Chemical Composition of Cleome amblyocarpa Barr. & Murb. Essential Oils Under Different Irrigation Levels in Sandy Soils with Antioxidant Activity

The essential oil of the whole plant of Cleome amblyocarpa growing in sandy soils of the United Arab Emirates (UAE) open field pot plant experiment was extracted by hydrodistillation. The influences of three soil matric potentials were created (pF levels: 1.7, 1.9, 2.1) by applying three irrigation schedules and measured by Stevens pF Sensors. The oil yield ranged from 0.00715% (at pF level: 1.9) to 0.02669% (at pF level: 2.1). The qualitative analysis of the extracted essential oils was conducted for the first time by a combination of gas chromatograph (GC) and gas chromatograph/mass spectrometer (GC/MS). Forty six (46) volatiles have been identified, showing a significant change in the chemical profile of the extracted essential oils under different pF levels. At 1.7 pF level, 27 volatile components were identified and the oil contained isobornyl formate (43.9%), tetrahydro-linalool acetate (7.45%), neo-menthyl acetate (5.8%), 1-dodecene (4.82%), and γ-elemene (4.8%). At 1.9 pF level, 20 volatiles were identified and the components were trans-chrysanthenyl acetate (38.6%), tetrahydro-linalool acetate (6.32%), verbenone (5.86%) and γ-elemene (5.66%). While at 2.1 pF level, 17 volatiles were identified and the major components were (e)-ocimenone (39.66%), γ-elemene (8.3%), methyl eugenol (7.41%), cis-chrysanthenyl acetate (7.12%) and tetrahydro-linalool acetate (7.1%). Scanning electron microscope (SEM) study showed variations in glandular trichomes of the leaf epidermis at pF 2.1. Results of DPPH, FRAP and ABTS assays (in vitro) showed that C. amblyocarpa EO (isolated from seeds and whole plant) is a good resource of natural bioactive antioxidants.