Wen Wang,Zhihui Ren,Li Wang,Ying Cai,Hang Ma,Liming Fang,Jianyu Su
Combinations of phytochemical(s) and engineered nanoparticles have attracted immense research interest due to their superior antimicrobial effects against contaminations. Herein, a Pickering emulsion is developed with capsulized phytochemicals including borneol and citral (BC–Cap) stabilized by hydrophilic amine-functionalized silica nanoparticles (SiO 2 ─NH 2 NPs). The droplet sizes of Pickering emulsion were 5.2 ± 1.4 µm under the condition that the concentrations of SiO 2 ─NH 2 NPs ranged from 0.6 to 1.2 wt.%, and the emulsion showed desirable stability during storage at 40°C for 365 days. In addition, the antibacterial and antibiofilm activities of the Pickering emulsion were investigated. The antibacterial effect of BC–Cap increased by two- to fourfold compared with citral or borneol alone. Treatment of BC/BC–Cap for 4 h eliminated the formation of biofilms generated by Listeria monocytogenes (at 5/1.25 mg/ml; 2 × MIC concentration) and Pseudomonas aeruginosa (at 5/2.5 mg/ml; 2 × MIC concentration). Further mechanistic studies revealed that the antibiofilm effects of BC–Cap were attributed to its ability to increase the porosity and lytic effects on the cell membrane of bacteria. Findings from the current study support the antibacterial and antibiofilm effects of BC–Cap Pickering emulsion as a promising food additive. Practical Application The Pickering emulsion has potential applications as bacteriostatic agent in packaging materials and general surface disinfectant. The combination of borneol and citral is stabilized by hydrophilic amine-functionalized silica nanoparticles (SiO 2 ─NH 2 NPs). With the synergistic effects of borneol and citral, the Pickering emulsion shows a promising elimination effect against the formation of biofilms produced by Listeria monocytogenes and Pseudomonas aeruginosa .
Coumarins are main active components of Peucedanum praeruptorum Dunn. Among them, methoxylated coumarin compound, such as bergapten, xanthotoxin, and isopimpinellin, has high officinal value and plays an important role in medicinal field. However, major issues associated with the biosynthesis mechanism of coumarins remain unsolved and no corresponding enzyme has been cloned from P. praeruptorum. In this study, a local BLASTN program was conducted to find the candidate genes from P. praeruptorum transcriptome database using the nucleotide sequence of Ammi majus bergaptol O-methyltransferase (AmBMT, GenBank accession No: AY443006) as a template. As a result, a 1335 bp full-length of cDNA sequence which contains an open reading frame of 1080 bp encoding a BMT polypeptide of 359 amino acids was obtained. The recombinant protein was functionally expressed in Escherichia coli and displayed an observed activity to bergaptol. In vitro experiments show that the protein has narrow substrate specificity for bergaptol. Expression profile indicated that the cloned gene had a higher expression level in roots and can be induced by methyl jasmonate (MeJA). Subcellular localization analysis showed that the BMT protein was located in cytoplasm in planta. Homology modeling and docking based site-directed mutagenesis have been employed to investigate the amino acid residues in BMT required for substrate binding and catalysis. Conservative amino acid substitutions at residue H264 affected BMT catalysis, whereas substitutions at residues F171, M175, D226, and L312 affected substrate binding. The systemic study summarized here will enlarge our knowledge on OMTs and provide useful information in investigating the coumarins biosynthesis mechanism in P. praeruptorum.
Grapefruit-mediated fruit–drug interaction has been well discussed in clinical practice. However, the biochemical mechanisms for such interaction are far beyond our understanding. The objectives of the present study aimed at the interaction between bergaptol (BGT) and CYP2C9. BGT, one of the major furanocoumarin constituents in grapefruit, has been reported to inhibit the activity of CYP2C9. And a number of furan-containing compounds are known to act as mechanism-based inactivators of CYP2C9. In this study, BGT was found to induce time-, concentration-, and NADPH-dependent irreversible inhibition of CYP2C9. A GSH conjugate was detected in an incubation mixture containing CYP2C9, BGT, NADPH, and GSH. Further mechanistic investigation revealed that a γ-ketoenal metabolite was responsible for the enzyme inactivation. The obtained data indicate that BGT was a mechanism-based inactivator of CYP2C9. The study would facilitate the understanding of the mechanistic insight into fruit–drug interactions mediated by grapefruits.
危险品化学品经营许可证（带存储）