Multivariate spectrochemical analysis of interactions of three common Isatin derivatives to calf thymus DNA in vitro.
Interactions of Isatin and its derivatives, Isatin-3-isonicotinylhydrazone (IINH) and Isatin-β-thiosemicarbazone (IBT), with calf thymus DNA (ctDNA) have been investigated to delineate pharmaceutical-physicochemical properties using UV-Vis/fluorescence/circular dichroism (CD) spectroscopy, viscosity measurements, and multivariate chemometrics. IINH and IBT molecules intercalate between base pairs of DNA, hypochromism in UV absorptions, increase in the CD positive band, sharp increase in specific viscosity, and the displacement of the methylene blue and Neutral Red dye in complexes with ctDNA, by the IINH and IBT molecules, respectively. The observed intrinsic binding constants (Kb[IBT-ctDNA]= 1.03 × 105and Kb[IINH-ctDNA]= 1.09 × 105L mol-1) were roughly comparable to other intercalators. In contrast, Isatin binds with ctDNA via groove mode (Kb[Isatin-ctDNA]= 7.32 × 104L mol-1) without any significant enhancement in ctDNA viscosity. The fluorescence quenching of Isatin by ctDNA was observed as static. CD spectra indicated that Isatin effectively absorbs into grooves of ctDNA, leading to transition from B to C form. Thermodynamic parameters like enthalpy changes (∆H < 0) and entropy changes (∆S > 0) were calculated according to Van't Hoff's equation, indicating the spontaneous interactions. The common soft/hard chemometric methods were used not only to resolve pure concentration and spectral profiles of components using the acquired spectra but also to calculate Stern-Volmer quenching constants, binding stoichiometry, apparent binding constants (Ka), binding constants (Kb), and thermodynamic parameters. The Kbvalues for Isatin, IINH, and IBT were calculated as 9.18 × 103, 1.53 × 105, and 2.45 × 104L mol-1, respectively. The results obtained from experimental-spectroscopic analyses showed acceptable agreement with chemometric outlines.
a Department of Chemistry , Institute for Advanced Studies in Basic Sciences (IASBS) , Zanjan 45137-66731 , Iran.
Mohammad
M
Shahbazy
b Department of Chemistry , Zanjan Branch, Islamic Azad University , Zanjan , Iran.
Parvaneh
P
Pakravan
a Department of Chemistry , Institute for Advanced Studies in Basic Sciences (IASBS) , Zanjan 45137-66731 , Iran.
Mohsen
M
Kompany-Zareh
D000818:Animals; D002417:Cattle; D002942:Circular Dichroism / Q000379:methods; D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006835:Hydrazones / Q000737:chemistry* / Q000378:metabolism; D066298:In Vitro Techniques; D007510:Isatin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D015999:Multivariate Analysis; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013816:Thermodynamics
D006835:Hydrazones; C573075:isatin-3-isonicotinylhydrazone; C013578:isatin beta-thiosemicarbazone; D007510:Isatin; D004247:DNA; C427203:calf thymus DNA
Isatin derivatives; binding/Stern–Volmer quenching constants; calf thymus DNA; soft/hard chemometric modeling; thermodynamic parameters