Invasive alien plants and weeds in South Africa: A review of their applications in traditional medicine and potential pharmaceutical properties.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional pharmacopoeias are constantly evolving and adapting, hence the assimilation of alien plants and weeds into traditional systems of healing. Invasive plants are detrimental to the ecosystem, however they are also potential sources of secondary metabolites with useful biological activities. AIM OF THE REVIEW: The aim of this review was to investigate published reports of traditional use and biological activity of declared invasive alien plants and other weeds in South Africa. MATERIALS AND METHODS: Information was retrieved from scientific databases including Scopus, Web of Science, ScienceDirect, Google Scholar, PubMed, Chemical Abstracts Services and books, theses, dissertations and technical reports. Keywords used for the search engines were "South Africa" or "southern Africa" in conjunction with "(native weeds OR alien invasive)" AND "medicinal". Separate searches were conducted on the individual invasive plant species recorded as having been used in ethnobotanical surveys to determine their known biological activities and chemical components. RESULTS: A total of 89 plant species regarded as invasive species or weeds in South Africa were identified as being used in traditional medicine. The most commonly mentioned plant family was the Asteraceae with a total of 15 species followed by the Fabaceae and Solanaceae with 6 species each. Of the 89 species recorded, 68% were reported to have traditional usage with both phytochemical and biological data available. A history of traditional usage coupled with biological data was available for 12% of species. Records of traditional usage alone were linked to 11% of species. Invasive alien species comprised 61% of recorded species, while native and non-invasive alien weeds formed the remaining 39%. CONCLUSIONS: The exploration of alternative uses for weeds and particularly invasive plants, whether native or alien, as medicines for possible commercialisation may lead to innovative mechanisms for putting such species to good use.

Bioassay-guided purification, GC-MS characterization and quantification of phyto-components in an antibacterial extract of Searsia lancea leaves.

Phytocompounds in an aqueous methanol (70% MeOH) leaf extract of Searsia lancea were separated using liquid-liquid partitioning techniques and gravity-assisted column chromatography. The resultant fractions were screened for antibacterial properties (minimum inhibitory concentration, MIC) against four bacterial strains (Enterococcus faecalis, Klebsiella pneumoniae, Neisseria gonorrhoeae and Staphylococcus aureus). Bioactive fractions were purified using preparative thin layer chromatography (TLC) and subjected to further antibacterial screening. Phytocompounds in antibacterial sub-fractions were characterized and quantified using Gas Chromatography-Mass Spectrometry (GC-MS). An ethyl acetate sub-fraction purified from the aqueous methanol extracts of the leaves demonstrated potent antibacterial properties (MIC range: 31-61 µg/ml against E. faecalis and S. aureus). Based on GC-MS analysis, 81.5% of the sub-fraction consisted of broad-spectrum antibacterial compounds namely tetracosanol (43.98%) and nonadecanol (37.5%). Current research findings support the traditional use of S. lancea leaves to manage gastro-intestinal disorders and gonorrhoea.

Strigolactones and their crosstalk with other phytohormones.

BACKGROUND: Strigolactones (SLs) are a diverse class of butenolide-bearing phytohormones derived from the catabolism of carotenoids. They are associated with an increasing number of emerging regulatory roles in plant growth and development, including seed germination, root and shoot architecture patterning, nutrient acquisition, symbiotic and parasitic interactions, as well as mediation of plant responses to abiotic and biotic cues. SCOPE: Here, we provide a concise overview of SL biosynthesis, signal transduction pathways and SL-mediated plant responses with a detailed discourse on the crosstalk(s) that exist between SLs/components of SL signalling and other phytohormones such as auxins, cytokinins, gibberellins, abscisic acid, ethylene, jasmonates and salicylic acid. CONCLUSION: SLs elicit their control on physiological and morphological processes via a direct or indirect influence on the activities of other hormones and/or integrants of signalling cascades of other growth regulators. These, among many others, include modulation of hormone content, transport and distribution within plant tissues, interference with or complete dependence on downstream signal components of other phytohormones, as well as acting synergistically or antagonistically with other hormones to elicit plant responses. Although much has been done to evince the effects of SL interactions with other hormones at the cell and whole plant levels, research attention must be channelled towards elucidating the precise molecular events that underlie these processes. More especially in the case of abscisic acid, cytokinins, gibberellin, jasmonates and salicylic acid for which very little has been reported about their hormonal crosstalk with SLs.

