Abstract
Di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) exhibits significant antitumor activity. However, the mechanism of its pharmacological interaction with human serum albumin (HSA) and DNA remains poorly understood. Here, we aimed to elucidate the interactions of Dp44mT with HSA and DNA using MTT assays, spectroscopic methods, and molecular docking analysis. Our results indicated that addition of HSA at a ratio of 1:1 did not alter the cytotoxicity of Dp44mT, but did affect the cytotoxicity of the Dp44mT-Cu complex. Data from fluorescence quenching and UV-VIS absorbance measurements demonstrated that Dp44mT could bind to HSA with a moderate affinity (Ka = approximately 104 M−1). CD spectra revealed that Dp44mT could slightly disrupt the secondary structure of HSA. Dp44mT could also interact with Ct-DNA, but had a moderate binding constant (KEB = approximately 104 M−1). Docking studies indicated that the IB site of HSA, but not the IIA and IIIA sites, could be favorable for Dp44mT and that binding of Dp44mT to HSA involved hydrogen bonds and hydrophobic force, consistent with thermodynamic results from spectral investigations. Thus, the moderate binding affinity of Dp44mT with HSA and DNA partially contributed to its antitumor activity and may be preferable in drug design approaches.
Highlights
Novel Fe and Cu chelators have emerged as a promising anticancer strategy [1]
We used spectroscopic and molecular modeling methods to investigate the interaction between Dp44mT and human serum albumin (HSA)
The results showed that Dp44mT was associated with HSA at three well-defined binding sites as other drugs via hydrogen bonds, hydrophobic forces, and van der Waals contacts as a spontaneous process
Summary
Novel Fe and Cu chelators have emerged as a promising anticancer strategy [1]. The iron chelator di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) exhibits excellent antitumor activities in human pancreatic, melanoma, and neuroepithelioma xenografts, and reduces metastasis in a breast cancer model [2,3,4,5,6]. TThheerreeffoorree,, wwee ddeetteerrmmiinneedd tthhee UUVV--VVIISS ssppeeccttrraa ooff HHSSAA iinn tthhee aabbsseennccee oorr pprreesseennccee ooff DDpp4444mmTT ttoo ddeetteerrmmiinnee tthheebbininddininggaffiafnfiitnyitoyf Dofp4D4pm4T4mwTithwHitShA.HASApe. aAk sphiefatkwasshiofbt sweravsedob(Fsiegruvreed2a(F).igMuorreeo2vae).r, Minotrheeodviefrfe, rienntcheespdeifcfterruemnc(eFisgpuercetr2ubm), a(nFiagpuprreo2xbim), aatnelayp7pnrmoxsimhiafttewlyas7onbmsersvheidftwwhaesnoebxsceersvseDdpw44hmenT ewxacessasdDdepd4,4fmuTrthwerassuapdpdoerdti,nfgurththeeirntseurpapctoiortninbgettwheeeinnttehreasceticoonmbpeotwneenetns.tThehseeBceonmespi-oHneilndtesb. Respectively; Ka is the effective quenching constant for the accessible fluorophores, which is analogous where, for our study, F0 and F are the fluorescence intensity in the absence and presence of the quencher, respectively; Ka is the effective quenching constant for the accessible fluorophores, which is analogous to the association binding constants for the quencher-acceptor system; [Q] is the concentration of the quencher; and fa is the fraction of accessible fluorescence. The equilibrium process of HSA and Dp44mT can be described by the following equation, and the the iicmmTouhppleoodrretbtaqaenunctitablilibbcnuirdnilaiudntmegindpgptahrrporaoamcureeagstmhserotesh,fteeiHnrpscSll,ouAitdnsiac[n2nlgu5d]td:hDienpags4st4ohmceiaTatiscosanonccoibanetsitdoaennstcc(roKinbb)setadanndbtyn(utKhmbe)bfeaornlodlof bwniunindmginbegeqrsuitoaefstib(oninn),,dainndg sites (n), could be calculated through the plots [25]: ˆ lloogg.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
