Mariska Lilly

Rooibos ( Aspalathus linearis ) is a rich source of bioactive polyphenols; however, most biological studies have focused on traditional aqueous tea extracts, despite extraction solvent and enrichment procedures substantially influencing phytochemical composition and biological activity. This study investigated whether chemically distinct enriched ethanolic extracts prepared from unfermented and fermented rooibos differentially modulate intestinal inflammation and barrier integrity. Following ethanol extraction and Amberlite XAD‐4 enrichment, the extracts were characterized for soluble solids, flavonoid composition and antioxidant capacity before evaluation in an Escherichia coli lipopolysaccharide (10 μg/mL)‐stimulated IPEC‐J2 intestinal epithelial cell model. Anti‐inflammatory activity was assessed by determining cell viability, caspase activity, IL‐8 protein production, and gene expression of IL‐8 , IL‐6 and TLR4 , while barrier integrity was evaluated using transepithelial electrical resistance (TEER), ZO‐1 immunofluorescence and tight junction gene expression. Ethanol extraction and enrichment generated extracts with markedly different phytochemical profiles. The enriched unfermented extract contained substantially higher soluble solids (77.72 g/100 g) and aspalathin (60 g/100 g soluble solids) than the fermented extract (53.10 g/100 g and 9.46 g/100 g, respectively), resulting in significantly greater antioxidant activity. Despite these compositional differences, both extracts attenuated LPS‐induced inflammation by reducing IL‐8 protein production and downregulating IL‐8 , IL‐6 and TLR4 gene expression. However, distinct biological activities were observed. The polyphenol‐rich unfermented extract provided superior protection of epithelial barrier integrity, demonstrated by increased TEER, enhanced ZO‐1 localisation and upregulation of tight junction markers, whereas the fermented extract exhibited pronounced anti‐inflammatory activity at lower concentrations despite its lower polyphenol content. These findings demonstrate that post‐harvest processing and extraction technique determine the phytochemical composition of rooibos and consequently influence its dose‐dependent biological activity. Tailoring extraction strategies may therefore enable the development of rooibos extracts towards certain product formulations with targeted anti‐inflammatory or barrier‐protective properties.

Fusarium species are significant phytopathogens responsible for major crop losses and contamination of food products with harmful mycotoxins, posing serious risks to food security and public health. In response to the limitations of conventional agrochemicals, this study explores sustainable antifungal strategies based on plant-derived products and nanotechnology. The aqueous extract of Ocimum basilicum was investigated as a bioresource for both direct antifungal activity and the green synthesis of silver nanoparticles (OB-AgNPs). Liquid chromatography–mass spectrometry (LC-MS) analysis of the O. basilicum aqueous extract revealed the presence of key compounds, including rosmarinic and chicoric acids, which can reduce and stabilize AgNPs. The biosynthesized nanoparticles were characterized using standard analytical techniques, including UV–visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM), and powder X-ray diffraction (PXRD). The OB-AgNPs exhibited a surface plasmon resonance (SPR) peak at 437 nm, a zeta potential of ~–16.3 mV, an average size of 28 nm (TEM) while the average hydrodynamic size is ≈57 nm (DLS). The synthesized AgNPs demonstrated stability in potato dextrose broth (PDB) for up to 24 h. The nanoparticles alongside the aqueous extract were evaluated against selected mycotoxigenic Fusarium species including F. verticillioides, F. proliferatum, F. subglutinans, F. graminearum, and F. globosum, following 96 h of exposure. Results showed that the aqueous O. basilicum extract exhibited limited antifungal activity, with significant inhibition observed only against F. globosum MRC 6122 at the highest concentration tested (400 ng/µL). In contrast, the biosynthesized OB-AgNPs demonstrated potent antifungal activity against most of the tested Fusarium strains, except for F. proliferatum MRC 8549 and MRC 8550, indicating substantially greater efficacy than the crude extract. These findings highlight the potential of O. basilicum-mediated AgNPs as effective and eco-friendly antifungal agents. The study underscores the value of integrating plant-based phytochemicals with nanotechnology for controlling Fusarium pathogens, while emphasizing the need for future studies to determine their effects on mycotoxin production, as well as their safety and phytotoxicity for agricultural applications.

