Constituents from Dolichos lablab L. Flowers and Their Anti-Inflammatory Effects via Inhibition of IL-1β Release

The occurrence of inflammation is closely related to the activation of the NLRP3 inflammasome. IL-1β produced during the activation of the NLRP3 inflammasome has strong pro-inflammatory activity and can also promote the release of inflammatory factors by other immune cells, exacerbating inflammatory damage to tissues. Utilizing IL-1β as the detection index to find small-molecule inhibitors targeting NLRP3 from natural products will benefit the search for drugs for inflammation-related diseases. During the exploration of anti-inflammatory active components derived from the flowers of L., an ingredient in traditional Chinese medicine with dual applications in both medicinal treatment and dietary consumption, fourteen compounds ( - ), including seven previously unreported ones, named flosdolilabnitrogenousols A-D ( - ) and flosdolilabsaponins A-C ( - ), were found. Their structures were established through extensive NMR spectra determination, HR-ESI-MS analysis, ECD calculations, and chemical reactions. Flosdolilabsaponin A ( ) stands out as an exceptionally rare tetracyclic lactone oleane-type saponin. Additionally, the inhibitory activity on IL-1β release of all compounds, without cytotoxicity, was evaluated using BMDMs stimulated with LPS/Nigericin. An Elisa assay revealed that compounds , , , and - exhibited significant inhibition of IL-1β release at a concentration of 30 μM. Structure-activity relationships were also discussed. This study indicates that flowers possess anti-inflammatory activity, which might exert its effect by suppressing the activation of the NLRP3 inflammasome.