Ultrastructure changes induced by the phloroglucinol derivative agrimol G isolated from Leucosidea sericea in Haemonchus contortus.

Plant extracts used for the treatment of helminth infections in sheep are an alternative to chemical anthelmintic drugs. Previous studies have reported the anthelmintic activity of acetone leaf extracts of Leucosidea sericea. For this study, we evaluate the ultrastructure changes induced by the acetone leaf extract of L. sericea and the component agrimol G (AG) that was isolated for the first time on adult haemonchus parasites. Adult haemonchus parasites harvested from sheep were incubated with the plant extract and AG for 3 h and evaluated by both scanning and transmission electron microscopy in comparison and in combination with albendazole or ivermectin. In all cases the method of evaluation shows ultrastructural changes, with albendazole inducing mitochondrial damage and ivermectin inducing muscle degeneration, both as previously described. Incubation with the plant extract and AG resulted in the formation of numerous non-membrane bound multi-vesicular like bodies and evenly spread disruptions/erosion in the epicuticle. Combining AG with ivermectin or albendazole resulted in an absence of effect of AG. Based on the structural changes induced by AG, together with the absence of an effect in combination with ivermectin and albendazole would suggest a disrupted microtubular network. The latter does however require biochemical confirmation.

Evaluation of six plant species used traditionally in the treatment and control of diabetes mellitus in South Africa using in vitro methods.

CONTEXT: Numerous plants are used by the local communities of South Africa for the treatment and management of type II diabetes. OBJECTIVES: For this study, we undertook a survey of the plants sold for the management of diabetes in the town of Newcastle, South Africa. Identified plants were subsequently evaluated for their in vitro antidiabetic activity. MATERIALS AND METHODS: Plants were identified through an interview with a herbalist at the market. Antidiabetic activity of extracts of purchased plants was evaluated using in vitro α-amylase and α-glucosidase activity, as well as islets of Langerhans excretory activity. RESULTS: Senna alexandrina Mill. (Fabaceae), Cymbopogon citrates Stapf. (Poaceae), Cucurbita pepo L. (Cucuribitaceae), Nuxia floribunda Benth. (Stilbaceae), Hypoxis hemerocallidea Fisch. and Mey (Hypoxidaceae), and Cinnamomum cassia Blume (Lauraceae) were identified. The hexane extract of S. alexandrina (EC50=0.083 mg/ml), ethyl acetate extract of H. hemerocallidea (EC50=0.29 mg/ml), and methanol extracts of Cymbopogon citratus (EC50=0.31 mg/ml) and Cinnamomum cassia (EC50=0.12 mg/ml) had the highest α-amylase inhibitory activity, albeit lower than acarbose (EC50=0.50 mg/ml). All the plants had good α-glucosidase inhibitory activity (>50%) with the exception of some methanol (Cinnamomum cassia, N. floribunda, and Cymbopogon citratus) and acetone extracts (Cucurbita pepo and N. floribunda). Only the H. hemerocallidea acetone extract had an insulin stimulatory effect (2.5 U/ml at 8 µg/ml). CONCLUSION: All the evaluated plants demonstrated inhibitory activity against the specific GIT enzyme systems evaluated. Only H. hemerocallidea had insulin secretory activity, adding evidence to the traditional use of these purchased plants in the management of the type II diabetic post-prandial hyperglycemia.

Verification of the folkloric and anecdotal antidiabetic effects of Hypoxis hemerocallidea (Fisch., C.A. Mey. & Avé-Lall) and isolated, ß-sitosterol using early-stage type II spontaneous diabetic mutant BKS-Leprdb mice.

