Study on the Optimization of an Extraction Process of Two Triterpenoid Saponins in the Root of Rosa laevigata Michx. and Their Protective Effect on Acute Lung Injury

<b>Objectives:</b> Kajiichigoside F1 and rosamultin are natural triterpenoid saponins found in the root of <i>Rosa laevigata</i> Michx. These compounds are isomers, making their separation challenging. Nonetheless, they have been reported to exhibit significant anti-inflammatory activity, although their mechanism of action remains unclear. This study aimed to optimize the extraction process of echinacoside and rosamultin from <i>R. laevigata</i> and to elucidate the anti-inflammatory mechanisms of these saponins in an LPS-induced acute lung injury (ALI) model. <b>Methods:</b> The extraction process was optimized using a single-factor experiment and the Box-Behnken response surface methodology, with the content of kajiichigoside F1, rosamultin, and their total content serving as evaluation indices. The acute lung injury model was induced by LPS, and lung tissue damage was assessed through hematoxylin and eosin (HE) staining. The secretion of relevant inflammatory factors was quantified using enzyme-linked immunosorbent assay (ELISA), and the expression levels of associated proteins were analyzed via Western blotting. <b>Results:</b> The optimal extraction conditions were determined to be an ethanol volume fraction of 80.0%, a solid-liquid ratio of 1:25, an extraction duration of 80 min, and three extraction cycles. Kajiichigoside F1 and rosamultin were found to mitigate alveolar inflammation in mice with acute lung injury (ALI) by effectively reducing the expression of the pro-inflammatory cytokines TNF-α and IL-6. Additionally, these compounds down-regulated the expression of phosphorylated NF-κB p65 and NF-κB IκBα proteins, thereby alleviating inflammatory symptoms. <b>Conclusions:</b> Kajiichigoside F1 and rosamultin attenuate the inflammatory response in acute lung injury induced by lipopolysaccharide (LPS) stimulation through modulation of the NF-κB signaling pathway. This study preliminarily elucidates their anti-inflammatory mechanism, suggesting that both compounds possess therapeutic potential for ALI. These findings provide significant guidance for the future development of active components derived from the root of <i>R. laevigata</i> and establish a foundation for enhancing the quality standards of its medicinal materials.