Spotlight on ethnomedicine: usability of Sutherlandia frutescens in the treatment of diabetes

Evaluation of the Neuroprotective Potential of Sutherlandia frutescens in a Rotenone-Induced Rat Model of Parkinson's Disease

Sutherlandia frutescens (SF) is a plant used traditionally in South Africa for various health conditions, including neurological disorders. Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra, resulting in motor symptoms. Rotenone, a pesticide, has been linked to PD-like symptoms in both in vitro and in vivo studies. However, SF-specific effects of SF on PD-related symptoms have not been extensively studied. This study was aimed at investigating the potential neuroprotective effects of SF against rotenone-induced PD using in vivo electrophysiological recordings from the hippocampus and an open-field test to assess motor behavior. Rats were divided into three groups: a control group receiving sunflower oil, a rotenone group treated with rotenone (2.0 mg/kg), and an SF group treated with hydroponically grown SF extract. Electrophysiological recordings from the hippocampus were conducted to assess neuronal activity, and an open-field test was used to evaluate motor behavior. Rats treated with SF exhibited significantly higher motor activity compared to both the sunflower oil and rotenone groups, suggesting an activating effect of SF on motor behavior. In contrast, the rotenone group displayed reduced activity levels and exploratory behavior, highlighting the suppressive impact of rotenone on motor function. These findings suggest that SF modulates hippocampal neuronal activity and may offer neuroprotective benefits against rotenone-induced PD-like symptoms. SF, a plant with traditional medicinal applications, shows potential in modulating motor behavior and hippocampal neuronal activity in a rotenone-induced PD model. Further studies are needed to clarify the underlying mechanisms and evaluate the clinical relevance of SF in PD management.

The effect of Aspalathin linearis, Cyclopia intermedia and Sutherlandia frutescene on sperm functional parameters of healthy male wistar rats

Introduction: Rooibos (Aspalathin linearis), honeybush (Cyclopia intermedia), and sutherlandia (Sutherlandia frutescene) are three Southern Africa indigenous plants, of which the extracts have become house-hold items and are consumed on a large scale. Although, they are known for their antioxidant properties, studies have highlighted danger in the excessive intake. Therefore, the current study investigated whether treatment with rooibos, honeybush, and sutherlandia will impact sperm functional parameters positively or otherwise, in healthy rats. Methods: Fourteen-week-old pathogen-free adult male Wistar rats (250-300 g) were randomly divided into four groups of ten, including a control, rooibos (RF), honeybush (HB) and a sutherlandia (SL) group. After 7 weeks of treatment, animals were sacrificed. Spermatozoa were retrieved from the cauda epididymis for motility, morphology and concentration analysis and the testis was used for all biochemical assays. Results: The infusion treated animals (RF, HB, and SL) presented with a non-significant decrease of -14.3%, -18.2%, -17.2% and -24.8%, -20.7%, -27.3% in total motility and progressive motility when compared to the control group, respectively. There was a significant increase in number of spermatozoa with slow speed (p = 0.03), especially in SL treated group compared to the control (p = 0.03). Additionally, there was an increase of 28.8%, 31.7%, 23% in superoxide dismutase (SOD) activity of RF, HB and SL compared to control, respectively. This was accompanied with a percentage decrease of -21.1%, -23.7%, 45.9% in malondialdehyde (MDA) levels compared to the control group. Conclusion: In summary, animals treated with the respective infusions presented with a percentage increase in SOD activity but have reduced sperm motility and decreased normal morphology. Paradoxically, they presented with increased sperm concentration. Hence, it is presumed that rooibos, honeybush and sutherlandia may enhance sperm quantity (concentration) but may impair sperm quality (motility morphology) when consumed by healthy animals.

The Potential of Rhizobacteria to Mitigate Abiotic Stress in Lessertia frutescens

Lessertia frutescens is a multipurpose medicinal plant indigenous to South Africa. The curative ability of the medicinal plant is attributed to its rich phytochemical composition, including amino acids, triterpenoids, and flavonoids. A literature review of some of the phytochemical compounds, particularly amino acids, in L. frutescens shows a steady decrease in concentration over the years. The reduction of the phytochemical compounds and diminishing biological activities may be attributed to drought and salt stress, which South Africa has been grappling with over the years. Canavanine, a phytochemical which is associated with the anticancer activity of L. frutescens, reduced slightly when the plant was subjected to salt stress. Like other legumes, L. frutescens forms a symbiotic relationship with plant-growth-promoting rhizobacteria, which facilitate plant growth and development. Studies employing commercial plant-growth-promoting rhizobacteria to enhance growth and biological activities in L. frutescens have been successfully carried out. Furthermore, alleviation of drought and salt stress in medicinal plants through inoculation with plant growth-promoting-rhizobacteria is well documented and effective. Therefore, this review seeks to highlight the potential of plant-growth-promoting rhizobacteria to alleviate the effect of salt and drought in Lessertia frutescens.

