Biological activities of Lippia gracilis Schauer essential oil and modelling of its effects on bacterial growth.

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The demand for healthier products by consumers has prompted research into the use of essential oils (EOs), which are known for their antimicrobial properties. This study investigated the antimicrobial properties of EOs as a potential alternative to synthetic preservatives, specifically, cinnamon, clove, and oregano EOs, as well as their majority compounds (cinnamaldehyde, eugenol, and carvacrol) on Clostridium sporogenes inoculated in hams. The findings of the study revealed that cinnamon EO and its major compound cinnamaldehyde were the most efficient in inhibiting the growth of C. sporogenes, demonstrating the lowest minimum bactericidal concentration MBC (0.1%). The combination of oregano EO, cinnamon EO, cinnamaldehyde, and carvacrol led to a significant decrease in bacterial growth (approximately 3 log) after 28 days in hams. Furthermore, the presence of spores was not observed for 14 days (at 14°C) and 21 days (at 7°C) of storage, indicating a delay in sporulation. The treatments using the combination of EOs, and their major compounds had minimal impact on the color of the hams while maintaining the physicochemical characteristics of the product. This study demonstrates that EOs and their major compounds can be applied as natural preservatives in ham, offering a potential alternative for reducing the use of nitrites in various food types. The research emphasizes the antibacterial efficacy of cinnamon, clove, and oregano EOs, along with their major compounds, in inhibiting C. sporogenes in ham. The findings indicate that these natural alternatives could be valuable in preserving food products and reducing the reliance on synthetic preservatives.

Background and Objective: In recent years, there has been a rapid development in prevention of bacterial growth and spoilage in foods by the application of preservatives. Essential oils, which are known to be harmless for human, have shown positive health effects in addition to their preservative role. Likewise, probiotics exert improvement in both food product and health level of consumers. With reference to these it is important to do more research on various effects of endemic essential oils on traditional food products. A survey was carried on effect of essential oil and combination of essential oil and probiotics on growth of Escherchia coli O157:H7.Material and Methods: Kishk samples treated with Teucrium polium essential oil (75 and 150 mg l-1) and Lactobacillus casei (108 -109 CFU ml-1) were stored up to 20 days at 4°C and the effect of Teucrium polium essential oils and probiotic fermentation on Escherchia coli O157:H7 counts were investigated.Results and Conclusion: Teucrium polium essential oils and probiotic fermentation reduced the number of Escherichia coli during the cold storage time. The combination of Teucrium polium essential oil and probiotics showed stronger effect rather than individually added. Initial count of inoculated Escherchia coli was 6.39 log CFU g-1. Essential oil compounds of Teucrium polium included Spathulenol, Epizonaren and Bicyclo hept-3-en-2-ol in 18.39, 9.62 and 6.76%, respectively. After 20 days storage at 4°C, the number of Escherchia coli in probiotic, combination of probiotic and essential oil (150 mg l-1) and control samples decreased from 6.39 log CFU g-1 to 4.95, 4.30 and 5.8 log CFU g-1, respectively. An increase in acidity and decrease in pH were observed for all samples (p≤0.05). Based on organoleptic tests, the most accepted sample was included 75 ppm of essential oil and probiotic. According to the antibacterial effect of essential oils extracted from plant and probiotic fermentation, it was predictable that they could decline the Escherchia coli count especially in fermented dairy products. Also, due to its probiotic nature, Kishk would bring numerous health advantageous for consumer.

Synergistic antimicrobial activities of plant essential oils against Listeria monocytogenes in organic tomato juice

The study aimed to assess the antifungal activity of twenty–five essential oils (EOs) and the potential synergistic activity of the most effective EOs against significant indoor fungi of the genus Aspergillus [A. fumigatus (KBio–122), A. flavus (KBio–134), A. terreus (KBio–145) and A. niger (KBio–202)]. The chemical composition of all EOs was evaluated by the gas chromatography coupled with mass spectrometry (GC/MS) and gas chromatography with flame ionization detector (GC–FID) analysis. The antifungal susceptibility of EOs was evaluated by using the broth microdilution method. The most effective EOs were selected to determine the minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) at a concentration range from 256 to 0.125 μg/mL. For the synergistic activities, the most effective EOs were tested using the chessboard pattern. The most sensitive strain to treatments with essential oils alone and in the combination of EOs was A. flavus (KBio–134). The chessboard assay showed that combinations of lemongrass and thyme EOs proved the most potent synergistic antifungal activity (FICI = 0.1875) against A. fumigatus (KBio–122). The synergy displayed by a combination of some EOs may be used to control fungal growth or increasing resistance to available synthetic antifungals, consequently permitting the reduction of their most active doses.

