Medicinal Plants In South Africa Research Articles

A human–wildlife conflict: potential impacts of fatal harvesting approaches on medicinal plants in Free State Province, South Africa

ABSTRACT Human-wildlife conflict has taken center stage in global biodiversity degradation, yet researchers have mainly focused on animals. Medicinal plants are declining globally, partly because of over-harvesting which is considered a form of human-wildlife conflict in this study. Compared with other provinces in South Africa, Free State has limited information on the use of medicinal plants and the impacts of over-harvesting the species. We investigated the potential impacts of over-harvesting the plant species for medicinal purposes and determined the potential conservation implications of the harvesting methods in Free State Province, South Africa. We show that 89 plant species from 43 families were used for traditional medicine. The most-used species were Pachycarpus rigidus (12%; N=211), followed by Dicoma anomala (9%) with the common plant families being Asteraceae (13.5%; N=89), and Fabaceae (7.9%). The perennial herbs were substantially harvested (58.4%; N=89). The wild indigenous plant species were more preferred compared to alien species (79.2%; N=89). The roots and bulbs were mostly utilized for medicinal material (48.3%; N=89), followed by the leaves (20.2%). We found one ‘rare’ species (Schizoglossum montanum), and two ‘nearly threatened’ species (Merwilla plumbea and Eucomis bicolor). We recommend a socio-ecologically orientated policy intervention for the sustainable use of medicinal plants in South Africa.

Phytochemical Profile and Bioactivity of the Methanolic Leaf and Root Extracts of South African Bulbine frutescens

Bulbine frutescens is an indigenous succulent medicinal plant in South Africa. The plant is commonly used traditionally for the treatment of skin related ailments. B. frutescens has been reported to possess antioxidant, anti-viral and antimicrobial properties. To date, most studies have been conducted on the leaves, while limited reports have been documented on the roots, as well as comparative analyses between both plant parts. The aim of this study was to determine the phytochemical content, antioxidant and antibacterial activities in the leaves and roots of B. frutescens. Methanolic extracts of each plant part were assessed on the phytochemical analysis, antioxidant (DPPH, hydrogen peroxide, metal chelating) and antibacterial activity against S. aureus and E. coli. The results from the phytochemical screening showed that the leaves contained more phytochemical groups than the roots. The roots displayed higher total phenolics (991.7 ± 54.1 mg GAE/g), total flavonoid (285.8 ± 60.6 mg QE/g) and total tannin contents (1698.75 ± 28.15 mg GAE/g) than the leaves. The roots also showed a stronger antioxidant activity in DPPH (3.43 ± 0.16 mg/ml) and metal chelating (0.54 ± 0.01 mg/ml) assays, compared to the leaves, which only showed a higher scavenging power against hydrogen peroxide radicals (1.48 ± 0.02 mg/ml) than the roots. Both plant parts showed intermediate zones of inhibition (10-19 mm) against both bacterial strains, with the exception of the leaves which had a 20.67 ± 0.67 mm inhibition against S. aureus. These results validate the uses of both leaves and roots of B. frutescens in traditional medicine and further suggests for the application of the roots in pharmaceutical and cosmetic industries.Bulbine frutescens is an indigenous succulent medicinal plant in South Africa. The plant is commonly used traditionally for the treatment of skin related ailments. B. frutescens has been reported to possess antioxidant, anti-viral and antimicrobial properties. To date, most studies have been conducted on the leaves, while limited reports have been documented on the roots, as well as comparative analyses between both plant parts. The aim of this study was to determine the phytochemical content, antioxidant and antibacterial activities in the leaves and roots of B. frutescens. Methanolic extracts of each plant part were assessed on the phytochemical analysis, antioxidant (DPPH, hydrogen peroxide, metal chelating) and antibacterial activity against S. aureus and E. coli. The results from the phytochemical screening showed that the leaves contained more phytochemical groups than the roots. The roots displayed higher total phenolics (991.7 ± 54.1 mg GAE/g), total flavonoid (285.8 ± 60.6 mg QE/g) and total tannin contents (1698.75 ± 28.15 mg GAE/g) than the leaves. The roots also showed a stronger antioxidant activity in DPPH (3.43 ± 0.16 mg/ml) and metal chelating (0.54 ± 0.01 mg/ml) assays, compared to the leaves, which only showed a higher scavenging power against hydrogen peroxide radicals (1.48 ± 0.02 mg/ml) than the roots. Both plant parts showed intermediate zones of inhibition (10-19 mm) against both bacterial strains, with the exception of the leaves which had a 20.67 ± 0.67 mm inhibition against S. aureus. These results validate the uses of both leaves and roots of B. frutescens in traditional medicine and further suggests for the application of the roots in pharmaceutical and cosmetic industries.

