Grayanane diterpenoids from the flowers of Rhododendron molle with cytotoxic activity against a Spodoptera frugiperda cell line.

Two new grayanane diterpenoids, rhodomolins A (1) and B (2), together with two known diterpenoids, rhodomolleins I and rhodojaponin III, were isolated from the flowers of Rhododendron molle. The structures of 1 and 2 were elucidated on the basis of interpretation of spectroscopic data. All compounds were evaluated for cytotoxic activity against the Spodoptera frugiperda cell line Sf-9 and gave IC(50) values in the range 12-80 microg/mL.