Phylogenetic exploration of commonly used medicinal plants in South Africa

The rapid growth rate of human population, along with the public health crisis encountered in many regions, particularly in developing world, creates an urgent need for the discovery of alternative drugs. Because medicinal plants are not distributed randomly across lineages, it has been suggested that phylogeny along with traditional knowledge of plant uses can guide the identification of new medicinally useful plants. In this study, we combined different statistical approaches to test for phylogenetic signal in 33 categories of plant uses in South Africa. Depending on the null models considered, we found evidence for signal in up to 45% of plant use categories, indicating the need for multiple tests combination to maximize the chance of discovering new medicinal plants when applying a phylogenetic comparative approach. Furthermore, although there was no signal in the diversity of medicinal uses—that is, total number of medicinal uses recorded for each plant—our results indicate that taxa that are evolutionarily closely related have significantly more uses than those that are evolutionarily isolated. Our study therefore provides additional support to the body of the literature that advocates for the inclusion of phylogeny in bioscreening medicinal flora for the discovery of alternative medicines.     

Status of medical parasitology in South Africa: new challenges and missed opportunities

In South Africa medical parasitology is neglected due to a shift in funding priorities to focus on HIV, tuberculosis and malaria. Evidence suggests that helminth infections have deleterious effects on HIV and tuberculosis. A multisectoral approach involving key government and research institutions is required to rekindle interest in medical parasitology.     

Density and potential utilisation of medicinal grassland plants from Abe Bailey Nature Reserve, South Africa

The Abe Bailey Nature Reserve, South Africa has been identified as a potential community resource reserve compatible with biodiversity conservation. As part of the planning and public participation phase this study investigated the potential for sustainably harvesting medicinal plants. Medicinal plant use data on local species, parts used and harvesting techniques, in collaboration with neighbouring traditional healers were collected. A census of these plants was conducted in the reserve and frequency, density and abundance were calculated. A medicinal plant rating system for assessing conservation priorities was used to combine both social-qualitative and ecological-quantitative data. Five medicinal species suitable for high impact harvesting were identified. Thirty-four species have potential to be set up as harvesting trials to determine sustainable quotas. Thirty-one medicinal species including Boophane disticha, Dicoma anomala, Eucomis autumnalis, Hypoxis hemerocallidea, Pentanisia prunelloides and Indigofera daleoides are considered to be site-specific sensitive species and should not be harvested from the reserve. Following this research an on site nursery has been started at the reserve. A multi-pronged approach involving harvesting trials, propagation and plant rescue from developments to cope with escalating demand and dwindling natural populations needs to be implemented.     

Unraveling the commercial market for medicinal plants and plant parts on the witwatersrand, South Africa

To unravel the market for commercial medicinal plants on the Witwatersrand in South Africa, a semiquantitative approach was taken. A stratified random sample of 50 herb-traders was surveyed, and an inventory of all plants and parts sold was compiled. Research participants were questioned on the scarcity and popularity of the plants traded, as well as suppliers and origins. The rarefaction method established that the sample size was adequate. The diversity of the sample was determined using ecological indices of diversity, and found to be comparatively high. In addition, Spearman rank correlations, chi-squared and Fisher’s exact probability tests were used to assess the probability of certain taxa being used. At least 46% of the taxa traded showed a higher than expected probability of being utilized, and taxa tended to be harvested from the largest families proximate to the markets. About 511 species are traded in the region, and there is a low dominance in the use of species. Ethnic and floristic diversity are influential in deciding the trading patterns that have emerged.     