Ethnobotany, phytochemistry, toxicology and pharmacological properties of Terminalia sericea Burch. ex DC. (Combretaceae) - A review.

ETHNOPHARMACOLOGICAL REFERENCE: The use of medicinal plants in the treatment of infections is ancient. A wide variety of ethnotherapeutic properties and pharmacological actions has been attributed to Terminalia sericea. Studies by various groups of investigators reveal that it is a multipurpose medicinal plant used mostly in the treatment of diarrhoea, sexually transmitted infections, skin rashes, tuberculosis and other infections. The current paper is aimed at providing an overview of the ethnomedicinal uses, toxicology, pharmacology and the phytochemistry of Terminalia sericea. MATERIALS AND METHODS: Information was retrieved using various search engines, including Pubmed, Science Direct, Google Scholar, Scielo, SciFinder and Scopus. The key words used included Terminalia sericea, secondary metabolites, phytochemistry, biological activity, pharmacology, ethnobotanical survey, medicinal uses, safety, toxicology and other related words. RESULTS: Terminalia sericea is an important medicinal plant which possesses anti-HIV, anti-fungal, anti-bacterial, anticancer, lipolytic, wound healing, antiparasitic, anti-inflammatory and anti-oxidant activity, as the most valuable biological activities, thus lending pharmacological support to the plant's folkloric uses in indigenous medicine. Toxicologically, the extracts and isolated compounds from the plant species may have mild toxic effects. Phytochemically, the plant species possesses valuable compounds including triterpenes, alkaloids and flavonoids which may well contribute to its biological activity. CONCLUSIONS: Terminalia sericea contains secondary metabolites which are valuable in the treatment of a variety of human infections, including community acquired infections which may be prevalent in developing countries. The degree of toxicity reported in various extracts warrants further exploration of the cytotoxicity of the plant species, both against normal human cell lines and in vivo. Moreover, the acetylcholinesterase inhibitory and anti-inflammatory effects also need to be further investigated as there are only a few reports from the literature on these aspects. There is also a need to further understand the mode of action of the extracts against various enzymes relating to inflammation. Antioxidant activity of the plant extracts against various forms of free radicals needs to be investigated. Although T. sericea is reported to be used for ethnoveterinary infections, there are no scientific reports on the anti-parasitic activity of the plant species against common animal parasites.

Investigating the effect of cadmium and aluminium on growth and stress-induced responses in the micropropagated medicinal plant Hypoxis hemerocallidea.

Hypoxis hemerocallidea is a highly utilized medicinal plant in South Africa. Its cultivation has received considerable attention in order to meet the high demand. High levels of cadmium (Cd) and aluminum (Al) in H. hemerocallidea plants sold in traditional medicinal markets was previously reported. The present study used an in vitro propagation model to investigate the uptake of Cd and Al by H. hemerocallidea and their effect on plant growth, elemental uptake and some stress-induced responses such as pigment, malondialdehyde (MDA), proline content and ultrastructural changes. Shoot and root growth of plantlets exposed to Cd, Cd:Al and high concentrations of Al was significantly reduced. Highest concentrations of Cd accumulated in the corms of Cd-treated plantlets while highest Al concentrations occurred in the leaves and roots. There was higher accumulation of Cd and Al when applied singularly compared to the Cd:Al combination treatments. Cd and Al also reduced accumulation of trace elements in micropropagted H. hemerocallidea with lowest concentrations in the Cd:Al combination treatments. Exposure to Cd, Al and Cd:Al significantly reduced the level of chlorophyll but increased the levels of carotenoids, MDA and proline. Ultrastructural changes were also observed in H. hemerocallidea exposed to Cd and Al. All these factors contributed to the inhibition of plant growth and could potentially affect the ability of this important medicinal plant to synthesize bioactive compounds. It is thus necessary to understand heavy metal stress-induced responses in this highly valued medicinal plant to ensure a high quality product for the consumer.

