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Acinetobacter baumannii is a nosocomial pathogen known for its ability to form biofilms, leading to persistent infections and antibiotic resistance. The limited effective antibiotics have encouraged the development of innovative strategies such as using essential oils and their constituents. This study evaluated the efficacy of oregano (Lippia graveolens) essential oil (OEO) and its terpene compounds, carvacrol and thymol, in inhibiting A. baumannii biofilms. These treatments showed a minimum inhibitory concentration of 0.6, 0.3, and 2.5 mg/mL and a minimum bactericidal concentration of 1.2, 0.6, and 5 mg/mL, respectively. Sub-inhibitory doses of each treatment and the OEO significantly reduced biofilm biomass and the covered area of A. baumannii biofilms as measured by fluorescence microscopy. Carvacrol at 0.15 mg/mL exhibited the most potent efficacy, achieving a remarkable 95% reduction. Sub-inhibitory concentrations of carvacrol significantly reduced the biofilm formation of A. baumannii in stainless steel surfaces by up to 1.15 log CFU/cm2 compared to untreated bacteria. The OEO and thymol exhibited reductions of 0.6 log CFU/cm2 and 0.4 log CFU/cm2, respectively, without affecting cell viability. Moreover, the terpenes inhibited twitching motility, a crucial step in biofilm establishment, with carvacrol exhibiting the highest inhibition, followed by OEO and thymol. The study provides valuable insights into the potential of terpenes as effective agents against A. baumannii biofilms, offering promising avenues for developing novel strategies to prevent persistent infections and overcome antibiotic resistance.

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Beef is a fundamental part of the human diet, but it is highly susceptible to microbiological and physicochemical deterioration which decrease its shelf life. This work aimed to formulate an active edible film (AEF) incorporated with amino-functionalized mesoporous silica nanoparticles (A-MSN) loaded with Mexican oregano (Lippia graveolens Kunth) essential oil (OEO) and to evaluate its effect as a coating on fresh beef quality during refrigerated storage. The AEF was based on amaranth protein isolate (API) and chitosan (CH) (4:1, w/w), to which OEO emulsified or encapsulated in A-MSN was added. The tensile strength (36.91 ± 1.37 MPa), Young's modulus (1354.80 ± 64.6 MPa), and elongation (4.71%) parameters of AEF made it comparable with synthetic films. The antimicrobial activity of AEF against E. coli O157:H7 was improved by adding 9% (w/w) encapsulated OEO, and interactions of glycerol and A-MSN with the polymeric matrix were observed by FT-IR spectroscopy. In fresh beef, after 42 days, AEF reduced the population growth (Log CFU/cm2, relative to uncoated fresh beef) of Brochothrix thermosphacta (5.5), Escherichia coli (3.5), Pseudomonas spp. (2.8), and aerobic mesophilic bacteria (6.8). After 21 days, odor acceptability of coated fresh beef was improved, thus, enlarging the shelf life of the beef and demonstrating the preservation capacity of this film.

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The development of greener nano-constructs with noteworthy biological activity is of supreme interest, as a robust choice to minimize the extensive use of synthetic drugs. Essential oils (EOs) and their constituents offer medicinal potentialities because of their extensive biological activity, including the inhibition of fungi species. However, their application as natural antifungal agents are limited due to their volatility, low stability, and restricted administration routes. Nanotechnology is receiving particular attention to overcome the drawbacks of EOs such as volatility, degradation, and high sensitivity to environmental/external factors. For the aforementioned reasons, nanoencapsulation of bioactive compounds, for instance, EOs, facilitates protection and controlled-release attributes. Nanoliposomes are bilayer vesicles, at nanoscale, composed of phospholipids, and can encapsulate hydrophilic and hydrophobic compounds. Considering the above critiques, herein, we report the in-house fabrication and nano-size characterization of bioactive oregano essential oil (Origanum vulgare L.) (OEO) molecules loaded with small unilamellar vesicles (SUV) nanoliposomes. The study was focused on three main points: (1) multi-compositional fabrication nanoliposomes using a thin film hydration-sonication method; (2) nano-size characterization using various analytical and imaging techniques; and (3) antifungal efficacy of as-developed OEO nanoliposomes against Trichophyton rubrum (T. rubrum) by performing the mycelial growth inhibition test (MGI). The mean size of the nanoliposomes was around 77.46 ± 0.66 nm and 110.4 ± 0.98 nm, polydispersity index (PdI) of 0.413 ± 0.015, zeta potential values up to -36.94 ± 0.36 mV were obtained by dynamic light scattering (DLS). and spherical morphology was confirmed by scanning electron microscopy (SEM). The presence of OEO into nanoliposomes was displayed by attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. Entrapment efficiency values of 79.55 ± 6.9% were achieved for OEO nanoliposomes. In vitro antifungal activity of nanoliposomes tested against T. rubrum strains revealed that OEO nanoliposomes exhibited the highest MGI, 81.66 ± 0.86%, at a concentration of 1.5 µL/mL compared to the rest of the formulations. In summary, this work showed that bioactive OEO molecules with loaded nanoliposomes could be used as natural antifungal agents for therapeutical purposes against T. rubrum.

