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The prevalence of cardiovascular disease (CVD) has increased in South Africa, emphasizing the importance of prevention strategies. This study used echocardiography to investigate the impact of Rooibos on cardiovascular function in those at risk of CVD. This research aims to contribute to understanding its effects on reducing cardiovascular risk factors. The study design involved a 12-week randomized, parallel, double-blinded, placebo-controlled dietary intervention trial using capsules containing standardized water-soluble extracts of green and traditional fermented Rooibos alongside a placebo control. Echocardiography was incorporated as a diagnostic imaging tool to assess cardiac function in the participant cohort. Aorta (AO) dimensions showed no significant change in any intervention group. Left atrium (LA) reduced in size from 3.832 ± 0.071 cm to 3.675 ± 0.067 cm (P = 0.01). There was no significant change in LA/AO ratio in any intervention group. Interventricular septum diameter in the placebo group decreased from 1.334 ± 0.030 cm to 1.250 ± 0.025 cm (P = 0.002), with no significance in fermented Rooibos, while green Rooibos resulted in a decrease from 1.282 ± 0.036 cm to 1.186 ± 0.029 cm (P = 0.002). Left ventricle posterior wall (LVPW) showed no significant changes in any of the intervention group. The left ventricle mass in the placebo and green Rooibos groups demonstrated no significance changes, while fermented Rooibos caused a decrease from 204.102 ± 7.102 g to 191.394 ± 6.707 g (P = 0.015). The phytochemical bioactive components, such as the polyphenolic antioxidants present in green and fermented Rooibos, improved cardiovascular function. This study confirms the effectiveness of echocardiography as imaging tool for assessing cardiac function in this particular population. Regular Rooibos consumption may offer promising therapeutic benefits for preventing and managing CVD risk. [ABSTRACT FROM AUTHOR]

Green rooibos' bioactive compounds contribute greatly towards its antioxidant activity. The anti-browning activity of aqueous (GRE) and beta-cyclodextrin (β-GRE)-assisted extracts of green rooibos was investigated in canned apples. Freeze-dried extracts (GRE and β-GRE) obtained at 40 °C for 60 min were added in canned apples at 0.25 and 0.5% prior to heat processing and stored at 23 and 37 °C for 24 weeks. Lightness (L*), colour difference (DE*), furfural and hydroxymethyl furfural (HMF) were determined to establish the effect of extracts against non-enzymatic browning (NEB) development. The L* value decreased, whereas DE*, HMF and furfural increased with increased storage time and temperature. A higher inhibition was observed for samples stored at 23 °C, and storage at 37 °C reduced (p < 0.05) the inhibitory capacity of extracts. Greater inhibition against NEB development was reported for β-GRE 0.25 and 0.5 via the L* value (40.93–46.67%), β-GRE 0.25 for DE* (46.67%) and β-GRE 0.25 and 0.5 for HMF (59.55–67.33%). No differences (p > 0.05) were observed in furfural inhibition between all extracts, although inhibition was reported at 62.69–72.29%. Browning inhibition correlated with the reaction rate constant (k0) and activation energy (Ea), exhibiting a correlation coefficient of 0.925, 0.964, 0.932 and 0.754 for L*, DE*, HMF and furfural, respectively. [ABSTRACT FROM AUTHOR]

Antioxidant activity associated with green rooibos infusions is attributed to the activity of polyphenols, particularly aspalathin and nothofagin. This study aimed to optimise β-cyclodextrin (β-CD)-assisted extraction of crude green rooibos (CGRE) via total polyphenolic content (TPC) and antioxidant activity assays. Response surface methodology (RSM) permitted optimisation of β-CD concentration (0–15 mM), temperature (40–90 °C) and time (15–60 min). Optimal extraction conditions were: 15 mM β-CD: 40 °C: 60 min with a desirability of 0.985 yielding TPC of 398.25 mg GAE·g−1, metal chelation (MTC) of 93%, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging of 1689.7 µmol TE·g−1, ferric reducing antioxidant power (FRAP) of 2097.53 µmol AAE·g−1 and oxygen radical absorbance capacity (ORAC) of 11,162.82 TE·g−1. Aspalathin, hyperoside and orientin were the major flavonoids, with quercetin, luteolin and chrysoeriol detected in trace quantities. Differences (p < 0.05) between aqueous and β-CD assisted CGRE was only observed for aspalathin reporting the highest content of 172.25 mg·g−1 of dry matter for extracts produced at optimal extraction conditions. Positive, strong correlations between TPC and antioxidant assays were observed and exhibited regression coefficient (R2) between 0.929–0.978 at p < 0.001. These results demonstrated the capacity of β-CD in increasing polyphenol content of green rooibos. [ABSTRACT FROM AUTHOR]

