Molecular Docking Analysis, Chemical Composition, and Evaluation of Antibacterial and Insecticidal Activity of Salvia officinalis Essential Oil

Salvia officinalis has been used for so many years as a traditional remedy and still used in pharmaceutical, cosmetics, and food industries, which made it an interesting subject for researcher of natural alternatives. Enhancing the value of Moroccan S. officinalis essential oil, which is grown at Sidi Taibi in the Rabat-Salé-Kénitra Region, was the goal of this project, through analyzing its chemical composition and assessing its insecticidal and antibacterial activities. This latter was estimated by comparison with the antibiotic ceftriaxone. The main components identified by gas chromatography–mass spectrometry (GC-MS) were camphor, eucalyptol (1,8-cineole), α-thujone, β-thujone, ledol, and isoterpinolene with values of 19.72%, 15.64%, 15.05%, 9.74%, 7.27%, and 3.24%, respectively. A study of antibacterial activity revealed that while ceftriaxone seemed useless against the bacteria tested (all the bacteria proved resistant to the antibiotic), the essential oil of S. officinalis showed an inhibitory effect on the four bacteria tested, with MIC values ranging from 1/100 to 1/500 and a CMB value of 1/100. Using several dosages of pure essential oils (0, 1, 5, 10, and 20 μL), fumigant toxicity was ascertained. The mortality rate in individuals of Sitophilus oryzae and Rhyzopertha dominica reached a value of 100% when applying a dose of 10.00 μL/L of air to individuals of S. oryzae during 36 h of exposure and 24 h to individuals of R. dominica. The LC₅₀ was determined at 2.51 and 6.02 μL/L for R. dominica and S. oryzae individuals successively, and the LC95 was determined at 5.45 and 12.61 μL/L of air over 12 h for R. dominica and S. oryzae individuals successively. Molecular docking analysis revealed ledol as a potent inhibitor of three key enzymes involved in the insecticidal effect of S. officinalis essential oil, mainly as an inhibitor of acetylcholinesterase (AChE), γ-aminobutyric acid receptor (GABA), and ryanodine receptor.