Phytochemical Analysis, Antimicrobial and Antioxidant Properties of Thymus zygis L. and Thymus willdenowii Boiss. Essential Oils

Abstract

Essential oils (EOs) are chemical products produced by odoriferous glands from a variety of plants. These essential oils have many health benefits: antiseptic, anti-inflammatory and antimicrobial activities. So due to these medicinal properties, the present study was designed to analyze essential oils of Thymus zygis L. and Thymus willdenowii Boiss. for their chemical composition and biological activities. These two thyme species were collected from the region of Ifrane, Middle Atlas of Morocco. The EO was obtained by hydrodistillation, and the yields were 5.25% for T. zygis and 3.00% for T. willdenowii. The chemical composition of the EOs was analyzed by gas chromatography coupled with mass spectrometry (GC-MS), and the results showed that T. zygis EO is dominated by carvacrol (52.5%), o-cymene (23.14%), and thymol (9.68%), while the EO of T. willdenowii contains germacrene D (16.51%), carvacrol (16.19%), and geranyl acetate (8.35%) as major compounds. The antioxidant activity assessed by Diphenylpicrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays revealed that both EOs have excellent antioxidant activities; by DPPH it resulted in IC50 = 6.13 ± 0.11 for T. zygis and 6.78 ± 0.3 µg/mL for T. willdenowii, while the one by FRAP yielded EC50 = 2.46 ± 0.01 (T. zygis) and 5.17 ± 0.2 (T. willdenowii) µg/mL. The antimicrobial activity of the two essential oils was evaluated against six bacterial strains and five fungal strains by the disk diffusion method to determine the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC). The EOs revealed variable antimicrobial activities against the different tested microbial strains and showed strong antimicrobial activities, even against strains known as multi-resistant to antibiotics (Acinetobacter baumannii) at low concentrations (2 µL/mL). T. zygis EO showed the most powerful activity against all the studied bacteria, while that of T. willdenowii recorded moderate activity when tested against Shigella dysenteriae and Salmonella Typhi. With inhibition diameters that vary between 75 mm and 84 mm for concentrations of 2 µL/mL up to 12 µL/mL, S. aureus was shown to be the most sensitive to T. zygis EO. For the antifungal activity test, T. zygis EO showed the best inhibition diameters compared to T. willdenowii EO. These results showed that T. zygis EO has more powerful antioxidant and antimicrobial activities than T. willdenowii EO, therefore, we deduce that thyme EOs are excellent antioxidants, they have strong antimicrobial properties, and may in the future represent new sources of natural antiseptics that can be used in pharmaceutical and food industry.

Chemical Composition, Antioxidant and Antibacterial Activities of Thymus broussonetii Boiss and Thymus capitatus (L.) Hoffmann and Link Essential Oils

“…Among the tested EOs, the most active is T. broussonetii essential oil with an IC 50 of around 3.48 ± 0.05 μL/mL. The high activity of T. broussonetii essential oil has already been indicated in several works including El Ouariachi et al, Alaoui Jamali et al and El Bouzidi et al, [ 14 , 31 , 41 , 47 ]. T. capitatus EO also demonstrated a high antioxidant power with an IC 50 of 4.88 ± 0.04 μL/mL.…”

A descriptive review on exploiting the therapeutic significance of essential oils as a potential nutraceutical and food preservative

“…It serves as a dependable representation of the EO components and acts as an identifying characteristic of the EOs. The chemical makeup of these oils can reflect the special properties of the oils, and GC–MS is a reliable method for determining the purity of EOs in most situations (Radi et al., 2021). The criteria of selection of EO depends on the features of the substance from which the oil will be extracted since they are present in varied parts of the plant, like fruits, leaves, roots, stems, and seeds.…”

A Status Review on Health-Promoting Properties and Global Regulation of Essential Oils

“…Moreover, these bioactive compounds have powerful anti-septic, anti-inflammatory, antibacterial, anti-oxidative, and immune-boosting properties [ 9 ]. A recent study revealed that EOs from thyme species have strong anti-oxidant and anti-microbial activities and showed action against multi-resistant bacteria known as Acinetobacter baumannii [ 10 ]. Another study demonstrated that EOs of citrus hystrix DC.…”