Abstract
This study was performed to determine the chemical composition, antioxidant and cytotoxic effects of essential oils extracted from the aerial parts of fresh (F-PSEO) and air-dried (D-PSEO) Pallenis spinosa. The composition of the oils was analyzed by gas chromatography (GC) and GC/mass spectrometry, the antioxidant activity by free radical scavenging and metal chelating assays, and their cytotoxicity by a flow cytometry analysis. The primary components in both oils were sesquiterpene hydrocarbons and oxygentated sesquiterpenes. F-PSEO contained 36 different compounds; -cadinol (16.48%), germacra-1(10),5-diene-3,4-diol (14.45%), -cadinene (12.03%), and -muurolol (9.89%) were the principal components. D-PSEO contained 53 molecules; -cadinol (19.26%), -cadinene (13.93%), -muurolol (12.88%), and germacra-1(10),5-diene-3,4-diol (8.41%) constituted the highest percentages. Although both oils exhibited a weak radical scavenging and chelating activity, compared to -tocopherol and ascorbic acid, D-PSEO showed a 2-fold greater antioxidant activity than F-PSEO. Furthermore, low doses of F-PSEO were able to inhibit the growth of leukemic (HL-60, K562, and Jurkat) and solid tumor cells (MCF-7, HepG2, HT-1080, and Caco-2) with an IC50 range of 0.25-0.66g/ml and 0.50-2.35g/ml, respectively. F-PSEO showed a ca. 2-3-fold stronger cytotoxicity against the tested cells than D-PSEO. The potent growth inhibitory effect of the plant essential oil encourages further studies to characterize the molecular mechanisms of its cytotoxicity.