Revised structure for a sesquiterpene lactone from Bombax malbaricum.

A sesquiterpene lactone isolated from Salmalia malbaricum (syn Bombax malbaricum) roots was previously identified as hemigossylic acid lactone-7-methyl ether (1). 2D NMR experiments have shown this is a new compound, isohemigossylic acid lactone-2-methyl ether (2).