BACKGROUND: Previous studies in our laboratory in ex vivo assays have demonstrated H. hemerocallidea extract as potential antidiabetic agent through increased insulin release from pancreatic beta cells. Thus, for this study the early stage type II spontaneous diabetic mutant mice model was used to evaluate and determine the degree of the antidiabetic efficacy of H. hemerocallidea. METHODS: Eight-weeks-old type II spontaneous pre-diabetic mutant BKS-Leprdb mice were fed with feed supplemented with either H. hemerocallidea extract, isolated compound (ß-sitosterol) or chlorpropamide (positive control) for 4 weeks. The haematological parameters, clinical chemistry, glucose tolerance, feed intake, faecal output and body weights were measured. RESULTS: The blood glucose concentrations of all the animals treated with plant extract, ß-sitosterol compound and non-treated pre-diabetic animals did not return to baseline levels. Only the ß-sitosterol treatment and positive control groups resulted in a respective small decrease of 5.8 and 5.2% in the mouse weights over the study period, with no significant changes (p > 0.05) in food intake. However, there was a general trend for decrease in faecal output for all the groups. Albumin, triglycerides, and total cholesterol levels in ß-sitosterol and chlorpropamide-treated animals were lower, relative to untreated-animals. Animals fed with plant extract showed large amounts of internal fat. There were no significant changes (p > 0.05) in total serum protein, globulin, alanine aminotransferase, alkaline phosphatase, urea nitrogen and creatinine attributed to administration of treatments. In all groups, some animals showed lesions associated with cardiac puncture. Few animals except animals treated with plant extract, showed presence of a left-ventricular hypertrophic cardiomyopathy. The liver and kidneys for all groups appeared macroscopically normal and the thymuses were small (±2 mg). There were pathological signs in some of the animals particularly in myocardial fibres, renal tubular, glomerular, hepatocyte granularity and pancreas islets. However, there was no significance trend between the groups. CONCLUSION: Based on the results, none of the treatments could be considered highly effective for the management of type II pre-diabetes as sole therapeutic intervention.

Anthelminthic activity of acetone extract and fractions of Vernonia amygdalina against Haemonchus contortus eggs and larvae.

The current control of parasitic nematodes in small ruminants relies on the use of chemical anthelminthics, but the development of resistance and the problem of drug residues require research into alternatives. Acetone extract and solvent-solvent fractions of Vernonia amygdalina Del. (Compositae) were evaluated in vitro for potential anti-parasitic effects against the eggs and larvae of Haemonchus contortus. Significant effects were obtained with the extract and fractions but differences were observed depending on the parasitic stage. The acetone extract and fractions inhibited egg hatching and inhibited larval development and killed larvae of H. contortus in a concentration-dependent manner. Best-fit 50% lethal concentration (LC(50)) values were 957.0, 76.0, 524.0, 309.0 and 224.0 µg/ml for the acetone extract, and the butanol, hexane, chloroform and 35% water in methanol fractions, respectively, when tested against nematode eggs. Best-fit LC(50) values for the larval viability test were 508.2, 485.5, 569.3, 348.9 and 196.6 µg/ml for the acetone extract, and the butanol, hexane, chloroform and 35% water in methanol fractions, respectively. The butanol fraction was most active against nematode eggs while the 35% water in methanol fraction was the most active on nematode larvae, although differences in activity between fractions were not significant (p > 0.05). Overall, these in vitro results suggest that V. amygdalina, traditionally used by small farmers in Western Africa, does possess anti-parasitic properties.

Ovicidal and larvicidal activity of Cassia alata leaf acetone extract and fractions on Haemonchus contortus: in vitro studies.

