Terpenoids from Rhizomes of Alpinia japonica Inhibiting Nitric Oxide Production

A new sesquiterpenoid, 1, and three new diterpenoids, 3-5, along with five known compounds, 2 and 6-9, were isolated from rhizomes of Alpinia japonica. The structures of the new compounds were determined as (1R,4R,6S,7S,9S)-4α-hydroxy-1,9-peroxybisabola-2,10-diene (1), methyl (12E)-16-oxolabda-8(17),12-dien-15-oate (3), (12R)-15-ethoxy-12-hydroxylabda-8(17),13(14)-dien-16,15-olide (4), and methyl (11E)-14,15,16-trinorlabda-8(17),11-dien-13-oate...