Chemical constituents and antimicrobial activities of the essential oil of Acroptilon repens (L.) DC

The volatile oil from the aerial parts of Acroptilon repens (L.) DC. (Russian knapweed) growing wild in Iran was investigated by GC and GC–MS. Twenty‐two components, representing 84.0% of the oil, were identified. The main constituents of the oil were caryophyllene oxide (36.6%), α‐copaene (15.6%), β‐caryophylene (10.0%) and β‐copaene‐4‐α‐ol (5.0%). In addition, the oil was assayed against six Gram‐positive and Gram‐negative bacteria by measuring the growth inhibitory zone. The oil of A. repens inhibited the growth of Gram‐positive bacteria. Staphylococcus saprophyticus and Staphylococcus epidermidis showed strong inhibition zones, while Staphylococcus aureus showed a lower inhibition. The Gram‐negative bacteria were insensitive to the oil. Copyright © 2005 John Wiley & Sons, Ltd.