Context and purpose of the study: Infectious diseases represent a serious problem of public health in countries where resistance of bacteria to antibiotics is spreading alarmingly. Such situation leads researchers to make efforts so they can isolate or synthesize new antimicrobial molecules or molecules that inhibit the resistance mechanisms. Medicinal plants can represent a rich source of such molecules. In this context, Borago offccinaiis L, a medicinal species which is used traditionally in Algeria to heal infectious diseases of respiratory system is studied. Both of chemical composition and biological activities were explored. Main findings: GC-MS analysis of the essential oil reveals the Spathulenol as the most abundant component (38.24%). The HPLC applied on flavonoids extract shows the presence of the Caffeic acid, p-coumaric acid, Rutin, Rosmarinic acid, Quercetin and the Gallic acid. The test of the antioxidant capacity using the DPPH method reveal an inhibiting effect which is more important with the flavonoid extract with an EC 50 = 4.02± 0.06μg/ml. Otherwise, resistant strains to conventional antibiotics seem to be sensitive to the flavonoids with MICs varying from10.14μg/ml to 81.12μg/ml. Brief summary and potential implications: This study indicates that Borago offccinalss L. has an important antimicrobial effect, which justifies its potential use in infectious diseases. This species remains poorly investigated, further refined studies on its pure secondary metabolites are needed, in the perspective of identifying new antimicrobial molecules from this plan
