Study On The Tissue Distribution In Vivo And Anticancer Activities Of Catesbeianalectin

Lectins were biological peptide which could agglutinate erythrocytes ? bind glycoproteins and sugar complexes,Wherein the low molecular weight lectin dued to the low toxicity and low immunogenicity could be used as an ideal drug targeting carrier.Currently marine organisms and crustaceans lectins were reported more,and most molecular weight exceeded 10 KDa,which had toxicity and immunogenicity.A lectin-like peptide named Catesbeianalectin was the first small molecular peptide that was screened from the c DNA library of Rana Catesbeiana skin,its molecular weight was only1.47 KDa,which was the smallest lectin so far.In our previous study,the structure of Catesbeianalectin was examined,the bacterial agglutination activity and special saccharide ligand were also studied.And it showed that its secondary structure was typical PP?heli,amphiphilic cationic polypeptide with low immunogenicity,and mainly interaction with glactose and polysaccharide containing glactosyl.It was classified S-lectin.It had not been reported about its metobolism and distribution in vivo and antitumor activity.To provide reliable experimental basis for the safety assessment and the targeting research,the metabolism and tissue distribution in vivo were studied.Radioisotope 125 I labeled Tyr-Catesbeianalectin by chloramine-T,it was purified and determined stability.Through intravenous(i.v.),intraperitoneal(i.p.)and irrigate(i.g.)adminstration routes of 125I-Tyr-CL,dynamic bioimagings were performed at the different times,Observed the dynamic changes of the distribution of radioactivity in the mice tissues with radiocounting-time curves.The results revealed that the labeling rates and radiochemical purities of the 125I-Tyr-CL were 97.3% and99.3%.And has the desired stability and tissue distribution in vivo and vitro simulated experiments.125I-Tyr-CL was proved to mainly accumulate in liver?spleen and lung after i.v.and delivery in liver,And mainly accumulate in stomach and spleen after i.p.and i.g.,and delivery in stomach.After three adminstration routs of 125I-Tyr-CL,it could not pass the blood-brain barrier,which laid the research function for its drug targeting carrier.In order to improve thet argeted inhibition of Catesbeianalectin,Temporin-La and its transformation Temporin-La1 peptide were coupling designed.Meanwhile,RGD is a small peptide amino acid residues,which could promote apoptosis of tumor cells with targeted,comparative study of targeted action with Catesbeianalectin.The MTT assay results showed Catesbeianalectin has the low cytotoxicity,Antimicrobial peptides and chimericpeptide has the killing effects in dose-dependent manner and the high sensitivity of human hepatoma cell(Hep G-2).Comprehensive results of this study,Catesbeianalectin had good stability and tissue distribution of mice in vivo and vitro,It showed faster metabolic rate in the liver tissue that is the main metabolic organ,and intravenous injection is the preferred mode of administration,with lower cell toxicity and hemolysis.For the first time established targeted chimeric peptide of Catesbeianalectin conjugated with antimicrobial peptides,in vitro experiments confirmed that the chimeric peptide had great tumor cell killing vitality.Thus,the present study provides a preliminary research basis for Catesbeianalectin on targeted cancer therapy as targeting carrier.