Labdane diterpenoids from Salvia reuterana

Three labdane diterpenoids, 14α-hydroxy-15-chlorosclareol (1), 14α-hydroxy-15-acetoxysclareol (2), and 6β-hydroxy-14α-epoxysclareol (3), together with the known diterpenoids sclareol (4), 6β-hydroxysclareol (5), and 14α-epoxysclareol (6), as well as other common plant constituents were isolated from the n-hexane extract of aerial parts of Salvia reuterana. The structures of the new compounds were established by extensive 1D and 2D NMR spectroscopic techniques. Compound 1 is the first example of a halogenated terpenoid in the genus Salvia. Compounds 1-6 were also tested for their inhibitory activity toward HeLa and MCF-7 cell lines. Preliminary structure-activity relationship studies indicated that double bond moiety in sclareol is an essential feature for activity and modification of this moiety significantly decreased the cytotoxic activity of the resulting compounds.