Rooibos Research Articles

Green rooibos extract attenuates high glucose induced oxidative stress in a human derived (HepG2) liver cell line

• Oxidative stress biomarkers are attenuated by REE in a glucotoxic HepG2 cell model. • REE enhances antioxidant enzyme profiles of HepG2 cells exposed to high glucose. • REE activates NRF2 antioxidant pathway in HepG2 cells exposed to high glucose. The exposure of hepatocytes to high concentrations of glucose results in a glucotoxic environment and ensuing hepatocellular injury, often due to oxidative stress. The popularly consumed herbal tea, Rooibos ( Aspalathus linearis ), demonstrates pleiotropic pharmacological and antioxidant activities. Our study investigated the molecular events regulating the antioxidant effects of a Rooibos ethanolic extract (REE) in a glucotoxic HepG2 liver cell model. It is hypothesized that REE enhances antioxidant enzyme profiles of HepG2 cells exposed to high glucose to attenuate glucotoxic damage. Glucotoxicity was induced by treating the cells with 25 mM glucose. For this study, colorimetric, luminometric and western blot analyses were used to determine the potential of the REE to reduce biomarkers associated with oxidative damage and its potential to enhance the intracellular antioxidant defense system. The REE was found to be hepatoprotective as evidenced by reduced levels of oxidative damage biomarkers (MDA and protein carbonylation) and enhanced antioxidant capacity under glucotoxic conditions as evidenced by elevated GSH (reduced form). We also observed decreased intracellular hydrogen peroxide levels and caspase activity in the REE treated cells and further showed that the REE enhanced SOD2, CAT, and GPx1 protein expression. These effects were dependent on the transcriptional activity of NRF2. Collectively, our results show that the REE enhances the cellular antioxidant defense capacity and may provide a relevant supportive therapeutic option for treating diabetic complications associated with oxidative stress.

Aspalathin and Other Rooibos Flavonoids Trapped α-Dicarbonyls and Inhibited Formation of Advanced Glycation End Products In Vitro

The excessive dietary intake of simple sugars and abnormal metabolism in certain diseases contribute to the increased production of α-dicarbonyls (α-DCs), such as methylglyoxal (MGO) and glyoxal (GO), the main precursors of the formation of advanced glycation end products (AGEs). AGEs play a vital role, for example, in the development of cardiovascular diseases and diabetes. Aspalathus linearis (Burman f.) R. Dahlgren (known as rooibos tea) exhibits a wide range of activities beneficial for cardio-metabolic health. Thus, the present study aims to investigate unfermented and fermented rooibos extracts and their constituents for the ability to trap MGO and GO. The individual compounds identified in extracts were tested for the capability to inhibit AGEs (with MGO or GO as a glycation agent). Ultra-high-performance liquid chromatography coupled with an electrospray ionization mass spectrometer (UHPLC-ESI-MS) was used to investigate α-DCs' trapping capacities. To evaluate the antiglycation activity, fluorescence measurement was used. The extract from the unfermented rooibos showed a higher ability to capture MGO/GO and inhibit AGE formation than did the extract from fermented rooibos, and this effect was attributed to a higher content of dihydrochalcones. The compounds detected in the extracts, such as aspalathin, nothofagin, vitexin, isovitexin, and eriodictyol, as well as structurally related phloretin and phloroglucinol (formed by the biotransformation of certain flavonoids), trapped MGO, and some also trapped GO. AGE formation was inhibited the most by isovitexin. However, it was the high content of aspalathin and its higher efficiency than that of metformin that determined the antiglycation and trapping properties of green rooibos. Therefore, A. linearis, in addition to other health benefits, could potentially be used as an α-DC trapping agent and AGE inhibitor.

Biopiracy: Crying wolf or a lever for equity and conservation?