Bioprospecting for Anti-COVID-19 Interventions From African Medicinal Plants: A Review

The emergence of the novel coronavirus (SARS-CoV-2) that emanated from Wuhan in China in 2019 has become a global concern. The current situation warrants ethnomedicinal drug discovery and development for delivery of phytomedicines with potential for the treatment of COVID-19. The aim of this review is to provide a detailed evaluation of available information on plant species used in African traditional medicines with antiviral, anti-inflammatory, immunomodulatory, and COVID-19 symptoms relieving effects. Literature from scientific databases such as Scopus, PubMed, Google scholar, African Journals OnLine (AJOL), Science Direct, and Web of Science were used for this review. A total of 35 of the 38 reviewed plants demonstrated a wide range of antiviral activities. Bryophyllum pinnatum, Aframomum melegueta, Garcinia kola, Sphenocentrum jollyanum, Adansonia digitata, Sutherlandia frutescens, Hibiscus sabdariffa, Moringa oleifera, and Nigella sativa possess a combination of antiviral, immunomodulatory, anti-inflammatory, and COVID-19 symptoms relieving activities. Nine, 13, and 10 of the plants representing 23.7%, 34.2%, and 26.3% of the plants studied had antiviral activity with 3 other activities, antiviral activity with 2 other activities, and antiviral with one pharmacological activity alone, respectively. The plants studied were reported to be relatively safe at the subchronic toxicity level, except for 2. The study provides baseline information on the pharmacological activities, toxicity, and chemical components of 9 African medicinal plants with antiviral, immunomodulatory, anti-inflammatory, and symptoms relieving activities, thereby making the plants candidates for further investigation for effectiveness against COVID-19.

Cycloartanol and Sutherlandioside C peracetate from Sutherlandia frutescens and their immune potentiating effects

A novel cycloartanol (1) and an acylated Sutherlandioside D (2) together with two known cycloartane derivatives, Sutherlandioside B (3) and Sutherlandioside A (4), were isolated from the aerial parts of Sutherlandia frutescens. The structures of these compounds were established by a combination of 1- and 2-D NMR techniques and further confirmed by high resolution ToF mass spectrometry (HRToFMS). Preliminary biological studies were also conducted to assess the activity of different plant extracts, fractions and compounds on cytokine expression. Compounds 1 and 2 prompted an increase in IL-6 expression while compound 4 showed a reduced IL-6 expression compared to the controls. Compound 1 is an effective suppressor of IL-10 expression. The plant compounds inhibited the expression of the two cytokines, IL-10 and TNFα. The results of the assays suggested that some components in the plant extract influence the immune system by suppressing the expression of IL-6, IL-10 and TNFα.

D-pinitol attenuates cisplatin-induced nephrotoxicity in rats: Impact on pro-inflammatory cytokines

Cisplatin has been widely used as a first-line agent against various forms of solid cancers. However, nephrotoxicity is the major limiting factor for its clinical use. Several clinical and pre-clinical studies have suggested different strategies for the reduction of cisplatin-induced nephrotoxicity. The present study was conducted to investigate the efficacy of D-Pinitol, against cisplatin-induced nephrotoxicity in Swiss albino mice. A single intraperitoneal injection of cisplatin (20 mg/kg) was used to induce nephrotoxicity in mice. Administration of cisplatin in mice is linked with elevated oxidative stress, imbalanced biochemical parameters, apoptosis and stimulation of mitogen-activated protein kinase (MAPK) pathway. D-Pinitol is a member of the flavonoid family and a chief constituent of Sutherlandia fruitesecnce. It was administered with saline water (10, 20, 40 mg/kg, p.o.) for seven consecutive days after a single dose of cisplatin. At the end of experiment, animals were sacrificed and biochemical parameters in serum and urine were recorded. Kidneys were isolated for the estimation of tumor necrosis factor-alpha, interleukin-1β, interlukin-6 levels and histopathological evaluations. It was noted that D-Pinitol significantly ameliorated biochemical levels of serum and urinary creatinine and blood urea nitrogen. Tissue homogenate levels of TNF-α, IL-6, IL-1β and the renal expression of tissue nitrites were also significantly decreased in D-Pinitol treated mice. These results were supplemented by histopathological findings. This study highlights the potential role of D-Pinitol against cisplatin-induced toxicity, exhibited through favorable alterations in biochemical and histological changes as well as reduction in oxidative stress and cytokine levels.