Green rooibos’ bioactive compounds contribute greatly towards its antioxidant activity. The anti-browning activity of aqueous (GRE) and beta-cyclodextrin (β-GRE)-assisted extracts of green rooibos was investigated in canned apples. Freeze-dried extracts (GRE and β-GRE) obtained at 40 °C for 60 min were added in canned apples at 0.25 and 0.5% prior to heat processing and stored at 23 and 37 °C for 24 weeks. Lightness (L*), colour difference (DE*), furfural and hydroxymethyl furfural (HMF) were determined to establish the effect of extracts against non-enzymatic browning (NEB) development. The L* value decreased, whereas DE*, HMF and furfural increased with increased storage time and temperature. A higher inhibition was observed for samples stored at 23 °C, and storage at 37 °C reduced (p < 0.05) the inhibitory capacity of extracts. Greater inhibition against NEB development was reported for β-GRE 0.25 and 0.5 via the L* value (40.93–46.67%), β-GRE 0.25 for DE* (46.67%) and β-GRE 0.25 and 0.5 for HMF (59.55–67.33%). No differences (p > 0.05) were observed in furfural inhibition between all extracts, although inhibition was reported at 62.69–72.29%. Browning inhibition correlated with the reaction rate constant (k0) and activation energy (Ea), exhibiting a correlation coefficient of 0.925, 0.964, 0.932 and 0.754 for L*, DE*, HMF and furfural, respectively.

In this study, we determined how unfermented and fermented rooibos tea (RTand GRT) amounts, tea leaf weight, extraction time, and temperature influence 1, 1-Diphenyl-2- Picrylhydrazyl (DPPH) radical-scavenging activity, and total polyphenol and aspalathin contents. When RTand GRTwere obtained through steeping 1.5, 2.5, 5, or 10 g of tea leaves in 500 mL of boiling water for 10 min, the total polyphenol and aspalathin contents and the DPPH radical scavenging activity increased with the increase in the amount of tea leaves used. When 10 g of tea leaves were extracted using 500mL of boiling water for 10 min, the total polyphenol and aspalathin contents and the DPPH scavenging activity of GRT(about 940 μg/mL, and 5.9mM ascorbic acid equivalent, respectively) were higher than those of RT(about 760 μg/mL, and 3.6mM ascorbic acid equivalent, respectively). When 5 g of tea leaves were extracted using 500mL of boiling water for 15-20 min, the total polyphenol and aspalathin contents and the DPPH scavenging activity of RTand GRTwere higher than those extracted in 5-10 min. Notably, we observed almost no difference in the total polyphenol and aspalathin contents of RTand GRTwhen extracted at 80℃ compared to decocted for 10 min. [ABSTRACT FROM AUTHOR]

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.

To evaluate the suppressive effects of green rooibos (Aspalathus linearis) unfermented tea on postprandial hyperglycemia, we orally administered four carbohydrates with or without green rooibos extract (GRE) and its major flavonoid aspalathin (Asp). GRE significantly suppressed the elevation of blood glucose levels after glucose, maltose, and starch intake. Asp also lowered the levels for all four carbohydrates. To clarify the mechanism underlying these results, we performed an intraperitoneal glucose tolerance test (IPGTT) and measured the ability of GRE and Asp to inhibit the activities of carbohydrate-hydrolyzing enzymes in vitro. In IPGTT, GRE and Asp did not show suppressive effects on blood glucose, while they dose-dependently inhibited the activities of α-glucosidase and α-amylase in vitro. These results showed that GRE and Asp suppress the elevation of blood glucose levels. It was indicated that these effects may result from the suppression of glucose absorption and the inhibition of carbohydrate-hydrolyzing enzyme activities by GRE and Asp. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]