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 received much consideration due to its technological and medicinal applications. In this study, we report on the synthesis process of ZnO nanoparticles using Athrixia phylicoides DC natural extract as a reducing agent. Methods: Liquid chromatography–mass spectrometry (LC-MS) was used to identify the compounds responsible for the synthesis of ZnO nanoparticles. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized through X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results: LC-MS results showed that different flavonoids and polyphenols, as well as Coumarin, an aromatic compound, reacted with the precursor to form ZnO nanoparticles. XRD and UV-Vis analysis confirmed the synthesis of ZnO nanoparticles, with a spherical shape showed in SEM images. The quasi-spherical ZnO crystals 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. phylicoides DC. can be used in the bio-reduction of zinc nitrate hexahydrate to prepare pure ZnO nanoparticles, thus, extending the use of this plant to an industrial level.

Response of Plant Growth and Development, and Accumulation of Hydroxyl-cinnamoyl Acid Derivatives to Selected Shade Nets and Seasonality of Field-grown Bush Tea (Athrixia phylicoides DC.)

Horticultural practices and quality of bush tea (Athrixia phylicoides DC.) are critical for herbal tea industrialization. The objective of the current study was to determine the effect of selected shade nets and seasonal variation on plant growth and development, and hydroxycinnamic acid content of field-grown bush tea. The trial was laid out in a randomized complete block design consisting of three shade nets (black, green, and white) and control or full sunlight with three different light intensities (40%, 50%, and 80%) replicated three times. Proportion of intercepted radiation by the canopy, chlorophyll content, plant height, and fresh and dry mass were measured, and hydroxycinnamic acid accumulation was determined. In addition, hydroxycinnamic acid composition was determined using liquid chromatography linked to mass spectrometry (LC-MS). The application of shade nets resulted in plant growth and yield reduction as compared with the plants exposed to full sunlight during summer followed by white shade net. The accumulation of hydroxycinnamic acid was higher in 80% white shade net plots compared with unshaded plants (control) and the other shade nets. Therefore, lack of shading provides a conducive environment to enhance plant growth and development of bush tea. The white shade net (80%) was an effective microclimate tool to enhance accumulation of caffeoylquinic acid (m/z 353), p-coumaric acids (m/z 337), dicaffeoylquinic acid (m/z 515), and tricaffeoylquinic acids of bush tea. This study is the first to demonstrate light as a determining factor for production of chlorogenates in bush tea plants. Future studies will be conducted to determine the effect of light on extracts of the bush tea using different solvents.

Athrixia phylicoides tea infusion (bushman tea) improves adipokine balance, glucose homeostasis and lipid parameters in a diet-induced metabolic syndrome rat model

Background Central obesity and insulin resistance are associated with metabolic syndrome (MetS) which is aggravated by diet and sedentary lifestyle. Athrixia phylicoides (AP) is reported by rural communities to have medicinal benefits associated with MetS such as obesity and type 2 diabetes. This study was aimed to investigate the effects of AP on diet-induced MetS in Wistar rats to validate its ethnopharmacological use. Methods AP was profiled for phytochemicals by LC-MS. After induction of MetS with high energy diet (HED), 30 male rats were divided into five treatment groups (n = 6): normal diet control, HED control, HED + AP 50 mg/Kg BW, HED + AP 100 mg/Kg BW and HED + 50 mg/Kg BW metformin. The rats were treated daily for 8 weeks orally after which weight gain, visceral fat, total cholesterol, free fatty acids (FFAs) and adipokine regulation; leptin: adiponectin ratio (LAR) were assessed. Also, glucose homeostatic parameters including fasting blood glucose (FBG), oral glucose tolerance test (OGTT), glucose transporter 4 (GLUT 4), insulin and homeostatic model assessment of insulin resistance (HOMA-IR) were determined. Results Findings showed that AP was rich in polyphenols. The HED control group showed derangements of the selected blood parameters of MetS. AP reversed diet-induced weight gain by reducing visceral fat, total blood cholesterol and circulating FFAs (p ≤ 0.05). Treatment with AP improved adipokine regulation depicted by reduced LAR (p<0.05). Treatment with AP improved parameters of glucose homeostasis as demonstrated by reduced FBG and HOMA-IR (p ≤ 0.05) and increased GLUT 4 (p<0.05). Conclusion Athrixia phylicoides tea infusion was shown to possess anti-obesity and anti-inflammatory properties, improved glucose uptake and reduce insulin resistance in diet-induced MetS in rats which could be attributed to its richness in polyphenols. Therefore, AP could have potential benefits against type 2 diabetes and obesity which are components of MetS validating its ethnopharmacological use.

