Rosemary, Rosmarinus officinalis or Salvia rosmarinus is a shrub of the Lamiaceae family. It is a melliferous plant whose flowers are blue and purple, rarely white. It is present in the wild in the Mediterranean region, especially in the limestone soil of the scrubland and in the maquis. Rosemary deliciously flavors dishes.
It is recognized for many therapeutic virtues and more particularly to its variety (chemotype) with cineole, richer in 1,8-cineole, a monoterpene also called eucalyptol. It is traditionally used for its tonic, mucolytic and expectorant effect. It helps to clear the bronchi, unclog the nose and facilitate breathing. It is also used for digestive disorders, hepato-biliary and muscle contractures.
In an experimental method used to measure stress in rodents suspended by the tail (TST: tail suspension test), it was observed that the inhalation of Rosemary reduces the production of corticosterone in subjects subjected to this test. The comparison with lavender essential oil showed that Rosemary was more effective. In this same test, it was found that dopamine levels in animals subjected to Rosemary vapors were higher than in the control group. Rodent immobilization time was also significantly reduced (BORGES & al., 2019 ; VILLAREAL & al., 2017 ; SEOL & al., 2010).
Rosemary essential oil has an antibacterial effect against Salmonella typhi, Salmonella paratyphi, Salmonella typhimurium, Shigella, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. In a 2016 study, the zone of inhibition of Rosemary essential oil was 6–32mm while that of gentamicin against the same bacteria was 18–21mm (WANI & al., 2021 ; BORGES & al., 2019 ; MEKONNEN & al., 2016).
A study conducted in 2017 proved its effectiveness against three pathogens involved in oral diseases: Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa. Indeed, it reduces between 67 and 99% the production of biofilms depending on the pathogen concerned after only 5 minutes of treatment. In this same study, the ability of Rosemary essential oil to reduce or even prevent the production of biofilms was also proven for E. faecalis and S. mutans. Some of its compounds reduce the adhesion capacity of microbes and weaken their plasma membrane (WANI & al., 2021 ; DE OLIVEIRA & al., 2017 ; DE OLIVEIRA & al., 2019).
A randomized double-blind study with a control group, carried out in 6 clinics in Israel, tested the effectiveness of an oral spray containing 20% essential oil of Rosemary on the improvement of symptoms related to damage to the upper respiratory tract. The result of this study showed an improvement after only 20 minutes of cough, sore throat and hoarseness (BEN ARYE & al., 2011).
Eucalyptol reduces the symptoms associated with acute non-purulent sinusitis. Indeed, in a human study, 92% of patients treated with systemic cineole showed an improvement in their symptoms (KEHRL & al., 2004).
1,8-cineole exerts a significant inhibitory effect in vitro on the pro-inflammatory cytokines TNF-α and IL-1β. The effect is less marked but existing on IL-4, IL-5, IL-8 and NF-kB (DE OLIVEIRA & al., 2017 ; JUERGENS & al., 2004 ; DO NASCIMENTO & al., 2020)..
