5.

Chemical Compositions and Biological Activities of Leaf Essential Oils of Six Species of Annonaceae from Monteverde, Costa Rica

Maria C. Palazzo, Hilary L. Wright, Brittany R. Agius, Brenda S. Wright, Debra M. Moriarity, William A. Haber and William N. Setzer

Department of Chemistry, University of Alabama in Huntsville, Huntsville, AL 35899, USA

Department of Biological Sciences, University of Alabama in Huntsville, Huntsville, AL 35899, USA

Missouri Botanical Garden, St. Louis, MO 63166, USA; Apdo. 50-5655, Monteverde, Costa Rica

Abstract: The leaf essential oils of six members of the Annonaceae from Monteverde, Costa Rica (Desmopsis bibracteata, Desmopsis microcarpa, Guatteria costaricensis, Guatteria diospyroides, Guatteria oliviformis, and Unonopsis costaricensis) have been obtained by hydrodistillation and analyzed by GC-MS in order to compare and contrast the volatile chemical compositions of these species. The essential oils were screened for in-vitro cytotoxic activity against MDA-MB-231 and Hs 578T human breast tumor cells, and antibacterial activity against Bacillus cereus, Staphylococcus aureus, and Escherichia coli. The principal components of D. bibracteata were germacrene D (29.9%), (E)-caryophyllene (11.5%), and δ-cadinene (9.2%). D. microcarpa was dominated by bicyclogermacrene (45.5%) and germacrene D (28.3%). G. costaricensis was rich in α- and β-pinenes (36.3% and 48.2%, respectively). The leaf oil of G. diospyroides was composed largely of germacrene D (46.4%), (Z)-β-ocimene (17.4%), (E)-β-ocimene (12.0%), and (E)-caryophyllene (10.3%). Germacrene D dominated the leaf oil of G. oliviformis (73.3%) as well as U. costaricensis (62.9%). The leaf essential oils of D. bibracteata, G. diospyroides, G. oliviformis, and U. costaricensis, showed notable cytotoxicity on MDA-MB-231 cells ( ³ 99% kill at 100 m g/mL) but only D. bibracteata leaf oil was cytotoxic to Hs 578T. D. bibracteata, G. diospyroides, G. oliviformis, and U. costaricensis leaf oils showed marginal antibacterial activity against B. cereus (MIC = 156 m g/mL). A cluster analysis of Guatteria species, based on the abundant essential oil components, has revealed a spathulenol-rich cluster (Brazilian species) and a germacrene D cluster (Costa Rican species).

Keywords: Desmopsis bibracteata ; Desmopsis microcarpa; Guatteria costaricensis ; Guatteria diospyroides; Guatteria oliviformis; Unonopsis costaricensis; Annonaceae; essential oil composition; cytotoxicity; antibacterial, germacrene D; cluster analysis