Anti-inflammatory Effects of Aspalathin and Nothofagin from Rooibos (Aspalathus linearis) In Vitro and In Vivo

Aspalathin (Asp) and nothofagin (Not) are two major active dihydrochalcones found in green rooibos, which have been reported for their anti-oxidant activity. Here, we investigated the anti-inflammatory effects and underlying mechanisms of Asp and Not against lipopolysaccharide (LPS)-mediated vascular inflammatory responses. The anti-inflammatory activities of Asp and Not were determined by measuring permeability, monocytes adhesion and migration, and activation of pro-inflammatory proteins in LPS-activated human umbilical vein endothelial cells (HUVECs) and mice. We found that each compound inhibited LPS-induced barrier disruption, expression of cell adhesion molecules (CAMs), and adhesion/transendothelial migration of neutrophils to human endothelial cells. Asp and Not also suppressed LPS-induced hyperpermeability and leukocyte migration in vivo. Furthermore, each compound suppressed the production of tumor necrosis factor-α (TNF-α) or interleukin (IL)-6 and the activation of nuclear factor-κB (NF-κB) or extracellular regulated kinases (ERK) 1/2 by LPS. Moreover, treatment with each compound resulted in reduced LPS-induced lethal endotoxemia. These results suggest that Asp and Not posses anti-inflammatory functions by inhibiting hyperpermeability, expression of CAMs, and adhesion and migration of leukocytes, thereby endorsing its usefulness as a therapy for vascular inflammatory diseases.