The effects of smoke derivatives on in vitro seed germination and development of the leopard orchid Ansellia africana.

Plant-derived smoke and smoke-isolated compounds stimulate germination in seeds from over 80 genera. It has also been reported that smoke affects overall plant vigour and has a stimulatory effect on pollen growth. The effect of smoke on orchid seeds, however, has not been assessed. In South Africa, orchid seeds from several genera may be exposed to smoke when they are released from their seedpods. It is therefore possible that smoke may affect their germination and growth. Therefore, the effects of smoke [applied as smoke-water (SW)] and two smoke-derived compounds, karrikinolide (KAR1 ) and trimethylbutenolide (TMB), were investigated on the germination and growth of orchid seeds in vitro. The effect of SW, KAR1 and TMB were investigated on the endangered epiphytic orchid, Ansellia africana, which is indigenous to tropical areas of Africa. Smoke-water, KAR1 and TMB were infused in half-strength MS medium. The number of germinated seeds and number of seeds and protocorm bodies to reach predetermined developmental stages were recorded on a weekly basis using a dissecting microscope for a 13-week period. Infusing SW 1:250 (v:v) into half-strength MS medium significantly increased the germination rate index (GRI) and the development rate index (DRI) of the A. africana seeds. All the SW treatments significantly increased the number of large protocorm bodies at the final stage of development. Infusing KAR1 into the growing medium had no significant effect on germination or development of the seeds. The TMB treatment, however, significantly reduced the GRI and DRI of A. africana seeds.

Securidaca longipedunculata Fresen (Polygalaceae): a review of its ethnomedicinal uses, phytochemistry, pharmacological properties and toxicology.

ETHNOPHARMACOLOGICAL RELEVANCE: Securidaca longipedunculata Fresen (Polygalaceae) is a multi-purpose plant with a long history of use in African traditional medicine to treat various sexually transmitted infections, hernias, coughs, fever, ascariasis, constipation, headaches, rheumatism, stomach ache, malaria, tuberculosis, pain, epilepsy, pneumonia, skin infections, and it is also used as an aphrodisiac for men. The current paper provides an overview of the present phytochemistry, toxicology, ethnomedicinal uses and pharmacological properties of S. longipedunculata. MATERIALS AND METHODS: The information reported in this paper was collected from a literature search using various computerised databases including ScienceDirect, Scopus, Scielo, PubMed and Google Scholar. The extra information was sourced from various academic dissertations, theses and botanical books. RESULTS: Phytochemically, extracts from various parts of S. longipedunculata, especially the root bark, contain numerous valuable compounds including xanthones, some benzyl benzoates and triterpene saponins amongst others. Toxicity studies, both in vivo and in vitro, revealed that extracts are only toxic at relatively high concentrations. Furthermore, extracts have antimicrobial, antioxidant, antiparasitic, anti-diabetic, anti-inflammatory, antimalarial, insecticidal, pesticidal, and anticonvulsant properties. CONCLUSIONS: S. longipedunculata is an important plant species with potential benefits in the treatment of transmissible and infectious diseases, including malaria, tuberculosis, and those caused by community acquired microorganisms. Although extracts from this species generally have little toxicity at low concentrations, further efforts are required to investigate the potential toxicity of S. longipedunculata. The antimicrobial properties of extracts and purified compounds against microorganisms causing sexually transmitted infections are also deserving of further research. Moreover, the pharmacokinetic properties of extracts and compounds of the species need to be explored as there is insufficient data available on these aspects.

Isolation and characterization of antimicrobial compounds from Terminalia phanerophlebia Engl. & Diels leaf extracts.