CONTEXT: The failure of modern anthelmintics to control nematode parasites of sheep and goats is a reality on many farms in the tropical/subtropical regions of the world. This necessitates chemotherapeutic control alternatives and plant secondary metabolite with activity is one of those potential solutions. OBJECTIVE: This study was design to evaluate the efficacy of solvent: solvent fractions of Cassia alata Gelenggang Besar (Leguminosae) leaf acetone extract against Heamonchus contortus Rudolphi (Trichostrongylidae). MATERIALS AND METHODS: C. alata leaf was extracted with 70% acetone and fractions were obtained by solvent: solvent group separation procedures. The acetone extract and the fractions were tested by egg hatch assay (EHA) and larval development and viability assay to assess relative bioactivity against H. contortus eggs and larvae. RESULTS: The extracts inhibited egg hatchability and killed infective larvae of H. contortus in a concentration-dependent manner. The best-fit LC(50) values were 0.562, 0.243, 0.490, 0.314, and 0.119 mg/mL for the acetone extract, chloroform, hexane, butanol and 35% water in methanol fractions, respectively, when tested against nematode eggs. The best-fit LC(50) values were 0.191, 0.505, 1.444, 0.306, and 0.040 mg/mL for acetone extract, chloroform, hexane, butanol and 35% water in methanol fractions, respectively, when tested against larvae. The 35% water in methanol fraction was the most active against the larvae and eggs of H. contortus demonstrating the lowest LC(50) values DISCUSSION AND CONCLUSION: This study demonstrates that the leaf extracts of C. alata have anthelmintic activity; therefore it could find application in the control of helminths in livestock.

In-vitro anthelminthic activity of crude aqueous extracts of Aloe ferox, Leonotis leonurus and Elephantorrhiza elephantina against Haemonchus contortus.

Aloe ferox (Mill), Leonotis leonurus (L) R. BR; and Elephantorrhiza elephantina (Burch.) Skeels are plants frequently used by resource-limited farmers in the Eastern Cape Province to control gastrointestinal parasites in goats. A study was conducted to validate their anthelminthic activities in-vitro on the egg and larvae of the nematode parasite Haemonchus contortus. The crude aqueous extracts of leaves of A. ferox and L. leonurus; and roots of E. elephantina were used. Eggs and larvae of the parasite were incubated at 25 degrees C in aqueous extracts at concentrations of 0.625-20 mg/ml for 48 h and 7 days for the egg hatch and larval development assays respectively. Albendazole and water were the positive and negative controls respectively. Inhibition of egg hatching and larval development increased significantly (P < 0.05) with increasing concentrations of the extracts. E. elephantina and L. leonurus extracts had 100% egg hatch inhibition at concentration as low as 2.5 mg/ml and 1.25 mg/ml respectively, whereas A. ferox extracts had 100% inhibition at concentrations of 20 mg/ml. At the lowest concentration tested (0.625 mg/ml), E. elephantina inhibited egg hatching >96% and this was comparable to albendazole at the same concentration. E. elephantina and L. leonurus also totally inhibited larval development at concentrations of 1.25 mg/ml. The study provided evidence that A. ferox, E. elephantina and L. leonurus extracts possess anthelminthic activity, thus justifying their use in the treatment of GI helminthosis. There is however need to assess the safety of these plants in vivo and also to undertake in vivo efficacy studies.

Antifungal efficacy of ten selected South African plant species against Cryptococcus neoformans.

Fungal infections are a major threat to public health care. Cryptococcosis in humans and animals, caused by Cryptococcus neoformans, is a life-threatening disease. In a random antifungal screening of acetone leaf extracts of 400 tree species against Cryptococcus neoformans, the following plant species had good activity: Zanthoxylum capense (Thunb.) Harv. (Rutaceae), Morusmesozygia Stapf (Moraceae), Calodendrum capense (L.f.) Thunb. (Rutaceae), Catha transvaalensis Codd (Celastraceae), Cussonia zuluensis Strey (Araliaceae), Ochna natalitia (Meisn.) Walp. (Ochnaceae), Croton sylvaticus Hochst. ex C. Krauss (Euphorbiaceae), Maytenus undata (Thunb.) Blakelock (Celastraceae), Celtis africana Burm.f. (Ulmaceae), and Cassine aethiopica Thunb. (Celastraceae). Hexane, dichloromethane, acetone, and methanol extracts of these 10 plants were tested against Cryptococcus neoformans using bioautography and microdilution assays. Acetone extracted the highest quantity of plant material. Dichloromethane and hexane extracts of Maytenus undata showed clear bands in bioautography while the other species did not produce good results in bioautography. Maytenus undata extracts had promising antifungal activity against C. neoformans, with average minimum inhibitory concentration (MIC) of 0.09 mg/mL after 24 h and 0.18 mg/mL after 48 h incubation. Croton sylvaticus and Catha transvaalensis extracts also had good activity, with average MIC values of 0.07 mg/mL and 0.09 mg/mL, respectively. Because of the clear bands on bioautograms and low MIC values compared to the other plant species investigated, M. undata was identified as a good candidate for further studies.

