Abstract
Salvia officinalis
is a medicinal plant used to treat some diseases, including microbial infections and diabetes. Different studies showed the biological and pharmacological properties of this species. The aim of this study was the determination of the chemical compounds of
S. officinalis
essential oils and the investigation of their antimicrobial, antioxidant, antidiabetic, and anti-inflammatory properties. The chemical compounds of
S. officinalis
were determined by GC-MS analysis. The antioxidant activity was assessed by DPPH, ABTS, H
2
O
2
, and FRAP assays. The in vitro antidiabetic effect was evaluated by the inhibition of α-amylase, α-glucosidase, and lipase activities, and the anti-inflammatory effect was evaluated using the 5-lipoxygenase assay. Moreover, antibacterial activity was assessed against six bacterial strains using agar well diffusion assay and microdilution method. The main compounds in essential oils of
S. officinalis
at three phenological stages were naphthalenone, camphor, 1.8-cineole, and α-thujone. The full flowering stage essential oil showed the best antioxidant activity with different IC
50
values according to the used tests. This oil also exhibited important inhibitory effects at the full flowering stage against α-amylase (IC
50
= 69.23 ± 0.1 μg/mL), α-glucosidase (IC
50
= 22.24 ± 0.07 μg/mL), and lipase (IC
50
= 37.3 ± 0.03 μg/mL). The 5-lipoxygenase inhibitory effect was the best at the full flowering stage (IC
50
= 9.24 ± 0.03 μg/mL). The results of the antibacterial evaluation revealed that, at three seasonal periods,
S. officinalis
essential oil demonstrated strong antibacterial activity. Although the full flowering stage had the best antibacterial activity, there were no significant differences between the three stages. Additionally, the essential oils showed bactericidal effects on
Listeria monocytogenes
,
Staphylococcus aureus
,
Bacillus subtilis
,
Proteus mirabilis
,
Escherichia coli
, and
Salmonella typhimurium
, respectively. The findings of this work showed remarkably that
S. officinalis
synthesizes essential oils according to different developmental stages. Moreover, it has exhibited interesting biological and pharmacological properties justifying its medicinal effects and suggesting it as a very important source of natural drugs.