Access and benefit sharing (ABS) is a central approach to address biopiracy – the misappropriation of genetic resources and traditional knowledge without consent or compensation, often tied to patenting. Benefit-sharing agreements comprise a core element of ABS and are intended to leverage greater social and economic justice, create incentives for biodiversity conservation, and strengthen the rights of indigenous and local communities. However, emerging evidence suggests otherwise. Through review of four cases of biodiversity commercialization in South Africa – Hoodia gordonii, Aspalathus linearis (rooibos), Sceletium tortuosum (kougoed) and Pelargonium sidoides, each with histories of biopiracy charges and associated benefit-sharing agreements, this paper aims to explain this apparent contradiction. The cases reveal that while ABS has succeeded in recognizing holders of traditional knowledge, the wider political and economic struggles faced by communities remain neglected. Power relations and economic disparities have not changed, and control remains vested in land, with ownership remaining highly skewed towards industry partners who have market dominance; and intellectual property, the benefits of which are disassociated from traditional knowledge holders and biodiversity custodians. ABS processes have also led to a clamor for representation, favoring groups that are politically connected, well organized and resourced, while excluding more marginalized groups who are less capacitated. Moreover, despite significant biodiversity concerns in each case, there are few conservation benefits. Such trends, combined with new forms of “digital biopiracy” and opportunities opening through the post 2020 Global Biodiversity Framework, emphasize the need to reconceptualize ABS to leverage more equitable and sustainable outcomes.

Is the Tea Bag Index (TBI) Useful for Comparing Decomposition Rates among Soils?

The Bag Index (TBI) is a novel approach using standardized materials (i.e., commercial tea bags) to evaluate organic matter decomposition by determining two indexes: the early stage decomposition constant k (k_TBI) and litter stabilization factor S (S_TBI). k_TBI is defined as the decomposition constant of an asymptote model describing the decomposition curve of rooibos tea, whereas S is the ratio of the stabilized to total hydrolysable fractions of green tea. However, it was recently revealed that both k_TBI and S_TBI deviate from the actual S and k values accurately determined by fitting an asymptote model to the time series mass of green and rooibos teas remaining (k_fitting and S_fitting, respectively). Nevertheless, k_TBI and S_TBI, which can be determined in a cost- and labor-effective manner, might indicate the relative values of k_fitting and S_fitting across different soils and be useful for comparative analyses. Therefore, this study investigated the positive correlations of k_TBI and S_TBI with k_fitting and S_fitting, respectively, in which case these indexes are useful for comparative analyses. However, the result showed that k_TBI was negatively correlated with k_fitting. This study underscores the importance of obtaining time-series data for accurately determining the decomposition constant of an asymptote model describing the decomposition curve of rooibos tea. S_TBI was positively correlated with S_fitting, implying that S_TBI can be used as an indicator of S.

Factors Influencing Rooibos Tea Certification and Quality Control for Smallholder Farmers in South Africa.

This study aimed to identify factors that influence the decisions of rooibos farmers in South Africa to implement certification and quality assurance systems. The study was conducted in the Western Cape region of South Africa. A structured questionnaire was distributed to 300 farmers in the form of interviews. In addition, an analysis of previously published data was also used. Results showed that membership in an association, land tenure, rooibos tea farm size, and education level were the main determinants of implementing certifications and quality assurance systems. Membership in the association and land tenure significantly negatively affected the adoption of certification. In contrast, farm size and level of education, translating to knowledge of certification systems, tended to have a significant positive effect on adoption. Continuous education, awareness of the process of certification and quality assurance systems, and the formation of farmers' support systems are recommended to improve the impact of smallholder rooibos farmers in the industry.

