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)
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.