Labdane Diterpenoid Glycosides from <i>Alpinia densespicata</i> and Their Nitric Oxide Inhibitory Activities in Macrophages

Abstract

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 microM against several human tumor cell lines.