The potential benefit of rooibos (Aspalathus linearis) in pulmonary arterial hypertension: A short review

Rooibos is a uniquely South African plant cultivated to produce rooibos herbal tea or extract and often incorporated into iced herbal tea, soap, skin lotion, facewash, and shampoo. Rooibos provides health benefits against multiple diseases including cardiac pathologies, skin disorders, obesity, and diabetes via its anti-inflammatory, antioxidant, anti-tumour, and anti-apoptotic properties. The pathophysiology of pulmonary arterial hypertension (PAH) includes increased lung inflammation and oxidative stress, and tumour-like growth (i.e., the increased proliferation of pulmonary arterial smooth muscle cells and apoptosis of pulmonary artery endothelial cells). In this review, we discuss literature supporting rooibos as a potential novel therapeutic agent to protect against PAH. We suggest that rooibos may reduce lung inflammation and oxidative stress and limit pulmonary arterial smooth muscle cell proliferation and endothelial cell apoptosis, thereby inhibiting PAH progression. • Rooibos is a unique South African plant, cultivated to produce rooibos tea or extract that is high in polyphenols. • Rooibos provides health benefits against cardiac pathologies, skin disorders, obesity, and diabetes. • The anti-inflammatory, antioxidant, anti-tumour, and anti-apoptotic actions of rooibos makes it a candidate therapeutic agent against pulmonary arterial hypertension (PAH). • Rooibos may reduce lung inflammation, oxidative stress, limit pulmonary arterial smooth muscle cell proliferation and endothelial cell apoptosis, thereby inhibiting PAH progression. • Evidence discussed in this paper supports the role of rooibos as a possible novel therapeutic agent in the context of PAH.

Fermented Rooibos Tea Ameliorates Sodium Fluoride-Induced Cardio-renal Injury, Oxidative Stress and Inflammation via Suppression of NF-κβ Signaling Pathway in Wistar rats

Fermented Rooibos Tea Ameliorates Sodium Fluoride-Induced Cardio-renal Injury, Oxidative Stress and Inflammation via Suppression of NF-κβ Signaling Pathway in Wistar rats

Leafhoppers of the Fynbos Biome of South Africa: Colistra, Proekes, Proekoides and a new genus (Insecta, Hemiptera, Cicadellidae, Deltocephalinae, Bonaspeiini)

The following leafhoppers (Deltocephalinae: Bonaspeiini) of the Fynbos Biome of South Africa are treated: Colistra parvulus (Linnavuori, 1961) is redescribed and three new species of Colistra Davies are described, i.e., C. acapitatus sp. n., C. bucapitatus sp. n. and C. semialius sp. n.; four species of Proekoides Stiller, 1986 are reviewed with the addition of P. postspina sp. n.; Proekes cephaleus (Naudé, 1926) is redescribed with details of the female ovipositor, and three new species, i.e., P. hemiplatyphalis sp. n., P. tetracaphalis sp. n., P. diacaphalis sp. n.; a new genus, Xhoreus gen. n. is described with one new species, X. ulosentus sp. n. All species are of similar appearance, size and with reduced hind wings. Two species, C. acapitatus and C. bucapitatus, were collected on Rooibos tea. Keys are provided to species of Colistra, Proekes and Proekoides. Distribution models show limited ranges in the Western Cape province and confined to the Fynbos Biome while Xhoreus ulosentus is possibly endemic to the Cape Peninsula. The validity of the tribe Bonaspeiini is discussed.

Network Pharmacology- and Molecular Dynamics Simulation-Based Bioprospection of Aspalathus linearis for Type-2 Diabetes Care.

The medicinal herb Aspalathus linearis (rooibos) is globally recognized in type-2 diabetes mellitus (T2DM) treatment due to its known and distinctive compounds. This work utilized network pharmacology (NP) coupled with molecular dynamics simulation in gaining new insight into the anti-diabetic molecular mechanism of action of rooibos teas. It looked at the interactions between rooibos constituents with various relevant protein receptors and signaling routes associated with T2DM progression. The initial analysis revealed 197 intersecting gene targets and 13 bioactive rooibos constituents linked to T2DM. The interactions between proteins and compounds to the target matrix were generated with the Cystoscope platform and STRING database. These analyses revealed intersecting nodes active in T2DM and hypoxia-inducible factor 1 (HIF-1) as an integral receptors target. In addition, KEGG analysis identified 11 other pathways besides the hub HIF-1 signaling route which may also be targeted in T2DM progression. In final molecular docking and dynamics simulation analysis, a significant binding affinity was confirmed for key compound-protein matrices. As such, the identified rooibos moieties could serve as putative drug candidates for T2DM control and therapy. This study shows rooibos constituents' interaction with T2DM-linked signaling pathways and target receptors and proposes vitexin, esculin and isovitexin as well as apigenin and kaempferol as respective pharmacologically active rooibos compounds for the modulation of EGFR and IGF1R in the HIF-1 signaling pathway to maintain normal homeostasis and function of the pancreas and pancreatic β-cells in diabetics.

