Rosemary essential oil: chemical composition, antiviral, cytotoxicity, and in silico molecular docking analysis against tobacco mosaic virus

Aromatic plants represent a significant source of bioactive compounds and have recently expanded their potential applications in agriculture. In the current study, the essential oil of Salvia rosmarinus (rosemary) was extracted, and its chemical composition was analyzed using gas chromatography-mass spectrometry (GC-MS). Under greenhouse conditions, the antiviral effectiveness of the essential oil against tobacco mosaic virus (TMV) was evaluated on Nicotiana glutinosa, marking the first comprehensive assessment of its impact on plant viruses. A computational analysis of molecular docking interactions was performed to explore the potential interactions of target compounds with the three protein components of TMV. Additionally, the influence of essential oil on the root tips of Allium cepa was assessed for its genotoxic effects. In comparison to untreated infected plants, the curative treatment demonstrated a peak viral inhibition rate of 76.3% at 300 µg/mL, while the protective and inactivation treatments reached maximum rates of 70.7% and 62.8%, respectively, at the same concentration. At elevated concentrations of essential oil (300 µg/mL), the genotoxicity assay showed a concentration-dependent decrease in the mitotic index and an increase in chromosomal abnormalities. The GC-MS analysis revealed that the primary constituents of the essential oil were α-terpineol (19.3%), isoborneol (14.1%), and camphor (13.2%). Furthermore, an in-silico assessment of the candidate phytoconstituents indicated that the antiviral properties are mainly associated with the isoaromadendrene epoxide (0.35%), cubenol (0.22%), epiglobulol (2.06%), caryophyllene (5.73%), and caryophyllene oxide (2.66%) compounds. Thus, we assert that the synergistic properties of oil components account for their significant antiviral efficacy. Overall, the results of our study suggest that rosemary essential oil demonstrates significant antiviral properties and may serve as a promising antiviral agent for combating plant viral infections. Nonetheless, additional field validation and investigations into individual components and their synergistic combinations are essential to comprehend their effectiveness and maximize their application.