Evaluation of selected South African plant species for antioxidant, antiplatelet, and cytotoxic activity.

The antioxidant, antiplatelet, and cytoxoxic effects of seven South African plant extracts, namely, Combretum vendae A.E. van Wyk (Combretaceae), Commiphora harveyi (Engl.) Engl. (Burseraceae), Khaya anthotheca (Welm.) C.DC (Meliaceae), Kirkia wilmsii Engl. (Kirkiaceae), Loxostylis alata A. Spreng. ex Rchb. (Anacardiaceae), Ochna natalitia (Meisn.) Walp. (Ochnaceae), and Protorhus longifolia (Bernh. Ex C. Krauss) Engl. (Anacardiaceae), were evaluated using established in vitro assays. All the extracts showed comparably low toxicity except for the extract of C. harveyi that showed high hemagluttination assay titer value, which indicates toxicity. The extracts of P. longifolia, K. wilmsii, O. natalitia, L. alata, C. harveyi, and C. vendae exhibited antioxidant properties in the qualitative assay using DPPH. In the quantification of antioxidation using ABTS, only the extracts of P. longifolia, L. alata, and C. vendae showed antioxidant activity with respective TEAC values of 1.39, 1.94, and 2.08. Similarly, in the quantitative DPPH assay, L. alata (EC50, 3.58+/-0.23 microg/mL) and K. wilmsii (EC50, 3.57+/-0.41 microg/mL) did not differ significantly (p

In vivo antifungal effect of Combretum and Terminalia species extracts on cutaneous wound healing in immunosuppressed rats.

Acetone leaf extracts of Combretaceae species Combretum imberbe Wawra, Combretum nelsonii Duemmer, Combretum albopunctatum Suesseng, and Terminalia sericea Burch ex DC and a mixture of asiatic acid and arjunolic acid isolated from C. nelsonii were tested for antifungal activity against Candida albicans, Cryptococcus neoformans, Microsporum canis, and Sporothrix schenckii on wounds of immunocompromised Wistar rats. The therapeutic agents were selected based on low MIC values ranging 0.02-2.5 mg/mL and low toxicity (LC50) ranging 75.7-168.6 microg/mL. Seven circular, full-thickness wounds were made on the back skin of 24 Wistar rats, under general anesthetic and using an aseptic technique. Rats were infected with different fungal pathogens in groups of six. The treatments were administered topically using 20% concentrations of each extract in aqueous cream. Amphotericin B was used as positive control. Erythema, exudate, crust formation, swelling, and ulceration were used to determine the wound healing process. Throughout the experiment, body temperature, measured using a subcutaneous probe, and weight of the rats were found to be within normal ranges. Epithelial closure in all rats occurred by 17 days. There was no significant difference in contraction of the lesion areas treated with different extracts. The variability in erythema at each lesion in rats infected with different fungal pathogens differed with treatments; the lesion without treatment took a longer time to heal in all cases. Exudate formation was observed until day 12 in rats infected with C. albicans and day 8 in rats infected with C. neoformans. In lesions infected with M. canis and S. schenckii, exudate formation was observed until day 10. The treated group presented a rigid, dark, and thick crust formation after day 3 until day 15. During histopathological evaluations, scant fungi were noted in all the wounds, indicating that infection had occurred but had generally cleared. The antifungal potential of crude extracts of selected plants and a mixture of asiatic acid and arjunolic acid on the wounds of immunocompromised rats was confirmed. The extracts of these plants may possibly be further developed into drugs for topical treatment of fungally infected wounds.

Antimycoplasmal activity of some plant species from northern Nigeria compared to the currently used therapeutic agent.

