Anti-neuroinflammatory Labdane Diterpenoids from the Rhizomes of Alpinia zerumbet.

Alpinia zerumbet, commonly known as shell ginger, is a plant of significant ornamental and medicinal value. In the present study, nine labdane-type diterpenoids, including four novel (1-4) and five known (5-9), were isolated and identified from the rhizomes of A. zerumbet. Anti-neuroinflammatory activities of the isolated labdane-type diterpenoids were evaluated in lipopolysaccharide (LPS) stimulated microglia BV2 cells. Compounds 3, 5, 6, and 8 could significantly inhibit the production of NO in LPS-stimulated BV2 cells. Among them, the IC50 values of compounds 5 and 8 were 26.14 ± 1.62 μM and 17.29 ± 6.28 μM, which were lower than that of the positive control, minocycline (IC50 = 30.26 ± 1.99 μM).