In vitro antimicrobial effects and mechanism of action of selected plant essential oil combinations against four food-related microorganisms

ABSTRACTThe effects of concentrations of Rosmarinus officinalis essential oil (EO) and nisin (N) as well as temperature and storage time on growth of Streptococcus iniae and Lactococcus garvieae in Oncorhynchus mykiss were evaluated. According to analysis of the rosemary EO, the 1, 8-cineol and α-pinene were the predominant components. The growth of S. iniae was significantly decrease by EO concentrations at 4 ºC. For L. garvieae, the viable count was significantly inhibited by EO and N singly and in combinations, incubated at bath storage of 0.25 and 0.5 µg/mL proved insufficient to act against S. iniae and L. garvieae. The combinations of the rosemary EO at 0.0015% with N at 0.5 µg/mL showed stronger antimicrobial effect against two bacterial than the rosemary EO at 0% but lower than the combination with N at 0.5 µg/mL and EO at 0.045% which in turn was lower than of the rosemary EO at 0.135%. In its turn, rosemary EO showed lower antimicrobial activity than its combinations with N, which showed a bactericidal effect against the pathogens. The best inhibitory effects of EO in combinations with N for two bacterial were obtained at combinations of EO=0.135% and N=0.5 µg/mL.

ABSTRACTThe combination of essential oils (EOs) is a novel alternative to improve their preservative effects and to reduce their organoleptic impact in food. In this context, this work aims to investigate the antibacterial combined effect of two EOs combinations through the calculation of the fractional inhibitory concentration index. The combinations tested consists of Lavandula dentata/Origanum majorana EOs and Thymus serpyllum/Origanum majorana EOs. Their chemical compositions were identified by CG/MS analyses. The main compounds of O. majorana EO were (-) - terpinene-4-ol and trans-4-thujanol. Those of L. dentata EO were β-pinene and 1,8-cineole, and those of T. serpyllum EO were p-cymene and γ-terpinene. Regarding the outcomes, results highlighted partial synergistic and additive interactions. Two combinations of marjoram and thyme EOs had antibacterial activities against S. aureus. The first one corresponded to the quarter of the minimum inhibitory concentration of marjoram and half that of thyme. The second one was the mix of half and quarter of the minimum inhibitory concentration of respectively marjoram and thyme EOs. This last combination also showed an antibacterial effect against E. coli. The quarter and the half of their minimum inhibitory concentration of marjoram and lavender combination, respectively, gave a partial synergy against both strains. Henceforth, these findings could be largely exploited in food preservation through the use of minimal doses of these plant products without affecting the antibacterial and the organoleptic properties in foods.

Aromatherapy in dermatology

Chemical composition and evaluation of antioxidant activities, antimicrobial, and anti-melanogenesis effect of the essential oils extracted from Dalbergia pinnata (Lour.) Prain

Anti yeast activities of some essential oils in growth medium, fruit juices and milk

Routine medical examinations can produce stress which can negatively impact the health and well-being of horses. Heart rate variability (HRV) is a non-invasive and inexpensive method to measure the balance between sympathetic and parasympathetic nervous system activity, which can help identify stress in horses. This study examined the effect of a combination of lavender and eucalyptus essential oil on stress responses in horses undergoing a routine medical exam. After a five-minute stall rest (baseline reading) data were collected in three, five-minute intervals (walk to and enter stock, medical exam, and recovery in stall). This study utilized a switch-back design where each horse (n = 10) received both treatments on different dates. The treatment groups received lavender (20%) and eucalyptus essential oil (5%) dissolved in petroleum jelly and virgin sunflower oil applied to inner nostrils. The control treatment consisted of only petroleum jelly and virgin sunflower oil applied to inner nostrils. The root mean square of the successive differences of heartbeats (RMSSD) was significantly reduced (P < 0.05) when horses were treated with essential oils while walking to stocks (51.7 ± 3.7), during the medical exam (50.5 ± 4.9), and during the recovery period (64.1.9 ± 5.7) compared with control treatment, to stocks (36.1 ± 4.4), the medical exam (39.0 .± 4.5), and during the recovery period (49.7 ± 5.5). The measured SD1 (parasympathetic) was significantly greater (P < 0.008) at walk to stocks in horses treated with essential oils (37.2 ± 1.9) compared with control treated (30.3 ± 3.1). The measured SD2 (sympathetic) was significantly less (P < 0.008) at walk to stocks in horses treated with essential oils (62.8 ± 1.9) compared with control treated (69.7 ± 6.8). The ratio of SD1/SD2 was significantly less (P < 0.008) at walk to stocks in horses treated with essential oils (1.7 ± 0.17) compared with control treated (2.4 ± 0.26). The high frequency percent (HF%) was also greater (P < 0.04) at walk to stocks in horses treated with essential oils (39.6 ± 4.9) compared with control treated (26.0 ± 4.1). The standard deviation of RR Interval (SDNN) values were increased (P < 0.03) in horses treated with essential oils during walking to stalks (50.8 ± 1.9), the medical exam (56.7 ± 5.0), and the recovery period (72.4 ± 12.9) compared with the control treatment, to stalks (44.5 ± 5.2), medical exam (44.0 ± 4.5), and during the recovery period (54.6 ± 6.2). The results of this study indicate that lavender and eucalyptus oil could be an effective means of reducing short-term stress in horses. The findings of this study can help develop more effective and humane management strategies for horses.