Diversity analysis of southern African Artemisia afra using a single nucleotide polymorphism derived from diversity arrays

Artemisia afra is an aromatic shrub used as a herbal remedy in southern Africa for various disorders, including coughs, colds, influenza, and, most notably, for the prophylaxis and treatment of Plasmodium falciparum infections. Modern high-throughput genotyping by sequencing, which combines next generation sequencing and diversity array technology (DArTseq) complexity reduction methods, allows for the generation of high-quality whole-genome profiles without any previous organismal genetic information that may hamper the diversity analyses. This study investigated the feasibility of incorporating DArTseq-derived single-nucleotide polymorphisms (SNPs) and bioactive compounds into a geographic information system to predict the spatial distribution of A. afra gene diversity in selected southern African environs. DNA extraction, sequencing, and SNP calling mineral analyses (using R Studio) were performed on a total of 80 genotypes collected around Roma and Mohale’s Hoek, Lesotho, and Wepener and Hobhouse, South Africa. The unweighted pair group method with arithmetic mean (UPGMA) and neighbour-joining dendrograms revealed three clusters of variation among genotypes; however, geographic distribution did not influence A. afra genetic diversity. The mean heterozygosity among genotypes was 7.7%. Genotypes collected in Roma and Mohale’s Hoek exhibited high levels of genetic diversity. Local A. afra genetic diversity was relatively low, indicating uniformity of subspecies per locality. The diversity among genotypes indicated that A. afra SNPs may occur despite the location. Given that genetic diversity enhances crop performance, our findings can be useful in germplasm management, industries producing by-products of A. afra, and plant breeding programs. For the long-term conservation of medicinal plants in South Africa, significant sampling and regional data are required. In addition to evaluating qualitative and quantitative assessments of phytochemicals, it is necessary to evaluate foliar mineral composition, as well as the agronomic and morphological characteristics of collected specimens from studied locations.

Optimizing extraction of Pelargonium sidoides roots: Impact of ethanol concentration on biological activity of extracts

Pelargonium sidoides DC. (Geraniaceae) is an important indigenous medicinal plant in South Africa, historically employed by various ethnic groups to treat respiratory and gastrointestinal ailments. The proprietary herbal tincture, Umckaloabo®, utilizes an ethanolic extract (EPs® 7630) from the roots of P. sidoides, and has demonstrated effectiveness in alleviating symptoms of respiratory infections.P. sidoides roots contain numerous highly oxygenated coumarins and phenolic metabolites, notably the marker compound umckalin. While Umckaloabo® is prepared using 11 % ethanol extraction, the South African commercial market predominantly employs 60 % ethanol extraction due to its consistent umckalin yield and antimicrobial activity. The effects of these extraction methods on chemical composition and in vitro pharmacological activity remain poorly understood.This study confirmed superior antibacterial and antifungal activity in the 60 % ethanol extracts prepared from six root samples compared to the 11 % ethanol extracts. MIC values for both Gram-negative and Gram-positive bacteria ranged from 0.078 to 2.5 mg/mL in the 60 % extracts. Remarkably, two of the root extracts exhibited excellent to very good activity against C. albicans and C. neoformans with MIC values of 0.039 and 0.078 mg/mL, respectively.A positive correlation was identified between total minimum inhibitory concentration (MIC) levels and polyphenol content, rather than umckalin levels. The influence of these extracts on the pro-inflammatory cytokine IL-6 was assessed. Both 60 % and 11 % root extracts of P. sidoides at 100 µg/mL significantly reduced IL-6 production, with the 60 % extracts demonstrating a more pronounced effect (p = 0.008).Statistical analysis revealed significant differences between 11 % and 60 % ethanol extractions in terms of average MIC overall, average Gram-negative MIC, average Gram-positive MIC, fungal MIC, and IL-6 levels. Extracts with higher polyphenol values exhibited superior antimicrobial activity and antioxidant potential, suggesting that polyphenol content may serve as a more reliable indicator of antimicrobial activity than umckalin levels. Additionally, polyphenol levels in the roots may vary with altitude and other environmental factors, warranting further research.