CONTEXT: Mycoplasma spp. are obligate parasites of humans and animals. But due to the special requirements needed to culture Mycoplasma in the laboratory, little or no research has been done to evaluate the efficacy of medicinal plants on the organism. OBJECTIVE: To screen medicinal plants traditionally used to treat infections for possible antimycoplasmal and cytotoxic activities. MATERIALS AND METHODS: Acetone extracts of 21 Nigerian medicinal plants were analyzed for antimycoplasmal and cytotoxicity activities using the metabolic inhibition and colorimetric methods, respectively. The extract with the best antimycoplasmal activities was also analyzed for its phytochemical constituents using the desktop method. RESULTS: Calotropis procera (Aiton) R.Br (Asclepiadaceae) extract had the best antimycoplasmal effect with a minimum inhibitory concentration (MIC) of 80 µg/mL and minimum mycoplasmacidal concentration (MMC) of 160 µg/mL. This extract contained saponins, tannins, cardiac glycosides, alkaloids, and flavonoids. The extract of Vernonia amygdalina Delile (Compositae) was the most cytotoxic with median lethal concentration (LC(50)) of approximately 17 µg/mL, and that of Anacardium occidentale L. (Anacardiaceae) was the least cytotoxic with an LC(50) of approximately 1919 µg/mL. DISCUSSION: Calotropis procera is a promising plant for an alternative antimycoplasmal agent because the crude acetone extract had a higher mycoplasmacidal activity than the conventional drug tylosin, which is currently used in treatment of the disease in Nigeria. CONCLUSION: The crude extract of Calotropis procera is worth investigating for the development of a potent agent against cattle Mycoplasma, which has long defied solution by conventional chemotherapy.

The use of a semiochemical bait to enhance exposure of Amblyomma variegatum (Acari: Ixodidae) to Metarhizium anisopliae (Ascomycota: Hypocreales).

Experiments were conducted to explore the use of a semiochemical bait to enhance exposure of Amblyomma variegatum Fabricius (Acari: Ixodidae) to different formulations of the entomopathogenic fungus Metarhizium anisopliae (Metsch.) Sorok. (Ascomycota: Hypocreales). Initially, the relative efficacies of attraction-aggregation-attachment pheromone (AAAP), made up of o-nitrophenol, methyl salicylate and nonanoic acid in the ratio 2:1:8, 1-octen-3-ol and butyric acid, were evaluated in an olfactometer. Only AAAP and 1-octen-3-ol were found to elicit attractive responses to the tick. Simultaneous release of 1-octen-3-ol and AAAP together with CO(2) from a trap in semifield plots attracted up to 94.0+/-6% of adult ticks from a distance of 6m, and up to 24.0+/-5.1% from 8m. Formulations of M. anisopliae (dry powder, oil, and emulsifiable) applied within the trap baited with AAAP, 1-octen-3-ol and CO(2) resulted in high levels of contamination of the ticks attracted to the traps. However, 48h after autoinoculation, 89.1 and 33.3% of conidia were lost in dry powder and oil formulations, respectively. Emulsifiable formulation showed least loss of propagules (17.1%). Samples of ticks attracted to the baited traps were transferred to plastic basins containing grass and maintained for 5 weeks. The experiment was conducted in rainy and dry seasons. Emulsifiable formulation gave the highest relative tick reduction in both seasons: 54.7 and 46.5% in rainy and dry seasons, respectively, followed by oil formulation (32.0 and 23.8%) and powder formulation (38.0 and 24.4%).

Curtisia dentata (Cornaceae) leaf extracts and isolated compounds inhibit motility of parasitic and free-living nematodes.

