Liquid Quality Recognition Of The Anticancer Drug NL-101 Interacting With Amino Acids And Polypeptides

Nitrogen mustard compounds are anti-tumor drugs that have been applied to the clinic and performed well since 1950s.Once a nitrogen mustard drug came into the body,an ethylene imide ion was formed through intramolecular cyclization and this active ion could react with the nucleophilic groups of various biomolecules such as protein and DNA,resulting in alkylation of these molecules and consequently the loss of their biological activities.The alkylated products of proteins,whose structural features are still seldom studied,can influence the metabolism of and consequently bring side effects on cancer patients.Therefore,it is important to develope a fast and valid method that can rapidly identify the structures of alkylated proteins.Due to its high sensitivity,less sample usage and capability to provide structural information for a given compound,mass spectrometry is playing a key role in the studies of drug metabolism.Here,by using the high performance liquid chromatography-electrospray ionization-tandem mass spectrometry(HPLC-ESI-MS/MS)technique,an analytical method was developed to identifiy the interactions between the nitrogen mustard drug NL-101 and amino acids/peptides.1.Study of the stability of NL-101.When NL-101 is dissolved in aqueous solution,the corresponding ethylene imide ion will be formed through the intramolecular cyclization process.Based on this property,we simulated physiological environment and investigated the effects of pH and incubating time on NL-101's in vivo evolution.NL-101 and the corresponding evolution products were identified by using HPLC-MS.The results showed that under the neutral and alkaline conditions,NL-101 was easier to react with the nucleophilic group or hydrolyze.After incubation of 9 hours,half of the NL-101 molecules were hydrolyzed.2.Study of the interactions between NL-101 and amino acids:NL-101 were combined with various amino acids and incubated for 4 hours under different pH conditions.The binding sites between ethylene imide ion and amino acids were investigated using HPLC-ESI-MS/MS under the CID condition.The binding sites were identified by analyzing the characteristics of fragment ions.Our results indicated that compared with the adducts between ethylene imide ion and carboxylic group,the adducts between ethylene imide ion and amino group were more fragile to collision and produced more fragment ions through which more structural information therefore can be obtained;for the adducts between ethylene imide ion and other groups of amino acids,particular fragmentation patterns were observed in their CID MS results.3.Study of the interactions between NL-101 and peptides:On the basis of the studies of the NL-101-amino acid interaction,the interaction between NL-101 and several peptides(carnosine,anserine,glutathione and glycyl-L-histidyl-L-lysine)were investigated.The binding sites were identified by analyzing the CID MS/MS fragment ions of the adducts between ethylene imide ion and peptides.