Disentangling drivers of litter decomposition in a multi-continent network of tree diversity experiments

Litter decomposition is a key ecosystem function in forests and varies in response to a range of climatic, edaphic, and local stand characteristics. Disentangling the relative contribution of these factors is challenging, especially along large environmental gradients. In particular, knowledge of the effect of management options, such as tree planting density and species composition, on litter decomposition would be highly valuable in forestry. In this study, we made use of 15 tree diversity experiments spread over eight countries and three continents within the global TreeDivNet network. We evaluated the effects of overstory composition (tree identity, species/mixture composition and species richness), plantation conditions (density and age), and climate (temperature and precipitation) on mass loss (after 3 months and 1 year) of two standardized litters: high-quality green tea and low-quality rooibos tea. Across continents, we found that early-stage decomposition of the low-quality rooibos tea was influenced locally by overstory tree identity. Mass loss of rooibos litter was higher under young gymnosperm overstories compared to angiosperm overstories, but this trend reversed with age of the experiment. Tree species richness did not influence decomposition and explained almost no variation in our multi-continent dataset. Hence, in the young plantations of our study, overstory composition effects on decomposition were mainly driven by tree species identity on decomposer communities and forest microclimates. After 12 months of incubation, mass loss of the high-quality green tea litter was mainly influenced by temperature whereas the low-quality rooibos tea litter decomposition showed stronger relationships with overstory composition and stand age. Our findings highlight that decomposition dynamics are not only affected by climate but also by management options, via litter quality of the identity of planted trees but also by overstory composition and structure.

Long-term effects of micro-fine and class A calcitic lime application rates on soil acidity and rooibos tea yields under Clanwilliam field conditions

Previous research on the effect of soil liming on rooibos tea growth was limited to short-term greenhouse trials. This is the first long-term field study to investigate the effect of lime application on rooibos tea production. Micro-fine and class A calcitic lime with similar levels of purity were applied at rates of 0, 0.5, 1.0, 2.0 and 5.0 tonnes ha−1 to a depth of 15 cm on an acid (pHKCl 4.4), sandy soil in Clanwilliam, prior to planting. Soil pH and electrical conductivity (EC), rooibos mortality and yields were then measured over a period of 4 years. Foliar nutrients were determined in Year 4. Micro-fine lime resulted in significantly higher soil pH values (0.5 pH units) than class A lime. Both limes achieved maximum soil pH and EC values in Year 2, but these values declined significantly in Years 3 and 4. This is most likely due to leaching and exhaustion of the most soluble lime fractions. Although micro-fine lime had positive effects on foliar nitrogen and calcium concentrations and bush survival, liming appeared to have a negative effect on rooibos tea yields. Yields tended to decline with increasing lime application rate. Thus, it appears that under the Clanwilliam field conditions in the present study, liming is unnecessary.

Aspalathin-rich green rooibos tea in combination with glyburide and atorvastatin enhances lipid metabolism in a db/db mouse model.