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BACKGROUND AND AIM: The use of antibiotics as growth promoters in the feed of poultry, has contributed to an increase in the antimicrobial resistance of foodborne pathogens worldwide. Hence, the development of new effective alternatives to antibiotics that do not hinder productivity is imperative. For this, the aim of the present study was to determine whether oregano essential oil (OEO) extracted from Lippia origanoides is a suitable alternative to growth-promoting antibiotics (GPAs) for improving the performance, egg quality, and intestinal morphometry of ISA Brown laying hens. MATERIALS AND METHODS: A total of ninety-six 70-week-old ISA Brown laying hens were randomly assigned to four treatment groups with four replicates per treatment and six hens per replicate. The treatments consisted of four different diets that were formulated according to the nutritional requirements of the genetic line and the production phase with and without the addition of GPA and OEO: NC, which did not contain OEO or GPA; GPA, which included 50 ppm zinc bacitracin as a GPA; 80OEO, which included 80 ppm OEO and no GPA; and 150OEO, which included 150 ppm OEO and no GPA. RESULTS: All of the OEO and GPA treatment groups had a better feed conversion ratio than the NC group. However, the addition of 150 ppm OEO to the diet improved the percentage egg production and egg mass, as well as the external and internal quality of the egg compared with the other treatments. In addition, both the 80OEO and 150OEO treatments improved the yolk color, shell thickness, and shell color, as well as parameters related to the intestinal morphometry compared with the NC group. CONCLUSION: The findings of this study indicate that 150 ppm OEO can be used as a substitute for GPA to improve the performance, egg quality, and parameters related to the intestinal morphometry of ISA Brown laying hens.

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Lactic acid bacteria are the main bacterial group associated to meat spoilage. Herbal essential oils are promising alternatives that can be used to retard lactic acid bacterial growth and extend shelf life of meat products. In this study, the influence of oregano and rosemary essential oils on the growth of lactic acid bacteria and the physicochemical properties of refrigerated vacuum-packed Tuscan sausage was evaluated. In addition to the control (without the addition of oil), the sausage samples were separately treated with different concentrations of each essential oil (0.05 wt%, 0.1 wt%, 0.2 wt%, and 0.4 wt%). The shelf life was evaluated as the time to the lactic acid bacteria population to reach the levels of 106 and 107 CFU/g. After the addition of 0.05 wt% and 0.1 wt% of essential oil to the sausage, the rosemary essential oil provided a higher extension of the shelf life of the sausages (approximately 3 and 5 days, respectively) than the oregano essential oil (approximately 1 and 3 days, respectively). After adding 0.2 wt% and 0.4 wt% of essential oil, the oregano essential oil resulted in a larger increase of the shelf life of the samples (about 8 and 14 days, respectively) when compared with the rosemary essential oil (about 7 to 11 days, respectively). All the treatments slowed the growth of the lactic acid bacteria but they did not change the maximum bacterial population. New empirical models that relate the shelf life of the sausage and the maximum specific growth rate of the lactic acid bacteria with the oil concentration were obtained. These results can be applied to model the influence of essential oils on the shelf life of different meat products.

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AIM: The molecular typing and the susceptibility of Staphylococcus aureus strains of swine origin to antibiotics, oregano (Origanum vulgare L.) essential oil (EO) and Chilean blackberry maqui (Aristotelia chilensis (Molina) Stuntz) extract were determined. METHODS AND RESULTS: Twenty S. aureus strains of swine origin were subjected to molecular typing, of which six strains were selected for antimicrobial susceptibility testing. The epsilon test (Etest) was used to determine the antibiotic susceptibility. The susceptibility to natural antimicrobials (NAs): oregano EO, maqui extract, thymol (Thy) and carvacrol (Carv), was carried out using the disk diffusion method. The S. aureus strains were genetically diverse. All strains were resistant to at least one class of antibiotic, and two strains were multidrug-resistant. The minimum inhibitory concentration of oregano EO, Thy and Carv was 0·01-0·04%. Maqui extract did not show antistaphylococcal activity. CONCLUSIONS: Natural antimicrobials extracted from oregano have an inhibitory activity against S. aureus strains from swine origin, with no effect using maqui extract. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides information about the characteristics of S. aureus strains of swine origin, and about the potential use of NAs from oregano to enhance the control of antibiotic-resistant S. aureus strains in the pork supply chain.

