[Purification and anti-cancer activity of ricin].
To extract and purify ricin from castor beans and to evaluate its anti-cancer activity.



Ricin was purified from castor beans according the modified method of Nicolson and Blaustin. The lectins were extracted in 0.01 mol/L phosphate buffered saline and isolated in the 40% to 80% fraction of ammonium sulfate precipitation. The dialyzed fractionated preparation was applied with a Sepharose 4B column. The lectins were eluted with a linear lactose gradient (0.01 mol/L approximately 0.5 mol/L). Ricin was separated from the ricinus agglutinin by gel filtration on a Sephadex G-100. MTT was applied to analyze the cytotoxicity with different dosage of ricin in different cancer cell lines.



There was no difference between the killing effect of normal cells and that of colon cancer cells by using the high dosage of ricin (5 x 10(-8) mol/L approximately 5 x 10(-10) mol/L). However, the cytotoxicity was significant different in those cells with the low dosage of ricin (5 x 10(-11) mol/L approximately 5 x 10(-13) mol/L). Meanwhile ricin had the similar cytotoxicity to leukemia cell K562 and colon cancer cell SW480.



Ricin is able to kill tumor cells selectively at low concentration, but the selectivity does not appear at high concentrations.
Zou
Li-bo
LB
Department of Biochemistry and Molecular Biology, College of Medicine, Zhejiang University, Hangzhou 310006, China.
Zhan
Jin-biao
JB
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020014:K562 Cells; D008297:Male; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley; D012276:Ricin / Q000302:isolation & purification* / Q000494:pharmacology*; D013602:T-Lymphocytes, Cytotoxic
D000972:Antineoplastic Agents, Phytogenic; D012276:Ricin