Effects of solvent extracts prepared from the cultivars and plant parts of Centella asiatica cultivated in Korea on macrophage activation

Abstract

SummaryPrevious studies demonstrated the interrelationship between antioxidant activity and solvent extracts prepared according to cultivars and plant parts of Centella asiatica (CA) cultivated in Korea. In this study, the macrophage‐stimulating activity of solvent extracts was assayed, and we analysed the characteristics of the active fractions of these extracts and the mechanisms underlying the macrophage‐stimulating activity of these fractions. Treatment of macrophages with cold water (CW) extracts (GO‐L‐CW) prepared from the leaves (L) of the ‘GOOD’ (GO) cultivar significantly increased the secretion of immunostimulatory factors. Specifically, the high molecular weight (HMW) fraction (GO‐L‐CW‐HMW) isolated from GO‐L‐CW potently activated the secretion of immunostimulatory factors and increased the mRNA levels of genes encoding these factors or involved in the production of these factors. In addition, GO‐L‐CW‐HMW triggered the phosphorylation of ERK and p38 of MAPK along with p65 and IκBα of the NF‐κB family in the intracellular signalling pathway. The GO‐L‐CW‐HMW was identified as a complex polysaccharide with a molecular weight of 93–129 kDa. In conclusion, polysaccharides present in GO‐L‐CW suggest the possibility of application as a new immunostimulating material.