The intestinal epithelium is frequently exposed to environmental contaminants such as fumonisins, mycotoxins implicated in the development of mycotoxicosis across various mammalian species, with fumonisin B ₁ (FB ₁ ) being the most prevalent and toxic congener. Fumonisin B ₁ (FB ₁ ) can be enzymatically hydrolysed to produce hydrolysed fumonisin B ₁ (HFB ₁ ) that displays reduced inhibitory activity toward ceramide synthase. Given the central role of ceramide synthase in sphingolipid metabolism and cellular homeostasis, the reduced inhibitory activity of HFB ₁ is considered toxicologically favourable, as it is less likely to disrupt membrane integrity and critical signalling pathways. However, the toxicity of HFB ₁ remains variable across different in vitro and in vivo models. In this study, we evaluated the impact of FB ₁ and HFB ₁ on cell viability, apoptosis, and proliferation in the porcine intestinal cell line (IPEC-J2), including inflammatory responses through interleukin 8 (IL-8). Molecular mechanisms and pathways influenced by FB ₁ and HFB ₁ exposure were investigated through proteomic and bioinformatic analyses. Differentially abundant proteins (DAPs) were identified and functionally characterised using Gene Ontology analysis based on the Sus scrofa (domestic pig) database, revealing 52 significant DAPs between FB ₁ and HFB ₁ treatments compared to the control. Fibronectin 1 (FN1), an adhesive glycoprotein of the intestine, was consistently detected as a DAP in cells exposed to FB ₁ and HFB ₁ . FB ₁ upregulates FN1, while HFB ₁ downregulates it, leading to different oncogenic pathways revealed by STRING enrichment analysis. Proteomic analysis further revealed distinct DAPs following FB ₁ and HFB ₁ exposure, implicating alterations in immune modulation (e.g. differential regulation of CD276), iron homeostasis (upregulation of FTL and FTH1), epithelial integrity (downregulation of NTN4, ST14), extracellular matrix remodelling (reduced SPARC), and angiogenesis-related pathways (decreased TINAGL1, FBLN2, SDC4) suggesting early changes in cellular signalling, stress response, and structural regulation that may be relevant to cancer biology and warrant further investigation. These findings also demonstrate that HFB ₁ activates distinct cancer-related pathways in vitro compared to FB ₁ , with in vivo studies suggesting divergent mechanisms. HFB ₁ also induces more extensive protein expression changes in IPEC-J2 cells, as reflected by the greater number of DAPs and the complexity of enriched pathways. However, further investigation is needed to determine whether these changes directly contribute to cytotoxicity or represent compensatory cellular responses.

The anti‐cancer potential of Cyclopia species (honeybush) has been demonstrated in several models. The present study investigated the effects of aqueous and polyphenol‐enriched (PE) extracts of C. subternata and C. genistoides , as well as mangiferin and hesperidin, on different cell growth parameters in human liver (HepG2) and colon (HT‐29) cancer cells. Mangiferin and hesperidin were most abundant in C. genistoides and C. subternata , respectively. Cyclopia subternata extracts had the highest ferric‐reducing antioxidant capacity. Following exposure of the cells to the extracts and compounds, cell viability, proliferation, and death (apoptosis and autophagy) were determined. Cyclopia subternata extracts reduced cell viability and inhibited cell proliferation the most, associated with depletion of ATP. In HepG2 cells, the PE extracts were less effective than the aqueous extracts in reducing cell viability but more effective in inhibiting cell proliferation. Despite disrupting cell growth, none of the extracts induced apoptosis. The aqueous extracts affected autophagy in both cancer cells. Disruption of mitochondrial membrane integrity by the different extracts, presumably via polyphenol/iron interactions, is postulated to be involved; however, mangiferin and hesperidin had no effect, suggesting that other polyphenols and/or complex interactions between compounds are likely responsible for the differential cytotoxic and/or cytoprotective effects of the extracts.