Essential oils from spices such as red galangal and cinnamon are known to have antimicrobial activity that is strong enough against pathogenic and food destroying bacteria, so it has the potential to be developed as a preservative, especially in food. High antimicrobial activity is generally obtained at high concentrations, which can affect sensory acceptance when applied to food. One way to overcome this problem is to combine the use of essential oils. This study aims to determine the effect of the ratio of the combination of red galangal and cinnamon essential oils to its antimicrobial activity on Escherichia coli and Staphylococcus aureus bacteria. The research was carried out with an experimental method which was analyzed descriptively. Antimicrobial activity testing was carried out by the agar diffusion method and contact method to determine the inhibition growth of E. coli and S. aureus bacteria. The treatment consists of 5 ratios combination of red galangal and cinnamon essential oils, which were 1:0, 0:1, 1:1, 1:2, and 2:1 (v/v). The results showed that the ratio of the combination of red galangal and cinnamon essential oils showed a strong effect on antimicrobial activity towards E. coli and S. aureus. The combination of essential oil at 1:1 (v/v) ratio showed the highest antimicrobial activity against E.coli which was 20.5 mm of inhibition zone, while toward S. aureus was 21.25 mm inhibition zone (strong activity); and could reduce the total test bacteria by reducing 16.85% of E. coli and 21.69% of S. aureus bacteria after 24-hour length incubation.

Bacterial resistance to classic antibiotics is an alarming rate to put this into control with the use of natural products of plant derivatives. The objective of this study was to determine the phytochemical of cinnamon essential oil (EO) and to evaluate its antibacterial activity alone and in combination with some main components of EOs such as thymol, carvacrol, eugenol, or geraniol against three bacterial strains (Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa). The phytochemical analysis of cinnamon EO was evaluated using gas chromatography-flame ionization detector and gas chromatography-mass spectrometer analysis. The antibacterial activity of tested compounds was determined by agar disk diffusion and minimum inhibitory concentration (MIC) assays. The checkerboard method was used to quantify the efficacy of cinnamon EO in combination with those compounds. The results showed that the major compound in the cinnamon EO was trans-cinnamaldehyde (91.01%). Cinnamon oil was the highest antibacterial activity with MIC of 0.005, 0.005, and 0.02 mg/mL against E. coli, S. aureus, and P. aeruginosa, respectively. Synergistic activity was shown only against S. aureus by the combination of cinnamon EO and thymol. The additive effect was found against E. coli when cinnamon EO was combined with thymol or carvacrol, and against S. aureus when cinnamon EO was combined with carvacrol. However, the combination of EO and thymol or carvacrol showed an indifference action against P. aeruginosa. The combination of cinnamon EO with thymol or carvacrol can be used as an alternative therapeutic agent for medical application and as a natural preservative.

Background: Globally enteric methane emission is the largest contributor of anthropogenic global warming and methane is the second largest driver of global radiative forcing after carbon dioxide. The present study was conducted to evaluate the effect of supplementing essential oils (EOs) in combination of garlic oil and peppermint oil on enteric methane emission in indigenous dairy cattle. Methods: Eight indigenous dairy cattle were divided into two groups supplemented with essential oils in combination of garlic oil and peppermint oil (2.4 mL/animal) as treatment group and without supplementation with paddy straw and concentrate feed (60:40) based diet. A digestibility trial was conducted during the last six days of 30 days feeding trial to evaluate the effect of essential oils in combination on nutrients digestibility. The total methane emission was estimated by sulfur hexa fluoride tracer gas technique (SF6). Result: No significant difference in DMI, TDN and DCP intake could be noted with supplementation of essential oils in indigenous dairy cattle. However, cows fed with combination of garlic oil (GO) and peppermint oil (PO) significantly (P less than 0.05) reduced the methane emission by 10.60% in comparison to control group. Hence, the feasibility of feeding essential oils can be considered at farm level as a methane mitigation strategy.