Akeem O Lawal1, Lester M Davids2, Jeanine L Marnewick3. 1. Oxidative Stress Research Centre, Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, Bellville Campus, Bellville 7535, South Africa. Electronic address: tolekan@hotmail.com. 2. Department of Medical Biosciences, Faculty of Natural Sciences, University of Western Cape, Bellville, 7535, South Africa. 3. Oxidative Stress Research Centre, Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, Bellville Campus, Bellville 7535, South Africa.
Abstract
BACKGROUND: Previous evidence show foods and beverages rich in polyphenolic compounds to have favourable effects on the cardiovascular system. HYPOTHESIS: The current study assessed the modulation of oxidative stress and associated inflammation induced by diesel exhaust particles (DEP - SRM 2975) by pre-treatment of human umbilical vein endothelial cells (HUVECs) with aqueous extracts of rooibos [fermented (FR) as well as green form (GR)] and honeybush [fermented form (FH)]. STUDY DESIGN: HUVEC are either exposed to DEP (10 µg/ml) for 4 h or pre-treated with 40 and 60 µg/ml of FR or GH or FR, or 50 µg/ml orientin (OR) for 6 h prior to DEP exposure. METHODS: In vitro antioxidant capacity of the extracts was assessed and the polyphenol contents were also assessed by HPLC. ROS, cell viability, lactate dehydrogenase leakage, lipid peroxidation, GSH:GSSG ratios, conjugated diene and protein carbonyl levels were determined as indices of oxidative stress and cytotoxicity. RT-qPCR and western blot were used to assess inflammatory cytokines and antioxidant genes expression. RESULTS: DEP caused a dose and time-dependent increase in ROS production, significant (p < 0.001) increase in protein carbonyl (PC) formation, thiobarbituric acid reactive substances and conjugated dienes levels (p < 0.01) and a significant reduction in glutathione (GSH) redox status. Pre-incubation with either the herbal extracts or orientin attenuated these effects. The significant increase in IL-1α, IL-6, IL-8, VCAM-1 and ATF4 gene expression caused by DEP (10 µg/ml) were also attenuated by the presence of the FR, GR and FH extracts, and OR . Pre-treatment with the rooibos extracts or flavone orientin enhanced cell viability, reduced LDH leakage, enhanced mRNA expression of NQO1 and Nrf2, but repressed CYP1B1 mRNA induced by DEP. Western blot showed both the herbal tea extracts and orientin to enhance NQO1 and γGSC protein induction by DEP. CONCLUSION: Taken together, the herbal extracts offer protection against DEP-induced oxidative stress and inflammatory response.
BACKGROUND: Previous evidence show foods and beverages rich in polyphenolic compounds to have favourable effects on the cardiovascular system. HYPOTHESIS: The current study assessed the modulation of oxidative stress and associated inflammation induced by diesel exhaust particles (DEP - SRM 2975) by pre-treatment of human umbilical vein endothelial cells (HUVECs) with aqueous extracts of rooibos [fermented (FR) as well as green form (GR)] and honeybush [fermented form (FH)]. STUDY DESIGN: HUVEC are either exposed to DEP (10 µg/ml) for 4 h or pre-treated with 40 and 60 µg/ml of FR or GH or FR, or 50 µg/ml orientin (OR) for 6 h prior to DEP exposure. METHODS: In vitro antioxidant capacity of the extracts was assessed and the polyphenol contents were also assessed by HPLC. ROS, cell viability, lactate dehydrogenase leakage, lipid peroxidation, GSH:GSSG ratios, conjugated diene and protein carbonyl levels were determined as indices of oxidative stress and cytotoxicity. RT-qPCR and western blot were used to assess inflammatory cytokines and antioxidant genes expression. RESULTS: DEP caused a dose and time-dependent increase in ROS production, significant (p < 0.001) increase in protein carbonyl (PC) formation, thiobarbituric acid reactive substances and conjugated dienes levels (p < 0.01) and a significant reduction in glutathione (GSH) redox status. Pre-incubation with either the herbal extracts or orientin attenuated these effects. The significant increase in IL-1α, IL-6, IL-8, VCAM-1 and ATF4 gene expression caused by DEP (10 µg/ml) were also attenuated by the presence of the FR, GR and FH extracts, and OR . Pre-treatment with the rooibos extracts or flavone orientin enhanced cell viability, reduced LDH leakage, enhanced mRNA expression of NQO1 and Nrf2, but repressed CYP1B1 mRNA induced by DEP. Western blot showed both the herbal tea extracts and orientin to enhance NQO1 and γGSC protein induction by DEP. CONCLUSION: Taken together, the herbal extracts offer protection against DEP-induced oxidative stress and inflammatory response.
Authors: Phiwayinkosi V Dludla; Christo J F Muller; Johan Louw; Sithandiwe E Mazibuko-Mbeje; Luca Tiano; Sonia Silvestri; Patrick Orlando; Fabio Marcheggiani; Ilenia Cirilli; Nireshni Chellan; Samira Ghoor; Bongani B Nkambule; M Faadiel Essop; Barbara Huisamen; Rabia Johnson Journal: Nutrients Date: 2020-04-20 Impact factor: 5.717