Comparison of the Effects of Chrysanthemum Extract from Cultivars Aboukyu and Enmeiraku on Microglial TNF-α Production

Abstract

Chrysanthemum flower extract has anti-inflammatory and neuroprotective effects on microglia, which play a central role in immune regulation in the brain. However, the exact immune regulatory activity of this extract on microglia requires clarification. The aim of this study was to investigate the different modes of regulating microglial TNF-α production by extracts of two cultivars of edible Chrysanthemum, Aboukyu and Enmeiraku, in relation to differences in the composition ratio of triterpenoids. GCMS analysis showed that the majority of compounds in hexane-soluble extracts were common between cultivars; however, the composition ratios of the triterpenoids faradiol and heliantriol C fatty acid esters in Aboukyu appeared to be lower than in Enmeiraku. Inhibition and promotion of microglial TNF-α production by hexane-soluble extracts of two Chrysanthemum cultivars were investigated at concentrations below 100µg/mL, which showed no apparent cytotoxicity. The Enmeiraku extract suppressed TNF-α production stimulated by LPS in a concentration-dependent manner, but did not alter ATP-stimulated TNF-α production. Conversely, the Aboukyu extract did not suppress LPS-stimulated TNF-α production, but increased ATP-stimulated TNF-α production. Because the Enmeiraku extract potently suppressed LPS-stimulated activation of IκB phosphorylation, it may attenuate TNF-α production mediated through NF-κB signaling blockage. This study suggests that the different effects Aboukyu and Enmeiraku extracts have on microglial TNF-α production are attributable to differences in the composition ratio of triterpenoids.