The mutagenic and antimutagenic activity of Sutherlandia frutescens extracts and marker compounds

BACKGROUND

Sutherlandia frutescens (L.) R. Br is endemic to Southern Africa where it has been traditionally used for cancer and diabetes. In recent times it has been marketed for its reputed (but not proven) anticancer, antidiabetic and anti-HIV properties. Little is known about the mutagenic and antimutagenic potential of extracts and common marker compounds of Sutherlandia frutescens. Therefore this study aimed to investigate the putative efficacy and possible long-term adverse effects of using this herb.

METHODS

Ethylacetate (EA) and 50% Methanol (MeOH) extracts were screened for mutagenic and antimutagenic activity using the Ames assay utilising TA97a, TA98, TA100 and TA102 in the presence and absence of metabolic activation. Four compounds, L-arginine, L-canavanine, GABA and D-pinitol known to occur in sutherlandia were also included. The total polyphenolic content of the both extracts was determined using the Folin-Ciocalteau method and FRAP and ABTS were used to determine the anti-oxidant potential of the extracts.

RESULTS

The extracts and the standards did not show any cytotoxicity except in TA97a. The EA extract exhibited antimutagenicity against all the bacterial strains at all concentrations tested. The MeOH extract showed both pro-mutagenic and antimutagenic activities with 2-acetamidofluorene and aflatoxin B1 in the presence of metabolic activation of TA98 and TA100, respectively. All compounds, except L-canavanine exhibited antimutagenic activity against all strains. L-canavanine, on the other hand showed co-mutagenicity with 9-aminoacridine on TA97a, at all test concentrations. The extracts and pure compounds exhibited their antimutagenic activity in a dose response manner. L-arginine and GABA showed an some antimutagenic response. EA extract had three times the total phenolic content (12.56 μg GE / mg) observed in the MeOH extract. There was correlation between total phenolic content, antioxidant potential and antimutagenicity.

CONCLUSION

Both extracts exhibited a protective effect, with the EA extract exhibiting greater potency. L-canavanine acted as a co-mutagen in a dose response manner without metabolic activation. It is suggested that the EA extract be priotized for future development work as it showed a better risk profile and activity.

Ethnobotanical survey of medicinal plants used to manage High Blood Pressure and Type 2 Diabetes Mellitus in Bitterfontein, Western Cape Province, South Africa

ETHNOPHARMACOLOGICAL RELEVANCE

The aim of this study was to identify and document medicinal plants used to manage High Blood Pressure and Type 2 Diabetes Mellitus in Bitterfontein, Western Cape Province, South Africa.

METHODS

One hundred and twelve (112) respondents were interviewed between August 2014 and September 2015 through semi-structured surveys to gather data on the percentage of people who had been diagnosed with High Blood Pressure and/or Type 2 Diabetes Mellitus and to determine the frequency of medicinal plant and allopathic medicine use. Twelve (12) key respondents were subsequently selected, using a non-probability snowball sampling method. They were interviewed in-depth concerning their plant practices and assisted with plant collection.

RESULTS

Twenty-four plant (24) species belonging to 15 families were identified for the management of High Blood Pressure and Type 2 Diabetes Mellitus. The most frequently reported families were Asteraceae (20.8%), Lamiaceae (16.67%), Crassulaceae (8.33%) and Aizoaceae (8.33%). The remaining (45.54%) were evenly split over eleven families- Fabaceae, Amaryllidaceae, Anacardiaceae, Capparaceae, Geraniaceae, Apiaceae, Convolvulaceae, Apocynaceae, Rutaceae, Asphodelaceae and Thymelaeaceae. The most commonly used plant species overall was Lessertia frutescens (96.55%). The most frequently used plant parts included leaves (57.63%) roots/bulbs (15.25%) and stems (11.86%), mostly prepared as infusions or decoctions for oral administration.

