Chemical composition and inhibitory effects of essential oils of two Lamiaceae of GHARDAIA province (southeast of Algeria): Ocimum basilicum L and Rosmarinus officinalis L.

The aim of this study was to investigate the biological activities and chemical composition of two essential oils (EOs) from Rosmarinus officinalis (L.) and Ocimum basilicum (L.) sourced from the Ghardaïa region. The organoleptic properties, yield, and physical characteristics of the selected EOs were determined. Their chemical compositions were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Antioxidant activity was assessed by evaluating the DPPH• free radical scavenging ability and comparing it with the standard ascorbic acid. The antimicrobial properties of the EOs were tested against six bacterial strains. The physicochemical parameters of the EOs indicated their high quality. GC-MS analysis revealed that Ocimum basilicum (L.) essential oil was predominantly composed of Estragole (27.16, while Rosmarinus officinalis (L.) essential oil was primarily composed of Borneol (16.85%). The antioxidant tests demonstrated significant activity, particularly for Ocimum basilicum (L.) essential oil, which showed a lower IC50 value of 1.4154 mg/mL compared to ascorbic acid (IC50 = 9.7339 µg/mL). Furthermore, the antibacterial efficacy of Ocimum basilicum (L.) essential oil exhibited promising inhibition against Listeria monocytogenes, Bacillus spizizenii, Bacillus subtilis, and Staphylococcus aureus, with inhibition zones ranging from 21 to 52 mm. These findings suggest that the EOs from Rosmarinus officinalis (L.) and Ocimum basilicum (L.) hold considerable potential for application in pharmaceutical, food, and cosmetic industries.