Natural neuro-inflammatory inhibitors from Caragana turfanensis

Because of the critical role of over-activated microglia in the progress of neurodegenerative diseases, it has been selected as a potential therapeutic target for drug discovery. In order to find natural neuroinflammatory inhibitors, we carried out a bioactivity-oriented phytochemical research of Caragana turfanensis Kom. (Krassn.), which is a folk medicine widely distributed in Xinjiang. As a result, a new coumarin lactone caraganolide A (1) and 35 known components were characterized from the effective extract of C. turfanensis. Furthermore, their anti-neuroinflammatory effects were evaluated in LPS-induced BV2 microglial cells using Griess assay to determine the release of nitric oxide (NO). Compounds 1, 2, 4-6, 9, 13-15, 20, 29 and 30 exhibited significant inhibitory activities and no obvious cytotoxicities were observed at their effective concentrations. It is noteworthy, the new compound caraganolide A (1) (IC₅₀ 1.01±1.57µM) and 3',7,8-trihydroxy-4'-methoxyisoflavone (5) (IC₅₀6.87±2.23µM) exhibited more excellent action than that of positive control minocycline (IC₅₀ 9.07±0.86μM).