Haemonchus contortus and Trichostrongylus colubriformis are among the most important parasitic nematodes of small ruminants. Caenorhabditis elegans, a free-living nematode, is used as a model for evaluating anthelmintic activity of a variety of test substances. Extracts of several medicinal plants are useful in vitro and in vivo against nematode development. Extracts of Curtisia dentata, a South African medicinal plant, and compounds isolated from leaves of this plant were investigated for anthelmintic activity against T. colubriformis, H. contortus and C. elegans. The acetone and dichloromethane extracts were active against all nematodes at concentrations as low as 160 microg/ml. Betulinic acid and lupeol were active against the parasitic nematodes only at the high concentrations of 1000 and 200 microg/ml, respectively. All compounds were effective against C. elegans with active concentrations as low as 8 microg/ml. Betulinic acid was less active than lupeol and ursolic acid against C. elegans. The acetone and dichloromethane extracts were also active against C. elegans with a concentration of 0.31 mg/ml resulting in almost 80% inhibition of larval motility. The use of free-living nematodes may provide information on the activity of potential anthelmintics against parasitic nematodes. Extracts of various medicinal plant species may provide solutions to ill-health of small ruminants caused by parasitic nematodes in poor communities of southern Africa.

The value of plant extracts with antioxidant activity in attenuating coccidiosis in broiler chickens.

Coccidiosis remains one of the most important diseases in the poultry industry and results in the annual loss of millions of US dollars by the poultry industry. In South Africa and other developing countries where a large percentage of the population is unemployed, cheap food production is necessary. If the control of the coccidian parasite could be made more economical, these savings could be passed on to the consumer. In Europe, where the economics are different, people are becoming more aware of the potential dangers of using antimicrobials in producing animal protein. A solution to both these problems could be the use of plant products that function by mechanisms other than those of chemotherapeutics, with the additional advantage of a natural origin. Antioxidant compounds could hold promise for the control of Eimeria infections due to the association of coccidial infection with lipid peroxidation of the intestinal mucosa. Four plant extracts with antioxidant activity were screened for their anticoccidial activity in vivo with toltrazuril as the positive control. Combretum woodii (160 mg/kg) proved to be extremely toxic to the birds, while treatment with Tulbaghia violacea (35 g/kg), Vitis vinifera (75 mg/kg) and Artemisia afra (150 mg/kg) resulted in feed conversion ratios similar to toltrazuril, and higher than the untreated control. T. violacea also significantly decreased the oocyst production in the birds. From this study we conclude that antioxidant-rich plant extracts have potential benefits in treating coccidial infections. The promising results obtained with T. violacea justify further studies on the potential value of the plant as a therapeutic or prophylactic anticoccidial agent.

Ethnoveterinary use of southern African plants and scientific evaluation of their medicinal properties.

AIM OF THE STUDY: Livestock keepers in many developing countries with restricted access to orthodox veterinary healthcare services commonly use traditional remedies to treat their animals when disease is encountered. This review collates the documented use of plants in South Africa for healing various ailments in domestic animals, and records bioactivity testing that has been carried out on these plants. MATERIALS AND METHODS: A literature survey was conducted on the use of plants in South African ethnoveterinary medicine (EVM), as well as on biological activity investigations relating to their ethnoveterinary use where available. RESULTS: The ethnoveterinary application of plants, and results of screening studies of EVM plant extracts in various bioassays is presented. For diseases such as coughs, wounds, skin diseases, mild diarrhoea and reproductive disorders, EVM may be a cheap and easily accessible alternative to expensive pharmaceuticals. Studies on biological activity of EVM plants can provide indications of promising leads for extracts that can be developed into standardized medications to be used on a commercial basis. Isolation studies on active plants may yield pure active compounds that could be chemically modified to optimize medicinal value and reduce possible toxic effects. CONCLUSION: In South Africa, a large proportion of the population relies on traditional remedies to treat themselves and their animals for common diseases. Only a small percentage of EVM plants have been analysed for biological activity or toxic effects, and hence research in this field offers fertile possibilities for future investigation.

The biological activity and chemistry of the southern African Combretaceae.

