Labdane Diterpenoid Glycosides from Alpinia densespicata and Their Nitric Oxide Inhibitory Activities in Macrophages

Four new labdane diterpene glycosides (1−4) named alpindenosides A, B, C, and D, two new norditerpene glycosides (5, 6) named noralpindenosides A and B, and three known flavonoid glycosides (7−9) have been isolated from the stems of Alpinia densespicata. Structural elucidation of compounds 1−6 was based on spectroscopic data. Compounds 1−9 all exhibited moderate NO inhibitory activities, whereas they were noncytotoxic at 20 μM against several human tumor cell lines.