Variation in essential oil composition of Iris nigricans Dinsm. (Iridaceae) endemic to Jordan at different flowering stages

Fresh aerial blooming parts of Iris nigricans Dinsm. (Iridaceae) were collected at different flowering stages. The essential oils obtained from the fresh aerial parts and from the rhizomes at the post flowering stage were investigated by gas chromatography-mass spectrometry (GC/MS) analysis. The essential oil at the pre-flowering stage was characterized by a high proportion of oxygenated monoterpenes (40.93%), while the oils obtained during the full flowering and post flowering stages were dominated by aliphatic hydrocarbons and their derivatives (81.28%, 79.52%, respectively). The oil of I. nigricans rhizomes was dominated by monoterpene hydrocarbons (35.47%) of the pinane skeleton (32.05%), represented by α- and β-pinenes (24.05% and 7.99%, respectively). In addition, rhizome's aqueous and ethanolic extracts were investigated for their antimicrobial activity and were found to be inactive against Escherichia coli, Klebsiella pneumonia, Salmonella typhi, Staphylococcus aureus, Bacillus subtilis and Micrococcus luteus.