Microbial contamination of traditional medicinal plants sold at the Faraday muthi market,Johannesburg, South Africa

The Faraday traditional healers' trading market is the hub of the medicinal plant trade in Johannesburg, South Africa. Modes of harvesting, transporting, storage and distribution of medicinal plants render them susceptible to microbial attack, and thereby make customers, especially patients with compromised immune systems, vulnerable to infections that could increase morbidity and mortality. This study evaluated the microbial contamination on five frequently used traditional medicinal plant species sold by traders in the Faraday market. Bacterial contamination was determined using serial macro dilutions, spread plate and streak plate techniques. Fifteen bacterial contaminants were identified, the most recurrent being Pantoea sp. and five strains of Bacillus spp. (non-pathogenic). There was little variation between contamination levels of the five different traders, and the mean CFU/g per species ranged from 3.03 × 10⁴ (Hypoxis sp.) to 4.22 × 10⁵ (Hydnora abyssinica). While there was no overall significant levels of contamination, the CFU counts for two plant species purchased from one specific trader (viz. H. abyssinica and Acacia xanthophloea) exceeded maximum acceptable contamination limits set by the World Health Organisation (i.e. ≤ 10⁵ to ≤ 10⁷ CFU/g). The levels of contamination varied greatly between the commercially available over the counter product and the plant samples investigated. The microbial types are predominantly opportunistic pathogens. The implementation of good processing practices therefore clearly influences the quality and safety of medicinal products, especially regarding microbial contamination. It is evident that policies and regulations need to be developed and implemented in order to address possible contamination by opportunistic pathogens.     

Mutagenic evaluation of 10 long-term stored medicinal plants commonly used in South Africa

The use of medicinal plants is an increasing phenomenon among the majority of people in many developing countries. Some of the harvested medicinal plants are often stored for shorter or longer periods prior to usage. Evidence from recent studies has demonstrated the pharmacological efficacy of short and long-term stored plant materials when compared to freshly-harvested ones. In an attempt to evaluate the effect of long-term storage on the safety of some commonly used medicinal plants, the Ames test which involved the use of three Salmonella typhimurium tester strains (TA98, TA100 and TA1535) were conducted. Current findings indicate the absence of any mutagenic effects resulting from the storage of medicinal plant materials for as long as 16 years. Although freshly collected Acokanthera oppositifolia extract demonstrated a mutagenic effect against TA1535 strain at the highest concentration tested, no such effect was observed in the stored material. Further studies involving metabolic activation systems and in vivo conditions may further elucidate the effect of long-term storage on the safety of medicinal plants.     

Yeast alpha glucosidase inhibitory and antioxidant activities of six medicinal plants collected in Phalaborwa,South Africa

Recent decades have experienced a sharp increase in the incidence and prevalence of diabetes mellitus. One antidiabetic therapeutic approach is to reduce gastrointestinal glucose production and absorption through the inhibition of carbohydrate-digesting enzymes such as α-amylase and α-glucosidase and α-amylase. The aim of the current study was to screen six medicinal plant species, with alleged antidiabetic properties for α-glucosidase inhibitory activities. Powdered plant materials were extracted with acetone, and tested for ability to inhibit baker's yeast α-glucosidase and α-amylase activities. The largest mass (440 mg from 10 g) of the extract was obtained from Cassia abbreviata, while both Senna italica and Mormordica balsamina yielded the lowest mass of the extracts. Extracts of stem bark of C. abbreviata inhibited baker's yeast α-glucosidase activity with an IC₅₀ of 0.6 mg/ml. This plant species had activity at low concentrations, with 1.0 mg/ml and above resulting in inhibition of over 70%. The other five plant extracts investigated had IC₅₀ values of between 1.8 and 3.0 mg/ml. Senna italica only managed to inhibit the activity of enzyme-glucosidase at high concentrations with an IC₅₀ value of 1.8 mg/ml, while Tinospora fragosa extracts resulted in about 55% inhibition of the activity of the enzyme at a concentration of 3.5 mg/ml, with an estimated IC₅₀ value of 2.8 mg/ml. The bark extract of C. abbreviata was the most active inhibitor of the enzyme, based on the IC₅₀ values (0.6 mg/ml). The bark extract of C. abbreviata contains non-competitive inhibitor(s) of α-glucosidase, reducing V_max value of this enzyme from 5 mM·s^–1 to 1.67 mM·s^–1, while K_m remained unchanged at 1.43 mM for para-nitrophenyl glucopyranoside. Antioxidant activity of the extracts was also investigated. The C. abbreviata extract was more active as an antioxidant than the positive control, trolox. The extracts did not inhibit alphaamylase activity more than about 20% at the highest concentration tested.     

