Phytochemical Analysis and Antimicrobial Activity of Rosmarinus officinalis L. Growing in Saudi Arabia: Experimental and Computational Approaches

Rosmarinus officinalis L. is widely distributed in Saudi Arabia. However, only a few studies have been reported regarding this species. In this study, we investigated the phytochemical analysis of R. officinalis essential oil using GC-MS analysis in order to identify its major components; the in vitro antimicrobial activity of the essential oil was also evaluated using disc diffusion assay against gram-positive (S. aureus) and gram-negative bacteria (E. coli), the antimicrobial activity was also assessed with molecular docking against several microbial proteins; TyRS, DNA gyrase and DHFR. The GC-MS analysis has indicated the presence of 18 constituents, representing 99.93 % of the total oil content. The major compounds detected were Bornyl acetate (26.59%), Eucalyptol (17.38%), Camphor (10.42%), Borneol (9.78%), Beta-Caryophyllene (7.80%) and α-pinene (3.85%). The antimicrobial study showed that R. officinalis has strong antimicrobial activity against S. aureus with an inhibition zone of 30 mm and E. coli with an inhibition zone of 25 mm. The affinities of molecular docking (TyrRS: between −4.8 and −4.9 Kcal/mol against −8.2 Kcal/mol obtained with Clorobiocin; DNA gyrase: between −4.5 and −4.9 Kcal/mol against −9.1 Kcal/mol obtained with Clorobiocin). However, strong affinities were obtained with the molecules when tested against DHFR (DHFR: between −5.8 and −6.0 Kcal/mol against −6.3 Kcal/mol obtained with SCHEMBL2181345). As a consequence, the pharmaceutical industry may use the essential oils from this plant to develop cutting-edge synthetic drugs to treat this illness infection.