Rooibos (Aspalathus linearis), an indigenous South African plant and its major flavonoid, aspalathin, exhibited positive effects on glycemia and dyslipidemia in animal studies. Limited evidence exists on the effects of rooibos extract taken in combination with oral hypoglycemic and lipid-lowering medications. This study investigated the combined effects of a pharmaceutical grade aspalathin-rich green rooibos extract (GRT) with the sulfonylurea, glyburide, and atorvastatin in a type 2 diabetic (db/db) mouse model. Six-week-old male db/db mice and their nondiabetic lean db+ littermates were divided into 8 experimental groups (n=6/group). Db/db mice were treated orally with glyburide (5 mg/kg bodyweight), atorvastatin (80 mg/kg bodyweight) and GRT (100 mg/kg bodyweight) as mono- and combination therapies respectively, for 5 weeks. An intraperitoneal glucose tolerance test was conducted at 3 weeks of treatment. Serum was collected for lipid analyses and liver tissues for histological examination and gene expression. A significant increase in the fasting plasma glucose (FPG) of the db/db mice compared to their lean counterparts (from 7.98 ± 0.83 to 26.44 ± 1.84, p < 0.0001) was observed. Atorvastatin reduced cholesterol (from 4.00 ± 0.12 to 2.93 ± 0.13, p < 0.05) and triglyceride levels (from 2.77 ± 0.50 to 1.48 ± 0.23, p < 0.05). In db/db mice, the hypotriglyceridemic effect of atorvastatin was enhanced when combined with both GRT and glyburide (from 2.77 ± 0.50 to 1.73 ± 0.35, p = 0.0002). Glyburide reduced the severity and pattern of steatotic lipid droplet accumulation from a mediovesicular type across all lobular areas, whilst combining GRT with glyburide reduced the abundance and severity of lipid droplet accumulation in the centri- and mediolobular areas. The combination of GRT, glyburide and atorvastatin reduced the abundance and severity of lipid accumulation and the intensity score compared to the administered drugs alone. The addition of either GRT or glyburide in combination with atorvastatin had no effect on blood glucose or lipid profiles, but significantly reduced lipid droplet accumulation.

Assessing the energy and water balance dynamics of rain-fed rooibos tea crops (Aspalathus linearis) under changing Mediterranean climatic conditions

Rooibos (Aspalathus linearis), a herbal tea crop and a member of the plant family Fabaceae, grows in a narrow ecological range under Mediterranean conditions in South Africa's fynbos biome. There is growing uncertainty on the sustainability of rooibos production under rain-fed conditions in a region which is expected to get warmer and drier in future. No accurate quantitative information currently exists on how the water use, growth and yield of this crop is affected by environmental factors, especially climate and soils. This paucity of data reduces the ability of farmers to develop effective strategies to cope and adapt to the negative effects of climate variability and change. The aim of this study was to investigate the seasonal changes in the energy and water balance of rooibos fields and to establish how this relates to crop yield. An open path eddy covariance system was used to quantify the actual evapotranspiration (ETa) and energy balance components over two growing seasons while sap flow was monitored using stem heat balance sap flow gauges. These data were used to develop and test a simple ETa and yield model which was applied to estimate changes in crop water use and yield under the predicted future climatic conditions. More than 36% of the annual total ETa (∼ 338 mm) was consumed during the first three months of the growing season (September to November) driven by residual soil moisture from the winter rains. Crop transpiration accounted for only 16% of ETa early in the growing season rising to almost 100% during the summer dry months. Daily peak transpiration at maximum canopy cover barely reached 1.0 mm suggesting that this crop uses very little water. Six climate change models were used to simulate crop water use and yield for the far future under the RCP 8.5 emission scenario. All the models predicted increases in both the annual ETa and yield by between 8% and 16% in the period 1961–2099. This study reveals that implementing water conservation and weed management practices early in the growing season can save substantial amounts of soil moisture which can sustain rooibos production under low rainfall conditions.

Aspalathus linearis (Rooibos) and Agmatine May Act Synergistically to Beneficially Modulate Intestinal Tight Junction Integrity and Inflammatory Profile.