Status of life cycle assessment and engineering research in South Africa

In view of the upcoming 2002 World Summit in Johannesburg, sustainable development is a topic of high priority in South Africa. Although the South African competency in Life Cycle Assessment (LCA) and Life Cycle Engineering (LCE) has grown to some extent over the last ten years, South African industry and government have been slow to realise the benefit of LCAs and LCE as tools to support cleaner production and sustainable development. However, the local application of these tools, as well as considerations during their use, differs from practices in developed countries. The applications of LCAs and LCE, the type of organisations involved and the limitations and common problems associated with these tools in South Africa are discussed.     

Bringing medicinal plants into cultivation: opportunities and challenges for biotechnology

Consumption of herbal medicines is widespread and increasing. Harvesting from the wild, the main source of raw material, is causing loss of genetic diversity and habitat destruction. Domestic cultivation is a viable alternative and offers the opportunity to overcome the problems that are inherent in herbal extracts: misidentification, genetic and phenotypic variability, extract variability and instability, toxic components and contaminants. The use of controlled environments can overcome cultivation difficulties and could be a means to manipulate phenotypic variation in bioactive compounds and toxins. Conventional plant-breeding methods can improve both agronomic and medicinal traits, and molecular marker assisted selection will be used increasingly. There has been significant progress in the use of tissue culture and genetic transformation to alter pathways for the biosynthesis of target metabolites. Obstacles to bringing medicinal plants into successful commercial cultivation include the difficulty of predicting which extracts will remain marketable and the likely market preference for what is seen as naturally sourced extracts.     

Seasonal variation in antimicrobial and phytochemical properties of frequently used medicinal bulbous plants from South Africa

The growing popularity of traditional medicine and the unrestricted collection of medicinal plants from the wild have put many of the slow growing bulbous plant species at the risk of over-exploitation and extinction in South Africa. This study was aimed at comparing the phytochemical composition and biological (antibacterial and anticandidal) activities of bulb and leaf extracts of Tulbaghia violacea, Hypoxis hemerocallidea, Drimia robusta and Merwilla plumbea between spring, summer, autumn and winter seasons, with the view of promoting the use of leaves, as a conservation strategy. Antibacterial and anticandidal activities of petroleum ether (PE), dichloromethane (DCM), 80% ethanol and water extracts of bulbs and leaves were tested against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae bacteria and the fungus Candida albicans using the microdilution bioassay. Spectrophotometric methods were used to evaluate saponin and phenolic compositions for the four seasons. Leaf and bulb extracts exhibited comparable anticandidal activity (MIC < 1 mg/ml) in all the plant species in all seasons. Only ethanol and water extracts of H. hemerocallidea corms (autumn and winter) showed correspondingly good fungicidal activity amongst the bulbs tested. Antibacterial activity was fairly comparable between bulbs and leaves with at least one extract of each plant species showing some good MIC values in most of the seasons. The best antimicrobial activities were recorded in winter and autumn seasons, with MIC values as low as 0.2 mg/ml in the DCM bulb extracts of T. violacea (winter) against K. pneumoniae and S. aureus. The amounts of total phenolic compounds in all plant samples were generally higher in spring compared to the other seasons. Condensed tannin, gallotannin and flavonoid levels, depending on the sample, were either higher in spring or winter except for H. hemerocallidea (corm) which had higher gallotannin levels in autumn. Total saponin levels were higher in winter in all plant samples. Although variation was observed in the phytochemical concentrations between the bulbs and leaves of each plant species, their antimicrobial activities were fairly comparable. Leaves may be used as substitutes for bulbs in the treatment of bacterial and fungal ailments.     