CONCLUSIONS

Medicinal plants are widely used by High Blood Pressure and Type 2 Diabetes Mellitus sufferers. They employ diverse plant species to manage both conditions. In addition, some sufferers often use prescribed allopathic medication, as well as medicinal plants, but at different intervals. Despite high usage the plants identified are not currently threatened (Red Data list status: least concern).

The immunomodulatory effects of Sutherlandia frutescens extracts in human normal peripheral blood mononuclear cells

Sutherlandia frutescens (SF) is one of the medicinal plants used as an immune booster in the treatment of chronic ailments such as HIV/AIDS and cancer. Limited data suggest that its efficacy is based on its regulatory effect on cytokines, the critical components of the immune response. In this study, we investigated the in vitro immunomodulatory effects of SF extracts on normal human peripheral blood mononuclear cells (PBMCs). An ELISA-based assay was used to assess the levels of expression of 12 cytokines in treated cells. An adenosine triphosphate (ATP) assay was used to assess cell viability in relation to cytokine secretion. SF ethanol extracts induced changes in cytokine secretion relative to the dose of the extract. Generally cytokine expression and secretion was low in concentration because were not stimulated with any endotoxin. The high SFE dose (2.5 mg/ml) significantly (p<0.001) decreased some cytokines including TNF-α and IL 1β. Low doses of this extract (0.5 mg/ml) did not change TNF-α and IL 1β secretion from the baseline (untreated cells). Changes in cytokine secretion of SFE treated cells tracked changes in ATP levels (cell viability). The SFW extract-induced changes in cytokine secretion were independent of cell viability. TNF-α was decreased (p<0.001) by the high dose of SFW extract while IL 1β and IFNγ were increased (p<0.01) by the same dose. High doses decreased cell viability which was reflected in cytokine secretion. It is evident, from these results, that SF extracts can modulate cytokine secretion in unstimulated normal PBMCs in vitro. Further studies in animal models are recommended to advance understanding of this immunomodulatory activity.

Effects of Sutherlandia frutescens extracts on normal T-lymphocytes in vitro

Sutherlandia frutescens (SF), a popular traditional medicinal plant found in various parts of southern Africa, is used for treatment or management of HIV/AIDS and other diseases including cancer. However, its toxicity profile has not been fully established. The aims of this study were to examine the effects of 70% ethanol (SFE) and deionised water (SFW) extracts on normal isolated human T cells. An experimental study on normal human lymphocytes treated with doses SF extract doses ranging from 0.25 to 2.5 mg/ml. Untreated, vehicle-treated (Ethanol) and camptothecin (CPT) treated normal T cells were used as controls. Induction of cell death, changes in intracellular ATP, caspase-3/-7 activity and nuclear changes were analysed using flow cytometry, luminometry and nuclear staining (Hoechst) respectively. The highest concentration (2.5 mg/ml) of SFE extract induced significant necrosis (95%), depletion of ATP (76%), and inhibition of caspase-3/-7 activity (11%) following a 24 hour incubation period (p< 0.001). The 2.5 mg/ml concentration of SFW showed the same trend but were less effective (necrosis- 26%, ATP- 91%, & caspase-3/-7- 15%). These effects showed a time-dependence over 48 hours of incubation, with high doses of SFE extracts eliminating viable cells by necrosis, depleting ATP levels and decreasing caspase-3/-7 activity (p< 0.001). The activity of SFE extract was independent of ethanol. The SFW extract dilutions were less toxic than the SFE extracts. Significant DNA fragmentation as demonstrated by Hoechst staining was also seen over 48-hour incubation for high doses of both types of SF extracts. These results showed that although high concentrations of SF extracts can be toxic to normal T cells in vitro, SFW fractions were relatively safe for use.

Effect of short term and chronic administration of Sutherlandia frutescens on pharmacokinetics of nevirapine in rats

