Rooibos Research Articles

A green synthesis of zinc oxide nanoparticles using Musa Paradisiaca and Rooibos extracts

This study describes the single pot synthesis of zinc oxide nanoparticles (ZnO NPs) using a mixture of Aspalathus linearis and Musa paradisiaca for use against the fungi Candida albicans. These nanoparticles are known to be one of the most multifunctional inorganic nanoparticles with effective antifungal and antibacterial activity. The synthesized ZnONPs were characterized by a peak at 290 nm in the UV–vis spectrum while HRSEM confirmed rod-shaped nanoparticles. The FTIR data clearly revealed that the extracts contained -OH functional groups whose role was capping agents during the nanoparticle synthesis. This study also found that the purity of the green synthesised ZnO NPs (GZnO NPs) was 94.4 %, 91.5 %, and 82.1 %, respectively, using XRD, HRTEM, and HRSEM-EDS. The antifungal activity of ZnONPs was tested against Candida albicans using the Kirby Bauer method. The maximum inhibition zone observed in the ZnO NPs against Candida albicans was confirmed to be 24 mm, a clear indication that the synthesized ZnO NPs have great potential to act as effective antifungal agents.•Zinc nitrate hexahydrate [Zn(NO3)2·6H2O] was used as the inorganic metal oxide precursor.•Extracts of banana (Musa paradisiaca) peel and tea leaves of Rooibos (Aspalathus linearis) infused with Buchu (Agathosma betulina) were the organic constituents used as reducing and capping agents during GZnO NPs synthesis.•Validation of the formed GZnO NPs was done using; Ultraviolet-visible spectroscopy (UV-Vis), X-ray spectroscopy (XRD), Fourier-transform Infrared Spectroscopy (FTIR), High-resolution Transmission Electron Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED), and High-Resolution Scanning Electron Microscopy with Energy-Dispersive Spectroscopy (HRSEM-EDS).

Impact of tree litter identity, litter diversity and habitat quality on litter decomposition rates in tropical moist evergreen forest

Attempts to restore degraded highlands by tree planting are common in East Africa. However, up till now, little attention has been given to effects of tree species choice on litter decomposition and nutrient recycling. In this study, three indigenous and two exotic tree species were selected for a litter decomposition study. The objective was to identify optimal tree species combinations and tree diversity levels for the restoration of degraded land via enhanced litter turnover. Litterbags were installed in June 2019 into potential restoration sites (disturbed natural forest and forest plantation) and compared to intact natural forest. The tested tree leaf litters included five monospecific litters, ten mixtures of three species and one mixture of five species. Standard green and rooibos tea were used for comparison. A total of 1,033 litters were retrieved for weight loss analysis after one, three, six, and twelve months of incubation. The finding indicates a significant effect of both litter quality and litter diversity on litter decomposition. The nitrogen-fixing native tree Millettia ferruginea showed a comparable decomposition rate as the fast decomposing green tea. The exotic conifer Cupressus lusitanica and the native recalcitrant Syzygium guineense have even a lower decomposition rate than the slowly decomposing rooibos tea. A significant correlation was observed between litter mass loss and initial leaf litter chemical composition. Moreover, we found positive non-additive effects for litter mixtures including nutrient-rich and negative non-additive effects for litter mixtures including poor leaf litters respectively. These findings suggest that both litter quality and litter diversity play an important role in decomposition processes and therefore in the restoration of degraded tropical moist evergreen forest.

