RESEARCH PROGRESS IN ANTITUMOR MECHANISMS AND APPLICATIONS OF PECTIN

Pectin is a major component of the primary cellular walls and middle lamella in plant tissues,which contains large amount of poly D-galacturonic acid bonded via α-1,4-glycosidic acid linkage.According to the different sources and extraction methods,the backbone structure of pectin consists of three types of galacturonic acids including homogalacturonan (HG),rhammogalacturonan-Ⅰ(RG-Ⅰ) and rhammogalacturonan-Ⅱ(RG-Ⅱ).At present,extensive studies of pectin antitumor activities have been focused on colon cancer and its direct or indirect roles on probiotics in intestine.As a dietary fiber,natural pectin can be degraded and fermented by colonic microbes,which is helpful to reduce the risk of colon cancer.However,to enhance its bioavailability and bioactivity,pectin is modified into bioavailable modified pectin fragments with low molecular mass and degree of esterification.Galectin-3(Gal-3),a member of the galectin family,binds with its glycol-ligands on the cell surface,and participates in multiple biological processes including tumor angiogenesis.It is reported that the antitumor activity of quite a number of modified pectin fragments arise from intervention in ligand recognition by Gal-3,a key target in cancer cells.Basing on the molecular structure of pectin,this paper mainly reviewed the results of recent investigations on antitumor activities and mechanisms of natural pectin and modified pectin as well as applications of the pectin in cancer therapy,which could provide certain references for further researches in the future.