ABSTRACT
Objective To find the efficient modification groups of anti-proteinase hydrolyzation in polypeptide by investigat-ing and comparing the relation between the functional groups and their ability to inhibit proteinase hydrolyzation. Methods Reverse phase-high performance liquid chromatography(RP-HPLC)method was developed to investigate in vitro metabolisms of new drug LXT101 and its structural modified analogs LZN series and LMP series in pancreatin system. All the separations of peptide drugs and their digested fragments were monitored at 225 nm. Results The good linear range was 4.0-400 μg/ml(r>0.9990)for new drug LXT101 and its structural modified analogs,i.e.,LZN series and LMP series. The recoveries of all peptide drugs ranged from 95.0%to 98.7%in pancreatin systems. The relative standard derivations(RSD)of intra-day and inter-day were less than 1.5%and 2.5%,re-spectively. The revealed order of digested half-life of the peptide drugs was LZN series>LMP series>LXT101. Conclusion The study of different sites and different functional groups on the lifetime indicates that the half-lives of peptides are prolonged by introducing the functional groups in the suitable sites of peptide,which feature as proteinase inhibitors,such as carbamoyl(Cbm),acetyl(Ac),para-amino-phenylalanine(Aph)or para-uramido-phenylalanine(Uph),which work as either proton donor or acceptor. Our results can pro-vide some useful and valuable information on structural design of peptide drug with long lifetime and high activity.