Anti-inflammatory Chalcone-Isoflavone Dimers and Chalcone Dimers from Caragana jubata

Two new chalcone-isoflavone dimers, caraganins A (1) and B (2), two new chalcone dimers, caraganins C (3) and D (4), and eight known compounds (5-12) were obtained from the red heartwood of the rhizomes of Caragana jubata. The structures of caraganins A-D were established by 1D and 2D NMR spectroscopy, HRMS and ECD analysis, and comparison with previously known compounds. The anti-inflammatory activities of the new compounds were evaluated by measuring the production of NO, IL-6, and TNF-α in mouse RAW 264.7 macrophages induced by lipopolysaccharide. Among these, compounds 2 and 4 showed the most potent inhibitory activities (IC₅₀: 4.1 and 5.2 μM, respectively) on nitric oxide formation, and compounds 1 and 4 displayed the most potent inhibitory activities on the secretion of inflammatory factor TNF-α, with IC₅₀ values of 11.4 and 14.7 μM. The possible biosynthetic pathways of the chalcone-isoflavone dimers and the chalcone dimers are proposed.