Safety and efficacy of feed additives consisting of essential oils derived from the flower buds or the leaves of Syzygium aromaticum (L.) Merr. & L.M. Perry (clove bud oil and clove leaf oils) for all animal species (FEFANA asbl).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of essential oils from the flower buds or the leaves of Syzygium aromaticum (L.) Merr. & L.M. Perry: clove bud oil, clove leaf oil and a ß-caryophyllene-rich fraction of clove leaf oil (CCL oil), when used as sensory additives in feed and water for drinking for all animal species. Clove oils contain methyleugenol (up to 0.13%). The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the use of clove oils was of low concern for long-living and reproductive animals and of no concern for target species for fattening at the following concentrations in complete feed: 25-50 mg/kg for clove bud oil, 28-100 mg/kg for clove leaf oil and 20 mg/kg for CCL oil. The FEEDAP Panel considered that the use in water for drinking alone or in conjunction with use in feed should not exceed the daily amount that is considered of low or no concern when consumed via feed alone. No concerns for consumers were identified following the use of clove oils up to the highest safe level in feed. The additives under assessment should be considered as irritant to skin and eyes and the respiratory tract and as skin sensitisers. When handling the essential oils, exposure of unprotected users to methyleugenol may occur. Therefore, to reduce the risk, the exposure of the users should be minimised. The use of clove oils at the proposed use level in feed was not expected to pose a risk for the environment. Since clove bud oil and clove leaf oil are recognised to flavour food and their function in feed would be essentially the same, no demonstration of efficacy was considered necessary.

Antimicrobial and indicator properties of edible film containing clove bud oil-loaded chitosan capsules and red cabbage for fish preservation.

For safe preservation and consumption of fish, freshness monitoring and antimicrobial control is crucial. Edible films comprising natural antimicrobial and spoilage indicator agents represent a convenient method for such preservation. Edible chitosan-based films were prepared using red cabbage (RC) and clove bud oil (CBO)-loaded chitosan/carrageenan capsules as spoilage indicator and antimicrobial agents, respectively. CBO-loaded capsules were prepared by the ionic gelation of chitosan and carrageenan. Films containing CBO capsules exhibited significantly higher antimicrobial activity than films containing non-encapsulated free CBO, as confirmed by minimum inhibitory concentration and time-kill assays. The highest antimicrobial activity was observed in the largest capsules (1.7 µm). After incubation for 48 h, the pH of fish peptone agar containing Pseudomonas fluorescens increased from approximately 6.0 to 9.0, and a color change from purple to deep blue was clearly observed during the growth of fish-spoiling bacteria. Thus, our results suggested that edible films containing CBO-loaded capsules and RC showed the potential to inhibit microbial growth in fish and to visibly indicate fish freshness.

Anticancer and antibacterial effects of a clove bud essential oil-based nanoscale emulsion system.

BACKGROUND AND PURPOSE: The essential oil derived from clove buds (Syzygium aromaticum) has been used as a chemopreventive agent in Ayurvedic medicine. The antiviral, antibacterial, and anticancer properties of its chemo-skeleton have motivated this study to explore its efficacy in pharmaceutics. METHODS: Nanoscale-based emulsions were prepared by employing a spontaneous emulsification technique through self-assembly using varying concentrations of Tween 20 and Tween 80 surfactants. Their physicochemical properties and stability were studied in order to choose an optimum formulation which was clear and stable. The cytotoxicity of the stable oil-based emulsion system was evaluated using MTT assay, colony formation assay, and Annexin V-FITC assay against the thyroid cancer cell line (HTh-7). RESULTS: All three methods verified apoptosis and reduction in cancer cell proliferation, making the formulation a promising candidate as an alternative cancer drug. The oil-based emulsion system was also tested for its antibacterial properties against Staphylococcus aureus. Membrane permeability studies proved its efficacy to permeate through cell membrane, thereby increasing the leakage of cytoplasmic contents. CONCLUSION: Many current treatments for cancers are aggressive yet ineffective. This study positions the clove bud-based nanoscale emulsion as a suitable candidate for further in vivo studies and trials as a cancer drug.

Prolonged Insecticidal Activity of Clove oil-Loaded Halloysite Nanotubes on Plodia interpunctella Infestation and Application in Industrial-Scale Food Packaging.

Previous study reported the development of insect-proof halloysite nanotubes (HNTs) and food packaging; however, the duration of their insecticidal properties remains unclear. Here, we aimed to (1) demonstrate the duration of repellency of clove bud oil (CO) encapsulated by HNTs for more than 30 days, and (2) manufacture insect-proof film containing HNTs for commercial use. Also, the release behavior of CO from insect-resistant HNTs was evaluated and HNTs were applied to food packaging composed of polypropylene and low-density polyethylene films to prevent Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) larva infestation. CO, a natural insecticide, was embedded with HNTs and polyethyleneimine (PEI) via vacuum pulling process to cause a slow and gradual release of CO. The sustained release profile of CO from CO-containing HNTs with a PEI coating [(HNTs/CO/layer-by-layer (LBL)] was verified by gas chromatography analysis. The repellent activity of HNTs/CO/LBL was observed for up to 46 days, whereas CO film and HNTs/CO film exhibited no insecticidal activities during the test period. After 30-day exposure, the HNTs/CO/LBL film exhibited a 7-day extension in the penetration test. To evaluate the insecticidal properties of the insect-proof film (HNTs/CO/LBL scale-up film) manufactured in an industrial facility, the inhibitory effects of HNTs/CO/LBL scale-up film on insect infestation was elucidated in both the segregation and combination tests. As a result, HNTs/CO/LBL alone or gravure-printed film treated with HNTs/CO/LBL were capable of protecting food from insect infestation. PRACTICAL APPLICATION: Halloysite nanotubes containing natural insect repellent were applied to industrial production of food packaging. Commercial cornflake cereal packaging using insect-resistant film successfully inhibited pest infestation. Insect-proof film produced at an industrial facility can be utilized to protect processed food from insect infestation.