Sutherlandia frutescens (sutherlandia), an African herbal supplement was recommended by the South African Ministry of Health for the treatment of AIDS patients. However, no reports yet exist delineating the effect of sutherlandia on pharmacokinetics of antiretroviral agents. Therefore, this investigation aimed at screening the effects of short term and chronic exposure of sutherlandia on oral bioavailability and pharmacokinetics of nevirapine (NVP), a non-nucleoside reverse transcriptase inhibitor, in Sprague Dawley rats. NVP (6 mg/kg) was administered orally alone (control) and with co-administration of sutherlandia; short term (12 mg/kg single dose) and long term (12 mg/kg, once a day for 5 days). No significant difference in the pharmacokinetic parameters of NVP was found upon short-term co-administration of Sutherlandia. However, there was a 50% decrease (p<0.05) in the AUC and C(max) values of NVP after 5 days of chronic exposure with Sutherlandia. In addition, quantitative RT-PCR studies demonstrated a 2-3-fold increase in the hepatic and intestinal mRNA expression of CYP3A2, relative to vehicle control. To further confirm, if this could translate into a clinically relevant pharmacokinetic interaction in patients, we tested this hypothesis employing LS-180 cells as an in vitro induction model for human CYP3A4. Ninety-six hours post treatment, similar to positive control rifampicin (25 μM), sutherlandia extract (300 μg/mL) resulted in elevated m-RNA expression levels and functional activity of CYP3A4 (human homologue of rodent CYP3A2) in LS-180 cells. Taken together, these results suggest that a potential drug-herb interaction is possible when NVP is co-administered with S. frutescens, although this hypothesis still remains to be investigated in a clinical setting.

A review of the taxonomy, ethnobotany, chemistry and pharmacology of Sutherlandia frutescens (Fabaceae)

Sutherlandia frutescens (tribe Galegeae, Fabaceae), a popular plant in traditional medicine, is indigenous to South Africa, Lesotho, southern Namibia and southeastern Botswana. It is chemically, genetically and geographically extremely variable and has been divided into three subspecies and several regional forms. A second species, Sutherlandia tomentosa, is localized along the Cape coast. Sutherlandia is sometimes treated as part of the genus Lessertia. There are numerous vernacular names and a wide diversity of uses, including poor appetite, indigestion, stomach complaints, dysentery, colds, influenza, kidney conditions, fever, diabetes, internal cancers, uterine troubles, liver conditions, backache, rheumatoid arthritis, urinary tract infections, stress and anxiety, dropsy and heart failure. Notable is the use as a bitter tonic ("blood purifier"), anti-stress medication ('musa-pelo) and, at least since 1895, specifically as a cancer tonic (both as treatment and as prophylaxis). Externally it is applied to haemorrhoids, inflamed wounds and eye infections. Recent in vitro and in vivo studies have shown antiproliferative, anti-HIV, anti-diabetic, anti-inflammatory, analgesic, antibacterial, anti-stress, anticonvulsant and antithrombotic activities. Aqueous extracts often differ in activity from organic solvent extracts. The presence of high levels of free amino acids, non-protein amino acids such as canavanine and GABA, the cyclitol pinitol, flavonols and triterpenes (including SU1, a cycloartane-type triterpene saponin) provide plausible hypotheses on how these compounds, individually or collectively, may be responsible for the reputed efficacy in a wide range of ailments. Results of animal studies, as well as a phase I clinical study, have shown no indications of toxicity. Sufficient preclinical data are now available to justify controlled clinical studies.

A broad review of commercially important southern African medicinal plants

AIMS OF THE STUDY

Commercially important indigenous medicinal plants of southern Africa are reviewed in the context of fundamental knowledge about their ethnobotany, phylogeny, genetics, taxonomy, biochemistry, chemical variation, reproductive biology and horticulture. The aim is to explore the rapidly increasing number of scientific publications and to investigate the need for further research.

MATERIALS AND METHODS

The Scopus (Elsevier) reference system was used to investigate trends in the number of scientific publications and patents in 38 medicinal plant species. Fifteen species of special commercial interest were chosen for more detailed reviews: Agathosma betulina, Aloe ferox, Artemisia afra, Aspalathus linearis, Cyclopia genistoides, Harpagophytum procumbens, Hoodia gordonii, Hypoxis hemerocallidea, Lippia javanica, Mesembryanthemum tortuosum, Pelargonium sidoides, Siphonochilus aethiopicus, Sutherlandia frutescens, Warburgia salutaris and Xysmalobium undulatum.

RESULTS

In recent years there has been an upsurge in research and development of new medicinal products and new medicinal crops, as is shown by a rapid increase in the number of scientific publications and patents. Despite the fact that an estimated 10% of the plant species of the world is found in southern Africa, only a few have been fully commercialized and basic scientific information is often not available.

CONCLUSIONS

The limited available information indicates that some of the plants display remarkable regional variation in morphological, genetic and chemical characters that should be more thoroughly investigated. Basic biological information is needed to guide the rapidly accelerating commercialization process, especially the selection of superior clones, the development of new cultivars and the standardization of raw materials.