Abstract
The effect of Total Essential Oil (TEO) extracted from Nigella Sativa Seeds on Human Neutrophil Elastase (HNE) activity was tested in this study. Gas Chromatography coupling to Mass Spectrometry (GC-MS) reveals the detection of 22 compounds , most are monoterpens , TEO (C=10%) was a strong inhibitor to HNE , aggregate effects of TEO constituents caused 100 % Inhibition. Microassays testing the inhibitory effects of major constituents of TEO on HNE activity reveal that 5-Isopropyl-2-Methyl Phenol was a strong inhibitor to HNE with a very low IC50 (12 µM).We conclude that after in-vivo studies this compound could be used as a natural anti-elastase drug in the treatment of some pathological cases such as COPD and Emphesyma

: Inhibition of HNE activity by essential oil constituents
CompoundsConcentration(µM)HNE Inhibition(% control)IC 50(µM)
Thymoquinone111830
Thymol157104
Carvacrol114512
Carvone72514
Cymene132725
Range of concentrations from each tested compound were diluted in DMSO and 10 µL was mixed with 10 µl of HNE solution , after incubation at 37ºc for 20 m with agitation (450 rpm), 30 µl volumes of substrate solution ( N-Methoxysuccinyl-Ala-Ala-pro-Val p-Nitro-Anilide) were added , all tubes were incubated under the same conditions . Absorbance was read at 405 nm Inhibition rates for each compound were calculated in percent to control assay . IC 50 values were calculated from the dose- inhibition curves by linear regression.