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Caffeic acid (CA) is a plant polyphenol which acts as an antioxidant and has various pharmacological effects. DNA is one of the major cellular targets of therapeutic molecules. Thus, studying the interaction of small molecules with DNA is of great importance. In the current article, we have studied the mode of binding of CA with calf thymus DNA (Ct-DNA) using a series of biophysical techniques. Formation of complex between CA and Ct-DNA is ascertained by analyzing the UV-vis absorbance and fluorescence emission spectra of CA upon successive addition of Ct-DNA. Binding constants of CA with Ct-DNA obtained using multiple experiments was in the order of 103 M-1 which is consistent with known groove binders. Analysis of thermodynamic parameters suggest that hydrogen bonding and van der Waal's forces played major role in the binding process. Competitive displacement studies confirmed that CA binds to the minor groove of Ct-DNA. These observations were further validated by KI quenching experiment, DNA melting studies, CD and viscosity measurements. In silico molecular docking further provided insight into the mode of binding of CA with Ct-DNA. Through in vitro experiments and in silico molecular docking studies, it was concluded that CA binds to the minor groove of Ct-DNA., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Drug-DNA interactions have been extensively studied in the recent past. Various techniques have been employed to decipher these interactions. DNA is a major target for a wide range of drugs that may specifically or non-specifically interact with DNA and affect its functions. Interaction between small molecules and DNA are of two types, covalent interactions and non-covalent interactions. Three major modes of non-covalent interactions are electrostatic interactions, groove binding and intercalative binding. This review primarily focuses on discussing various techniques used to study non-covalent interactions that occur between drugs and DNA. Additionally, we report several techniques that may be employed to analyse the binding mode of a drug with DNA. These techniques provide data that are reliable and simple to interpret., (Copyright © 2015 Elsevier Inc. All rights reserved.)

DNA is the major target for a wide range of therapeutic substances. Thus, there has been considerable interest in the binding studies of small molecules with DNA. Interaction between small molecules and DNA provides a structural guideline in rational drug designing and in the synthesis of new and improved drugs with enhanced selective activity and greater clinical efficacy. Plant derived polyphenolic compounds have a large number of biological and pharmacological properties. Coumarin is a polyphenolic compound which has been extensively studied for its diverse pharmacological properties. However, its mode of interaction with DNA has not been elucidated. In the present study, we have attempted to ascertain the mode of binding of coumarin with calf thymus DNA (Ct-DNA) through various biophysical techniques. Analysis of UV-visible absorbance spectra and fluorescence spectra indicates the formation of complex between coumarin and Ct-DNA. Several other experiments such as effect of ionic strength, iodide induced quenching, competitive binding assay with ethidium bromide, acridine orange and Hoechst 33258 reflected that coumarin possibly binds to the minor groove of the Ct-DNA. These observations were further supported by CD spectral analysis, viscosity measurements, DNA melting studies and in silico molecular docking., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Non-covalent interactions of chlorambucil with calf thymus DNA was investigated using multi-spectroscopic techniques and molecular docking study. Binding constant calculated was found to be 1.54×10(4)M(-1) at 290K, significantly lower than various known intercalators. Quenching process was found to be static as evident by biomolecular quenching constant. Thermodynamic parameters revealed the involvement of hydrophobic interactions and hydrogen bonds in the binding. Chlorambucil was found to interact via external binding mode and follow groove binding as it replaces Hoechst (a typical groove binder) from the groove of DNA but does not replace intercalating dyes including ethidium bromide and acridine orange from the DNA helix. These results were further supported by KI quenching experiments, DNA melting studies, CD spectroscopy and molecular docking., (Copyright © 2014 Elsevier Inc. All rights reserved.)