In Vitro Structure–Activity Relationships Between Dammarane-Type Saponins Isolated From Panax notoginseng and Their Anti-inflammatory Properties

Objectives: Total saponin extracts from the roots of Panax notoginseng have been proven to have anti-inflammatory properties. Dammarane-type saponins isolated from the roots of P notoginseng have been shown to be active inhibitors of nitric oxide (NO) and tumor necrosis factor-α (TNF-α). To clarify the structural requirements for inhibition, some structure–activity relationships (SARs) were determined. Methods: RAW264.7 macrophages were maintained in vitro under standard cell culture conditions. The release of NO and TNF-α from these cells was induced by lipopolysaccharides (LPS) and was measured. The primary SAR inhibitory activity of LPS-induced NO and TNF-α and production in RAW264.7 macrophage cells were evaluated by cytotoxicity assays. Results: SAR studies of dammarane-type saponins revealed that the glycosides substituent at C-3, C-6, and C-20 were important features for the NO and TNF-α production in RAW264.7 cells induced LPS. Moreover, the 5(6)-double bond and the OH group at C-7 improved the TNF-α inhibitory activity. In the case of ginsenoside Rh2, the C-20 configuration was needed for potent TNF-α inhibition. Conclusions: These results provide an approach for understanding the structural requirements of dammarane-type saponins isolated from P notoginseng for optimum anti-inflammatory properties of these compounds.