In vitro and in vivo hepatotoxicity study of Afriplex™ GRT through an inflammatory response

BackgroundThe focus on traditional and complementary medicine for supplementation and treatment of diseases is high. Aspalathus linearis commonly known as Rooibos showed several beneficial effects, this led to the standardized production of a pharmaceutical grade green rooibos extract (Afriplex TM GRT) with enhanced polyphenolic content. The aim of this study was to assess toxicity of Afriplex TM GRT in HepG2/C3A cells and Sprague Dawley rats. MethodsAfriplex GRT TM (0.1, 1, 10, 100, or 1000 μg/mL) in DMSO was added to the media to the final 0.01% DMSO for treatment of HepG2/C3A for 1, 24 and 48 hrs followed by MTT and ATP assays. Sprague Dawley rats were grouped to Control, Afriplex TM GRT treated (10, 100 and 300 mg/kg); and acute (24hrs tetrachloromethane (CCl 4) injected hepatotoxicity control). Serum biochemistry, histology and Western blot analysis on liver were performed. ResultsAfriplex TM GRT significantly reduced cell viability at 100 and 1000μg/mL after 48 hrs. Acute CCl 4 treatment significantly increased serum alanine aminotransferase in rats. The highest extract treatment of 300 mg/kg significantly elevated aspartate amino transferase. There was severe macro vesicular in the CCl 4 group whereas mild to moderate micro vesicular steatosis was seen in the 300 mg/kg Afriplex TM GRT treated group. Highest extract treatment significantly reduced NFkB expression on Western blot analysis. ConclusionThe beneficial effects of pharmaceutical grade Afriplex GRT TM are concentration and dosage based. Afriplex GRT TM exerts its beneficial effects via NFkB as demonstrated by the dose dependent reduction of NFkB on Western blot analysis. More work need to be done to explore the exact mechanism that occurs in the NFkB pathway.

A Case of Premature Constriction of the Ductus Arteriosus in an Infant Caused by Intake of Rooibos Tea during Pregnancy

A Case of Premature Constriction of the Ductus Arteriosus in an Infant Caused by Intake of Rooibos Tea during Pregnancy

Antioxidant and Anti Inflammatory Activity of Copper Nanoparticles Synthesized Using Red Tea

Background: Recently, nanoparticles have been playing a pivotal role in modern material development. Nanotechnology has provided great possibilities in various fields of science and technology. The antioxidant characteristics of Aspalathus linearis, also known as rooibos, include antimutagenic, anticarcinogenic, anti-inflammatory, and antiviral capabilities.
 Aim: To determine the anti-inflammatory and antioxidant activity of copper nanoparticles synthesized using red tea.
 Materials and Methods: Preparation of the red tea extract, synthesis of copper nanoparticles, preparation of nanoparticles powder and then antioxidant and anti-inflammatory activity of nanoparticles were analysed. Antioxidant activity and anti- inflammatory activity was assessed using DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assay and inhibition of albumin denaturation assay. The standard used was diclofenac sodium in various concentrations.
 Results: The formation of copper nanoparticles was indicated by the peak found in the spectroscopy. Copper nanoparticles synthesized using red tea showed highest absorbance at a concentration of 50μl (82%) when it was subjected to DPPH assay to check for its antioxidant property at a wavelength of about 517 nm. Copper nanoparticles synthesized using red tea showed highest absorbance at a concentration of 50μl (92.2%) when it was subjected to inhibition of albumin denaturation assay to analyse for its anti-inflammatory activity at a wavelength of about 660 nm.
 Conclusion: The present study suggests that red tea mediated copper nanoparticles showed good antioxidant activity and anti-inflammatory activity. It can be concluded that the antioxidant activity of red tea is not as efficient as Diclofenac but it can be more efficient when it’s concentration is raised to safe levels and anti-inflammatory activity of red tea is as efficient as Diclofenac.

New Insights into the Efficacy of Aspalathin and Other Related Phytochemicals in Type 2 Diabetes-A Review.