In order to promote gastrointestinal health, significant increases in the prevalence of gastrointestinal disorders should be paralleled by similar surges in therapeutics research. Nutraceutical interventions may play a significant role in patient management. The current study aimed to determine the potential of Aspalathus linearis (rooibos) to prevent gastrointestinal dysregulation resulting from high-dose trace-amine (TA) exposure. Considering the substantial female bias in functional gastrointestinal disorders, and the suggested phytoestrogenicity of rooibos, the study design allowed for a comparison between the effects of an ethanol extract of green rooibos and 17β-estradiol (E2). High levels of ρ-tyramine (TYR) and agmatine (AGM), but not β-phenethylamine (PEA) or tryptamine (TRP), resulted in prostaglandin E2 (PGE2) hypersecretion, increased tight-junction protein (TJP; occludin and ZO-1) secretion and (dissimilarly) disrupted the TJP cellular distribution profile. Modulating benefits of rooibos and E2 were TA-specific. Rooibos pre-treatment generally reduced IL-8 secretion across all TA conditions and prevented PGE2 hypersecretion after exposure to both TYR and AGM, but was only able to normalise TJP levels and the distribution profile in AGM-exposed cells. In contrast, E2 pre-treatment prevented only TYR-associated PGE2 hypersecretion and TJP dysregulation. Together, the data suggest that the antioxidant and anti-inflammatory effects of rooibos, rather than phytoestrogenicity, affect benefits illustrated for rooibos.

Effect of Optimized Precursor Concentration, Temperature, and Doping on Optical Properties of ZnO Nanoparticles Synthesized via a Green Route Using Bush Tea (Athrixia phylicoides DC.) Leaf Extracts.

Nanoparticles possess several properties, such as antimicrobial, anti-inflammatory, wound healing, catalytic, magnetic, optical, and electronic properties, that have allowed them to be used in different fields. Among them, zinc oxide (ZnO) has received copious consideration due to its technological and medicinal applications. Plant-mediated synthesis of ZnO nanoparticles has provided a cost-effective and eco-friendly method. Therefore, the objective of the study is to assess the effect of the precursor concentration and silver and cerium doping on the optical properties of ZnO nanoparticles synthesized via a green process using bush tea leaf extract as the chelating agent. Zinc nitrate hexahydrate was used as the precursor. Quasi-spherical-shaped ZnO nanoparticles were obtained with an average crystallite size ranging between 24.53 and 63.02 nm. The crystallite size was found to decrease with the increase of precursor concentration at 43.82 nm (0.05 g), 37.25 nm (0.10 g), 26.53 nm (0.50 g), and 24.53 nm (1 g); thereafter, the size increases with an increase in precursor concentration. The optimum precursor concentration was 1 g with the smallest grain size and a high purity level. The increase in annealing temperature induced an increase in the crystallite size of ZnO nanoparticles from 24.53 nm (600 °C) to 34.24 nm (800 °C), however, increasing the level of purity of the nanopowders. The band gap energies were 2.75 and 3.17 eV as calculated using the Tauc plot with variations due to the precursor concentrations. Doping with both silver and cerium increased the band gap of ZnO nanoparticles up to 3.19 eV and the increase in annealing temperature slightly augmented the band gap energy from 3.00 and 3.16 eV, respectively. Hence, doping with Ag and Ce induced the formation of nanorods at higher concentrations. This study successfully demonstrated that the natural plant extract of bush tea can be used in the bioreduction of zinc nitrate hexahydrate to prepare pure ZnO nanoparticles, thus extending the use of this plant to the nano producing industry.

Green synthesis and characterization of zinc oxide nanoparticles using bush tea (Athrixia phylicoides DC) natural extract: assessment of the synthesis process.

