Compositional Variation and Bioactivity of the Leaf Essential Oil of Montanoa guatemalensis from Monteverde, Costa Rica: A Preliminary Investigation

BACKGROUND Montanoa guatemalensis is a small to medium-sized tree in the Asteraceae that grows in Central America from Mexico south through Costa Rica. There have been no previous investigations on the essential oil of this tree. METHODS The leaf essential oils of M. guatemalensis were obtained from different individual trees growing in Monteverde, Costa Rica, in two different years, and were analyzed by gas chromatography-mass spectrometry. RESULTS The leaf oils from 2008 were rich in sesquiterpenoids, dominated by α-selinene, β-selinene, and cyclocolorenone, with lesser amounts of the monoterpenes α-pinene and limonene. In contrast, the samples from 2009 showed no α- or β-selinene, but large concentrations of trans-muurola-4(14),5-diene, β-cadinene, and cyclocolorenone, along with greater concentrations of α-pinene and limonene. The leaf oils were screened for cytotoxic and antimicrobial activities and did show selective cytotoxic activity on MDA-MB-231 breast tumor cells. CONCLUSION M. guatemalensis leaf oil, rich in cyclocolorenone, α-selinene, and β-selinene, showed selective in vitro cytotoxic activity to MDA-MB-231 cells. The plant may be a good source of cyclocolorenone.