Akeem Olalekan Lawal et al. /Afr.J.Bio.Sc. 4(1) (2022) 22-36 Page 22 of 36 Volume 4, Issue 1, January 2022 Received : 13 July 2021 Accepted : 15 December 2021 Published : 05 January 2022 doi: 10.33472/AFJBS.4.1.2022.22-36 Article Info © 2022 Akeem Olalekan Lawal. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. A bstract Diesel Exhaust Particles (DEP) have been reported to be mainly responsible for most of the toxic effects of air pollution probably via a mechanism that involves induction of oxidative stress and proinflammatory response. Rooibos (A spalathus linearis) and Honeybush (Cyclopia species) are widely used due to their health promoting effects. This study examined the effect of Rooibos tea and Honeybush on the prooxidative and proinflammatory effects of standard reference material (SRM) 2975 DEP in human skin fibroblasts and immortalized keratinocyte cell lines. The cells were either exposed to different concentrations (5-50 g/ml) of DEP for 4 h or pre-treated with 40 and 60 g/ml of fermented (FR) or green (GR) Rooibos or fermented Honeybush (FH) for 6 h prior to 4 h exposure to 10 g/ml DEP. Exposure to DEP caused a significant decrease in cell viability, and increase in LDH leakage, ROS production, oxidative stress biomarkers and pro- inflammatory cytokines in both cell lines compared to control. However, the presence of the extracts significantly (p < 0.001) attenuate these effects. This study highlights the potential of FR, GR and FH in protecting against DEP-induced oxidative stress and proinflammatory effect in fibroblasts and keratinocytes probably. Keywords: Fibroblasts, Keratinocytes, Diesel Exhaust Particles (DEP), Rooibos extracts, Honey bush 1. Introduction Several epidemiological studies have shown an association between environmental pollution and various health hazards (Kelly and Fussell, 2015). Diesel exhaust particles (DEP) are important and major component of air particulate matter in the environment, which contribute significantly to the adverse human health effects of air pollution (Lawal et al., 2015; and Lawal et al., 2016). As an environmental pollutant, DEP is capable of interacting directly with the epidermal skin layer, which is the largest organ in the body, that forms * Corresponding author: Akeem Olalekan Lawal. Department of Biochemistry, Federal University of Technology Akure. P.M.B. 704 Akure, Nigeria. E-mail: lawalao@futa.edu.ng 2663-2187/© 2022. Akeem Olalekan Lawal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. African Journal of Biological Sciences ISSN: 2663-2187 Journal homepage: http://www.afjbs.com The effects of Rooibos ( Aspalathus linearis ) and honeybush ( Cyclopia species ) on air pollutant chemicals-induced cytoxicity in human skin fibroblasts and keratinocytes Akeem Olalekan Lawal 1* , Davids M. Lester 2 and Jeanine L. Marnewick 3 1 Oxidative Stress Research Centre, Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, Bellville Campus, Bellville 7535, South Africa. E-mail: lawalao@futa.edu.ng 2 Redox Laboratory, Department of Human Biology, University of Cape Town, Observatory, 7925, South Africa. E-mail: lesterdavids@gmail.com 3 Department of Biomedical Sciences, Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, Bellville Campus, Bellville 7535, South Africa. E-mail: marnewickj@cput.ac.za Research Paper Open Access A keem Olalekan Lawal et al. /Afr.J.Bio.Sc. 4(1) (2022) 22-36 https://doi.org/10.33472/AFJBS.4.1.2022.22-36