The purpose of this study was to investigate antibacterial activity of essential oil from Cinnamomum camphora var. linaloofera Fujita (EOL) at vapor phase and its mechanism of bactericidal action against
Escherichia coli
. Results showed that the vapor‐phase EOL had significant antibacterial activity with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 200 μl/L. Further analyses showed that treatment of
E. coli
with vapor‐phase EOL resulted in partial degradation of cell membrane, increased membrane permeability, leakage of cytoplasm materials, and prominent distortion and shrinkage of bacterial cells. FTIR showed that EOL altered bacterial protein secondary and tertiary structures. GC/MS analysis showed that the components of vapor‐phase EOL included linalool (69.94%), camphor (10.90%), nerolidol (10.92%), and safrole (8.24%), of which linalool had bactericidal activity. Quantum chemical analysis suggested that the antibacterial reactive center of linalool was oxygen atom (O
10
) which transferred electrons during antibacterial action by the donation of electrons.
Activity-based method in English reading teaching in senior high school is put forward in the new National English Curriculum Standards for Senior High School (NECS). With the development of the times, the demand for hundreds of thousands of senior high school English teachers is changing, because educators stress a great attention to the application of the modern information technology and activity-based method. Therefore, around how to apply English activity-based method in the reading teaching in high school, this paper designs three learning activities to address the problems of the traditional teacher-centered teaching and the knowledge-orientated leaning. The result of this study can penetrate the consciousness of practical meaning into the frontline teachers by fully understanding the new conception and implementing it based on their own teaching needs.
Compared with traditional liquid–liquid embedding method and solid–liquid embedding method of inclusion complexes of β‐cyclodextrin (β‐CD) inclusion of essential oil to form stable properties, the gas–liquid embedding method was applied to encapsulate vaporized illicium verum essential oil (IvEO), with β‐CD as wall materials so that core and wall materials molecules are in active state during complexing process. At optimal conditions with a mass ratio of 1:10, temperature of 80°C, time of 1 h, the β‐CD‐IvEO inclusion complexes (β‐CD‐IvEO‐ICs) had an encapsulation efficiency (EE) of 84.55 ± 2.31%. Fourier transform infrared spectroscopy (FTIR) revealed the encapsulation of IvEO into inclusion complexes, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) demonstrated the enhanced thermal stability of IvEO after embedding. Furthermore, the reducing power and 2‐phenyl‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (PTIO)‐scavenging capacity displayed certain capacity of antioxidation in a short time but stronger antioxidative activities as reaction time was extended. The diameter of growth zone (DGZ) indicated stronger antibacterial activity of β‐CD‐IvEO‐ICs against Escherichia coli, Bacillus subtilis, Staphylococcus epidermidis, and Staphylococcus aureus. Moreover, the β‐CD‐IvEO‐ICs could induce the bacteria producing more reactive oxygen species (ROS) than IvEO, resulting in bacterial death.
Essential oils (EOs) have good natural antioxidant and antimicrobial properties; however, their volatility, intense aroma, poor aqueous solubility, and chemical instability limit their applications in the food industry. The encapsulation of EOs in β-cyclodextrins (β-CDs) is a widely accepted strategy for enhancing EO applications. The complexation of cinnamon essential oil (CEO) with five types of β-CDs, containing different substituent groups (β-CD with primary hydroxyl, Mal-β-CD with maltosyl, CM-β-CD with carboxymethyl, HP-β-CD with hydroxypropyl, and DM-β-CD with methyl), inclusion process behaviors, volatile components, and antioxidant and antibacterial activities of the solid complexes were studied. The CEOs complexed with Mal-β-CD, CM-β-CD, and β-CD were less soluble than those complexed with DM-β-CD and HP-β-CD. Molecular docking confirmed the insertion of the cinnamaldehyde benzene ring into various β-CD cavities via hydrophobic interactions and hydrogen bonds. GC-MS analysis revealed that HP-β-CD had the greatest adaptability to cinnamaldehyde. The CEO encapsulated in β-, Mal-β-, and CM-β-CD showed lower solubility but better control-release characteristics than those encapsulated in DM- and HP-β-CD, thereby increasing their antioxidant and antibacterial activities. This study demonstrated that β-, Mal-β-, and CM-β-CD were suitable alternatives for the encapsulation of CEO to preserve its antioxidant and antibacterial activities for long-time use.
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