A Review Study on Alternative Conservation and Management Methods to Sustain Medicinal Plants in South Africa

The use of indigenous medicinal plants is still prevalent as the most trusted form of health care, predominantly in developing countries. Overuse of medicinal plant resources, coupled with the negative impacts of unpredictable rainfall and rising temperatures, necessitated the development of local methods to conserve medicinal plants. These indigenous conservation methods have proved to be failing and aggravating threats to medicinal plants. This study aimed to review the alternative conservation and management methods to protect medicinal plants in South Africa. A review of the literature presents in situ, ex situ, natural reserves, wild nurseries, botanical gardens, and seed banks as alternative conservation methods proposed and used by scientists to conserve and manage medicinal plant species. These methods are Western practices introduced to the local communities in an effort to conserve and protect the indigenous medicinal plant species for future use and as a cultural heritage. From a qualitative standpoint, this study adopted the interpretivist research design to offer support to employ the systematic review method. Seminal studies on this subject were purposively collected using keywords extracted from the research topic. The collected data was analysed using the inductive Textual Content Analysis (TCA) method. The results of this study reveal that there are various conservation methods that are implemented as strategies to safeguard the existing medicinal plants, and this proves if these methods are implemented correctly these plants will still be available for future use. It is concluded and recommended that the demand for medicinal plants imposes huge threats to their anticipated availabilities, therefore, the relevant stakeholders need to take urgent corrective measures ­concerned parties should be consistently exposed to improved resources, advanced training and better education about the benefits and importance of these plants. Keywords: Medicinal plants, conservation method, In situ, natural resource

Assessment of natural radionuclides in some prominent South African medicinal plants

The activities of radionuclides in some medicinal plants in South Africa were determined using gamma-ray spectrometry to assess the radiological health hazards and excess lifetime cancer risks associated with their use. The activity of 238U(eU), 232Th(eTh), and 40K ranged from 20 to 57 Bq kg−1, 15–48 Bq kg−1, and 110–570 Bq kg−1, with the highest of 238U (38–57) Bq kg−1, and 232Th (32–48) Bq kg−1 recorded for the Gunnera perpensa and 40K (390–570) Bq kg−1 for the Passiflora suberosa. The estimated annual committed effective dose (0.009–0.017) mSv y−1 and lifetime cancer risk (0.285–0.536) × 10−4 values are well within worldwide recommended limits of 0.3 mSv y−1 and 2.9 × 10−4 set by the United Nations Scientific Committee on the Effect of Atomic Radiations for radiological risks.

Predicting the Geographical Distribution Shift of Medicinal Plants in South Africa Due to Climate Change

There has been a recent rise in the number of medicinal plant users in Southern Africa, with approximately a million users reported to utilize these plants for various health conditions. Unfortunately, some of these plants are reportedly endangered and facing extinction due to harvesting pressure. In addition, climate change is likely to negatively affect the geographical distribution of these medicinal plants. In the current study, future greenhouse gas emission scenarios of the representative concentration pathways, RCP2.6 and RCP8.5, for future projections to 2050 and 2080 were used to simulate the effect of climate change on three medicinal plants’ (Aloe ferox, Bowiea volubilis, and Dioscorea elephantipes) distribution in South Africa. We studied these plant species as the International Union for Conservation of Nature stated that A. ferox is currently of least concern in South Africa, while B. volubilis and D. elephantipes are categorised as declining and vulnerable, respectively. Specifically, we utilised a species distribution model (i.e., the maximum entropy: MaxEnt) to investigate the effect of climate change on the future spatial distribution of medicinal plants in South Africa. In 2050 and 2080, under both RCP scenarios, the suitable habitat of the studied plant species will reduce in the country’s northern parts. Specifically, the habitat for D. elephantipes will totally disappear in the country’s northern parts. However, there will be slight additions of suitable habitats for the species in the country’s southern parts. Model validation indicated that the area under curve (AUC) for A. ferox was 0.924 ± 0.004, while for B. volubilis and D. elephantipes it was 0.884 ± 0.050 and 0.944 ± 0.030, respectively. Using the results from this study, there is a need for the long-term in situ and ex situ conservation of these medicinal plants. The results of the present study could guide the development of effective and efficient policies and strategies for managing and conserving medicinal plants in South Africa.

