Composition and cytotoxic activity of the leaf essential oil of Comptonia peregrina (L.) Coulter.

Comptonia peregrina (L.) Coulter, a native plant from Canada used in traditional medicine against cancer, was extracted by hydrodistillation. Two fractions were collected, one over 0-30 min and one over 30-60 min, to assess the influence of time of hydrodistillation on the composition of essential oil. The chemical composition of these two extracts was determined by GC and GC-MS analyses. Fifty five components were identified: beta-caryophyllene (23.69% and 15.16%) and alpha-humulene (9.67% and 7.43%) were the major components in the 0-30 min and 30-60 min fractions, respectively, while beta-myrcene was detected in a higher amount in the 0-30 min fraction (12.58%) than in the 30-60 min fraction (0.15%). The cytotoxic activities of these fractions were assessed against human lung carcinoma cell line A-549 and human colon adenocarcinoma cell line DLD-1. Only the 30-60 min fraction was found to be active against both tumor cell lines, with GI(50) values of 66 +/- 12 microg/mL for A-549 and of 46 +/- 7 microg/mL for DLD-1. Two sesquiterpenes present in the oil, alpha-humulene and (E)-nerolidol, have been found to be cytotoxic against both tumor cell lines.