Developing the medicinal plants sector in northern India: challenges and opportunities

The medicinal properties of plant species have made an outstanding contribution in the origin and evolution of many traditional herbal therapies. These traditional knowledge systems have started to disappear with the passage of time due to scarcity of written documents and relatively low income in these traditions. Over the past few years, however, the medicinal plants have regained a wide recognition due to an escalating faith in herbal medicine in view of its lesser side effects compared to allopathic medicine in addition the necessity of meeting the requirements of medicine for an increasing human population. Through the realization of the continuous erosion of traditional knowledge of plants used for medicine in the past and the renewed interest at the present time, a need existed to review this valuable knowledge of medicinal plants with the purpose of developing medicinal plants sectors across the different states in India. Our major objectives therefore were to explore the potential in medicinal plants resources, to understand the challenges and opportunities with the medicinal plants sector, and also to suggest recommendations based upon the present state of knowledge for the establishment and smooth functioning of the medicinal plants sector along with improving the living standards of the underprivileged communities. The review reveals that northern India harbors a rich diversity of valuable medicinal plants, and attempts are being made at different levels for sustainable utilization of this resource in order to develop the medicinal plants sector.     

Plant biotechnology in South Africa: Micropropagation research endeavours, prospects and challenges

Research in plant biotechnology is playing a crucial role in the production and conservation of plant-based resources globally. Being a country with rich and diverse floral resources, South Africa has a genuine opportunity to develop efficient and competitive plant biotechnology sectors. South Africa has a policy framework, in the form of a National Biotechnology Strategy that supports biotechnology research. The presence of competitive research infrastructure coupled with the government's willingness to commit significant resources will certainly help realise this. South Africa's plant biotechnology research has potential to make more significant contributions to the national economy. In this review, whilst highlighting the success, the research endeavours, prospects and challenges hindering the practical application of micropropagation research outputs are discussed.     

A phytogeographic assessment of the Nuweveldberge, South Africa

The Nuweveldberge forms the central and most arid component to the southern Great Escarpment in South Africa. Situated between the Sneeuberg in the east and the Hantam-Roggeveld in the west, the Nuweveldberge has elements of both the Succulent Karoo and Grassland Biomes. The Nuweveldberge has low endemism (0.5%) compared to the adjacent Sneeuberg (2.3%) and Roggeveldberge (ca. 8%). Following an extensive floristic survey of the Nuweveldberge, a contribution of 473 taxa is provided. Together with the flora by Rubin et al., 2001 for the Karoo National Park this provides a total flora of 1139 taxa for the Nuweveldberge. Numerous range extensions of (previous) Sneeuberg endemics and Drakensberg near-endemics onto the Nuweveldberge are recorded. Although the Nuweveldberge may have been a corridor facilitating the movement of species from the Cape Floristic Region via the Komsberg through the Nuweveldberge onto the Sneeuberg (and of Drakensberg elements westwards from the Sneeuberg) there is currently little evidence of such connectivity. This is postulated to be due to aridification of the Nuweveldberge since the Last Glacial Maximum, and also likely explains the low endemism on the Nuweveldberge.     

Changing trends in biotechnology of secondary metabolism in medicinal and aromatic plants