Metabolomic Analysis for Compositional Differences of Bush Tea (Athrixia phylicoides DC.) Subjected to Seasonal Dynamics

Bush tea (Athrixia phylicoides DC.) is a South African indigenous herbal tea rich in secondary metabolites with medicinal significance. However, studies on the effects of seasonal changes on bush tea and quantification of its metabolites using untargeted approach have not been explored. Therefore, this study’s objective was to investigate the effects of seasonal variation on the metabolites of bush tea using LC-MS/MS (Liquid Chromatography with Tandem Mass Spectrometry) and 1H NMR (High-Resolution Proton Nuclear Magnetic Resonance) techniques. Bush tea leaves were plucked once in each season namely, autumn (March to May), winter (June to August), spring (September to November), and summer (December to February). The primary metabolites including non-essential amino acids, organic acids, and vitamins in bush tea were predominantly elevated during summer and spring. The 1H NMR-based metabolomic analysis revealed that bush tea metabolome was strongly affected by seasonal variations, using the partial least squares-discriminant analysis (PLS-DA) which demonstrated four distinct groups of seasons. Similarly, the 1H NMR based metabolic profiling of bush tea subjected to different seasons resulted in putative annotation of six phenolic compounds which included rutin, 4-(hydroxyphenyl) propyl coumarate, caffeic acid, hymenoxin, quercetin, and kaempferol. The phenolics and primary metabolites differed remarkably per season with enhanced accumulation observed in the summer and spring harvested bush tea. The LC-MS and 1H NMR metabolomics analysis suggests that summer and spring can be recommended as preferred plucking seasons for bush tea leaves and twigs.

Anti-diabetic and anti-proliferative activities of herbal teas, Athrixia phylicoides DC and Monsonia burkeana Planch. ex Harv, indigenous to South Africa

Purpose The purpose of this paper is to investigate the health and medicinal importance of bush tea (Athrixia phylicoides DC) and special tea (Monsonia burkeana Planch. ex Harv), two of Southern African indigenous herbal teas. Design/methodology/approach The two herbal teas, A. phylicoides and M. burkeana were extracted individually and in combined ratios for analysis. The phenolic content was determined and the different phenolic compounds were identified using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The anti-diabetic activity of the teas was determined by evaluating the inhibition of both α-amylase and α-glucosidase in vitro. The anti-proliferative activity was measured on human cervical cancer (HeLa) cell line using the MTT (3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium) assay. Findings Gallic acid, chlorogenic acid and quercetin were identified to be present in significant quantities by TLC. The HPLC quantified the presence of catechin (1.567 mg/g) and chlorogenic acid (1.862 mg/g) in special tea while chlorogenic acid (1.288 mg/g) was present in bush tea. Bush tea and special tea expressed significant levels of phenolic content and high antioxidant activities. Special tea (S100) expressed high inhibition of α-amylase, α-glucosidase and HeLa cell line proliferation when compared to bush tea (B100). Originality/value Both bush tea and special tea could provide an alternative for treatment and management of both diabetes and cervical cancer. However, future studies are needed to investigate their synergistic effect with a wide range of other commercial herbal teas.

Metabolic Profiling of Cultivated Bush Tea (Athrixia phylicoides DC.) in Response to Different Pruning Types

Bush tea (Athrixia phylicoides DC.) is a popular medicinal South African indigenous plant and it has been used for many decades as a health beverage and medicine. The objective of the study was to profile metabolites for assessment of quality of bush tea (A. phylicoides DC.) subjected to different pruning levels. Treatments consisted of untreated control, top-branch pruning, middle pruning, and basal pruning arranged in a randomized complete block design (RCBD) using 10 single trees as replications. The liquid chromatography quadrupole time-of-flight mass spectrometry (LC–QTOF–MS) was carried out to annotate the bush tea metabolites present in bush tea. Orthogonal partial least square-discriminatory analysis (OPLS-DA) from 1H nuclear magnetic resonance (NMR) revealed a separation between the basal, middle, top pruning, and the unpruned bush tea plants. The pruned (top) and unpruned tea plants, exhibited higher levels of metabolites than the basal and middle pruned. Pruning bush tea showed a significant effect on accumulation of secondary metabolites and thus could enhance bush tea quality. The study successfully annotated 28 metabolites (compounds), which elucidated canonical differences in pruning treatment of bush tea, as validated through multivariate analysis. Top pruning (apically pruned) resulted in improved metabolite accumulation than other treatment and can be recommended in bush tea cultivation. Future studies to enhance vegetative enhancement after pruning will be evaluated.