Harnessing natural polysaccharides-based nanoparticles for oral delivery of phytochemicals: Knocking down the barriers

Natural polysaccharides are one of the most abundant and renewable biocompatible and biodegradable natural materials. Since the beginning of the 21st century, natural polysaccharides-based nanoparticles have been extensively investigated for oral delivery of drugs/phytochemicals owing to their excellent characteristics including non-immunogenicity, biodegradability, and biocompatibility. Phytochemicals are natural bioactive compounds abundantly present in different plants, fruits, vegetables, grains, and spices. A wide variety of phytochemicals are used clinically to treat different diseases, to prevent as well as maintain health since the ancient era. Despite the exceptional therapeutic efficacy of phytochemicals, their administration via the oral route to treat any ailment is limited owing to their high lipophilicity, instability in the gastrointestinal environment, and poor intestinal permeation, thereby low oral bioavailability. In addition, some potential barriers in the gastrointestinal tract (GIT) like metabolizing enzymes, efflux transporter, mucus, and tight junctions between the epithelial cells also limit their overall bioavailability. The encapsulation of phytochemicals in these natural polysaccharides based nanocarriers represents the advantages like, (i) protection of phytochemicals from the harsh environment of GIT, (ii) protection from the pre-systemic metabolism from by different enzymes present in the GIT, (iii) controlled dissolution rate, (iv) enhanced intestinal permeation by the opening of tight junction and by increasing mean residence time in GIT due to mucoadhesiveness, and (v) enhanced oral bioavailability. These benefits make the natural polysaccharides-based NPs ideal nanocarriers for improved oral delivery of phytochemicals. This review aimed to discuss the recent advancement in phytochemical loaded natural polysaccharides particularly chitosan, alginate, dextran, pectin, and starch-based nanoparticles for enhanced oral bioavailability and bioactivity.