Abstract: Citrus pectin （CP） was prepared from peel and pomace of Satsuma-mandarin and Changshan-huyou by acid extraction and ethanol precipitation method. The CP was treated at 121℃ for 30 min to prepare low molecular weight citrus pectin （LMCP）. The molecular properties including weight，galacturonic acid content and degree of esterification （DE） of LMCP and CP were determined and their resistance capacities on hormone-independent prostate cancer PC 3 cells in vitro were investigated as well. The results indicated that after the high-temperature treatment of four kinds of CP，their molecular weight （Mw） were decreased by 64%-92% with the most for that from Satsuma-mandarin peel and the least for that from Changshan\|huyou peel; the galacturonic acid content were increased by 6%-14% with the highest for that from Satsuma-mandarin peel and the least for that from Satsuma-mandarin pomace; the DE values were declined by 8%-21% with the most for that from Changshan-huyou peel and the least for that from Changshan-huyou pomace. The inhibition of the four kinds of LMCP in high dose （10 mg·mL-1） to PC 3 cell viability were above 70%，among which more than 90% for those were prepared by Satsuma-mandarin peel and Changshan-huyou pomace.

Key words: Satsuma-mandarin peel, Changshan\|huyou pomace, low molecular weight citrus pectin, molecular characteristics, anticancer activities, PC-3 cell