Background:Nanoparticles are globally synthesized for their antimicrobial, anti-inflammatory, wound healing, catalytic, magnetic, optical, and electronic properties that have put them at the forefront of a wide variety of studies. Among them, zinc oxide (ZnO) has receivedmuchconsideration due to its technological and medicinal applications.In this study, we report on the synthesis process ofZnOnanoparticles using AthrixiaphylicoidesDC natural extract asareducing agent. Methods:Liquidchromatography-massspectrometry(LC-MS) was used to identify the compounds responsible for the synthesis ofZnOnanoparticles. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized through X-raydiffraction (XRD),Ultraviolet-visible spectroscopy (UV-Vis),Fouriertransforminfrared spectroscopy(FTIR),scanningelectronmicroscopy (SEM) andenergy-dispersiveX-rayspectroscopy (EDS). Results:LC-MS results showedthat different flavonoids and polyphenols, as well as Coumarin, an aromatic compound, reacted with the precursor to formZnOnanoparticles. XRD and UV-Visanalysis confirmed the synthesis ofZnOnanoparticles, with a spherical shape showed in SEM images. The quasi-sphericalZnOcrystals had an average crystallite size of 24 nm. EDS and FTIR analysis confirmed that the powders were pure with no other phase or impurity. Conclusions:This study successfully demonstrated that the natural plant extract of A.phylicoidesDC. can be used in the bio-reduction of zinc nitrate hexahydrate to prepare pureZnOnanoparticles, thus, extending the use of this plant to an industrial level.

Establishing MinION Sequencing and Genome Assembly Procedures for the Analysis of the Rooibos (Aspalathus linearis) Genome.

While plant genome analysis is gaining speed worldwide, few plant genomes have been sequenced and analyzed on the African continent. Yet, this information holds the potential to transform diverse industries as it unlocks medicinally and industrially relevant biosynthesis pathways for bioprospecting. Considering that South Africa is home to the highly diverse Cape Floristic Region, local establishment of methods for plant genome analysis is essential. Long-read sequencing is becoming standard procedure for plant genome research, as these reads can span repetitive regions of the DNA, substantially facilitating reassembly of a contiguous genome. With the MinION, Oxford Nanopore offers a cost-efficient sequencing method to generate long reads; however, DNA purification protocols must be adapted for each plant species to generate ultra-pure DNA, essential for these analyses. Here, we describe a cost-effective procedure for the extraction and purification of plant DNA and evaluate diverse genome assembly approaches for the reconstruction of the genome of rooibos (Aspalathus linearis), an endemic South African medicinal plant widely used for tea production. We discuss the pros and cons of nine tested assembly programs, specifically Redbean and NextDenovo, which generated the most contiguous assemblies, and Flye, which produced an assembly closest to the predicted genome size.

Enzyme kinetics inform about mechanistic changes in tea litter decomposition across gradients in land-use intensity in Central German grasslands.

Grassland ecosystems provide important ecosystem services such as nutrient cycling and primary production that are affected by land-use intensity. To assess the effects of land-use intensity, operational and sensitive ecological indicators that integrate effects of grassland management on ecosystem processes such as organic matter turnover are needed. Here, we investigated the suitability of measuring the mass loss of standardized tea litter together with extracellular enzyme kinetics as a proxy of litter decomposition in the topsoil of grasslands along a well-defined land-use intensity gradient (fertilization, mowing, grazing) in Central Germany. Tea bags containing either green tea (high-quality litter) or rooibos tea (low-quality litter) were buried in 5 cm soil depth. Litter mass loss was measured after three (early-stage decomposition) and 12 months (mid-stage decomposition). Based on the fluorescence measurement of the reaction product 4-methylumbelliferone, Michaelis-Menten enzyme kinetics (Vmax: potential maximum rate of activity; Km: substrate affinity) of five hydrolases involved in the carbon (C)-, nitrogen (N)- and phosphorus (P)-cycle (β-glucosidase (BG), cellobiohydrolase (CBH), cellotriohydrolase (CTH), 1,4-β-N-acetylglucosaminidase (NAG), and phosphatase (PH)) were determined in tea litter bags and in the surrounding soil. The land-use intensity index (LUI), summarizing fertilization, mowing, grazing, and in particular the frequency of mowing were identified as important drivers of early-stage tea litter decomposition. Mid-stage decomposition was influenced by grazing intensity. The higher the potential activity of all measured C-, N- and P-targeting enzymes, the higher was the decomposition of both tea litters in the early-phase. During mid-stage decomposition, individual enzyme parameters (Vmax of CTH and PH, Km of CBH) became more important. The tea bag method proved to be a suitable indicator which allows an easy and cost-effective assessment of land-use intensity effects on decay processes in manged grasslands. In combination with enzyme kinetics it is an appealing approach to identify mechanisms driving litter break down.

