Biological functions of citrus pectin and its applications in biomedicine

Abstract:Polysaccharides from different sources have been studied for a long time. Currently, the poly-saccharides used in the pharmaceutical and biomedical domains are primarily chitin, chitosan, alginates,hyaluronan and pectin. The biological functions and applications of citrus pectin(CP) in biomedicine aresummarized in this paper. CP has important biological functions, such as antioxidant, anti-inflammatory,anticancer, hypolipidemic, heavy metal adsorption and drug or cell delivery. As a miracle polymer, CP is ahigh value food additive used in the food industry. During recent researches, CP attracted extensive atten-tion in the biomedical domain. It has been exploited for different biomedical applications, such as drug de-livery, wound healing, gene delivery and tissue engineering due to its eminent biodegradability, biocom-patibility, safety, non-toxic, low cost and other characteristics. Sometimes, CP is used for anti-aging pur-poses in cosmetic formulations. As we all know, pectin remains intact in the upper gastrointestinal tractwhere it can be rapidly degraded by colonic microorganisms. Thus, pectin-derived drug carriers whichwere used as colon targeted drug delivery carriers and for cancer treatment have attracted more and moreattention in recent years. China is rich in Citrus germplasms and has an ongoing annual production of Citrus fruits. The by-products of the citrus juice processing industry account for almost 30% of the totalweight of the citrus fruits processed, of which about 25% is pectin. Studies on CP can not only make fulluse of various resources but can also solve the environmental pollution caused by the juice processing in-dustry. CP-based biomaterials including hydrogels, films, microspheres and nanoparticles have broaderapplications in the biomedical domain primarily owing to their important biological functions. Recently,there has been growing interest in the potential role of CP in prevention and reduction of carcinogenesis.To improve the biological functions and bioavailability of CP, it can be modified into bioavailable modi-fied pectin fragments(MPs) which have a low molecular mass and degree of esterification(DE). Modifica-tion leads to the alterations in physical and chemical properties of CP by allowing ease in transforming theacidic group into ester, amide or other forms, which play an important role in its biological activities. Ithas been suggested that the antitumor activity of MPs primarily is the result of the intervention in ligandrecognition by galectin-3(Gal-3). Several studies have demonstrated the efficiency of MPs in cancer treat-ment, but the underlying mechanisms still need to be fully explored. Using different CP-based vehiclescan protect drug or bioactive compounds from the harsh environment. In addition, they can also controlthe drug release, and achieve sustained release of the carried-drug. Reducing the toxic and side effects ofdrugs is also one of their advantages. However, the hydrophilic of CP restricts its application in pharma-ceutical sciences. In recent years, many new technologies have occurred which can overcome this short-coming, such as nanotechnology, which combines the advantages of pectin and nanomaterials. Nanotech-nology used in drug delivery has increasingly substituted traditional methods of administration for drugs,which can improve the solubility of some hydrophobic medicines and protect their natural macromoleculefrom the physical environment. CP-based carriers with negative charges and hydrophilic groups on theirsurfaces, can absorb proteins and adhere to cell membranes. However, they can be easily cleaned up bythe reticuloendothelial system. In this paper, the current research status of the biological functions and ap-plications in biomedicine of CP are fully presented. Our aim is to grasp the advances and trends of the CP-based biomaterials, and move outside the traditional scopes of their applications. The biological functions,CP-based formations, new progresses and utilizations of CP or MCPs were systematically introduced. Now-adays, CP is considered as a novel candidate for drug delivery systems, soft and hard tissue engineeringand dental titanium coatings and are under enthusiastic investigations in the biomaterial domains. Thoughsome advances have been made, there still exists some novel applications that need to be explored. Wehope to provide new information for utilization of the rich citrus genetic resources in China and investigatethe tremendous benefits of CP for different human health applications.