Proximate, Vitamins, Minerals and Anti-Nutritive Constituents of the Leaf and Stem of Helichrysum odoratissimum (L.) Sweet: A Folk Medicinal Plant in South Africa

Helichrysum odoratissimum (L.) Sweet (Asteraceae) is a perennial shrub used in South African folk medicine to combat human diseases such as diabetes, coughs, asthma, and diarrhoea, and for wound treatment. This study evaluated the leaf and stem of H. odoratissimum for their nutritive and anti-nutritive qualities using the standard methods of the Association of Official Analytical Chemists (AOAC), atomic absorption spectrometry (AAS) and colorimetry. Crude fat and protein were high in the leaf (7.61% and 7.82% DW), but low in the stem (2.25% and 3.4%), respectively. The neutral detergent fibre (NDF) content was significantly higher in the stem (68.5%) compared to the leaf (43.6%), while non-fibre carbohydrate (NFC) in the leaf (24.93%) was higher than in the stem (15.67%). Mineral analysis showed that both the leaf and stem of H. odoratissimum are good sources of potassium, calcium, sodium, magnesium, phosphorus and iron. Appreciable amounts of vitamins B2, C and E in the leaf and stem supports the folkloric utility of the plant in the traditional treatment of wounds, coughs and colds. A tolerable amount of phytate in both leaf (0.36%) and stem (1.06%) might be a factor for safer consumption of the plant as food and medicine. These findings suggest the use of the plant as a source for dietary supplementation and ethnomedicinal applications.

Bulbous Plants Drimia: "A Thin Line between Poisonous and Healing Compounds" with Biological Activities.

Drimia (synonym Urginea) plants are bulbous plants belonging to the family Asparagaceae (formerly the family Hyacinthaceae) and are distinctive, powerful medicinal plants. Just some species are indigenous to South Africa and have been traditionally utilized for centuries to cure various diseases and/or ailments. They have been recognized among the most famous and used medicinal plants in South Africa. Traditionally, the plants are used for various illnesses such as dropsy, respiratory disease, bone and joint complications, skin disorders, epilepsy and cancer. A number of studies have reported biological properties such as antiviral, antibacterial, antioxidant and anti-inflammatory, immunomodulatory, and anticancer activities. Their bulbs are a popular treatment for colds, measles, pneumonia, coughs, fever and headaches. However, some plant species are regarded as one of the six most common poisonous plants in Southern Africa that are toxic to livestock and humans. Due to the therapeutic effects of the Drimia plant bulb, research has focused on the phytochemicals of Drimia species. The principal constituents isolated from this genus are cardiac glycosides. In addition, phenolic compounds, phytosterols and other phytochemical constituents were identified. This study constitutes a critical review of Drimia species’ bioactive compounds, toxicology, biological properties and phytochemistry, advocating it as an important source for effective therapeutic medicine. For this purpose, various scientific electronic databases such as ScienceDirect, Scopus, Google Scholar, PubMed and Web of Science were researched and reviewed to conduct this study. Despite well-studied biological investigations, there is limited research on the toxic properties and the toxic compounds of certain Drimia species. Searching from 2017 to 2021, Google Scholar search tools retrieved 462 publications; however, only 3 investigated the toxicity and safety aspects of Drimia. The aim was to identify the current scientific research gap on Drimia species, hence highlighting a thin line between poisonous and healing compounds, dotted across numerous publications, in this review paper.

Anthelmintic, antimycobacterial, antifungal, larvicidal and cytotoxic activities of acetone leaf extracts, fractions and isolated compounds from Ptaeroxylon obliquum (Rutaceae)