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This study examined the impact of emulsifier type on the physicochemical characteristics and antifungal capacity of oregano oil-in-water emulsions: Tween 80, hydroxylated soy lecithin, and gum arabic. GC/MS analysis showed that the major components of the Lippia graveolens essential oils were thymol (31.7%), p-cymene (18.7%), and carvacrol (14.6%). The oil-in-water emulsions were made using ultrasonic technology in which thymol and carvacrol quantities were 12.26-13.67 g/L and 5.6-6.2 g/L, respectively. The droplet size of the emulsions followed the next descendent order: gum arabic > lecithin > T80. The zeta potential of the emulsions favored the stability against coalescence. Finally, the antifungal activity of the emulsions was evaluated, in which, 30 µL/mL of gum arabic or hydroxylated soy lecithin emulsions inhibited the growth of Candida albicans. The result suggests that Mexican oregano essential oil emulsions can be used as an antifungal against of C. albicans.

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Poliomintha longiflora is a Mexican oregano, which has not been widely studied. This work aimed to describe the chemical composition, antimicrobial and antioxidant activities present in P. longiflora essential oil (EO), the hydrosol from EO extraction and extracts from waste solid residues (WSRs), identified as ethanol extract, ethyl acetate extract and the subfractions of ethanol and ethyl acetate extracts. The chemical characterization of the EO, hydrosol and WSR extracts was performed by GC⁻MS and HPLC. Their antioxidant activity was evaluated using two methods, and their antimicrobial activity was evaluated against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, and Salmonella Typhimurium. Thirty-one chemical components were identified in the EO. The subfractions from the ethanol and ethyl acetate extracts contain methylmaleic anhydride, thymoquinone, thymol, carvacrol, thymol acetate, carvacrol acetate, and phenolic acids. The EO presented the highest biological activities for antioxidant (136.05 mg equivalent of ascorbic acid/g (AAE/g); IC50 83.70 µg/mL of 2, 2-diphenyl-1-picrylhydrazyl (DPPH)) and antimicrobial tests (minimal inhibitory concentration (MIC) value of 250⁻750 mg/L), while the hydrosol and the ethyl acetate extract from WSRs had the lowest antioxidant activity (14.16 and 12.29 mg AAE/g respectively), and the hydrosol had the lowest antimicrobial activity (MIC of 3000 mg/L). The data suggest that Mexican oregano P. longiflora hydrosol and extracts from waste solid residues can still have compounds with antimicrobial and antioxidant capacities.

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The effects of the addition of Origanum syriacum L. essential oil (OE) on the lipid and protein oxidation, and sensory attributes of cooked chicken meat were compared with those of synthetic commercial meat preservatives. Ground deboned and skinless chicken breast and thigh meat were distributed according to six treatments: (T1) control (no addition of meat preservative); or the addition of (T2) 100 ppm OE; (T3) 150 ppm OE; (T4) 300 ppm L-ascorbic acid (E-300); (T5) 5 and 14 ppm butylated hydroxyanisoleadded to breast and thigh meat, respectively, (BHA/E-320); and (T6) 150 ppm sodium nitrite (E-250). Meat samples were cooked and analyzed for lipid oxidation (TBARS levels) and protein oxidation (carbonyl levels) on days 0, 4, and 7 days of storage. In addition, cooked meat thigh patties were evaluated for cooking loss and sensory attributes. All additives were showed significant lipid and protein antioxidant effects (p 0.05) compared with the control treatment during storage, with the strongest effects obtained with OEat 150 ppm and E-250. Cooking loss was not influenced (p>0.05) by the treatments. The best sensory attribute scores were obtained with OEat 150 ppm and E-250 treatments. L-ascorbic acid and BHA also showed significant effect (p 0.05) on both lipid and protein oxidation values, and sensory attributes. Based on the results study, it concluded that OEat 150 ppm may be used in replacement of synthetic antioxidants to improve the storage stability of chicken meat.