In the pursuit of bioactive phytochemicals as a therapeutic strategy to manage metabolic risk factors for type 2 diabetes (T2D), aspalathin, C-glucosyl dihydrochalcone from rooibos (Aspalathus linearis), has received much attention, along with its C-glucosyl flavone derivatives and phlorizin, the apple O-glucosyl dihydrochalcone well-known for its antidiabetic properties. We provided context for dietary exposure by highlighting dietary sources, compound stability during processing, bioavailability and microbial biotransformation. The review covered the role of these compounds in attenuating insulin resistance and enhancing glucose metabolism, alleviating gut dysbiosis and associated oxidative stress and inflammation, and hyperuricemia associated with T2D, focusing largely on the literature of the past 5 years. A key focus of this review was on emerging targets in the management of T2D, as highlighted in the recent literature, including enhancing of the insulin receptor and insulin receptor substrate 1 signaling via protein tyrosine phosphatase inhibition, increasing glycolysis with suppression of gluconeogenesis by sirtuin modulation, and reducing renal glucose reabsorption via sodium-glucose co-transporter 2. We conclude that biotransformation in the gut is most likely responsible for enhancing therapeutic effects observed for the C-glycosyl parent compounds, including aspalathin, and that these compounds and their derivatives have the potential to regulate multiple factors associated with the development and progression of T2D.

Comparison of Phenolic Content and Antioxidant Activity for Fermented and Unfermented Rooibos Samples Extracted with Water and Methanol.

Rooibos is brewed from the medicinal plant Aspalathus linearis. It has a well-established wide spectrum of bio-activity properties, which in part may be attributed to the phenolic antioxidant power. The antioxidant capacity (AOC) of rooibos is related to its total phenolic content (TPC). The relation between TPC and AOC of randomly selected 51 fermented (FR) and 47 unfermented (UFR) rooibos samples was studied after extraction using water and methanol separately. The resulted extracts were assessed using two antioxidant assays, trolox equivalent antioxidant capacity (TEAC) and ferric reducing antioxidant power (FRAP). The results were analyzed using both simple statistical methods and machine learning. The analysis showed different trends of TPC and AOC correlations of FR and UFR samples, depending on the solvent used for extraction. The results of the water extracts showed similar TPC and higher AOC of FR than UFR samples, while the methanolic extracted samples showed higher TPC and AOC of UFR than FR. As a result, the methanolic extracts showed better agreement between TPC and AOC than water extracts. Possible explanations are given for these observed results. Although, the current literature demonstrates direct correlations of the TPC and AOC of rooibos water extracts. This study showed deviation and highlighted the importance of solvent selection and analysis methodology as an important factor in determining the TPC/AOC correlation and subsequently the expectation of the actual health benefits of rooibos herbal tea. In particular, unfermented and fermented samples can be accurately identified on the basis of a combination of assays (any two of TPC, FRAP and TEAC), especially if methanol is the solvent used. Machine learning analysis of assay data provides nearly identical results with classical statistical analytical methods. This is the first report on machine learning analysis and comparison of the TPC and AOC of rooibos herbal tea extracted with methanol and water, and highlights the importance of using methanol as a solvent to evaluate its AOC.

Resprouters Versus Reseeders: Are Wild Rooibos Ecotypes Genetically Distinct?

Aspalathus linearis (Burm. F.) R. Dahlgren (Fabaceae) or rooibos, is a strict endemic species, limited to areas of the Cederberg (Western Cape) and the southern Bokkeveld plateau (Northern Cape) in the greater Cape Floristic Region (CFR) of South Africa. Wild rooibos, unlike the cultivated type, is variable in morphology, biochemistry, ecology and genetics, and these ecotypes are broadly distinguished into two main groups, namely, reseeders and resprouters, based on their fire-survival strategy. No previous assessment of genetic diversity or population structure using microsatellite markers has been conducted in A. linearis. This study aimed to test the hypothesis that wild rooibos ecotypes are distinct in genetic variability and that the ecotypes found in the Northern Cape are differentiated from those in the Cederberg that may be linked to a fire-survival strategy as well as distinct morphological and phytochemical differences. A phylogeographical and population genetic analyses of both chloroplast (trnLF intergenic region) and newly developed species-specific nuclear markers (microsatellites) was performed on six geographically representative wild rooibos populations. From the diversity indices, it was evident that the wild rooibos populations have low-to-moderate genetic diversity (He: 0.618–0.723; Ho: 0.528–0.704). The Jamaka population (Cederberg, Western Cape) had the lowest haplotype diversity (H = 0.286), and the lowest nucleotide diversity (π = 0.006) even though the data revealed large variations in haplotype diversity (h = 0.286–0.900) and nucleotide diversity (π = 0.006–0.025) between populations and amongst regions where wild rooibos populations are found. Our data suggests that populations of rooibos become less diverse from the Melkkraal population (Suid Bokkeveld, Northern Cape) down towards the Cederberg (Western Cape) populations, possibly indicative of clinal variation. The largest genetic differentiation was between Heuningvlei (Cederberg, Western Cape) and Jamaka (FST = 0.101) localities within the Cederberg mountainous region, and, Blomfontein (Northern Cape) and Jamaka (Cederberg) (FST = 0.101). There was also a significant isolation by distance (R2 = 0.296, p = 0.044). The presence of three main clusters is also clearly reflected in the discriminant analysis of principal components (DAPC) based on the microsatellite marker analyses. The correct and appropriate management of wild genetic resources of the species is urgently needed, considering that the wild Cederberg populations are genetically distinct from the wild Northern Cape plants and are delineated in accordance with ecological functional traits of reseeding or resprouting, respectively. The haplotype divergence of the ecotypes has also provided insights into the genetic history of these populations and highlighted the need for the establishment of appropriate conservation strategies for the protection of wild ecotypes.

