Composition and Antimicrobial Studies of the Oils ofOriganum calcaratumJuss. andO. scabrumBoiss. et Heldr. from Greece

Abstract
The chemical composition of the oils from two endemic and rare taxa of the genus Origanum L., i.e O. calcaratum Juss. = O. tournefortii Aiton and O. scabrum Boiss. et Heldr., from Greece, were investigated by GC and GC/MS. Twenty-two compounds were identified into the oil of O. calcaratum, representing 98.0% of the oil composition. The main compounds were p-cymene (18.1%), γ-terpinene (9.6%), thymol (42.8%), carvacrol (12.9%) and isocaryophyllene (4.7%). In the oil of O. scabrum, 28 compounds were identified, representing 98.0% of the oil composition. The main compound was carvacrol (66.7%), while p-cymene (7.8%), γ-terpinene (3.6%), caryophyllene oxide (2.1%) and manool (2.7%) were found in large amounts. The oils were investigated for their antimicrobial activity against Gram-positive, i.e., Staphylococcus aureus, S. epidermidis and Gram-negative, i.e., Escherichia coli, Klebsiella pneumoniae microorganisms.