Response surface methodology optimization of extraction and enrichment conditions of total triterpenoid saponins from Celosiae Semen and evaluation of its lipid‐lowering activity

Abstract The saponin‐enriched extract from Celosiae Semen is a promising resource owing to its lipid‐lowering activity. However, triterpenoid saponins are difficult to extract owing to their high molecular weight and strong water solubility. The aim of this paper was to explore an eco‐friendly and effective technology of extraction and enrichment of total triterpenoid saponins to obtain high lipid‐lowering fractions. Initially, Box–Behnken design experiments were employed to optimize the heat reflux extraction process on the basic of mono‐factor experiments. Afterwards, the crude extract was further purified using D‐101 resin, and the purification parameters were investigated based on adsorption/desorption experiments and biological activity assay. Under optimal conditions, the purity of the finally obtained total triterpenoid saponins was increased by 7.28‐fold. The lipid‐lowering activities of the six main triterpenoid saponins were evaluated in HepG2 cells induced by palmitic acid. The results of Oil Red O staining showed that the compounds all exhibited potential lipid‐lowering activity. The structure–activity relationship analysis suggested that the oligosaccharide chain at C‐28 played an essential role in their lipid‐lowering activity and the substituent group at C‐23 site also showed important effects. The optimal extraction and purification methods may facilitate the utilization of Celosiae Semen for the industrial production as a functional food and drug.