Ethnopharmacological relevancePtaeroxylon obliquum (Thunb.) Radlk, sneezewood, is a commonly used medicinal plant in South Africa for the treatment of parasitic infections in animals, tuberculosis (TB) and related symptoms, and other microbial infections. Aim of the studyIn this study anthelmintic, antifungal, antimycobacterial, larvicidal and cytotoxic activities of the acetone leaf extract of P. obliquum, solvent-solvent derived fractions of the extract and isolated compounds (obliquumol and a mixture of lupeol and β-amyrin) were determined. Materials and methodsThe in vitro anthelmintic activity was tested against Haemonchus contortus ova and larvae using the egg hatch inhibition and larval development assays. The antifungal activity was investigated using a serial microplate dilution method against Aspergillus fumigatus, Cryptococcus neoformans and Candida albicans. Antimycobacterial activity was evaluated by a tetrazolium violet-based broth microdilution method against pathogenic Mycobacterium tuberculosis and Mycobacterium bovis. The larvicidal activity was evaluated against Aedes aegypti. Cytotoxicity was determined using human liver (C3A) and Vero African green monkey kidney cell lines. ResultsObliquumol (ptaeroxylinol acetate) was more effective than the crude acetone extract against H. contortus ova and larvae with an LC50 of 95 μg/mL against the larvae. Obliquumol had very good antifungal activity with minimal inhibitory concentrations (MIC) values from 2 to 16 μg/mL. Lupeol and β-amyrin mixture also had good activity against C. neoformans and C. albicans with an MIC of 16 μg/mL against both fungi. The crude extract and fractions had average to weak antimycobacterial activity against the two pathogenic mycobacteria with MICs of 313–625 μg/mL for the extract and fractions tested. Obliquumol had good activity with an MIC of 63 μg/mL against pathogenic M. tuberculosis ATCC 27115. The acetone crude extract was toxic against Vero cells with an CC50 of 14.2 μg/mL. Obliquumol and the mixture of lupeol and β-amyrin were not toxic against both Vero and C3A cells at the highest concentration tested of 200 μg/mL and had good selectivity index values against the opportunistic fungal pathogens. No tested samples had any larvicidal activity against A. aegypti at the concentrations tested. ConclusionThe activity noted against H. contortus may support the ethnoveterinary use of this plant against animal parasites in South Africa although aqueous extracts were not active. The activity of obliquumol against opportunistic fungal pathogens was also promising. The cytotoxicity of the acetone leaf extract, however, raises concerns about the traditional use of P. obliquum to treat a wide range of diseases although if an aqueous extract is used the toxicity concern may not be relevant.

South Africa's Best BARK Medicines Prescribed at the Johannesburg Muthi Markets for Skin, Gut, and Lung Infections: MIC's and Brine Shrimp Lethality.

Indigenous trade of medicinal plants in South Africa is a multi-million-rand industry and is still highly relevant in terms of primary health care. The purpose of this study was to identify today’s most traded medicinal barks, traditionally and contemporaneously used for dermatological, gastrointestinal, and respiratory tract infections; then, to investigate the antimicrobial activity and toxicity of the respective extracts and interpret outcomes in light of pharmacokinetics. Thirty-one popularly traded medicinal barks were purchased from the Faraday and Kwa Mai-Mai markets in Johannesburg, South Africa. Information on the medicinal uses of bark-based medicines in modern commerce was recorded from randomly selected traders. The minimum inhibitory concentration (MIC) method was used for antimicrobial screening, and brine shrimp lethality was used to determine toxicity. New medicinal uses were recorded for 14 bark species. Plants demonstrating some broad-spectrum activities against tested bacteria include Elaeodendron transvaalense, Erythrina lysistemon, Garcinia livingstonei, Pterocelastrus rostratus, Rapanea melanophloeos, Schotia brachypetala, Sclerocarya birrea, and Ziziphus mucronata. The lowest MIC value of 0.004 mg/mL was observed against Staphylococcus epidermidis for a dichloromethane bark extract of E. lysistemon. The tested medicinal barks were shown to be non-toxic against the Artemia nauplii (brine shrimp) bioassay, except for a methanol extract from Trichilia emetica (69.52% mortality). Bacterial inhibition of bark extracts with minimal associated toxicity is consistent with the safety and valuable use of medicinal barks for local muthi market customers. Antimicrobial outcomes against skin and gastrointestinal pathogens are feasible because mere contact-inhibition is required in vivo; however, MIC values against respiratory pathogens require further explaining from a pharmacokinetics or pharmacodynamics perspective, particularly for ingested rather than smoked therapies.

Lobostemon trigonus (Thunb.) H. Buek, a medicinal plant from South Africa as a potential natural microbicide against HIV-1