Quantifying the nutritional and income loss caused by crop raiding in a rural African subsistence farming community in South Africa.

Globally, crop damage by wildlife contributes to food insecurity through the direct loss of food and income. We investigated the calories lost and the potential economic impact of crop raiding at subsistence homesteads abutting the Hluhluwe Game Reserve, and assessed mitigation measures to combat crop raiding. We quantified the seasonal loss of calories (kJ/g) of four common crops, namely, beetroot, common bean, maize, and spinach, and determined the seasonal potential income loss. We used a stratified sampling approach to sample the homesteads. We found that season, crop type and the interaction between season and crop type predicted relative calorie loss and potential income loss, with the highest income loss recorded for spinach in the dry season. Significant differences were found for the potential income loss for all crop types in the wet season, and for the interaction between the crop types (maize, spinach) and the wet season. Farm slope was also a significant predictor of the relative calorie loss. Crop raiding animals, crops raided and distance of farms from the reserve all had a significant effect on the choice of mitigation measures of farmers. The highest relative calorie loss was for maize during the dry season, which could affect the subsistence farmers by reducing their daily calorie intake. This has an impact on their food security, especially during the dry season. Moreover, the most preferred mitigation measure used by farmers can have opportunity costs. These results have important implications for food security policies and practices.

Application of direct injection-ion mobility spectrometry-mass spectrometry (DI-IMS-MS) for the analysis of phenolics in honeybush and rooibos tea samples

Consumer awareness of the health benefits of herbal teas such as rooibos and honeybush has led to an increase in production demand and to inevitable accidental or deliberate adulteration. In this study, direct injection-ion mobility spectrometry-mass spectrometry (DI-IMS-MS) is proposed as a rapid methodology for the differentiation of rooibos and honeybush blends (adulterations). Analytical data was obtained from 100 rooibos, 130 honeybush and 7 blend samples. Principal component analysis (PCA) showed differences between samples of rooibos and honeybush blends, and further showed the diagnostic value of marker compounds in distinguishing Cyclopia intermedia, C. genistoides and C. subternata, mainly used for honeybush production. Markers such as eriodictyol-C-hexose isomers, orientin, aspalathin, and vitexin were characteristic of blends containing more than 80 % rooibos plant material, and quinic acid, iriflophenone-3-C-glucoside-4-O-glucoside, C-glycosylxanthones isomers (mangiferin and isomangiferin), and eriodictyol were characteristic of blends containing more than 80 % C. intermedia plant material. Furthermore, the C-glycosylxanthones isomers (mangiferin and isomangiferin) were prominent in C. genistoides, quinic acid was prominent in C. subternata and piscidic acid was prominent in C. intermedia plant material. Phenolic compounds in the herbal teas were further characterised based on an array of complementary descriptors (e.g., retention time, arrival times, accurate mass information, tandem MS fragmentation data, and TWCCSN2) to strengthen compound identification.