ETHNOPHARMACOLOGICAL RELEVANCE: The emergence of drug resistant-tuberculosis and other pathogenic diseases over the past decades, constitutes a serious threat to human health worldwide. According to a 2012 report by the World Health Organization (WHO), South Africa, China, India and Russia are the countries with the highest prevalence of Multi-Drug Resistant tuberculosis (MDR-tuberculosis) as they represented 60% of the total. Several reports have documented antimycobacterial properties of Terminalia species but only a few species from this genus have been explored for their antimycobacterial constituents. The crude extracts of Terminalia phanerophlebia showed good antimicrobial activities in our previous study against two Mycobacterium as well as two other bacterial strains responsible for opportunistic infections related to respiratory ailments. This paper studies the isolation of compounds responsible for such activities and to isolate compounds responsible for antimicrobial activities from the crude extracts of Terminalia phanerophlebia leaves. MATERIALS AND METHODS: Terminalia phanerophlebia crude extracts obtained from 80% methanol was successively extracted with hexane, dichloromethane (DCM), ethyl acetate (EtOAc) and n-butanol. The fractions obtained and isolated compounds were tested for their antibacterial activities against Mycobacterium aurum, Mycobacterium tuberculosis, Staphylococcus aureus and Klebsiella pneumoniae. Bioguided fractionation of the EtOAc fraction afforded two bioactive compounds. Structure elucidation was carried out using NMR (1D and 2D) spectroscopic methods. RESULTS: EtOAc fraction exhibited highest antimicrobial activities and its fractionation afforded methyl gallate (methyl-3,4,5-trihydroxybenzoate) (1) and a phenylpropanoid glucoside, 1,6-di-O-coumaroyl glucopyranoside (2) These compounds are reported from Terminalia phanerophlebia for the first time. Both compounds showed good antimicrobial activity against all bacterial strains tested with minimum inhibitory concentration (MIC) values ranging from 63 to 250 µg/mL. Inhibition of Mycobacterium tuberculosis by 1,6-di-O-coumaroyl glucopyranoside (2) at a MIC value of 63 µg/mL was noteworthy, as this bacterial strain is reported to be the leading cause of tuberculosis worldwide. CONCLUSIONS: Good antimicrobial activities exhibited by the compounds isolated from Terminalia phanerophlebia authenticate the traditional use of this plant in treating tuberculosis and its related symptoms. Compound (2), 1,6-di-O-coumaroyl glucopyranoside could serve as a lead compound for tuberculosis drug discovery.

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.

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.

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 12.5mg/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 0.098mg/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.

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

ETHNOPHARMACOLOGICAL RELEVANCE: The evaluated medicinal plants are used in South African traditional medicine in treating stomach-related ailments. AIMS OF THE STUDY: The study aimed at evaluating the pharmacological, genotoxic and phytochemical properties of the seven selected medicinal plants used for treating stomach-related ailments. MATERIALS AND METHODS: Ethyl acetate (EtOAc), ethanol (EtOH) 70% and water extracts of the selected plant parts were evaluated for their antimicrobial and anthelmintic activities using microdilution assays. Gram-positive bacteria (Enterococcus faecalis and Staphylococcus aureus), Gram-negative bacterium (Escherichia coli) and Candida albicans were used for antimicrobial assays. Caenorhabditis elegans was used for the anthelmintic assay. Plant extracts were also assayed for their cyclooxygenase-inhibitory activity against cyclooxygenase-1 and -2 enzymes. The Ames test was used to evaluate the genotoxicity of the plant extracts. A spectrophotometric method was used to determine the total phenolics, gallotannins, flavonoids and saponins. RESULTS: Twelve extracts exhibited minimum inhibitory concentration (MIC) <1 mg/mL against the bacterial test strains, and five extracts exhibited MIC <1 mg/mL against Candida albicans. The EtOAc extract of Tetradenia riparia had the best minimum lethal concentration (MLC) value (0.004 mg/mL) against Caenorhabditis elegans. All the EtOAc extracts exhibited percentage inhibition in the range of 50.7-94.7% against COX-1 and -2 enzymes at 250 µg/mL. All the plant extracts were non-mutagenic towards Salmonella typhimurium tester strains TA98, TA100 and TA1537 without metabolic activation. Phytochemical analysis revealed relatively high amounts of total phenolics, gallotannins and flavonoids in the evaluated plant extracts. CONCLUSIONS: The general pharmacological activities exhibited by some of the plant extracts in this study support the traditional uses of the selected plants in treating stomach-related ailments. The Ames test showed that all the plant extracts were non-mutagenic but cytotoxicity tests are needed to ascertain the safety for long-term consumption.

