The hydrodistilled essential oils of fresh aerial parts of I. viscosa (L.) Ait., collected at Ain El-Bey (Southern Constantine), was characterized by nerolidol (25.3%), isocostic acid (10.1%), costic acid (8.0%), neo-intermedeol (6.4%) and caryophyllene oxide (5.5%), as major components. The essential oil of hydrodistilled fresh aerial parts of I. viscosa (L.) Ait., collected at Hamma-Bouziane (Northern Constantine), was mainly represented by isocostic acid (25.1%), costic acid (15.2%), nerolidol (9.6%), linoleic acid (9.1%), neo-intermedeol (7.5%) and fokienol (7.2%). The present compositions are quite different from those reported for species growing over the world. The essential oil of the plant collected at Ain El-Bey inhibited considerably the growth of K. pneumoniae (24mm), P. aeruginosa ATCC (21mm), P. aeruginosa HS (21mm), E. coli ATCC (20mm) and E. coli HS (20mm) while the essential oil of the species growing at Hamma Bouziane exhibited a good antibacterial activity against P. aeruginosa ATCC (21mm), P. aeruginosa HS (21mm) and K. pneumoniae (20mm).