Aspalathus Linearis extract ameliorate Haematological disorder, Dyslipidaemia and Tissue toxicity associated with Arsenic exposure in Rats

Background: Exposure of human to heavy metals has been shown to pose serious health risk. Aspalathus linearis is enriched with polyphenolic compounds that have been demonstrated to have several medicinal value. This study therefore investigated the roles of Aspalathus linearis extract in ameliorating tissue toxicity associated with Arsenic exposure in Rats Method: Twenty-eight male Wistrar Rats weighing 150 g were randomly divided into four groups containing seven rats each; Group A (10 ppm Arsenic only), group B (10 ppm Arsenic and aqueous extract), Group C (distilled water only) and Group D (aqueous extract only) given for 14 days. Biochemical and haematological analysis were performed using standard methods. Histological analysis was done using Haemtoxylin and Eosin stain Data were analysed using one-way ANOVA followed by Tukey's test using SPSS statistical software. Results: Result showed that arsenic induced significant (p < 0.05) increases in White blood cell and Platelet counts, but decrease in packed cell volume and red blood cell count. The significant (p < 0.05) increases in the concentration of bilirubin, creatinine and urea upon arsenic exposure was decreased when co-administered with A. linearis. Animals exposed to arsenic only showed significant (p < 0.05) increases in hepatic and renal catalase (CAT), and glutathione S-transferase (GST) while the activities in testes were significantly (p < 0.05) decreased. Superoxide dismutase activity and GSH concentration decreased significantly (p < 0.05) in the liver and testes of arsenic exposed group relative to the control and the extract treated groups. Malondialdehyde concentration in the testes of arsenic exposed rats increased significantly (p < 0.05) when compared with the control and the extract treated groups. Conclusion: The result of this study showed that the aqueous extracts of A. linearis demonstrated protection against renal and liver tissues and maintained normal testicular redox status.

Microbial colonization and decomposition of commercial tea and native alder leaf litter in temperate streams

Leaf litter decomposition in streams is a fundamental ecosystem process that allows for the cycling of nutrients. The rate at which leaf litter decomposes is greatly controlled by its intrinsic characteristics. However, intraspecific variation in leaf litter characteristics poses a major challenge for large-scale studies aiming at identifying the environmental moderators of leaf litter decomposition. Thus, several standardized organic substrates have been proposed as surrogates for leaf litter. Tea bags were proposed as a standardized alternative to leaf litter for studies in soil and their use in aquatic ecosystems has been growing in recent years. It is therefore necessary to evaluate how tea is colonized and decomposed by aquatic microbial decomposers to assess its usefulness as a surrogate for leaf litter in litter decomposition studies. Here we compared the microbial colonization (based on the reproductive activity of aquatic hyphomycetes) and decomposition of green and rooibos teas and native alder leaf litter in two streams differing in environmental conditions. Colonization of green tea was lower than that of alder leaf litter, but their decomposition rates were similar. In contrast, colonization of rooibos tea was similar to that of alder leaf litter, but it decomposed 3–4 × slower. Results were consistent in both streams. Despite differences in magnitude, dynamics of microbial colonization and decomposition of tea were similar to those of alder leaf litter and were sensitive to substrate characteristics. Tea may be used as a surrogate for leaf litter in studies addressing microbial-driven leaf litter decomposition in streams.

Hypoglycemic effects of antioxidant-rich plant extracts on postprandial glycemic responses in participants with prediabetes (GLARE study)

