Antioxidant and Antibacterial Activity of Mexican Oregano Essential Oil, Extracted from Plants Occurring Naturally in Semiarid Areas and Cultivated in the Field and Greenhouse in Northern Mexico

Antibacterial activities of oregano essential oils and their active components

Background: Oregano essential oils (OEOs) and their biological active components are of great interest due to their potent pharmaceutical and antibacterial activities. Methods: OEOs were extracted from wild and cultivated oregano with white or purple flower using our extraction process. We investigated the in vitro antibacterial effects of OEOs and the main active components, carvacrol and thymol. The synergistic effects of carvacrol and thymol were evaluated using checkerboard assay, time-kill assays and systemic infection mice model. The synergistic mechanism was also revealed using scanning electron microscopy (SEM) assay and DAPI/PI staining. Results: Essential oil extracted from wild and cultivated oregano with white flower exhibited potent antibacterial activities against standard strains of Gram-positive and -negative bacteria, with minimum inhibitory concentrations (MICs) range from 0.25-1 mg/mL. The antibacterial activities of carvacrol were obvious higher than that of thymol with MICs values of 0.005-0.04 mg/mL. Carvacrol combining with tobramycin exhibited highly promising synergistic effects (with FICI = 0.25 against E.coli and 0.125 against MRSA) which were further confirmed by the time-kill assays. In the systemic infection mice model, carvacrol combining with tobramycin exhibited potent in vivo antibacterial effects, with significantly improving the survival rate of mice, reducing the MRSA load and alleviating the pathological changes in the lungs of the infected mice. Preliminary explorations for synergistic mechanism suggested that the enhanced antibacterial potential of tobramycin might be attributed to carvacrol with the ability to perforate membrane and induce holes on it.

Recent Advances, Challenges, and Functional Applications of Natural Phenolic Compounds in the Meat Products Industry

Natural phenolic compounds (NPCs) have been proven to effectively extend the storage time of meat products in recent years. To promote the discovery of more NPCs and their applications, this review examines recent progress in the classification, antioxidant, and antibacterial mechanisms of NPCs used in meat products. These compounds are found in both edible and inedible parts of plants, including fruits, vegetables, and trees. The recycling of agricultural by-products aligns with green agricultural trends and serves as a guideline for developing new sources of natural additives. Studies on the application of NPCs in various livestock and poultry products, either directly mixed into the matrix or indirectly contacted by preparation into bioactive films and packaging materials, has highlighted the great potential of NPCs. The pro-oxidative effects of NPCs on proteins and their interactions with biological macromolecules, such as proteins, provide new ideas for in-depth research on antioxidant and antibacterial mechanisms.

Characterization of sodium alginate film containing zein-Arabic gum nanoparticles encapsulated with oregano essential oil for chilled pork packaging

Chilled pork retains most of its nutrients but is prone to deterioration during the production-to-consumption process. To address this issue this study aimed to develop zein-Arabic gum composite nanoparticles loaded with oregano essential oil (ZAG-OEO) and incorporate them into sodium alginate films to enhance the freshness and shelf life of chilled pork. Sodium alginate, known for its excellent film-forming properties, was selected as the matrix to prepare ZAG-OEO-containing sodium alginate films (SA-ZAG-OEO). The results revealed that the tensile strength and elongation at break of the prepared films were 47.73 ± 2.15 MPa and 6.27 ± 0.21 %, respectively, at a 2.5 % nanoparticle concentration. The water contact angle of the films incorporating nanoparticles reached 81.5 ± 1.95°. The incorporation of nanoparticles enhanced the thermal stability and antibacterial activity of the films. The prepared films were utilized for the storage of chilled pork, and the quality changes were analyzed. The results demonstrate that SA-ZAG-OEO films inhibit microbial growth and lipid oxidation, thereby delaying pork spoilage. This study offers new insights into extending the shelf life of chilled pork and developing advanced meat preservation methods for the future development of the meat industry.

Plants from Arid and Semi-Arid Zones of Mexico Used to Treat Respiratory Diseases: A Review

Medicinal plants have been a traditional remedy for numerous ailments for centuries. However, their usage is limited due to a lack of evidence-based studies elucidating their mechanisms of action. In some countries, they are still considered the first treatment due to their low cost, accessibility, and minor adverse effects. Mexico is in second place, after China, in inventoried plants for medicinal use. It has around 4000 species of medicinal plants; however, pharmacological studies have only been carried out in 5% of its entirety. The species of the Mexican arid zones, particularly in semi-desert areas, exhibit outstanding characteristics, as their adverse growing conditions (e.g., low rainfall and high temperatures) prompt these plants to produce interesting metabolites with diverse biological activities. This review explores medicinal plants belonging to the arid and semi-arid zones of Mexico, focusing on those that have stood out for their bioactive potential, such as Jatropha dioica, Turnera diffusa, Larrea tridentata, Opuntia ficus-indica, Flourensia cernua, Fouquieria splendes, and Prosopis glandulosa. Their extraction conditions, bioactive compounds, mechanisms of action, and biological efficacy are presented, with emphasis on their role in the treatment of respiratory diseases. Additionally, current research, novel applications, and perspectives concerning medicinal plants from these zones are also discussed.

Chemical Composition, and Antioxidant and Antimicrobial Activity of Oregano Essential Oil

Antimicrobial resistance (AMR) is a global public health problem, and the rapid rise in AMR is attributed to the inappropriate and/or overuse of antibiotics. Therefore, alternative antimicrobial agents, including those of natural origin, are being sought for the development of new drugs. The purpose of our study was to analyze the chemical composition, and antimicrobial and antioxidant activities of four oregano essential oils (OEOs) from Poland, Europe, Turkey and the USA. The antimicrobial activity (AMA) was evaluated using 23 strains, including Gram-positive bacteria, Gram-negative bacteria and Candida species. The antioxidant activity (AA) of essential oils (EOs) was determined by the DPPH method. The main component of the EOs tested was carvacrol (76.64-85.70%). The highest amount of this compound was determined in the Polish OEO. The OEOs we tested showed antimicrobial resistance, which was especially strong against fungi (MIC = 0.06-0.25 mg/mL-1). These products also showed high AA (71.42-80.44%). OEOs high in carvacrol should be the subject of further research as potential antimicrobial and antioxidant agents.