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.

An ethnobotanical survey of mosquito repellent plants in uMkhanyakude district, KwaZulu-Natal province, South Africa.

ETHNOPHARMACOLOGICAL RELEVANCE: The aim of the study was to document plants traditionally used to repel mosquitoes in the uMkhanyakude district, KwaZulu-Natal, South Africa. The specific objectives of the study were to: (1) identify plant species and their parts being used; (2) determine the condition of plant material used and the method of application. MATERIALS AND METHODS: Data was collected from 60 respondents in five villages in the district using standardised and pre-tested questionnaires. RESULTS: Thirteen plant species are used in the study area to repel mosquitoes. These species belong to 11 genera from 9 families. Meliaceae and Anacardiaceae were the most represented families with two species each. The most frequently recorded species were Lippia javanica (91.67%), followed by Aloe ferox (11.67%), Sclerocarya birrea (5%), Melia azedarach (3%), Balanite maughamii (3%) and Mangifera indica (3%). Leaves were the most (38%) common plant part used. The majority (82%) of the plant parts were used in a dry state. Burning of plant materials to make smoke was the most (92%) common method of application. Nine plant species, namely: A. ferox, Calausena anista, Croton menyharthii, S. birrea, B. maughamii, Olax dissitiflora, Trichilia emetic, M. indica, and Atalaya alata are documented for the first time as mosquito repellents. CONCLUSION: This documentation provides the basis for further studies in developing new, effective, safe and affordable plant-derived mosquito repellents especially for Africa where malaria is highly prevalent. The study also plays a part in documenting and conserving traditional knowledge of mosquito repellent plants for future use.

Antimicrobial properties and phenolic contents of medicinal plants used by the Venda people for conditions related to venereal diseases.

ETHNOPHARMACOLOGY RELEVANCE: Many people are infected by venereal diseases and the human immunodeficiency virus (HIV) in rural areas. Sexual transmitted diseases are considered a disgrace in the community because of the stigmas attached to them. Indigenous people tend to use several medicinal plants to treat these infectious diseases rather than western medicines. AIM OF THE STUDY: This study was aimed to evaluate the antibacterial, antifungal, antigonococcal, HIV-type 1 reverse transcriptase (RT) and to determine phenolic content of twelve medicinal plants used by the Venda people to treat venereal diseases. MATERIALS AND METHODS: The dried plant materials of twelve medicinal plants were extracted with petroleum ether (PE), dichloromethane (DCM), 80% ethanol (EtOH) and water. The extracts were evaluated for their antimicrobial properties against two Gram-positive (Bacillus subtilis and Staphylococcus aureus), three Gram-negative (Neisseria gonorrhoeae, Escherichia coli and Klebsiella pneumoniae) bacteria and a fungus Candida albicans. The phenolic contents including total phenolics, flavonoids, gallotannins and condensed tannins of the methanolic extracts of the same plants were also determined. RESULTS: DCM and EtOH extracts of Bolusanthus speciosus bark and stems exhibited good activity (<0.1mg/ml) against Escherichia coli and Staphylococcus aureus with MIC values ranging from 0.098 to 0.012 mg/ml. The DCM extracts of Bolusanthus speciosus bark showed the best activity against Candida albicans with MIC and MFC values of 0.012 mg/ml. Water and 50% methanol extracts of Acacia karroo bark, Bolusanthus speciosus stems and Ximenia caffra roots and leaves showed good RT inhibition percentages (>70%) at 1mg/ml. All tested extracts exhibited dose dependent IC(50) values ranging from (0.1 to 0.6 mg/ml). Almost all plant species investigated contained phenolic compounds, which were greater than 5mg/g with the exception of Adansonia digitata bark and Aloe chabaudii roots. The highest level of flavonoids (11.9 µg/g) were detected in Ximenia caffra leaves. Whereas the highest amount of gallotannins were detected in Ekebergia capensis bark (69 µg/g). Condensed tannins were higher in Ekebergia capensis bark and Ximenia caffra roots (0.47 and 0.48% respectively). Adansonia digitata bark and Aloe chabaudii roots exhibited low levels of phenolic compounds as well as antimicrobial activities. CONCLUSION: The presented results offer supporting evidence for effective use of selected plant extracts. More in vitro confirmatory tests using other assays and/or in vivo tests are required. Toxicity studies are urgently needed to support the safe usage of these plants.