Background: Plant extracts may help to improve glycemic control in individuals with poor glycemic control. However, few studies have been investigated in the prediabetes cohort, which is a high-risk condition for T2DM. Thus, this study aimed to investigate the acute effect of grape seed, rooibos tea, and olive leaf extracts on postprandial blood glucose and insulin in participants with prediabetes. Methods: An acute, single-blind, placebo-controlled, non-randomized, crossover study (ACTRN12617000837325) where placebo and extracts of grape seed, rooibos tea and olive leaf standardized for total antioxidant capacity were given separately during an oral glucose tolerance test to participants (n=19, five men and fourteen women, aged 65.0 ± 1.6 years, Body Mass Index (BMI) 27.3 ± 1.1 kg/m2) with prediabetes (Glycated hemoglobin A1c (HbA1c) 42 ± 1 mmol/mol). The primary outcome incremental area under the curve of glucose (iAUCglucose) was examined with other glycemic measures. Data was analyzed using linear mixed model for repeated measures. Secondary analysis was conducted by stratifying participants into either a healthier or less healthy subgroup based on the postprandial time to glucose and insulin peaks, with the less healthy subgroup experiencing delayed glucose and/or insulin peaks.Results: There were no overall significant changes to glucose and insulin measures between all plant extracts and placebo (p&gt;0.05). Upon secondary analysis, all extracts affected glycemic responses in the less healthy subgroup. Compared to placebo, grape seed reduced plasma iAUCglucose(p=0.016, 21.9% reduction), 2 h postprandial glucose (2hPG) (p=0.034, 14.7% reduction) and metabolic clearance rate of glucose (MCRglucose) (p=0.016, 16.7% increase). It also improved insulin indices such as 2 h postprandial insulin (2hPI) (p=0.029, 22.4% reduction) and Stumvoll overall insulin sensitivity index (ISIoverall) (p=0.028, 15.0% increase). Rooibos tea extract significantly improved β-cell function as demonstrated by the increased oral disposition index (DI) (p=0.031, 32.4% increase) compared to placebo. Olive leaf extract significantly increased incremental area under the curve of insulin (iAUCinsulin) (p=0.040, 16.7% increase). Conclusion: Grape seed, rooibos tea and olive leaf extracts demonstrated acute hypoglycemic benefits in adults with prediabetes and having less healthy metabolic profiles. A chronic study on the plant extracts is warranted to determine their longer-term impact on prediabetes.Trial Registration ID: ACTRN12617000837325Keywords: grape seed extract; rooibos tea extract; olive leaf extract; impaired glycemic control; hyperglycemia; hypoglycemic effects; insulin sensitivity; beta-cell function

Cytotoxic Effects of Phytomediated Silver and Gold Nanoparticles Synthesised from Rooibos (Aspalathus linearis), and Aspalathin.

The green chemistry approach has continuously been applied for the synthesis of functional nanomaterials to reduce waste, environmental hazards, and the use of toxic chemicals among other reasons. Bioactive natural compounds have been found great potential in this regard and are used to improve the stability, activity, and biodistribution of metal nanoparticles (MNPs). Aspalathin (ASP) from Aspalathus linearis (rooibos) has a well-defined pharmacological profile and functional groups capable of both reducing and capping agents in the synthesis of metallic nanoparticles (NP). This study provides the first report of the phytomediated synthesis of gold and silver nanoparticles (AuNPs/AgNPs) via ASP and the green rooibos (GR) extract. The study demonstrated a green chemistry approach to the biosynthesis of nanoparticles of GR-AuNPs, ASP-AuNPs, GR-AgNPs, and ASP-AgNPs. The results showed that GR and ASP could act both as reducing and stabilising agents in the formation of crystalline, with different shapes and dispersity of NPs in the ranges of 1.6–6.7 nm for AgNPs and 7.5–12.5 nm for the AuNPs. However, the ASP NPs were less stable in selected biogenic media compared to GR NPs and were later stabilised with polyethene glycol. The cytotoxicity studies showed that GR-AgNPs were the most cytotoxic against SH-SY5Y and HepG2 with IC50 108.8 and 183.4 μg/mL, respectively. The cellular uptake analysis showed a high uptake of AuNPs and indicated that AgNPs of rooibos at a lower dose (1.3–1.5 μg/mL) is favourable for its anticancer potential. This study is a contribution to plant-mediated metallic nanoparticles using a pure single compound that can be further developed for targeted drug delivery for cancer cells treatments in the coming years.

Green synthesis and characterization ofzinc oxidenanoparticles using bush tea ( AthrixiaphylicoidesDC) 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.

