Browsing by Author "Gelderblom, Wentzel"

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    Anti-inflammatory effects of Aspalathus linearis and Cyclopia spp. extracts in a UVB/keratinocyte (HaCaT) model utilising interleukin-1α accumulation as biomarker
    (MDPI, 2016-10-02) Magcwebeba, Tandeka; Swart, Pieter; Swanevelder, Sonja; Joubert, Elizabeth; Gelderblom, Wentzel
    Ultraviolet B (UVB) radiation is one of the major predisposing risk factors of skin cancer. The anticancer and photoprotective effects of unoxidized rooibos (Aspalathus linearis) and honeybush (Cyclopia) herbal teas, containing high levels of dihydrochalones and xanthones, respectively, have been demonstrated in skin cancer models in vivo. In the current study, the anti-inflammatory effects of methanol and aqueous extracts of these herbal teas were investigated in a UVB/HaCaT keratinocyte model with intracellular interleukin-1α (icIL-1α) accumulation as a biomarker. Extracts of green tea (Camellia sinensis) served as benchmark. Both extracts of green tea and rooibos, as well as the aqueous extract of C. intermedia, enhanced UVB-induced inhibition of cell viability, proliferation and induction of apoptosis, facilitating the removal of icIL-1α. The underlying mechanisms may involve mitochondrial dysfunction exhibiting pro-oxidant responses via polyphenol-iron interactions. The methanol extracts of honeybush, however, protected against UVB-induced reduction of cell growth parameters, presumably via antioxidant mechanisms that prevented the removal of highly inflamed icIL-1α-containing keratinocytes via apoptosis. The dual antioxidant and/or pro-oxidant role of the polyphenolic herbal tea constituents should be considered in developing preventive strategies against UVB-induced skin carcinogenesis. The indirect removal of UVB damaged keratinocytes by herbal tea extracts via apoptosis may find application in the prevention of photo-induced inflammation.
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    Detoxification of the fumonisin mycotoxins in maize : an enzymatic approach
    (MDPI, 2019-09-10) Alberts, Johanna; Schatzmayr, Gerd; Moll, Wulf-Dieter; Davids, Ibtisaam; Rheeder, John; Burger, Hester-Mari; Shephard, Gordon; Gelderblom, Wentzel
    Enzymatic detoxification has become a promising approach for control of mycotoxins postharvest in grains through modification of chemical structures determining their toxicity. In the present study fumonisin esterase FumD (EC 3.1.1.87) (FUMzyme®; BIOMIN, Tulln, Austria), hydrolysing fumonisin (FB) mycotoxins by de-esterification, was utilised to develop an enzymatic reduction method in a maize kernel enzyme incubation mixture. Efficacy of the FumD FB reduction method in “low” and “high” FB contaminated home-grown maize was compared by monitoring FB1 hydrolysis to the hydrolysed FB1 (HFB1) product utilising a validated LC-MS/MS analytical method. The method was further evaluated in terms of enzyme activity and treatment duration by assessing enzyme kinetic parameters and the relative distribution of HFB1 between maize kernels and the residual aqueous environment. FumD treatments resulted in significant reduction (≥80%) in “low” (≥1000 U/L, p < 0.05) and “high” (100 U/L, p < 0.05; ≥1000 U/L, p < 0.0001) FB contaminated maize after 1 h respectively, with an approximate 1:1 µmol conversion ratio of FB1 into the formation of HFB1. Enzyme kinetic parameters indicated that, depending on the activity of FumD utilised, a significantly (p < 0.05) higher FB1 conversion rate was noticed in “high” FB contaminated maize. The FumD FB reduction method in maize could find application in commercial maize-based practices as well as in communities utilising home-grown maize as a main dietary staple and known to be exposed above the tolerable daily intake levels.
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    Differential modulation of gene expression encoding hepatic and renal xenobiotic metabolizing enzymes by an aspalathin-enriched rooibos extract and aspalathin
    (Thieme Gruppe, 2019) Abrahams, Sameega; Samodien, Sedicka; Lilly, Mariska; Joubert, Elizabeth; Gelderblom, Wentzel
    Modulation of the expression of hepatic and renal genes encoding xenobiotic metabolizing enzymes by an aspalathin-enriched green rooibos (Aspalathus linearis) extract (GRE) was investigated in the liver and kidneys of F344 rats following dietary exposure of 28 d, as well as selected xenobiotic metabolizing genes in rat primary hepatocytes. In the liver, GRE upregulated genes (p < 0.05) encoding aldehyde dehydrogenase, glucose phosphate isomerase, and cytochrome P450 while 17β-hydroxysteroid dehydrogenase 2 (Hsd17β2) was downregulated. In primary hepatocytes, GRE lacked any effect, while aspalathin downregulated Hsd17β2, mimicking the effect of GRE in vivo, and upregulated catechol-O-methyl transferase and marginally (p < 0.1) cytochrome P450 2e1. In the kidneys, GRE upregulated (p < 0.05) genes encoding the phase II xenobiotic metabolism enzymes, glutathione-S-transferase mµ and microsomal glutathione-S-transferase, while downregulating genes encoding the ATP binding cassette transporter, cytochrome P450, gamma glutamyltransferase 1, and N-acetyltransferase 1. Differential modulation of the expression of xenobiotic metabolizing genes in vivo and in vitro by GRE is dose-related, duration of exposure, the tissue type, and interactions between specific polyphenol and/or combinations thereof. Aspalathin is likely to be responsible for the downregulation of estradiol and testosterone catabolism by GRE in the liver. The differential gene expression by GRE in the liver and kidneys could, depending on the duration exposure and dose utilized, determine the safe use of such an extract in humans for specific health and/or disease outcomes.
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    Value of antioxidant capacity as relevant assessment tool for “health benefits” of fruit - understated or inflated?
    (MedPharm Publications, 2016) Joubert, Elizabeth; Gelderblom, Wentzel
    Consumption of fruit and vegetables is considered to be an inherent part of a healthy diet, but more so since plant antioxidants, and in particular polyphenols, have been linked through in vivo and epidemiological studies with positive health outcomes.1–3 As a result, polyphenols have been elevated to “lifespan essentials”, because scientific evidence indicated that they are needed by humans to achieve a full lifespan by reducing the risk of a range of chronic diseases.4 No Dietary Reference Intake values exist for polyphenols, however, it has been suggested that their target intake value should be based on the total polyphenol content provided by the “5-a-day” portions of fruit and vegetables recommendation by the World Health Organisation.