Modification of parthenin

Parthenin, the principal chemical constituent of Parthenium hysterophorus weed has been transformed chemically and photochemically with a view to study the structure-activity relationship for allelopathic effects. Chemical transformation gives three products replacing the exocyclic methylene double bond of the lactone ring by a pyrazoline nucleus, a cyclopropane ring and a propenyl group. Photochemical reaction leads to the formation of a hemiacetal and a lactone in place of the cyclopentenone moiety alongwith dehydrated parthenin. Cyclopropyl analogue has been found to be most eifective against Phaseolus aureus when compared to parthenin