In vitro and in silico binding studies of phytochemical isochroman with calf thymus DNA using multi-spectroscopic and computational modelling techniques

Abstract

A wide range of therapeutic molecules uses deoxyribonucleic acid (DNA) as an intracellular target. The interaction of small molecules to DNA is a key feature in pharmacology and plays a vital role in the development of novel and more efficient drugs with increased selective activity and enhanced therapeutic effectiveness. Isochroman (IC) is a constituent of Olea europea plant, which has been shown to exhibit several beneficial pharmacological activities. At present, its interaction studies using calf thymus DNA (ct-DNA) have not been explained. A set of multi-spectroscopic techniques has been performed to determine the interaction mechanism of isochroman with ct-DNA. Absorption spectra and quenching in fluorescence studies show that isochroman and ct-DNA form a complex. The static mode of quenching was determined by the Stern-Volmer plot. The value of binding constant, K_b = 4.0 × 10³ M⁻¹ revealed moderate type of binding. Effects of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) and ionic strength were studied to examine the isochroman binding to ct-DNA. Potassium iodide (KI) quenching effects and competitive binding studies clearly showed that isochroman binds in the minor groove of ct-DNA. Circular dichroic and DNA melting experiments also confirmed these results. The experimental outputs were further corroborated via in silico computational modelling studies. Lipinski’s rule of 5 and SwissADME showed drug-likeness and oral bioavailability scores. Protox ІІ online software predicts oral and organ toxicity.

Communicated by Ramaswamy H. Sarma

Keywords:

• Isochroman (IC)
• calf thymus DNA (ct-DNA)
• spectroscopy
• fluorescence quenching
• circular dichroism
• computational modelling

Acknowledgement

The authors gratefully acknowledge DBT for providing JRF to SF, ICMR for providing JRF to IH, UGC Non-NET for providing to SA. We also thankful to SS for her help and support. We also appreciate the significant funding provided to the Department of Biochemistry, Faculty of Life Sciences, by the UGC-DRS-SAP and DST-FIST. The authors also thank the Department of Biochemistry (Aligarh Muslim University) for providing the necessary experimental facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Funding

The author(s) reported there is no funding associated with the work featured in this article.