The effects of Rooibos (Aspalathus linearis) and honeybush (Cyclopia species) on air pollutant chemicals-induced cytoxicity in human skin fibroblasts and keratinocytes

Abstract

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 (Aspalathus 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 μg/ml) of DEP for 4 h or pre-treated with 40 and 60 μg/ml of fermented (FR) or green (GR) Rooibos or fermented Honeybush (FH) for 6 h prior to 4 h exposure to 10 μg/ml DEP. Exposure to DEP caused a significant decrease in cell viability, and increase in LDH leakage, ROS production, oxidative stress biomarkers and proinflammatory 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