Development of Natural Insect-Repellent Loaded Halloysite Nanotubes and their Application to Food Packaging to Prevent Plodia interpunctella Infestation.

The aims of this study were to develop insect-proof halloysite nanotubes (HNTs) and apply the HNTs to a low-density polyethylene (LDPE) film that will prevent Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), commonly known as Indian mealmoth, from infesting the food. Clove bud oil (CO), an insect repellent, was encapsulated into HNTs with polyethylenimine (PEI) to bring about controlled release of CO. Chemical composition and insecticidal effect of CO were examined. The Fourier transform infrared (FTIR) spectrum of encapsulated CO was confirmed. The surface charges of uncoated HNTs (HNTs/CO) and coated HNTs with PEI by the layer-by-layer (LBL) method (HNTs/CO/LBL) were determined to be -37.23 and 36.33 mV, respectively. HNTs/CO/LBL showed slow, controlled release of CO compared to HNTs/CO. After 30 d, the residual amounts of CO in HNTs/CO and HNTs/CO/LBL were estimated to be 13.43 and 28.66 mg/g, respectively. HNTs/CO/LBL showed the most sustainable repellent effect. HNTs applied to gravure printing ink solution did not affect mechanical, optical, or thermal properties of the developed film. Gravure-printed LDPE film containing HNTs/CO/LBL displayed the greatest preventive effect on insect penetration, indicating its potential for use as insect-resistant food packaging materials.

Clove bud oil reduces kynurenine and inhibits pqs A gene expression in P. aeruginosa.

Quorum sensing (QS), a communication system involved in virulence of pathogenic bacteria like Pseudomonas aeruginosa is a promising target to combat multiple drug resistance. In vitro studies using clove bud oil (CBO) in P. aeruginosa revealed a concentration dependent attenuation of a variety of virulence factors including motility, extracellular DNA, exopolysaccharides and pigment production. Furthermore, treatment with CBO demonstrated a distinct dose-dependent reduction in biofilm formation as well as promoting dispersion of already formed biofilm, observations that were also supported by porcine skin ex vivo studies. Expression studies of genes involved in signalling systems of P. aeruginosa indicated a specific decrease in transcription of pqsA, but not in the lasI or rhlI levels. Additionally, the expression of vfr and gacA genes, involved in regulation, was also not affected by CBO treatment. CBO also influenced the PQS signalling pathway by decreasing the levels of kynurenine, an effect which was reversed by the addition of exogenous kynurenine. Though the synthesis of the signalling molecules of the Las and Rhl pathways was not affected by CBO, their activity was significantly affected, as observed by decrease in levels of their various effectors. Molecular modelling studies demonstrated that eugenol, the major component of CBO, favourably binds to the QS receptor by hydrophobic interactions as well as by hydrogen bonding with Arg61 and Tyr41 which are key amino acid residues of the LasR receptor. These results thus elucidate the molecular mechanism underlying the action of CBO and provide the basis for the identification of an attractive QS inhibitor.

Study of Permeation Enhancers of Shuxiong Cataplasm / 中国中医药信息杂志

Objective To investigate the effect of two kinds of permeation enhancers,azone and clove bud oil,on transdermal permeation of Shuxiong cataplasm. Methods Cataplasm containing azone and clove bud oil,at different concentrations were prepared,with ferulic acid as the index,the role of enhancing permeation of azone and clove bud oil for the main active component were studied by in vitro permeation experiments. Results Both azone and clove bud oil at different concentrations could increase permeation. Clove bud oil was better than azone and the best concentration of Clove bud oil is 3%. Meanwhile,the permeation enhancing multiple of clove bud oil group was the highest which was 3.68. Conclusion With the cumulative permeation quantity of ferulic acid as the index,3% clove bud oil is more suitable to act as a permeation enhancer of Shuxiong cataplasm.

Acaricidal Activity of Clove Bud Oil against Dermatophagoides farinae (Acari:Pyroglyphidae) / 中国寄生虫学与寄生虫病杂志

Volatile oil from the clove bud was extracted by petroleum ether using Soxhlet Extractor.The acaricidal activity was examined using direct contact and vapour phase toxicity bioassays.In a filter paper contact toxicity bio-assay,at 2.5 h after treatment,clove bud oil at a dose of 12.20 ?g/cm2 killed all dust mites.As judged by 24-h LD50 values,potent fumigant action was observed with clove bud oil(12.20 ?g/cm2),showing an adequate acaricidal activity against indoor Dermatophagoides farinae.