Study On The Physical Preparation Of Low Molecular Citrus Pectin And Preliminary Evaluation Of Its Anti-Cancer Activity

Citrus pectin (CP) is a kind of dietary fiber. However, it cannot be enoughly absorbed and used by human body due to its large molecular mass and the lack of degraded enzymes in human gastrointestinal tract. Accoding to the report, CP owns the anti-cancer activity. Similarly, the CP is hard to achieve better anti-cancer effectiveness because of its large molecular weight. Nevertheless, the molecular weight of CP can be reduced after treated by chemical method, namely pH modification, with the product Low Molecular Citrus Pectin (LMCP) obtained. LMCP is readily absorbed by the intestinal tract and entered into blood circulation to play its roles. Currently, the pH modification technology to prepare LMCP tends to be mature, but this method is time-consuming with cumbersome operations. On the contrary, the operation of physical methods is simple, resource and time saving. However, the study of physical methods to prepare LMCP is less and not systemic. LMCP preparation using physical methods was studied and preliminary evaluation of its anti-cancer activity was carried on in this paper. The results were summarized as follows.With Satsuma mandarin peel as raw material, the citrus pectin solution extracted was treated with high pressure steam or high pressure homogenization. On comprehensive consideration of molecular weight, pectin yield and sensory evaluation, the method to prepare LMCP was preferentially chosen as high pressure steam with the treatment condition under120℃,101.2MPa for30minutes. LMCP was yellow solid powder with the yield of3.1%and molecular weight of16kDa.The physical and chemical properties of Satsuma mandarin peel LMCP were determined. The results showed that Satsuma mandarin peel LMCP was uniform polysaccharide and didn’t contain protein and nucleic acid. Compared with the CP, the galacturonic acid content of LMCP was increased from74%to88%and the degree of esterification declined from70% to62%. The moisture content of LMCP was6.15%and the acid insoluble ash content was0.48%. The contents of heavy metals as lead, arsenic, mercury and cadmium were conformed to the stipulation of Chinese National Food Safety Standards. The LMCP was composed of rhamnose, arabinose, xylose, glucose and galactose in monosaccharide and had powerful capability to scavenge hydroxyl free radicals.With Satsuma mandarin pomace, Citrus changshan-huyou peel and Citrus changshan-huyou pomace as raw material, LMCP was respectively prepared by treating the CP extracted with the same method of high pressure steam as above for Satsuma mandarin peel. The results showed that the molecular weight of Satsuma mandarin peel and Citrus changshan-huyou pomace declined significantly with the Mw decreased by92%and89%respectively, and their molecular weight were around10kDa. The Mw of Satsuma mandarin pomace and Citrus changshan-huyou peel decreased by70%and65%respectively, with the molecular weight more than50kDa. After treated with high pressure steam, galacturonic acid contents of four pectins were increased to different extent, and the degrees of esterification were declined differently.The anti-cancer activities of LMCPs were preliminaryly evaluated. The results showed that LMCPs had strong inhibition capacity against prostate cancer PC3cells. The inhibition of LMCPs in high doses (5-10mg/mL) to PC3cells viability was between70%-90%and the half inhibition concentrations (IC50) of LMCPs declined obviously compared with those of CPs. The anti-cancer activities of Satsuma mandarin peel LMCP and Citrus changshan-huyou pomace LMCP were higher and more stable than the other two. Compared with natural CPs, the inhibition capacity against prostate cancer cells increased significantly in LMCPs.In this research, the molecular weight of LMCP prepared respectively from Satsuma mandarin peel and Citrus changshan-huyou pomace by the method of high pressure steam was lower and the anti-cancer activity was better. Therefore, Satsuma mandarin peel and Citrus changshan-huyou pomace were regarded as the better raw materials to prepare LMCP.