AIM OF THE STUDY: Members of the Combretaceae family are widely traded in the traditional medicine market in southern Africa. The family is also used for medicinal purposes in the rest of Africa and Asia for close to 90 medicinal indications. Many of these indications are related to treating infections. This contribution summarizes work done to date and identifies avenues for future research. MATERIALS AND METHODS: Substantial work has already been done on the chemistry of especially Combretum and Terminalia species over many years. During the last decade we have focussed on bio-assay guided isolation of biologically active compounds with the aim of producing new effective antimicrobial products. RESULTS AND DISCUSSION: Methods developed to facilitate this process and data on 25 compounds isolated from 7 species are presented. The large majority of compounds isolated were known, but the biological activities were not known. In practically all cases the antibacterial or antifungal activity of compounds isolated were much lower than expected from the activity of the crude extracts. It appears that synergism plays a role in antimicrobial activity of plant extracts and that the hope of isolating a single compound that can be used as a new agent to address antibiotic resistance has been frustrated. By simple manipulation such as selective extraction the activity of some crude extracts could however, be increased substantially and this offers a new approach to address antibiotic resistance via the herbal medicine industry. Practically all extracts obtained using intermediate polarity extractants had reasonable to very good activity with MICs as low as 40 microg/ml, validating the traditional use for infectious diseases. Aqueous extracts however, generally had hardly any activity. CONCLUSIONS: The Combretaceae contains a diversity of antimicrobial compounds. Because poor people usually have only water available as extractant, it raises the question how plants growing in poor rural communities can be used to treat infections more effectively, and what the mechanism of activity of aqueous extracts used to treat infections in traditional medicine are.

The potential of South African plants against Mycobacterium infections.

ETHNOPHARMACOLOGICAL RELEVANCE: In South Africa, tuberculosis (TB) caused by Mycobacterium tuberculosis is the most commonly notified disease and the fifth largest cause of mortality, with one in ten cases of TB resistant to treatment in some areas. Many plants are used locally in traditional medicine to treat TB-related symptoms. AIM OF THE STUDY: The aim was to summarize currently available knowledge on South African plants used to treat TB symptoms, and antimycobacterial efficacy of plant-derived extracts and compounds. MATERIALS AND METHODS: The traditional uses of plants for respiratory ailments and TB were collated and tabulated. The antimycobacterial activity tests of extracts and chemical constituents of several of these plants and others using different methods and target organisms were summarized. RESULTS: Almost 180 plants used for TB-related symptoms in South African traditional medicine were documented. About 30% of these have been tested for antimycobacterial efficacy, mostly against fast-growing, non-pathogenic Mycobacterium species. CONCLUSIONS: Many plant species are used in traditional South African medicine to alleviate symptoms of TB, and several interesting leads have originated for further inquiry following in vitro antimycobacterial activity evaluation. However, much work remains to be done on the systematic assessment of anti-TB efficacy of local plants against pathogenic Mycobacterium species, both in vitro and in vivo.

Four pentacyclic triterpenoids with antifungal and antibacterial activity from Curtisia dentata (Burm.f) C.A. Sm. leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Curtisia dentata is used in southern Africa to treat various diseases of bacterial and fungal origin in humans and animals to such a degree that the species is vulnerable and declining [Dold, A.R., Cocks, M.L., 2001. Traditional veterinary medicine in the Alice district of the Eastern Cape Province, South Africa. South African Journal of Science 97, 375-379]. Preliminary studies indicated good activity against Candida albicans. AIM OF THE STUDY: The phytochemistry and antimicrobial activity of this plant species has not been extensively investigated, and a closer examination of the compounds responsible for antimicrobial activity was warranted. MATERIALS AND METHODS: Broth microdilution assay and bioautography were used to evaluate antibacterial and antifungal activity in Curtisia dentata leaf extracts and fractions. Bioassay-directed fractionation using column chromatography yielded four compounds characterised by spectroscopic methods. RESULTS: Lupeol (1), betulinic acid (2), ursolic acid (3) and 2alpha-hydroxyursolic acid (4) were isolated from Curtisia dentata leaves. Betulinic acid, ursolic acid and 2alpha-hydroxyursolic acid appreciably inhibited fungal growth with MIC values ranging from 8 to 63mug/mL. CONCLUSIONS: The isolation of four antibacterial and antifungal triterpenoids is reported for the first time from Curtisia dentata. This study provides information on the antimicrobial compounds of this species, as well as a preliminary rationale for the use in traditional South African medicine.