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The effects of the addition of Origanum syriacum L. essential oil (OE) on the lipid and protein oxidation, and sensory attributes of cooked chicken meat were compared with those of synthetic commercial meat preservatives. Ground deboned and skinless chicken breast and thigh meat were distributed according to six treatments: (T1) control (no addition of meat preservative); or the addition of (T2) 100 ppm OE; (T3) 150 ppm OE; (T4) 300 ppm L-ascorbic acid (E-300); (T5) 5 and 14 ppm butylated hydroxyanisoleadded to breast and thigh meat, respectively, (BHA/E-320); and (T6) 150 ppm sodium nitrite (E-250). Meat samples were cooked and analyzed for lipid oxidation (TBARS levels) and protein oxidation (carbonyl levels) on days 0, 4, and 7 days of storage. In addition, cooked meat thigh patties were evaluated for cooking loss and sensory attributes. All additives were showed significant lipid and protein antioxidant effects (p 0.05) compared with the control treatment during storage, with the strongest effects obtained with OEat 150 ppm and E-250. Cooking loss was not influenced (p>0.05) by the treatments. The best sensory attribute scores were obtained with OEat 150 ppm and E-250 treatments. L-ascorbic acid and BHA also showed significant effect (p 0.05) on both lipid and protein oxidation values, and sensory attributes. Based on the results study, it concluded that OEat 150 ppm may be used in replacement of synthetic antioxidants to improve the storage stability of chicken meat.(AU)

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The objective of this study was to evaluate the antifungal activity of nanoemulsions encapsulating essential oil of oregano (Origanum vulgare), both in vitro and after application on Minas Padrão cheese. Nanodispersions were obtained by the phase inversion temperature method. Cladosporium sp., Fusarium sp., and Penicillium sp. genera were isolated from cheese samples and used to evaluate antifungal activity. Minimal inhibitory concentrations of non-encapsulated and encapsulated oregano essential oil were determined, and they were influenced by the encapsulation of the essential oil depending on the type of fungus. The antifungal activity of the nanoencapsulated oregano essential oil in cheese slices showed no evidence of an effect of the MICs, when applied in the matrix. On the other hand, an influence of contact time of the nanoemulsion with the cheese was observed, due to the increase in water activity. It was concluded that nanoencapsulated oregano essential oil presented an inhibitory effect against the three genera of fungi evaluated. If environmental parameters, such as storage temperature and water activity, were controlled, the inhibitory effect of nanoemulsions of oregano oil could possibly be greatly improved, and they could be presented as a potential alternative for the preservation of Minas Padrão cheese against fungal contamination.(AU)

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Resumen Objetivo: evaluar parámetros sanguíneos en pollos de engorde de la línea genética Cobb500, luego de la administración de aceite esencial de orégano (Lippia origanoides) (AEO). Materiales y métodos: se utilizaron 200 pollos de línea genética Cobb 500 y se realizaron mediciones los días 14, 28 y 42. Los animales fueron aleatorizados a una de dos dietas: dieta comercial con antibiótico y sin este. A esta última se adicionaron diferentes concentraciones de AEO (75 ppm, 100 ppm o 200 ppm AEO). Se realizó un diseño estadístico de bloques al azar en un arreglo de parcelas dividas. Resultados: los pollos del grupo D5 (200 ppm) presentaron mayores valores en glucosa, fosfatasa y fósforo que los pollos alimentados con antibiótico (D2) a lo largo del experimento. Conclusión: la adición de 200 ppm de AEO en el alimento de pollos de engorde de la línea genética Cobb 500 induce una mejora en metabolitos sanguíneos. Este trabajo permitió evaluar las variables metabólicas de pollos que consumieron AEO.

Abstract Objective: To evaluate blood parameters in broiler chickens of the Cobb 500 genetic line, after the administration of oregano essential oil (Lippia origanoides) (OEO). Materials and methods: 200 chickens of the Cobb 500 genetic line were used, and measurements were taken on days 14, 28, and 42. The animals were randomly assigned to one of two diets: commercial diet with and without antibiotic supplementation. To the antibiotic-free diet different concentrations of OEO were added (75 ppm, 100 ppm, or 200 ppm). A statistical randomized block design was used in an array of divided plots. Results: Chickens from group D5 (200 ppm of OEO) had higher values in glucose, phosphatase, and phosphorus than chickens fed with antibiotic supplementation (D2) throughout the experiment. Conclusion: The addition of 200 ppm of OEO in the food of broiler chickens of the Cobb 500 genetic line induces an improvement in blood metabolites. This work allowed evaluating metabolic variables of chickens that consumed OEO.