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 (<1mg/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 3.125-12.5mg/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.

Anti-inflammatory, antioxidant, anti-tyrosinase and phenolic contents of four Podocarpus species used in traditional medicine in South Africa.

ETHNOPHARMACOLOGICAL RELEVANCE: Species of Podocarpus are used traditionally in their native areas for the treatment of fevers, asthma, coughs, cholera, chest complaints, arthritis, rheumatism, venereal diseases and distemper in dogs. AIMS OF THE STUDY: To investigate the antioxidant, anti-inflammatory and anti-tyrosinase activities of four Podocarpus species, Podocarpus elongatus, Podocarpus falcatus, Podocarpus henkelii and Podocarpus latifolius, used in traditional medicine in South Africa. Phytochemical analysis to determine the phenolic contents was also carried out. MATERIALS AND METHODS: DPPH, FRAP and ß-carotene-linoleic acid assays were used to determine the antioxidant/radical scavenging activities of these species. Anti-inflammatory activity of these species was assayed against two cyclooxygenase enzymes (COX-1 and COX-2). Tyrosinase inhibition activity was analysed using the modified dopachrome method with l-DOPA as the substrate. Phenolics were quantitatively determined using spectrophotometric methods. RESULTS: Stems of Podocarpus latifolius exhibited the lowest EC(50) (0.84 µg/ml) inhibition against DPPH. The percentage antioxidant activity based on the bleaching rate of ß-carotene ranged from 96% to 99%. High ferric reducing power was observed in all the extracts. For COX-1, the lowest EC(50) value was exhibited by stem extracts of Podocarpus elongatus (5.02 µg/ml) and leaf extract of Podocarpus latifolius showed the lowest EC(50) against COX-2 (5.13 µg/ml). All extracts inhibited tyrosinase activity in a dose-dependent manner with stem extract of Podocarpus elongatus being the most potent with an EC(50) value of 0.14 mg/ml. The total phenolic content ranged from 2.38 to 6.94 mg of GAE/g dry sample. CONCLUSION: The significant pharmacological activities observed support the use of these species in traditional medicine and may also be candidates in the search for modern pharmaceuticals in medicine, food and cosmetic industries.

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.

In vitro antimicrobial, anthelmintic and cyclooxygenase-inhibitory activities and phytochemical analysis of Leucosidea sericea.

