A number of bioactive components have been extracted from neem (. Azadirachta indica) essential oil, including azadirachtin, gedunin, isomargolonone, margolone, margolonone, nimbidin, nimbin, nimbolide, and salannin. These phytochemicals contribute to the various biological activities of neem essential oil, such as acaricidal, antibacterial, anticarcinogenic, antifungal, antihyperglycaemic, anti-inflammatory, antimalarial, antimutagenic, antiprotozoan, antioxidant, antiulcer, antiviral, immunomodulatory, insect-repellent, and spermicidal properties. Neem essential oil has potential antibacterial activity against foodborne pathogens such as Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enteritidis, Staphylococcus aureus, and Vibrio parahaemolyticus; and four different food-spoilage bacteria such as Aeromonas hydrophila, Alcaligenes faecalis, Pseudomonas aeroginosa, and Pseudomonas putida. Neem oil is reported to have considerably higher antibacterial activity than antibiotics such as tetracycline, ampicillin, and ciprofloxacin. Neem cake exhibits antimicrobial activity against bacteria spoiling the quality of retail fresh meat in a broth model meat system, thereby preserving the food system against microbial spoilage. © 2016 by Elsevier, Inc.. All rights reserved.

Amitava Mukherjee

Centre for Nanobiotechnology

Vellore Campus

Chandra Sekaran N

Ghosh V

Sugumar S

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Neem (Azadirachta indica) Oils

Essential Oils in Food Preservation, Flavor and Safety

Oil-in-water nanoemulsion was formulated using sesame oil, non-ionic surfactant (Tween20/Tween80) and water by ultrasound cavitation method. Development of nanoemulsion was optimized for process parameters such as surfactant type, surfactant concentration and emulsification time to obtain lower droplet diameter with greater stability. Increase in surfactant concentration and emulsifi{ligature}cation time resulted in nanoemulsion with minimized droplet diameter. Tween80 was more effective in reducing droplet size when compared to that of Tween20. Selected formulation with optimized process parameter (with oil-surfactant mixing ratio of 1:3 v/v and Tween80 as surfactant) was used for delivery of eugenol. Eugenol-loaded nanoemulsion was formulated with droplet diameter of 13. nm and was stable for more than 1 month. Sesame oil blended eugenol-loaded nanoemulsion demonstrated lower droplet size and higher stability than only-eugenol (without sesame oil) nanoemulsion. Eugenol-loaded nanoemulsion S3E3 exhibited antibacterial activity against Staphylococcus aureus. Inactivation kinetics of S. aureus showed time and concentration killing of bacteria upon treatment with S3E3 nanoemulsion. Fluorescence microscopy results demonstrated that S3E3 nanoemulsion treatment resulted in alteration of membrane permeability. In situ assessment of S3E3 in orange juice exhibited a significant reduction in the native bacteria population. © 2013 Elsevier B.V.

Colloids and Surfaces B: Biointerfaces

Eugenol-loaded antimicrobial nanoemulsion preserves fruit juice against, microbial spoilage

Microemulsions are thermodynamically stable isotropic systems comprising of oil, surfactant and water. Cinnamon oil (Cinnamomum zeylanicum) microemulsion was formulated using non-ionic surfactant Tween 20 and water. With oil to surfactant (v/v) ratio of 1:4, cinnamon oil microemulsion (CMF4) was formulated having droplet diameter of 5.79 and kinetically stable for 240 days. TEM images confirmed the spherical morphology of emulsion droplets. Surfactant concentration demonstrated a negative correlation with droplet diameter and turbidity but positive correlation with stability and viscosity. Formulated microemulsion (CMF4) was evaluated for bactericidal activity against . Staphylococcus aureus by dose and time dependent killing experiment. SEM analysis suggested that microemulsion treatment resulted in alteration of permeability and surface features of bacterial cell membrane which lead to lysis and cell death. CMF4 showed no erythema for skin irritation test in wistar rats and triggered wound-healing process in wistar rats. Control group without any treatment, cinnamon oil only and neomycin treated group healed in 20, 16 and 16 days, whereas cinnamon oil formulation (CMF4) treated group was healed in 14 days. © 2013 Elsevier B.V.

