Multifunctional molecular encapsulating agents - Cyclodextrins: Physicochemical properties, safety, solubility, bioavailability and applications in pharmaceuticals and foods.

Cyclodextrins (CDs) are cyclic oligosaccharides made up of α-(1 → 4)-linked d-glucopyranose units and are generally obtained by enzymatic conversion of starch. The purpose of this review is to give a comprehensive overview about the cyclodextrins and their physicochemical properties, safety & toxicological aspects, enhancement of aqueous solubility, stability and bioavailability and applications in pharmaceutical and food system. The published scientific literature was reviewed as a narrative review to investigate structure, physicochemical properties, safety profile, functional mechanisms, and applications of cyclodextrins. Evidence describing their effects on solubility, dissolution, stability, bioavailability, protection of sensitive ingredients, masking of undesirable tastes and odours, and controlled delivery of bioactive compounds was critically evaluated. The evidence reviewed suggests that cyclodextrins can form a stable inclusion complex with appropriate hydrophobic and/or amphiphilic molecules, which can alter the physicochemical and functional properties of the modified molecule. As a result, cyclodextrins have been studied as excipients for oral, ocular, dermal, nasal and rectal drug-delivery systems. Cyclodextrins have been shown to be useful in food systems for the protection of sensitive flavors and aromas, vitamins, lipids and other bioactive ingredients from environmental degradation. Their relative ease of safety, especially for suitably chosen and controlled cyclodextrins, also contributes to their technological usefulness. Cyclodextrins are versatile multifunctional excipients and encapsulation materials, which play significant roles in pharmaceutical and food technology. They can form inclusion complexes with great efficacy for enhancing the solubility, stability, dissolution, and bio-accessibility as well as sensory acceptability of a variety of compounds. Native and modified cyclodextrins thus hold a great potential for the formulation of new drug delivery systems, functional foods, nutraceutics and biotechnology products. Future studies are needed to optimize the cyclodextrin-guest interactions, enhance the formulation efficiency, assess the safety of the long-term use, and develop commercially viable and regulatory-approved products based on laboratory research.