Rooibos Flavonoids, Aspalathin, Isoorientin, and Orientin Ameliorate Antimycin A-Induced Mitochondrial Dysfunction by Improving Mitochondrial Bioenergetics in Cultured Skeletal Muscle Cells.

The current study investigated the physiological effects of flavonoids found in daily consumed rooibos tea, aspalathin, isoorientin, and orientin on improving processes involved in mitochondrial function in C2C12 myotubes. To achieve this, C2C12 myotubes were exposed to a mitochondrial channel blocker, antimycin A (6.25 µM), for 12 h to induce mitochondrial dysfunction. Thereafter, cells were treated with aspalathin, isoorientin, and orientin (10 µM) for 4 h, while metformin (1 µM) and insulin (1 µM) were used as comparators. Relevant bioassays and real-time PCR were conducted to assess the impact of treatment compounds on some markers of mitochondrial function. Our results showed that antimycin A induced alterations in the mitochondrial respiration process and mRNA levels of genes involved in energy production. In fact, aspalathin, isoorientin, and orientin reversed such effects leading to the reduced production of intracellular reactive oxygen species. These flavonoids further enhanced the expression of genes involved in mitochondrial function, such as Ucp 2, Complex 1/3, Sirt 1, Nrf 1, and Tfam. Overall, the current study showed that dietary flavonoids, aspalathin, isoorientin, and orientin, have the potential to be as effective as established pharmacological drugs such as metformin and insulin in protecting against mitochondrial dysfunction in a preclinical setting; however, such information should be confirmed in well-established in vivo disease models.

Orientin Improves Substrate Utilization and the Expression of Major Genes Involved in Insulin Signaling and Energy Regulation in Cultured Insulin-Resistant Liver Cells.

Our group has progressively reported on the impact of bioactive compounds found in rooibos (Aspalathus linearis) and their capacity to modulate glucose homeostasis to improve metabolic function in experimental models of type 2 diabetes. In the current study, we investigated how the dietary flavone, orientin, modulates the essential genes involved in energy regulation to enhance substrate metabolism. We used a well-established hepatic insulin resistance model of exposing C3A liver cells to a high concentration of palmitate (0.75 mM) for 16 hrs. These insulin-resistant liver cells were treated with orientin (10 µM) for 3 h to assess the therapeutic effect of orientin. In addition to assessing the rate of metabolic activity, end point measurements assessed include the uptake or utilization of glucose and palmitate, as well as the expression of genes involved in insulin signaling and regulating cellular energy homeostasis. Our results showed that orientin effectively improved metabolic activity, mainly by maintaining substrate utilization which was marked by enhanced glucose and palmitate uptake by liver cells subjected to insulin resistance. Interestingly, these effects can be explained by the improvement in the expression of genes involved in glucose transport (Glut2), insulin signaling (Irs1 and Pi3k), and energy regulation (Ampk and Cpt1). These preliminary findings lay an important foundation for future research to determine the bioactive properties of orientin against dyslipidemia or insulin resistance in reliable and well-established models of type 2 diabetes.

Tacrolimus and herbs interactions: a review.

The calcineurin inhibitor tacrolimus (TAC) shows inter-and intra-individual variability in blood levels and has a narrow therapeutic index. To reduce the chance of fluctuations in immunosuppressive activity and potential drug interactions, it is critical to keep track of drug concentrations. Cytochrome-P450 (CYP) isoenzymes CYP3A4 and CYP3A5, as well P-glycoprotein (P-gp) are involved in TAC bioavailability. TAC's interactions with herbal extracts are reviewed here, because with more people using TAC, it is becoming crucial to know which extracts, which are often part of self-medication, can alter TAC blood concentrations. TAC bioavailability was decreased when co-administered with St John's wort (SJW), cranberry, rooibos tea, and boldo in human models by induction of the CYP450 system and/or P-gp efflux pump, meanwhile, the TAC bioavailability was increased when co-administered with grapefruit juice (GFJ), schisandra, berberine, turmeric, pomegranate juice, pomelo, and ginger in human and or animal models by inhibition effect on CYP450 system and/or P-gp efflux pump. Thus, physicians and pharmacists should thoroughly educate their patients regarding the use of supplemental herbs before administering TAC. Furthermore, patients who are already undergoing TAC treatment should be informed about the possibility of dangerous interactions between herbal remedies and TAC.