Ethnopharmacological relevanceThere have been different methods proposed to prevent the sexual transmission of HIV-1 and many of them have centered on the use of anti-retrovirals as microbicides. Given that a large section of the African population still relies on herbal medicine, Lobostemon trigonus (L. trigonus), a traditionally used medicinal plant in South Africa to treat HIV-1 was further investigated for its potential as a natural microbicide to prevent the sexual transmission of HIV-1. MethodsThe aerial parts of L. trigonus were oven-dried at 80 °C, ground, extracted with boiling water for 30 min and then filtered. The aqueous extract produced was then bioassayed using different HIV-1 inhibition assays. The active components were purified and chemically profiled using ultra-performance liquid chromatography/quadrupole time-of flight mass spectrometry (UPLC-qTOF-MS). The mechanism of HIV-1 inhibition was determined by fusion arrest assay and time of addition assay. Molecular modelling and molecular dynamic simulations, using Schrödinger, were used to better understand the molecule's mechanism of entry inhibition by evaluating their docking affinity and stability against the gp120 of HIV-1. ResultsThe aqueous extract of this plant had a broad spectrum of activity against different subtypes of the virus; neutralizing subtype A, B and C in the TZM-bl cells, with IC50 values ranging from 0.10 to 7.21 μg/mL. The extract was also inhibitory to the virus induced cytopathic effects in CEM-SS cells with an EC50 of 8.9 μg/mL. In addition, it inhibited infection in peripheral blood mononuclear cells (PBMC) and macrophages with IC50 values of 0.97 and 4.4 μg/mL, respectively. In the presence of vaginal and seminal simulants, and in human semen it retained its inhibitory activity albeit with a decrease in efficiency, by about 3-fold. Studies of the mode of action suggested that the extract blocked HIV-1 attachment to target cells. No toxicity was observed when the Lactobacilli strains, L. acidophilus, L. jensenii, and L. crispatus that populate the female genital tract were cultured in the presence of L. trigonus extract. UPLC-qTOF-MS analyses of the purified fraction of the extract, confirmed the presence of six compounds of which four were identified as rosmarinic acid, salvianolic acids B and C and lithospermic acid. The additional molecular dynamic simulations provided further insight into the entry inhibitory characteristics of salvianolic acid B against the HIV-1 gp120, with a stable pose being found within the CD4 binding site. ConclusionThe data suggests that the inhibitory effect of L. trigonus may be due to the presence of organic acids which are known to possess anti-HIV-1 properties. The molecules salvianolic acids B and C have been identified for the first time in L. trigonus species. Our study also showed that the L. trigonus extract blocked HIV-1 attachment to target cells, and that it has a broad spectrum of activity against different subtypes of the virus; thus, justifying further investigation as a HIV-1 microbicide.

A Chewable Cure "Kanna": Biological and Pharmaceutical Properties of Sceletium tortuosum.

Sceletium tortuosum (L.) N.E.Br. (Mesembryanthemaceae), commonly known as kanna or kougoed, is an effective indigenous medicinal plant in South Africa, specifically to the native San and Khoikhoi tribes. Today, the plant has gained strong global attraction and reputation due to its capabilities to promote a sense of well-being by relieving stress with calming effects. Historically, the plant was used by native San hunter-gatherers and Khoi people to quench their thirst, fight fatigue and for healing, social, and spiritual purposes. Various studies have revealed that extracts of the plant have numerous biological properties and isolated alkaloids of Sceletium tortuosum are currently being used as dietary supplements for medicinal purposes and food. Furthermore, current research has focused on the commercialization of the plant because of its treatment in clinical anxiety and depression, psychological and psychiatric disorders, improving mood, promoting relaxation and happiness. In addition, several studies have focused on the isolation and characterization of various beneficial bioactive compounds including alkaloids from the Sceletium tortuosum plant. Sceletium was reviewed more than a decade ago and new evidence has been published since 2008, substantiating an update on this South African botanical asset. Thus, this review provides an extensive overview of the biological and pharmaceutical properties of Sceletium tortuosum as well as the bioactive compounds with an emphasis on antimicrobial, anti-inflammatory, anti-oxidant, antidepressant, anxiolytic, and other significant biological effects. There is a need to critically evaluate the bioactivities and responsible bioactive compounds, which might assist in reinforcing and confirming the significant role of kanna in the promotion of healthy well-being in these stressful times.

Local processing methods for commonly used medicinal plants in South Africa

The processing of medicinal plants aims to add value and extract as many ingredients as possible while improving the shelf-life of herbal ingredients. However, the methods used for local processing of medicinal plants remain a grey area. Using a survey of available literature, this study reported on the processing methods used by local processors of herbal products in South Africa. Thirty plant species belonging to four families Fabaceae, Apiaceae, Hyacinthaceae and Asteraceae, listed as having high medicinal value were identified and the methods of processing of herbal ingredients were explored. Decoctions were found to be the most used method followed by infusions, drying, powdering and fermentation of various plant parts. Primary processing methods were mostly carried out by households, traders and traditional medicine practitioners, with minimal reporting of industrial-level processing activities. While there is immense interest in the preparation of medicinal plants for their therapeutic uses, uniformity and standard methods of processing will ensure higher quality and reliability of herbal medicines.

