Seasonal variation and bioactivity in the leaf oil of Liriodendron tulipifera growing in Huntsville, Alabama.

The seasonal variation in the chemical composition of the leaf essential oil of Liriodendron tulipifera has been analyzed by GC-MS. Two individual trees were sampled five times during the course of the growing season. Twenty components were identified in the leaf oils, which were dominated by sesquiterpene hydrocarbons, principally germacrene D and beta-elemene, in the early part of the season (42-44% and 18-23%, respectively,) but monoterpene hydrocarbons, largely (Z)-beta-ocimene, dominated the later season leaf oils (40-60%). The leaf oils exhibited in-vitro antibacterial activity against Bacillus cereus and Staphylococcus aureus as well as cytotoxic activity on MDA-MB-231 and Hs 578T human breast tumor cells.