Pyrrolizidine alkaloids in tea, herbal tea and iced tea beverages– survey and transfer rates

ABSTRACT The transfer rate of 37 pyrrolizidine alkaloids (PA) found in ten naturally contaminated teas and herbal teas to their brews was studied in detail. Mixed herbal, peppermint, red bush, senna, black tea and green tea infusions were prepared according to the ISO guide and vendor’s instructions, respectively, and parameters like herb-to-water ratio, steeping time and multiple extractions studied. In general, a transfer rate of 38–100% (median 95%) for brews following vendor’s instructions was determined. The total concentration range of PA in these ten samples was 154–2412 ng/g (median 422 ng/g) in the herb and for single analytes 0.1–170 ng/g. Seven of the 37 PA occurred unexpectedly; these were tentatively identified and quantified by liquid chromatography-high resolution mass spectrometry (LC-HR-MS), since their contributions to total PA-content matter. Additionally, 46 iced tea beverages were analysed for their PA-load, determined to be in the range 0–631 ng/L (median 40 ng/L). The applied solid-phase extraction (SPE) clean-up turned out to be capable of separating PA in the free base pyrrolizidine alkaloids (PAFB) and their N-oxides (PANO) in a two-step elution, which was a valuable tool to support identification of unexpected PA. Further, atropine was found in 50% of the ten tea herb samples (range: 1–4 ng/g) and in 13% of the iced tea beverage samples (range: 2–65 ng/L).

Protective Effects of Linearthin and Other Chalcone Derivatives from Aspalathus linearis (Rooibos) against UVB Induced Oxidative Stress and Toxicity in Human Skin Cells.

Skin cells suffer continuous damage from chronic exposure to ultraviolet light (UV) that may result in UV-induced oxidative stress and skin thinning. This has necessitated the formulation of cosmeceutical products rich in natural antioxidants and free radical scavengers. Aspalathus linearis (rooibos) is an endemic South African fynbos plant growing naturally in the Western Cape region. The plant is rich in phenolics and other bioactives with a wide spectrum of health benefits. The chemical study of an acetonic extract of green A. linearis afforded a novel compound named linearthin (1) and two known dihydrochalcones, aspalathin (2) and nothofagin (3). The chemical structure of the novel compound was elucidated based on spectroscopic data analysis. The bio-evaluation of the isolated chalcones in vitro for protection against UVB-induced oxidative stress were systematically assessed by examining cell viability, metabolic activity, apoptosis, and cytotoxicity using HaCaT and SK-MEL-1 skin cells models. It was observed that pre-treatment with tested samples for 4- and 24 h at low concentrations were sufficient to protect skin cells from UVB-induced damage in vitro as evidenced by higher cell viability and improved metabolic activity in both keratinocytes (HaCaT) and melanocytes (SK-MEL-1). The results further show that the pre-treatment regimen employed by this study involved some degree of cellular adaptation as evidenced by higher levels of reduced glutathione with a concomitant decrease in lipid peroxidation and lowered caspase 3 activity. Furthermore, compound 1 was most cytoprotective against UVB irradiation of HaCaT cell line (over 24 h) with an IC50 of 282 µg/mL and SK-MEL-1 cell line with IC50 values of 248.3 and 142.6 µg/mL over 4 and 24 h, respectively. On the other hand, HaCaT cells exposed to 2 over 4 h before UVB irradiation showed the highest degree of cytoprotection with an IC50 of 398.9 µg/mL among the four studied samples. These results show that linearthin (1) and the two glycoside dihydrochalcone of A. linearis have the potential to be further developed as antioxidant cosmeceutical ingredients that may protect skin against UVB-induced damage.