Phytotoxic effects of essential oils of Nepeta curviflora Boiss and Nepeta nuda L.subsp. albiflora growing wild in Lebanon

The chemical composition of the essential oils of two Nepeta species collected in Lebanon was studied by means of GC and GC-MS analysis. The essential oil from N. curviflora Boiss. contained high amounts of β-caryophyllene (41.6%), caryophyllene oxide (9.5%), (E)-β-farnesene (6.2%) and (Z)-β-farnesene (4.8%); in the oil from N. nuda L. subsp. albiflora (Boiss.) Gams. collected in Laklouk the main compounds were β-bisabolene (11.8%), pulegone (10.8%), (E,Z)-nepetalactone (8.0%), (E)-β-farnesene (7.1%) and caryophyllene oxide (6.9%), while N. nuda L. subsp. albiflora collected in Tannourine Cedar Forest contained high percentages of hexadecanoic acid (10.1%), β-bisabolene (7.8%), caryophyllene oxide (7.3%), pulegone (7.2%) and (E,Z)-nepetalactone (4.4%). The effects of the essential oils on germination and initial radical elongation of Raphanus sativus L. (radish) and Lepidium sativum L. (garden cress) were studied, resulting in a significant inhibitory activity against radical elongation of the species tested.