Sceletium Tortuosum: Effects on Central Nervous System and Related Disease

Sceletium tortuosum is a well-known medicinal plant in South Africa with potential applications. Its raw material, extracts and isolated alkaloids are used as dietary supplements, natural medicines and health food. In this paper, methods of planting, extraction, isolation and identification of Sceletium tortuosum , as well as its chemical structure of main extracted alkaloids, their related pharmacological effects and mechanisms for treating the disease are reviewed. In general, Sceletium tortuosum is active to central nervous system (CNS) by inhibiting phosphodiesterase isozyme 4 (PDE4), serotonin (5-HT) uptake and acetylcholinesterase (AChE). It also acts as a monoamine releasing agent for antidepressant effects. Therefore, it is a useful therapeutic agent in clinical use.

Value Chain Analysis of Medicinal Plants in South Africa

Value Chain Analysis of Medicinal Plants in South Africa

Bulbine frutescens phytochemical inhibits notch signaling pathway and induces apoptosis in triple negative and luminal breast cancer cells

Breast cancer (BCa) is the most commonly diagnosed lethal cancer in women worldwide. Notch signaling pathway is directly linked to BCa recurrence and aggressiveness. Natural remedies are becoming a prime choice to overcome against cancer due to lesser side effect and cost-effectiveness. Bulbine frutescens (Asphodelaceae), a traditional medicinal plant in South Africa possess bioactive flavonoids and terpenoids. Polar (methanol) and non-polar (hexane) B. frutescens plant extracts were prepared. GC–MS analysis revealed the differential presence of secondary metabolites in both methanolic and hexane extracts. We hereby first time evaluated the anticancer potential of B. frutescens methanolic and hexane extract in triple-negative and luminal BCa cells. B. frutescens extracts significantly decreased cell viability (IC50 4.8–28.4 μg/ml) and induced cell cycle arrest at G1 phase in MDA-MB-231 and T47D cells as confirmed by spectrophotometry and flow cytometry technique. RT-PCR analysis of cell cycle (cyclin D1, CDK4, and p21) and apoptosis modulating genes (caspase 3, Bcl2 and survivin) revealed upexpression of p21, and caspase 3, and down expression of cyclin D1, CDK4, Bcl2 and survivin genes in extract-treated BCa cells. Fluorescence spectrophotometry and confocal microscopy showed B. frutescens induced nuclear morphology and mitochondrial integrity disruption, and increased reactive oxygen species production in MDA-MB-231 and T47D cells. Flow cytometric apoptosis analysis of B. frutescens extracts treated MDA-MB-231 cells showed ≈13% increase in early apoptotic population in comparison to non-treated cells. Dual-Luciferase Reporter assay confirmed notch promoter inhibitory activity of B. frutescens extracts. Moreover, RTPCR analysis showed down regulation of notch responsive genes (Hes1 and Hey1) at transcription levels in extract-treated BCa cells. Western Blot analysis showed increased procaspase 3 protein expression in extract-treated BCa cells. In all the assays methanolic extract showed better anti-cancer properties. Literature-based identification of methanol soluble phytochemicals in B. frutescens and in silico docking study revealed Bulbineloneside D as a potent ϒ-secretase enzyme inhibitor. In comparison to standard notch inhibitor, lead phytochemical showed two additional hydrophobic interactions with Ala80 and Leu81 amino acids. In conclusion, B. frutescens phytochemicals have cell cycle arrest, ROS production, apoptosis induction, and mitochondria membrane potential disruption efficacy in breast cancer cells. B. frutescens phytochemicals have the ability to downregulate the notch signaling pathway in triple-negative and luminal breast cancer cells.

Antidiabetic, anti-inflammatory, anticholinesterase and cytotoxicity determination of two Carpobrotus species

Carpobrotus edulis (L.) N. E. Br., commonly grown in many parts of the world, and C. dimidiatus (Haw.) L. Bolus are highly used medicinal plants in South Africa for treating diabetes, wounds, inflammation and other closely-related diseases. This study was aimed at evaluating the antidiabetic, anti-inflammatory, and acetylcholinesterase inhibitory activities as well as cytotoxicity effects (using RAW 264.7, Vero kidney and HepG2 liver cells) of different solvent (water, 70% acetone, and 50% methanol) extracts obtained from the leaves of C. edulis and C. dimidiatus. Antidiabetic and anti-inflammatory activities were evaluated using alpha-glucosidase and 15-lipoxygenase (LOX) enzyme inhibition assays, respectively. In addition, the phenolic content of the two plant species was quantified. Water extract of C. edulis leaves exhibited noteworthy alpha-glucosidase inhibitory activity with an IC50 value of 5 μg/ml. Acetone and water extracts of C. edulis showed promising 15-LOX inhibition activity with IC50 values of 22.3 and 59.8 μg/ml, respectively. These same extracts demonstrated strong free radical scavenging activity as reflected by their EC50 values of 5.6 and 6.2 μg/ml, respectively. Carpobrotus edulis leaves had a significantly high total phenolic and flavonoid contents when compared to C. dimidiatus. Furthermore, all extracts exhibited very low cytotoxicity against all the tested cells. The current findings offer supporting evidence for the use of these plant species in the development of natural products to treat diabetes, among other ailments. These plant species can be used in the production of natural supplements or functional food for the management of pain, diabetes and free radical-induced disorders.

