Phytochemicals from a Desert Crop, Sand Rice (Agriophyllum squarrosum), and Their Inflammatory Activity

Agriophyllum squarrosum (sand rice), a resilient desert plant with ecological and nutritional significance, has applications in food, forage, and traditional medicine. Despite its traditional use in China for treating inflammatory symptoms such as ophthalmia, urethritis, and oral ulcers, limited phytochemical studies restrict its pharmacological exploration. In this study, ten undescribed isoflavanone derivatives, including dihydroisoflavanones (1-6) and coumaronochromones (7-10), along with thirty-six known compounds (11-46), were isolated from A. squarrosum. The new structures were determined by NMR, HRESIMS, and DFT calculations of their NMR and ECD data, which also led to the structural revision of suaeglaucin C. Anti-inflammatory assays revealed compounds 5 and 21 as potent inhibitors, outperforming L-NMMA, and the structure-activity relationship of the optically active dihydroisoflavones was briefly discussed. All compounds were isolated from this plant for the first time, except for compounds 11, 19, and 20.