Anti-Inflammatory, Anti-Diabetic, Anti-Oxidant and Cytotoxicity Assays of South African Herbal Teas and Bush Tea Blends.

South Africa is home to a variety of herbal teas, such as bush tea (Athrixia phylicoides DC.), honeybush tea (Cyclopia intermedia E. Mey and C. subternata Vogel), special tea (Monsonia burkeana Planch. ex Harv.), and rooibos tea (Aspalathus linearis (Burm.f.) R. Dahlgren) that are known to possess anti-oxidant, anti-inflammatory and anti-diabetic properties. The objective of this study was to determine the in vitro anti-oxidant activity of selected tea blends using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays, as well as to assess their anti-inflammatory properties using the 15-lipoxygenase inhibitory assay. Furthermore, the study measured glucose utilisation in C2C12 myotubes. Lastly, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to test the safety of the tea extracts on Vero cells (African green monkey kidney cell line). Special tea and its blend with bush tea exhibited potent anti-oxidant and anti-inflammatory activity. The blending of bush tea with special tea at different ratios resulted in increased anti-oxidant activity. Although special tea had a level of cell toxicity, its toxicity was lowered during blending. All of the tea samples showed anti-diabetic effects, although with less potency as compared to insulin. The current investigation supports the use of blended herbal teas, and the positive anti-inflammatory effect of special tea warrants further research.

Rooibos (Aspalathus linearis) alters secretome trace amine profile of probiotic and commensal microbes in vitro

Ethnopharmacology relevanceAspalathus linearis (Burm.f.) R. Dahlgren (rooibos) tea is anecdotally renowned for its calming effect in the context of gastrointestinal discomfort, but little scientific support is available to elucidate potential mechanisms of action. Enhancement of dietary polyphenol content to improve gut health via prebiotic-like modulation of the gut microbiota has gained significant research interest. Given the known high polyphenol content of rooibos, rooibos tea may potentially exert a prebiotic effect in the gut to facilitate an improvement in chronic inflammatory gastrointestinal conditions.Aim of the study: This study aimed to determine the prebiotic or health-modulating potential of rooibos tea in terms of its effect on gut microbial growth and secretome trace amine composition, as well as to determine how differential rooibos processing alters this activity. MethodsThree rooibos preparations (green and fermented leave aqueous extracts, as well as a green leaf ethanol extract) were compared in terms of their phenolic composition (qTOF-LC/MS). Moreover, the effect of rooibos exposure on growth and secretome trace amine levels of probiotic and commensal microbes were assessed (LC/MS). In addition, given the known female bias prevalent for many gastrointestinal disorders, experiments were conducted in the absence and presence of estradiol. ResultsPolyphenolic composition of rooibos was drastically reduced by fermentation. Aqueous extracts of both green and fermented rooibos improved microbial growth, although fermented rooibos had the most pronounced effect (p < 0.01). In terms of secretome trace amine profile, both aqueous extracts of rooibos seemed to facilitate increased putrescine secretion (p < 0.0001) and decreased tryptamine production (p < 0.0001). Estradiol seemed to suppress trace amine secretion by bacteria (Lactobacillus plantarum, Lactobacillus reuteri and Enterococcus mundtii) but increased it in yeast (Saccharomyces boulardii). ConclusionRooibos altered gut probiotic and commensal microbial growth and secretome trace amine profiles in vitro, suggesting it has potential to modulate gut microbial composition and functionality as a prebiotic. Current data suggest that these effects are highly dependent on raw material processing. Finally, rooibos may be able to prevent estradiol-associated alterations in trace amine profile, which may have important implications for patient management in female-predominant gastrointestinal disorders.