Chemical composition, antioxidant effects and antimicrobial activities of some spices essential oils on food pathogenic bacteria

Abstract

Thymus vulgaris, Cinnamomum zeylanicum and Ocimum gratissimum are spices widely used as aroma enhancers and food preservatives. This work assessed the chemical composition, antioxidant and antimicrobial effect of their essential oils on some food pathogenic bacteria, namely, Staphylococcus aureus, Citrobacter freundii, Enterobacter cloacae, Morganella morganii, Escherichia coli, Salmonella typhimurium, Proteus vulgaris and Shigella flexineri. After chemical analyses of the essential oils by gas chromatography and gas chromatography coupled to mass spectroscopy, the antimicrobial effects were subsequently assessed by disk and microdilution methods, while the antioxidant evaluations were performed by free radical scavenging activity. T. vulgaris essential oil composed of p-cymene (45.90%) and thymol (23.72%) which exhibited the highest inhibitory diameters of 20.33±0.58 and 18.00±1 mm, respectively, on the growth of S. aureus and C. freundii. O. gratissimum essential oil with thymol as major compound (47.11%) was more active to inhibit the growth of C. freundii and S. flexineri with respective inhibitory diameters of 18±1.73 and 16±2 mm. Essential oil from dry leaves of C. zeylanicum containing cinnamaldehyde (82.23%) and linalool (12.12%) was found to have the lowest values for minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) (≤3.53 mg/mL) considering the growth of S. flexineri, C. freundii and E. cloacae. Regarding the antioxidant effect, C. zeylanicum and T. vulgaris essential oil showed the most scavenging effect with half-maximal DPPH scavenging concentration (SC 50 ) of 2.5 × 10 -5 and 6.5 × 10 -5 mg/ml, respectively. Their antioxidant effects were higher than conventionally used antioxidants in food products, butylhydroxyltoluene (BHT) and vitamin C.

In vitro and in vivo evaluation of thyme (Thymus vulgaris) essential oil as an alternative for antibiotic in quail diet1

“…For example, Boskovic et al (2015) showed that thymol, p-cymene, linalool, γ-terpinene, and 1,8-cineole were the most dominant compounds of thyme essential oil (50.48%, 24.79%, 4.69%, 4.14%, and 4.35% of the oil, respectively). Additionally, the results of other previous studies revealed that thymol was the most common components of T. vulgaris oil (Lee et al, 2005;Ferreira et al, 2016;Foe et al, 2016;Moghaddaszadeh-Ardebili, 2016;Mohammed et al, 2016;Szczepanik et al, 2012). In contrast, Quesada et al (2016) used a chemotype of TVE with low odor intensity that did not have any thymol and had a very low content of linalool with the major component of 1,8 cineole.…”

Thyme essential oil inhibits intracellular replication of CyHV‐3 and inactivates extracellular virus. An in vitro study

“…The plant material, known as Thyme white, containing a slight prevalence of p‐cymene over thymol was applied in the studies by Kim et al (2019) and Shin et al (2019). A higher level of p‐cymene prevalence (45.90%) over thymol (23.72%) was demonstrated in the study by Foe et al (2016), who classified this chemotype as a p‐cymene. The prevalence of p‐cymene (32.18%) over thymol (19.38%) was found in the essential oil of two‐year‐old plants that were collected in December, while thymol dominated in essential oils of two‐ and five‐year‐old plants that were collected in June and July.…”

“…The plant material, known as Thyme white, containing a slight prevalence of p-cymene over thymol was applied in the studies by Kim et al (2019) and Shin et al (2019). A higher level of p-cymene prevalence (45.90%) over thymol (23.72%) was demonstrated in the study by Foe et al (2016), who classified this chemotype as a p-cymene.…”