Geographic-based metabolomic variation and toxicity analysis of Sutherlandia frutescens L. R.Br. – An emerging medicinal crop in South Africa

Sutherlandia frutescens (syn. Lessertia frutescens), an indigenous southern African species, is important for the local and global phytomedicine's industry. As farming of medicinal plants in South Africa is not extensive, wild populations are also used as a source of material to bulk available cultivated yields prior to industrial processing. This may cause inconsistency in the quality of medicinal products derived from this species, inducing discrepancies in the plant’s therapeutic profile. The current study aimed to elucidate the phytochemical variations among S. frutescens plants growing in different geographical localities, especially in areas which have not been studied before. One set of extracts were generated using a 50% acetonitrile and formic acid solution (0.1%) (v/v). By using a targeted metabolomics approach, two major phytochemical groups, sutherlandins and sutherlandiosides were used to display metabolite-based clusters after LC–MS/MS analysis. Plants from different geographical locations grouped into separate chemical lineages. Another set of ethanol and aqueous extracts of pooled leaf materials were screened for their toxicity effect on the hatching rate of zebrafish embryos and mortality of larvae at different concentrations, ranging from 5 to 300 μg ml−1. We also calculated the LC50 values using a zebrafish microplate bioassay and this value was 297.57 μg ml−1 for the water extract. The aqueous extracts were relatively less toxic compared to ethanol extracts (LC50 value of 40.54 μg ml−1). Both the hatching rate and mortality were negatively affected by increasing extract dosages. The highest concentrations, between 200 to 300 μg ml−1, caused acute lethal effects for both extract types. This study adds additional evidence of the cytotoxicity reported by others in this species and will further aid in the domestication of S. frutescens.

Comparative cardio and developmental toxicity induced by the popular medicinal extract of Sutherlandia frutescens (L.) R.Br. detected using a zebrafish Tuebingen embryo model

BackgroundSutherlandia frutescens is one of the most promising commercialized, indigenous and medicinal plants of South Africa that is used as an immune-booster, and a traditional treatment for cancer. However, few studies report on its toxicology and dosage in vivo. There is still room to better understand its cytotoxicity effects in animal systems.MethodsWe prepared two extracts, one with 80% (v/v) ethanol, and the other, with water. Both were studied to determine the maximum tolerable concentration when extracts were applied at 0 to 200 μg/ml to a Tuebingen zebrafish embryo line. The development of zebrafish embryos after 24 h post fertilization (hpf) was studied. A concentration range of 5 μg/ml to 50 μg/ml was then chosen to monitor the ontological development of cultured embryos. A liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method was used to study the differences of the two experimental extracts. Chemical variation between the extracts was illustrated using chemometrics.ResultsBoth extracts led to bleeding and pericardial cyst formation when applied at high concentrations to the zebrafish embryo culture. Chronic teratogenic toxicities, leading to pericardial edema, yolk sac swelling, and other abnormal developmental characteristics, were detected. The aqueous extracts of S. frutescens were less toxic to the larvae than the ethanol extracts, validating preference for aqueous preparations when used in traditional medicine. Chemical differences between the water extracts and alcoholic extracts were analysed using LC-MS/MS. A supervised metabolomics approach, targeting the sutherlandiosides and sutherlandins using orthogonal partial least squares-discriminant analysis (OPLS-DA), illustrated that sutherlandiosides were the main chemical features that can be used to distinguish between the two extracts, despite the extracts being highly similar in their chemical constituents.ConclusionThe water extract caused less cytotoxic and abnormal developmental effects compared to the ethanolic extract, and, this is likely due to differences in concentrations of extracted chemicals rather than the chemical profile per se. This study provides more evidence of cytotoxicity effects linked to S. frutescens using the zebrafish embryo bioassay as a study tool.