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

An updated inventory of medicinal and ritual plants of southern Africa

ETHNOPHARMACOLOGICAL RELEVANCE

For the first time in two decades, a comprehensive, up-to-date overview of the medicinal and ritual plants of southern Africa is presented. This data is analysed and compared with a previous survey done in 2002.

STUDY AIM

The main aim is to update the checklist of medicinal and ritual plants of southern Africa and to determine the number of new records since 2002. We also provide a high-level perspective on the selection of medicinal and ritual plant species in southern Africa, a taxonomic analysis of the new checklist as well as a chronological perspective on the citation of medicinal and ritual species before and after 2002.

MATERIALS AND METHODS

The most recently published medicinal and ritual plants checklist for southern Africa was reviewed and updated. A wide range of ethnobotanical literature, including books, field guides and electronic journals, was used. All calculations were done by using formulas and functions in Microsoft Excel and R Studio.

RESULTS

4120 medicinal and ritual taxa and 3784 medicinal and ritual species have been recorded. Compared with the 2002 checklist, there are 1239 new taxa (1228 new species). A strong correlation between available taxa and selected medicinal taxa exists on order level, which corresponds with the results of an analysis done in 2008. The top 10 species-rich medicinal plant families of southern Africa are Asteraceae, Fabaceae, Apocynaceae, Euphorbiaceae, Asphodelaceae, Malvaceae, Lamiaceae, Poaceae, Rutaceae and Rubiaceae. Different patterns of plant family representation can be seen across certain cultural healing systems of southern Africa. The species popularity (number of citations) of Hypoxis hemerocallidea Fisch. & C.A.Mey. Has increased substantially after 2002. Other medicinal and ritual plant species have been consistently researched, such as Artemisia afra Jacq. ex Willd., Carpobrotus edulis (L.) L.Bolus, Aloe ferox Mill., Leonotis leonurus (L.) R.Br. and Gunnera perpensa L.

CONCLUSIONS

The numerous new medicinal and ritual plant records that have been reported in the last two decades provide evidence of an incompletely documented ethnobotanical heritage that urgently requires documentation. Patterns of taxonomic diversity on family level indicate distinctive differences between cultural healing systems. Signs of the adaptability and dynamics of traditional healing systems in southern Africa can be seen in the changes in the citation of species over time.

New frontiers of invasive plants for biosynthesis of nanoparticles towards biomedical applications: A review

Above 1000 invasive species have been growing and developing ubiquitously on Earth. With extremely vigorous adaptability, strong reproduction, and spreading powers, invasive species have posed an alarming threat to indigenous plants, water quality, soil, as well as biodiversity. It was estimated that an economic loss of billions of dollars or equivalent to 1 % of gross domestic product as a consequence of lost crops, control efforts, and damage costs caused by invasive plants in the United States. While eradicating invasive plants from the ecosystems is practically infeasible, taking advantage of invasive plants as a sustainable, locally available, and zero-cost source to provide valuable phytochemicals for bionanoparticles fabrication is worth considering. Here, we review the harms, benefits, and role of invasive species as important botanical sources to extract natural compounds such as piceatannol, resveratrol, and quadrangularin-A, flavonoids, and triterpenoids, which are linked tightly to the formation and application of bionanoparticles. As expected, the invasive plant-mediated bionanoparticles have exhibited outstanding antibacterial, antifungal, anticancer, and antioxidant activities. The mechanism of biomedical activities of the invasive plant-mediated bionanoparticles was insightfully addressed and discussed. We also expect that this review not only contributes to efforts to combat invasive plant species but also opens new frontiers of bionanoparticles in the biomedical applications, therapeutic treatment, and smart agriculture.

Lanceolanone A, a new biflavanone, and a chalcone glucoside from the flower heads of Coreopsis lanceolata and their aldose reductase inhibitory activity and AMPK activation

The MeOH extract of the flower heads of Coreopsis lanceolata L. (Asteraceae) exhibited aldose reductase (AR) inhibitory activity (IC₅₀ 8.36 µg/mL). Bioassay-guided fractionation of the extract resulted in the isolation of a new biflavanone-named Lanceolanone A (1) and a chalcone glucoside (6), along with 12 known compounds (2-5 and 7-14), of which 4, 7, 9, 10, and 12 were isolated from C. lanceolata for the first time. The structures of the new compounds (1 and 6) were determined by extensive spectroscopic analysis, including two-dimensional (2D) NMR, and ECD calculation method. Compounds 2, 4, 11, 13, and 14 exhibited AR inhibitory activities with IC₅₀ values between 2.40 and 9.99 µM. Furthermore, 8-13 at 1.0 mM activated AMPK expression in HepG2 human hepatoma cells compared to the control.

Traditional uses of wild and tended plants in maintaining ecosystem services in agricultural landscapes of the Eastern Cape Province in South Africa

BACKGROUND

Many communities in developing countries rely on ecosystem services (ESs) associated with wild and cultivated plant species. Plant resources provide numerous ESs and goods that support human well-being and survival. The aim of this study was to identify and characterize wild and tended plant species, and also investigate how local communities in the Eastern Cape Province in South Africa perceive ESs associated with plant resources.

METHODS

The study was conducted in six local municipalities in the Eastern Cape Province, between March 2016 and September 2021. Data on socio-economic characteristics of the participants, useful plants harvested from the wild and managed in home gardens were documented by means of questionnaires, observation and guided field walks with 196 participants. The ESs were identified using a free listing technique.

RESULTS

A total of 163 plant species were recorded which provided 26 cultural, regulating and provisioning ESs. Provisioning ESs were the most cited with at least 25 plant species contributing towards generation of cash income, food, traditional and ethnoveterinary medicines. Important species recorded in this study with relative frequency of citation (RFC) values > 0.3 included Alepidea amatymbica, Allium cepa, Aloe ferox, Artemisia afra, Brassica oleracea, Capsicum annuum, Cucurbita moschata, Hypoxis hemerocallidea, Opuntia ficus-indica, Spinacia oleracea, Vachellia karroo and Zea mays.

CONCLUSION

Results of this study highlight the importance of plant resources to the well-being of local communities in the Eastern Cape within the context of provision of essential direct and indirect ESs such as food, medicinal products, construction materials, fodder, regulating, supporting and cultural services. The ESs are the basis for subsistence livelihoods in rural areas, particularly in developing countries such as South Africa. Therefore, such body of knowledge can be used as baseline data for provision of local support for natural resource management initiatives in the province and other areas of the country.