Variability in chemical composition and antibacterial activity of Salvia majdae essential oil under various extraction techniques

Salvia majdae (Lamiaceae) is an aromatic herb of pharmaceutical interest in Iran due to its several biological properties. In the present study, we studied the chemical composition and antibacterial activity of S. majdae essential oil (EO) by comparing several extraction methods, including hydrodistillation (HD), steam distillation (SD), ultrasound-assistedSalvia majdae (Lamiaceae) is an aromatic herb of pharmaceutical interest in Iran due to its several biological properties. In the present study, we studied the chemical composition and antibacterial activity of S. majdae essential oil (EO) by comparing several extraction methods, including hydrodistillation (HD), steam distillation (SD), ultrasound-assisted hydrodistillation (UAHD), microwave-assisted hydrodistillation (MAHD) and ohmic-assisted hydrodistillation (OAHD). The major EOs compounds obtained with all methods included linalool (39.4–45.7%) and camphor (30.9–34.3%). The highest EO yield was obtained using HD and MAHD, with 9 and 5% (w/w), respectively. The shortest extraction time (20 Min) was obtained using MAHD. The antibacterial activity of S. majdae EOs was evaluated by the minimum inhibitory concentration (MIC) method on a panel of Gram-positive (Bacillus subtilis, Staphylococcus aureus and Curtobacterium flaccumfaciens) and Gram-negative (Agrobacterium tumefaciens, Xanthomonas citri and Escherichia coli) bacteria. Notably, the EO obtained by HD demonstrated the highest antibacterial activity. hydrodistillation (UAHD), microwave-assisted hydrodistillation (MAHD) and ohmic-assisted hydrodistillation (OAHD). The chemical compositions of the obtained EOs were studied by gas chromatography-mass spectrometry (GC-MS). The major EOs compounds obtained with all methods included linalool (39.4–45.7%) and camphor (30.9–34.3%). The highest EO yield was obtained using HD and MAHD, with 9 and 5% (w/w), respectively. The shortest extraction time (20 Min) was obtained using MAHD. The antibacterial activity of S. majdae EOs was evaluated by the minimum inhibitory concentration (MIC) method on a panel of Gram-positive (Bacillus subtilis, Staphylococcus aureus and Curtobacterium flaccumfaciens) and Gram-negative (Agrobacterium tumefaciens, Xanthomonas citri and Escherichia coli) bacteria. Notably, the EO obtained by HD demonstrated the highest antibacterial activity which is possibly due to the presence of a number of antibacterial compounds like limonene with the highest abundance which might be responsible for this effect. In conclusion, HD allowed to obtain the highest yield and antibacterial activity or EO, whereas MAHD revealed to be the rapidest technique.