Abstract
Antioxidant activity and chemical compositions of essential oils of Cleome rupicola Vicary , Cleome ramosissima Webb ex Parl. and Cleome amblyocarpa Barratte & Murb. growing in Saudi Arabia were investigated. GC-FID/MS analysis allowed the identification of 52, 57 and 74 compounds, comprising 98.63%, 91.19% and 99.10% of the oils, respectively. In C. rupicola oils, 2-Methyl butyl isothiocynate (42.16%) and cubenol (20.09%) were the major compounds In the case of C. ramosissima, the major compounds were cubenol (18.20%) and 3E-cembrene (6.12%), whereas the major compounds of C. amblyocarpa were 2-methoxy-4-vinyl phenol (20.06%), cis-Dihydro carvone (13.09%) and beta-cubebene (7.46%). Antioxidant activity of essential oils of the three Cleome species was examined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and ferrous ion chelating activity assay. The results indicated that the essential oils extracted from the three species have good antioxidant activity.