Plant growth inhibitory terpenes from Eupatorium adenophorum leaves

Eupatorium adenophorum is commonly known as Crofton weed, growing widely throughout the northern hilly terrains. Bioactive potential of E. adenophorum leaves was investigated through phytochemical study and in vitro plant growth inhibitory. Essential oil was hydrodistilled from leaves and analyzed by GCMS. Leaf material was extracted using cold extraction process followed by evaporation of solvent under reduced pressure. Five cadinene sesquiterpenes and one sterol were isolated from hexane and EtOAc concentrates and their structures were established spectroscopically. Plant growth inhibitory activity of extractives and isolated terpenes were studied against different seeds of weed and crops. Essential oil was moderate seedling growth inhibitor. Among various extracts, EtOAc extract was found to be most inhibitory to Phalaris minor seeds (EC50 117 mu g mL(-1)). Among the sesquiterpenes, 5,6-dihydroxycadinan-3-ene-2,7-dione was found to be most active and inhibited both shoot and root growth of Phalaris minor seed (EC50 97 mu g mL(-1)) and Polygonum plebejum (EC50 117 mu g mL(-1)).