ETHNOPHARMACOLOGICAL RELEVANCE: Leucosidea sericea is used as a vermifuge and in the treatment of ophthalmia by various tribes in southern African countries. AIM OF THE STUDY: The study aimed at screening leaves and stems of Leucosidea sericea for pharmacological activity and validating the plant's traditional use. A general phytochemical screening was also carried out. MATERIALS AND METHODS: Petroleum ether (PE), dichloromethane (DCM), ethanol (EtOH) and water extracts of the plant parts were investigated for antimicrobial, anthelmintic and cyclooxygenase (COX) inhibitory activities. Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and Candida albicans were used for the antimicrobial evaluation. Caenorhabditis elegans was used for the anthelmintic assay using the microdilution technique. Cyclooxygenase-1 and -2 (COX-1 and -2) were used to evaluate the anti-inflammatory potential of the plant extracts. Phytochemical analysis for phenolic compounds, including gallotannins, condensed tannins and flavonoids was done using 50% methanol extracts of the leaves and stems employing spectrophotometric methods. RESULTS: The leaf extracts exhibited broad spectrum antibacterial activity ranging from 0.025 to 6.25mg/ml. The most noteworthy minimum inhibitory concentration (MIC) of 0.025 mg/ml was exhibited by PE and DCM leaf extracts against Bacillus subtilis and Staphylococcus aureus, respectively. In the anthelmintic assay, the best minimum lethal concentration (MLC) value of 0.26 mg/ml was observed for the DCM and EtOH leaf extracts. Both leaf and stem organic solvent extracts exhibited high to moderate inhibition against COX-1 and -2 at a screening concentration of 250 microg/ml. At lower concentrations, the extracts displayed a dose-dependent inhibition, with the lowest IC(50) values of 0.06 microg/ml (COX-1) and 12.66 microg/ml (COX-2) exhibited by the PE extract of the leaves. Generally, the leaf extracts exhibited better pharmacological activities and contained higher amounts of phenolic compounds than the stem extracts. Alkaloids and saponins were only detected in the leaf and stem extracts, respectively. CONCLUSION: The reported results support the local use of Leucosidea sericea against eye infections and as a vermifuge. The pharmacological activities exhibited by the leaf extracts are probably due to their higher phenolic levels.

Anti-inflammatory, anticholinesterase, antioxidant and phytochemical properties of medicinal plants used for pain-related ailments in South Africa.

ETHNOPHARMACOLOGICAL RELEVANCE: Extracts of seven South African medicinal plants used traditionally for the treatment of pain-related ailments were evaluated. AIMS OF THE STUDY: The study was aimed at evaluating medicinal and therapeutic potentials of the investigated traditional medicinal plants. Plant extracts were evaluated for anti-inflammatory activity and other pharmacological properties such as anticholinesterase and antioxidant activities. Phytochemical analysis of total phenolic contents, condensed tannins, gallotannins and flavonoids in the aqueous methanol extracts of the medicinal plants were also carried out. MATERIALS AND METHODS: The evaluation of anti-inflammatory activity of 50% methanol (50% MeOH), petroleum ether (PE), dichloromethane (DCM) and ethanol (EtOH) plant extracts was done against cyclooxygenase-1 and -2 (COX-1 and COX-2) enzymes. 50% MeOH, PE, DCM and EtOH extracts were tested for acetylcholinesterase (AChE) inhibition, while 50% MeOH extracts were tested for 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity and ferric-reducing power in the antioxidant assays. Total phenolic compounds, condensed tannins, gallotannins and flavonoids were quantitatively determined using spectrophotometric methods. RESULTS: At the screening assay concentration (0.25 microg/microl), 13 extracts showed good COX-1 inhibitory activity (>50%), while good activity was observed in 15 extracts against COX-2 enzyme. All the extracts of Crinum moorei (bulbs) showed good inhibition against both COX-1 and COX-2 enzymes. Though not significantly different (P=0.05), the highest COX-1 percentage inhibition (100%) was shown by Aloe ferox leaf PE and Colocasia antiquorum tuber DCM extracts, while Colocasia antiquorum tuber PE extract exhibited the highest (92.7%) percentage inhibition against COX-2. Crinum moorei bulb DCM extract showed the lowest EC(50) value (2.9 microg/ml) in the AChE assay. In addition, good to moderate bioactivities were observed in some extracts of Aloe ferox (leaves), Crinum moorei (bulbs) and Pycnostachys reticulata (leaves) in all the assays. The presence and/or amounts of phenolic compounds varied with plant species. CONCLUSION: The results obtained in this study validate the use of the investigated medicinal plants in South African traditional medicine for pain-related ailments.