Natural potential neuroinflammatory inhibitors from Alhagi sparsifolia Shap.

Neuroinflammation is a key contributor to neuronal damage in neurodegenerative diseases. In our previous work on natural effective neuroinflammatory inhibitors, Alhagi sparsifolia Shap. (Leguminosae), a folk medicine widely distributed in Xinjiang, attracted our attention because of its significant anti-neuroinflammatory effect. Therefore, further investigation of the bioactive material basis was carried out. As a result, 33 major components were characterized and identified by chromatographic and spectral methods, respectively. Furthermore, the anti-neuroinflammatory effects of the extract and purified constituents were evaluated in LPS-induced N9 cells in vitro. The results displayed that compounds 1, 2, 3, 5, 6, 8, 11, 15, 16, 17, 22, 23, 25, 26, 28, 30, 33 could exhibit significant inhibitory activities without obvious cytotoxicities at their effective concentrations. Especially, isorhamnetin (1) (IC50 17.87μM), quercetin (2) (10.22μM), 3',7-dihydroxyl-4'-methoxylisoflavone (5) (17.43μM), 3',7-dihydroxyl-4',6-dimethoxylisoflavone (6) (11.21μM), syringgaresinol (16) (2.68μM), bombasinol A (17) (7.61μM), aurantiamide (23) (14.91μM) and 1,3,3,4-tetramethyl cyclopentene (33) (2.63μM) showed much stronger inhibiting effect than that of the positive control minocycline (19.89μM). Therefore, the effective compositions might be responsible for the significant neuroinflammation inhibitory activities exhibited by the herb. Moreover, compounds 16 and 33 could be good leading compounds for the development of potential therapeutic agents against neurodegenerative diseases.