Main conclusion

Medicinal and aromatic plants are known to produce secondary metabolites that find uses as flavoring agents, fragrances, insecticides, dyes and drugs. Biotechnology offers several choices through which secondary metabolism in medicinal plants can be altered in innovative ways, to overproduce phytochemicals of interest, to reduce the content of toxic compounds or even to produce novel chemicals. Detailed investigation of chromatin organization and microRNAs affecting biosynthesis of secondary metabolites as well as exploring cryptic biosynthetic clusters and synthetic biology options, may provide additional ways to harness this resource. Plant secondary metabolites are a fascinating class of phytochemicals exhibiting immense chemical diversity. Considerable enigma regarding their natural biological functions and the vast array of pharmacological activities, amongst other uses, make secondary metabolites interesting and important candidates for research. Here, we present an update on changing trends in the biotechnological approaches that are used to understand and exploit the secondary metabolism in medicinal and aromatic plants. Bioprocessing in the form of suspension culture, organ culture or transformed hairy roots has been successful in scaling up secondary metabolite production in many cases. Pathway elucidation and metabolic engineering have been useful to get enhanced yield of the metabolite of interest; or, for producing novel metabolites. Heterologous expression of putative plant secondary metabolite biosynthesis genes in a microbe is useful to validate their functions, and in some cases, also, to produce plant metabolites in microbes. Endophytes, the microbes that normally colonize plant tissues, may also produce the phytochemicals produced by the host plant. The review also provides perspectives on future research in the field.

     

Status,trends and drivers of kelp forests in Europe: an expert assessment

A comprehensive expert consultation was conducted in order to assess the status, trends and the most important drivers of change in the abundance and geographical distribution of kelp forests in European waters. This consultation included an on-line questionnaire, results from a workshop and data provided by a selected group of experts working on kelp forest mapping and eco-evolutionary research. Differences in status and trends according to geographical areas, species identity and small-scale variations within the same habitat where shown by assembling and mapping kelp distribution and trend data. Significant data gaps for some geographical regions, like the Mediterranean and the southern Iberian Peninsula, were also identified. The data used for this study confirmed a general trend with decreasing abundance of some native kelp species at their southern distributional range limits and increasing abundance in other parts of their distribution (Saccharina latissima and Saccorhiza polyschides). The expansion of the introduced species Undaria pinnatifida was also registered. Drivers of observed changes in kelp forests distribution and abundance were assessed using experts’ opinions. Multiple possible drivers were identified, including global warming, sea urchin grazing, harvesting, pollution and fishing pressure, and their impact varied between geographical areas. Overall, the results highlight major threats for these ecosystems but also opportunities for conservation. Major requirements to ensure adequate protection of coastal kelp ecosystems along European coastlines are discussed, based on the local to regional gaps detected in the study.     

An ethnobotanical survey of indigenous knowledge on medicinal plants used by the traditional healers of the Lwamondo area,Limpopo province,South Africa

The use of medicinal plants in the treatment and prevention of diseases is attracting the attention of scientists worldwide. Approximately 3000 plant species are currently used by an estimated 200,000 indigenous traditional healers in South Africa. The specific part of the plant used for medicinal applications varies from species to species, and from one traditional healer to another. This study was carried out to explore and record those plants and plant parts used for treating various human ailments by the traditional healers of the Lwamondo area in the Limpopo province, South Africa for medicinal purposes. Ethnobotanical data were collected from 30 traditional healers (24 females and 6 males) in the Lwamondo area of Venda, by means of a data capture questionnaire focusing on the local names of the medicinal plants, their medicinal uses, the plant parts used, and methods of preparation and of administering treatments to patients. The survey identified 16 medicinal plants from 7 families, with 14 genera, used to treat a range of ailments in the Lwamondo area. The Fabaceae family was the most commonly used plant family representing 43.8% of all the medicinal plants species recorded by this study, followed by the Varbenaceae family at 18.8%. The plant parts most frequently used were the roots (44.5%), followed by the leaves (25.9%), bark (14.8%), the whole plant (11%), and flowers (3.7%). Most of the traditional healers obtained their extracts by boiling the medicinal plants. The most often recurring ailment treated by healers was stomach problems, using 31.3% of all the medicinal plants reported in this study for preparing such treatments. The following medicinal plants were covered by this study: Annona senegalensis, Schkuhria pinnata, Diospyros mespiliformis, Piliostigma thonningii, Senna obtusifolia, Bauhinia galpinii. The rural communities of the Lwamondo area possess a wealth of information on medicinal plants and their applications. This ethnobotanical survey can help scientists identify for further research those plants whose medicinal properties may be useful in the development of new drugs.