Antibacterial microemulsion prevents sepsis and triggers healing of wound in wistar rats

Cinnamon oil (extracted from Cinnamomum zeylanicum) nanoemulsion was formulated using Tween 80 and water by ultrasonic emulsification. Process of nanoemulsion formulation was optimized for parameters such as surfactant concentration, oil-surfactant mixing ratio and emulsification time. Surfactant concentration was found to be inversely related to droplet size and directly related to stability. Increase in emulsification time resulted in decrease in droplet diameter. Stable cinnamon oil formulation (CF3) having droplet diameter of 65 nm was formulated after sonication for 30 min. Formulated nanoemulsion was evaluated for bactericidal efficacy against Bacillus cereus. Time and concentration dependent killing of B. cereus cells was observed upon treatment with nanoemulsion. Even at a higher dilution of CF3, significant reduction in bacterial population was observed. Alteration in membrane permeability of interacted samples was suggested by quantifying the release of UV absorbing materials. Bacterial staining with acridine orange/ethidium bromide supported kinetics of killing data and also substantiated the above findings of alteration in membrane permeability. FTIR illustrated disappearance of peak corresponding phosphate vibration at 1078 cm-1 and 536 cm-1, and peak associated with vibration of acyl chains of lipid at 2852 cm-1 was shifted to 2854 cm-1 which suggested deformation of membrane phospholipids in nanoemulsion treated cells. SEM observations demonstrated membrane distortion leading to cell lysis. These results propose the potential use of cinnamon oil nanoemulsion for preservation of minimally processed food. Copyright © 2013 American Scientific Publishers All rights reserved.

Journal of Nanoscience and Nanotechnology

Cinnamon Oil Nanoemulsion Formulation by Ultrasonic Emulsification: Investigation of Its Bactericidal Activity

Basil oil (Ocimum basilicum) nanoemulsion was formulated using non-ionic surfactant Tween80 and water by ultrasonic emulsification method. Process of nanoemulsion development was optimized for parameters such as surfactant concentration and emulsification time to achieve minimum droplet diameter with high physical stability. Surfactant concentration was found to have a negative correlation with droplet diameter, whereas emulsification time had a positive correlation with droplet diameter and also with intrinsic stability of the emulsion. Stable basil oil nanoemulsion with droplet diameter 29.3 nm was formulated by ultrasonic emulsification for 15 min. Formulated nanoemulsion was evaluated for antibacterial activity against Escherichia coli by kinetics of killing experiment. Fluorescence microscopy and FT-IR results showed that nanoemulsion treatment resulted alteration in permeability and surface features of bacterial cell membrane. © 2012 Elsevier B.V. All rights reserved.

Fulltext

Ultrasonics Sonochemistry

Ultrasonic emulsification of food-grade nanoemulsion formulation and evaluation of its bactericidal activity

Background: Nanoemulsion composed of neem oil and non-ionic surfactant Tween 20, with a mean droplet size ranging from 31.03 to 251.43 nm, was formulated for various concentrations of the oil and surfactant. The larvicidal effect of the formulated neem oil nanoemulsion was checked against Culex quinquefasciatus. Results: O/W emulsion was prepared using neem oil, Tween 20 and water. Nanoemulsion of 31.03 nm size was obtained at a 1:3 ratio of oil and surfactant, and it was found to be stable. The larger droplet size (251.43 nm) shifted to a smaller size of 31.03 nm with increase in the concentration of Tween 20. The viscosity of the nanoemulsion increased with increasing concentration of Tween 20. The lethal concentration (LC 50) of the nanoemulsion against Cx. quinquefasciatus was checked for 1:0.30, 1:1.5 and 1:3 ratios of oil and surfactant respectively. The LC 50 decreased with droplet size. The LC 50 for the ratio 1:3 nanoemulsions was 11.75 mg L -1. Conclusion: The formulated nanoemulsion of 31.03 nm size was found to be an effective larvicidal agent. This is the first time that a neem oil nanoemulsion of this droplet size has been reported. It may be a good choice as a potent and selective larvicide for Cx. quinquefasciatus. © 2011 Society of Chemical Industry.

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