Volatile Constituents of Three Invasive Weeds of Himalayan Region

The volatile constituents of three most common aromatic exotic weeds viz. Lantana camara L., Eupatorium adenophorum Spreng and Ageratum conyzoides L. of the Uttarakhand, India were analyzed by GC and GC-MS. The essential oil of Lantana camara L. was dominated by sesquiterpenoids (70.8%) represented by sesquiterpene hydrocarbons (68.7%) with germacrene D (27.9%), germacrene B (16.3%), b-caryophyllene (9.6%), b-selinene (6.2%), α-humulene (5.8%) as major constituents. Other constituents in significant amount were sabinene (5.6%) and 1,8-cineole (4.8%). Amorphenes viz. amorph-4-en-7-ol (9.6%), 3-acetoxyamorpha-4,7(11)-dien-8-one (7.8%) and amorph-4,7(11)-dien-8-one (5.7%) were identified as the marker constituents of Eupatorium adenophorum Spreng along with p-cymene (16.6%), bornyl acetate (15.6%) and camphene (8.9%). On the contrary, the essential oil of Ageratum conyzoides L. was characterized by the presence of high percentages of ageratochromene (precocene II, 42.5%), β-caryophyllene (20.7%), demethoxyageratochromene (precocene I, 16.7%), a-humulene (6.6%) and p-cymene (3.3%).