title: Enhancement of aqueous stability of allyl isothiocyanate using nanoemulsions prepared by an emulsion inversion point method.
abstract: Allyl isothiocyanate (AITC), an organosulfur compound in cruciferous vegetables, is a natural antimicrobial and potential chemopreventive agent. However, the instability of AITC in aqueous systems restrains its applications. In this study, oil-in-water AITC nanoemulsion was prepared by the emulsion inversion point (EIP) method, aiming at improving the aqueous stability of AITC. The optimal hydrophilic-lipophilic balance (HLB(op)) value of surfactants containing Tween 80 and Span 80 was established at 11.0-13.0, yielding nanodroplets with diameters of 137-215 nm. The mechanism of droplet formation within the HLP(op) region was discussed in terms of the possible structure of adsorbed surfactant layers at the oil-water interface in multiple emulsion droplets. In a 6.5-month storage test, the droplet sizes and the count rates (intensity of scattered light) of nanoemulsions decreased only slightly by 4-13% (depending on surfactant-to-oil ratio), even in highly diluted status, indicating the desirable stability of the nanoemulsions. Moreover, the nanoemulsion demonstrated superior protection against AITC degradation (78% remaining after 60 d at 30 °C), compared with protein nanoparticles as well as non-encapsulated aqueous dispersion. This work shows for the first time that AITC can be formulated into nanoemulsions and thus obtains satisfactory aqueous solubility and chemical stability.
authors.affiliation: Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, United States.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, United States.
authors.forename: Zi
authors.initials: Z
authors.lastname: Teng
authors.affiliation: US Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Food Composition and Methods Development Laboratory, Beltsville, MD 20705, United States.
authors.forename: Pei
authors.initials: P
authors.lastname: Chen
authors.affiliation: Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, United States.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, United States.
authors.forename: Yangchao
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, United States. Electronic address: wangqin@umd.edu.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D004655:Emulsions / Q000138:chemical synthesis* / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D017879:Isothiocyanates / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D004655:Emulsions; D017879:Isothiocyanates; D013501:Surface-Active Agents; D014867:Water; C004471:allyl isothiocyanate
keywords: Allyl isothiocyanate; Emulsion inversion point (EIP); Hydrophilic–lipophilic balance (HLB); Nanoemulsion; Nanoparticles; Span 80; Stability; Storage; Tween 80