Evaluation of Athrixia bush tea for cytotoxicity, antioxidant activity, caffeine content and presence of pyrrolizidine alkaloids.

In South Africa, Athrixia phylicoides DC. (bush tea) is widely used as a beverage, cough remedy and purgative. The commercialization of this tea in a similar vein to rooibos (Aspalathus linearis), is being considered. Traditional infusions and decoctions, as well as water and ethanol extracts, were prepared and screened. A related species, Athrixia elata Sond. (daisy tea), was included in many of the assays as a comparison. Extracts of Athrixia phylicoides and Athrixia elata were tested for toxic effects to brine shrimp larvae and the Vero kidney cell line. In both assays, the traditional preparations and aqueous extracts had little effect, but the ethanol extracts were relatively toxic. Antioxidant activity comparable to that found in rooibos was established. No detectable levels of caffeine were present in the Athrixia extracts following analysis using TLC and I/HCl spray reagent. Neither screening using spectrophotometry nor confirmation using gas chromatography-mass spectrometry analyses showed evidence of pyrrolizidine alkaloids in Athrixia phylicoides. Although a wider range of studies needs to be conducted prior to commercialization, these results support the development of bush tea as a healthy alternative to caffeine-containing beverages.

Antimicrobial and anti-inflammatory activity of four known and one new triterpenoid from Combretum imberbe (Combretaceae).

Combretum imberbe is used widely in Africa inter alia for treating bacterial infections. In addition to four known triterpenoids, 1alpha,3beta-dihydroxy-12-oleanen-29-oic (1), 1-hydroxy-12-olean-30-oic acid (2), 3,30-dihydroxyl-12-oleanen-22-one (3), and 1,3,24-trihydroxyl-12-olean-29-oic acid (4), a new pentacyclic triterpenoid (1alpha,23-dihydroxy-12-oleanen-29-oic acid-3beta-O-2,4-di-acetyl-L-rhamnopyranoside) 5 has been isolated through a bioassay-guided procedure from the leaves of Combretum imberbe. The structures of the compounds were elucidated on the basis of 1D and 2D NMR experiments, as well as mass spectrometric data. All compounds isolated had moderate (62 microg/ml) to strong (16 microg/ml) antibacterial activity (MIC values) against Staphylococcus aureus and Escherichia coli, with 1 and 5 being most active. Compounds 1 and 5 also showed very strong inhibition of 3alpha-hydroxysteroid dehydrogenase with an IC(50) of 0.3 microg/ml. Compound 5 indicated a moderate anti-proliferative (GI(50)=16.5 and 13.2 microg/ml) and cytotoxic activity (CC(50)=17.6 micro/ml) against K-562, L-929 and HeLa cell lines, respectively. The results of this study give credence to the ethnomedicinal use of Combretum imberbe and expand our knowledge on the biological activity of its metabolites.

In vitro anthelmintic, antibacterial and cytotoxic effects of extracts from plants used in South African ethnoveterinary medicine.

Many plants are used for ethnoveterinary purposes in South Africa, particularly in rural areas. Extracts of 17 plant species employed to treat infectious diseases were prepared using three solvents and the antibacterial activity of the extracts was determined against two Gram-positive and two Gram-negative bacteria. Anthelmintic activity was evaluated against the free-living nematode Caenorhabditis elegans and toxicity was determined using the brine shrimp larval mortality test. Most of the plant extracts demonstrated antibacterial activity, with the best minimum inhibitory concentration (MIC) being 0.1 mg mL(-1). More than a third of the extracts displayed anthelmintic activity. Toxic effects against brine shrimp larvae were shown by 30% of extracts, with the lowest LC(50) recorded as 0.6 mg mL(-1). The promising biological activity displayed by a number of plant extracts supports the ethnoveterinary use of these plants but in vivo tests are required to ascertain fully their medicinal properties and potential toxicity.