Phytochemical components and antioxidant and antimicrobial activities of essential oils from native Tunisian Thymus capitatus and Rosmarinus officinalis

Abstract

Introduction. Essential oils and their components are currently of great interest as a potential source of highly bioactive natural molecules. They are being studied for their possible use as safe alternative for food protection against oxidation and microbial spoilage. Objective. This study aimed on the phytochemical prospection of Thymus capitatus and Rosmainus officinalis essential oils and their oral toxicity evaluation. Material and methods. Chemical analysis of tested essential oils was carried out using gas chromatography combined to mass spectroscopic (GC-MS). Their safety limit was evaluated by acute toxicity. The antioxidant activity was estimated using in vitro methods. The antimicrobial activity was evaluated against twelve pathogenic germs. Results. Results showed that carvacrol and 1,8-cineol were the major compounds of Thymus capitatus and Rosmarinus officinalis essential oils. Acute toxicity results exhibited that both tested essential oils were inoffensive at 2000 mg/kg. Additionally, Thymus capitatus essential oil presented higher antioxidant activity than Rosmarinus officinalis: 2,2-diphényl-1-picrylhydrazyl (DPPH) assay results showed lower IC50 for Thymus capitatus essential oil than Rosmarinus officinalis. Concerning the antimicrobial results, Thymus capitatus essential oil presented greater efficacy than R. officinalis. Indeed, the minimal growth inhibition diameter generated by thyme essential oil exceeded 38 mm (except for Salmonella typhirium) and reached 60 mm (against C. tropicalis and C. albicans). However, the maximal growth inhibition diameter generated by R. officinalis essential oil was limited to 36 mm (against Shigella sonnei). Conclusion. Overall, Thymus capitatus and Rosmarinus officinalis essential oils have strong potential applicability for pharmaceutical industries.

Keywords

• acute toxicity
• antioxidant activity
• antimicrobial activity
• essential oils
• gc-ms