Synthesis Of Rare Earth Complexes With The Derivatives Of Chitosan Oligosaccharides

It is known to all that rare earth(RE) salts have the anticancer effects, but are difficult to be absorbed by human body. On the other hand, chitosan oligosaccharide derivatives(COD) can be absorbed by human body easily, and can prepare complexes with trivalent rare earth metal ions(RE3+). Therefore, complexes of COD with RE3+were prepared so as to utilize the anti-cancer ability of RE3+in human body.In this research, three kinds of COD were prepared. They are carboxymethyl chitosan oligosaccharide(CM-COS), N-methylene phosphonic chitosan oligosaccharide(NMCP), sulfhydryl chitosan oligosaccharide (SH-COS). Each of the three kinds of COD was used to synthesize complexes with lanthanum(La3+), samarium(Sm3+), gadolinium(Gd3+), respectively. All of the nine complexes were respectively characterized by FTIR, TG, EDX. The effects of DS, pH, reaction time and dose of RE(NO3)3on the formation of coordination compound were investigated, and the coordination mechanism was also studied by conductometric analysis(CA). The results showed that the content of RE3+in the complexes appeared to increase with the increase of DS and dose of RE(NO3)3. The effects of reaction time and pH value on the content of RE3+in the complexes are great, but different to each derivative. The CA indicated that the coordination number of CM-COS with La3+, Sm3+, Gd3+is109,8; NMCP with La3+, Sm3+, Gd3+is9,6,6; SH-COS with La3+, Sm3+, Gd3+is12,10,12, respectively.Finally, the complexes’antitumor activity was tested by MTT method. The results illustrated that the nine complexes can inhibite HepG2and HepG2/ADM cells’proliferation, and NMCP-Sm with a inhibition efficiency of22%comes to the best.The porpose of this research is to provide some help to explore rare earth complexes’ antitumor activity furtherly and to develope new rare earth complexes anticancer medicines.