with IC₅₀ 12.5 ± 0.3 μg/ml comparable to l-ascorbic acid (7.3 ± 0.1 μg/ml).

Conclusion

The antibacterial, modest fibroblast stimulation activity and relatively strong antioxidant activity lend some support to the topical use of Bridelia ferruginea leaf for wound-healing in the traditional medicine of South-western Nigeria.     

Pharmacological potential and conservation prospect of the genus Eucomis (Hyacinthaceae) endemic to southern Africa

Ethnopharmacological relevance

The genus Eucomis (Hyacinthaceae) consists of 10 species that are extensively used in African traditional medicine. This review is an appraisal of current information on the distribution and morphology, traditional uses, pharmacology, toxicology and approaches devised to enhance the conservation of the genus.

Methods

A systematic and comprehensive literature search using electronic searches such as Scopus, Google Scholar, Web of Science and ethnobotanical books was conducted.

Results

Evidence from traditional medicine usage shows wide utilization of this genus for ailments such as respiratory, venereal diseases, rheumatism as well as kidney and bladder infections. Pharmacological screening reported antimicrobial, antiplasmodial, antitumor, cytotoxic, phytotoxic and anti-inflammatory properties.

Conclusions

The potential of the genus Eucomis especially in terms of pharmacology cannot be overemphasized. Apart from the anti-inflammatory properties, the antifungal activity of Eucomis remains a valuable reservoir with potential application in the agriculture sector as a source of an affordable biocontrol agent. Based on the speculated toxic constituents in the genus Eucomis, it will be valuable to conduct detailed toxicological studies. Extensive utilization of members of the genus Eucomis is causing severe strain on wild populations. Although conventional propagation has been relatively effective in the alleviation of the declining status, micropropagation of members may be vital to guarantee the conservation of wild populations.     

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

Aim of the study

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

Material and Methods

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

Results

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

Conclusion

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

Antimycobacterial,anti-inflammatory and genotoxicity evaluation of plants used for the treatment of tuberculosis and related symptoms in South Africa

Ethnopharmacological relevance

Emergence of drug-resistant tuberculosis strains and long duration of treatment has established an urgent need to search for new effective agents. The great floral diversity of South Africa has potential for producing new bioactive compounds, therefore pharmacological screening of plant extracts within this region offers much potential. To assess the in vitro antimycobacterial, anti-inflammatory and genotoxicity activity of selected plants that are used for the treatment of TB and related symptoms in South Africa.

Materials and methods

Ground plant materials from 10 plants were extracted sequentially with four solvents (petroleum ether, dichloromethane, 80% ethanol and water) and a total of 68 extracts were produced. A broth microdilution method was used to screen extracts against Mycobacterium tuberculosis H37Ra. The cyclooxygenase-2 (COX-2) enzyme was used to evaluate the anti-inflammatory activity of the extracts and the Salmonella microsome assay using two Salmonella typhimurium strains (TA98 and TA100) to establish genotoxicity.

Results

Six out of 68 extracts showed good antimycobacterial activity. Three extracts showed good inhibition (>70%) of COX-2 enzyme. All the extracts tested were non-genotoxic against the tested Salmonella strains.

Conclusion

The results observed in this study indicate that some of the plants such as Abrus precatorius subsp. africanus, Ficus sur, Pentanisia prunelloides and Terminalia phanerophlebia could be investigated further against drug-resistant TB strains.     

Antibacterial activity of the roots,stems and leaves of Alchornea floribunda

Ethnopharmacological relevance

Alchornea floribunda Müll. Arg. is used in traditional medicine across Africa for the treatment of bacterial, fungal, parasitic and inflammatory disorders.

Aim of the study

To evaluate the antibacterial activity of the crude extracts of different plant parts in order to provide a scientific rationale for the proposed broad efficacy of Alchornea floribunda in the treatment of bacterial infections.

Materials and methods

Extracts of roots, stems and leaves were prepared using solvents of various polarities in order to extract a wide range of phytochemicals. The antibacterial activity of these crude extracts was evaluated by micro-dilution assay, against Gram-positive (i.e. Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus and Staphylococcus saprophyticus) as well as Gram-negative (i.e. Escherichia coli, Klebsiella pneumoniae, Moraxella catarrhalis and Proteus mirabilis) bacteria.

