Alginate: A Promising Polysaccharide For Delivery Of Essential Oils

Naturally occurring polysaccharides are of interest in pharmaceutical and cosmetic applications due to their biodegradability, biocompatibility and non-toxicity. Among these polysaccharides, alginate, a linear polysaccharide that is extracted from marine brown algae, is widely used as a particulate carrier for encapsulation, controlled release and delivery of a variety of bioactive compounds to target organs. Due to its bioadhesive, anionic and colloidal properties, alginate can interact with divalent cations or cationic polymers to form hydrogel micro- or nanoparticles that have specificity for mucosal tissues. A particular area of interest is the use of alginate as a shell or matrix material for encapsulation of essential oils. These oils have therapeutic properties that include antibacterial, antifungal, antiviral, antioxidant, and insect-repellent effects, but are insoluble in water, volatile and unstable in certain environments. This has limited development of new formulations and encapsulation of the oil in carriers is required to overcome these problems. Size reduction of the carriers to the nanometer scale greatly improves the efficacy of the delivery system and may allow targeting of the pharmacological activity of the oil to specific organs. In this review, we focus on an overview of alginate and essential oils, the preparation of alginate matrices from large to nanometer scale, and encapsulation of essential oils in these matrices. The prospects for development of improved alginate nanoparticles as delivery systems for essential oils are discussed at the end of the chapter.