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.