Results

Generally, the ethanol (EtOH), methanol (MeOH), ethyl acetate (EtOAc) and chloroform (CHCl₃) extracts demonstrated the best activities, with the leaves exhibiting the highest average activity for six of the eight pathogens. Of these, the ethanolic leaf extract was the most active against Staphylococcus aureus with an MIC value of 50 µg/mL. Some other notable activity was observed for the ethyl acetate and chloroform root extracts against Staphylococcus aureus (50 µg/mL), and for selected stem extracts against Staphylococcus aureus (50 µg/mL), Klebsiella pneumoniae (63 µg/mL) and Staphylococcus saprophyticus (63 µg/mL).

Conclusion

This study demonstrates the promising antibacterial activity of Alchornea floribunda against both Gram-positive and Gram-negative bacteria responsible for gastrointestinal, skin, respiratory and urinary ailments, and validates its use in the ethnopharmacology of the region.     

The antimicrobial,antioxidative, anti-inflammatory activity and cytotoxicity of different fractions of four South African Bauhinia species used traditionally to treat diarrhoea

Ethnopharmacological importance

Many Bauhinia species, including those indigenous to South Africa, are used in traditional medicine across the world for treating ailments such as gastrointestinal tract (GIT) disorders, diabetes, infectious diseases and inflammation.

Aims

Several relevant aspects of different fractions of leaf extracts of Bauhinia bowkeri (BAB), Bauhinia galpinii (BAG), Bauhinia petersiana (BAP), and Bauhinia variegata (BAV) used in South African traditional medicine to alleviate diarrhoea related symptoms were evaluated.

Materials and Methods

The antioxidative activities of the extracts were determined using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS⁺) radical scavenging and ferric reducing antioxidant power (FRAP) methods. In vitro antimicrobial activities of the extracts were determined against bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis) and clinical isolates of the opportunistic fungal strains (Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans) using a serial dilution microplate method. The polyphenolic contents were quantified using standard methods, and anti-inflammatory activities of the crude extracts were determined using the cyclooxygenase and soybean 15-lipoxygenase enzyme inhibitory assays. The safety of the extracts was evaluated by determining the cytotoxicity against Vero cell lines.

Results

The acidified 70% acetone crude extract and their fractions had good antiradical potency against the DPPH and ABTS radicals. The methanol soluble portions of the butanol fractions were more potent (EC₅₀ ranges from 0.64±0.05 to 1.51±0.07 and 0.88±0.18 to 1.49±0.09 μg/ml against DPPH and ABTS radical respectively) compared to the standard, trolox and ascorbic acid (EC₅₀ ranges from 1.47±0.24 to 1.70±0.27 μg/ml) for both DPPH and ABTS. The crude extracts contained variable quantities of phenolic content. The crude extracts and their fractions had weak to good antimicrobial activities, inhibiting the growth of the organisms at concentrations ranging from 39 to 2500 μg/ml. The BAG crude extract and its fractions were the most active against the fungi (MICs ranging from 39 to 625 μg/ml) while the BAB extract and its fractions were the least active with the MICs ranging between 39 and 2500 μg/ml. Aspergillus fumigatus was the least susceptible fungus while Cryptococcus neoformans was the most susceptible.The phenolic-rich crude extracts of BAB, BAG, and BAP had moderate to good dose-dependent cyclooxygenase-1 enzyme inhibitory activity with inhibitions between 22.8% and 71.4%. The extracts were however, inactive against cyclooxygenase-2. The extracts had some level of cytotoxicity towards Vero cell lines, reducing cell viability to less than 10% at concentrations more than 50 μg/ml.

Conclusion

The biological activities observed in Bauhinia species provide a scientific basis for the use of the plants in traditional medicines to treat diseases with multi-factorial pathogenesis such as diarrhoea, with each aspect of activity contributing to the ultimate therapeutic benefit of the plants. However, the use of the phenolic-rich extracts of these plants to treat diarrhoea or any other ailments in traditional medicine needs to be monitored closely because of potential toxic effects and selective inhibition of COX-1 with the associated GIT injury.