Resumo Objetivo: avaliar parâmetros sanguíneos em frangos de corte da linha genética Cobb500, após administração de azeite essencial de orégano (Lippia origanoides) (AEO). Materiais e métodos: Foram utilizados 200 frangos de linha genética Cobb 500 e foram realizadas medições nos dias 14, 28 e 42. Os animais foram submetidos aleatoriamente a uma de duas dietas: dieta comercial com antibiótico e sem este. A esta última foram adicionadas diferentes concentrações de AEO (75 ppm, 100 ppm ou 200 ppm AEO). Se realizou um desenho estatístico de blocos aleatórios em uma matriz de parcelas dividas. Resultados: os frangos do grupo D5 (200 ppm) apresentaram maiores valores em glicose, fosfatase e fósforo que os frangos alimentados com antibiótico (D2) ao longo do experimento. Conclusão: a adição de 200 ppm de AEO no alimento de frangos de corte da linha genética Cobb 500 induz a uma melhora em metabolitos sanguíneos. Este trabalho permitiu avaliar as variáveis metabólicas de frangos que consumiram AEO.

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ABSTRACT The objective of this study was to evaluate the antifungal activity of nanoemulsions encapsulating essential oil of oregano (Origanum vulgare), both in vitro and after application on Minas Padrão cheese. Nanodispersions were obtained by the phase inversion temperature method. Cladosporium sp., Fusarium sp., and Penicillium sp. genera were isolated from cheese samples and used to evaluate antifungal activity. Minimal inhibitory concentrations of non-encapsulated and encapsulated oregano essential oil were determined, and they were influenced by the encapsulation of the essential oil depending on the type of fungus. The antifungal activity of the nanoencapsulated oregano essential oil in cheese slices showed no evidence of an effect of the MICs, when applied in the matrix. On the other hand, an influence of contact time of the nanoemulsion with the cheese was observed, due to the increase in water activity. It was concluded that nanoencapsulated oregano essential oil presented an inhibitory effect against the three genera of fungi evaluated. If environmental parameters, such as storage temperature and water activity, were controlled, the inhibitory effect of nanoemulsions of oregano oil could possibly be greatly improved, and they could be presented as a potential alternative for the preservation of Minas Padrão cheese against fungal contamination.

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Peanut oil is widely used in food but is susceptible to oxidation. This study investigated the antioxidant stability of high oleic (HO: 78.85 g/100 g oleic acid) and regular (C: 43.85 g/100 g oleic acid) peanut oils with oregano essential oil (OEO) added as a natural antioxidant. OEO contained γ-terpinene (25.71%), carvacrol (16.73%) and terpinen-4-ol (16.17%) as the principal compounds. Thermal processing (60 °C for 28 days) of OEO increased the carvacrol and o-cymene contents and decreased the terpinen-4-ol, linalool and γ-terpinene levels. Thus, carvacrol was the major compound with high oxidative stability. Thermal processing of the peanut oils showed that HO peanut oil developed less oxidation than C peanut oil. OEO provided antioxidant activity, which increased as its concentration increased (at 0.02 and 0.10% p/p of OEO, the peroxide value decreased by 18 and 46%, respectively). OEO displayed 54.7% free radical scavenging activity and 9.2 mg/g total phenolic content, explaining its antioxidant activity. Sensory analysis showed that OEO was detected in all samples, but consumer acceptance was greater when OEO was present (hedonic values of 7.4 and 6.8 for OEO at 0.02 and 0.10 g/100 g, respectively) compared to the peanut oil only control (hedonic value of 6.0).

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The objective of this study was to evaluate the antifungal activity of nanoemulsions encapsulating essential oil of oregano (Origanum vulgare), both in vitro and after application on Minas Padrão cheese. Nanodispersions were obtained by the phase inversion temperature method. Cladosporium sp., Fusarium sp., and Penicillium sp. genera were isolated from cheese samples and used to evaluate antifungal activity. Minimal inhibitory concentrations of non-encapsulated and encapsulated oregano essential oil were determined, and they were influenced by the encapsulation of the essential oil depending on the type of fungus. The antifungal activity of the nanoencapsulated oregano essential oil in cheese slices showed no evidence of an effect of the MICs, when applied in the matrix. On the other hand, an influence of contact time of the nanoemulsion with the cheese was observed, due to the increase in water activity. It was concluded that nanoencapsulated oregano essential oil presented an inhibitory effect against the three genera of fungi evaluated. If environmental parameters, such as storage temperature and water activity, were controlled, the inhibitory effect of nanoemulsions of oregano oil could possibly be greatly improved, and they could be presented as a potential alternative for the preservation of Minas Padrão cheese against fungal contamination.

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