Handbook of Vitamin C Research

186Magdalena Stevanović and Dragan Uskokovićwhich ascorbic acid can be successfully encapsulated are poly (DL-lactide-co-glycolide),tripolyphosphate cross-linked chitosan, liposomes, maltodextrin, dendrimers, etc.Encapsulation efficiency, release rate, size distribution of particles with encapsulatedascorbic acid, are some of the parameters which are used for evaluating encapsulationsystem characteristics.1. IntroductionAscorbic acid (vitamin C) is essential for preserving optimal health and it is used by thebody for many purposes [1]. Vitamin C has many functions such as: stimulates white bloodcells and antibody production; it is vital component of all body cells; essential formanufacture of collagen; needed for healthy connective tissue, skin, bones and vascularsystem; it is powerful antioxidant; required for proper wound healing and tissue regeneration;has powerful effects on the production of important chemicals for the control of hormonesand brain function; assists iron absorption and it is natural antihistamine [2].The problem is that ascorbic acid easily decomposes into biologically inactivecompounds making its use very limited in the field of pharmaceuticals, dermatologicalproductss and cosmetics [1]. In order to overcome chemical instability of ascorbic acid, aconsiderable amount of research has been staged towards its encapsulation or immobilization.Ascorbic acid cannot be synthesised and stored in the body. The ascorbic acid introduced inthe body in the greater portion is isolated from the body. However, the encapsulated ascorbicacid within, for example, polymeric particles should have significantly higher stability andefficiency [3].Encapsulation provides an invaluable tool to the pharmaceutical and/or cosmeticformulator, providing great flexibility in the choice of delivery mechanisms and excipientsthat can be used [4-7]. For example, active pharmaceutical ingredients can be delivered insystems that would otherwise be unacceptable or hostile to them. For example, water-solubleingredients can be delivered in non-aqueous systems such as ointments. The matrix of thecapsule can be chosen from a wide variety of materials (usually selected from a list ofmaterials ―generally recognized as safe‖ (GRAS) for pharmaceutical applications [8]) tomeet the needs of the application as well as regulatory demands, e.g., biodegradability.Multiple actives can also be delivered in the same particle; indeed, mutually chemicallyincompatible actives can be formulated together. A further way to exploit this technology isto encapsulate one ingredient that can facilitate, or stabilize, a second [9,10]. By isolatingproblematic ingredients, formulation and processing issues are minimized; undesirableproperties can be masked.Micro and nanoparticles can be used to deliver a wide variety of substances ashydrophilic or hydrophobic drugs, proteins, vaccines, biological macromolecules, vitaminsetc. and they can be administrated in different ways in the body [11-18].Generally recognized as safe (GRAS)--substances for which use in food has a proven track record of safety basedeither on a history of use before 1958 or on published scientific evidence, and that need not be approved bythe FDA prior to being used.