Radioprotection of thymine and calf thymus DNA by an azo compound: mechanism of action followed by DPPH radical quenching & ROS depletion in WI 38 lung fibroblast cells

Durba Ganguly,Ramesh Chandra Santra,Swagata Mazumdar,Abhijit Saha,Parimal Karmakar,Saurabh Das

doi:10.1016/j.heliyon.2020.e04036

Durba Ganguly, Ramesh Chandra Santra + Show 4 more

Open Access

https://doi.org/10.1016/j.heliyon.2020.e04036

Copy DOI

Abstract

PurposeTo explain the observed radio-protection properties of an azo compound, 2-(2-hydroxyphenylazo)-indole-3∕-acetic acid (HPIA). Materials and methodsMechanism of radioprotection by HPIA was attempted using the stable free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) using UV-Vis and electron paramagnetic resonance (EPR) spectroscopy. The radical destroying ability of HPIA was studied by depletion of reactive oxygen species (ROS) in WI 38 lung fibroblast cells. Results & DiscussionStudies indicate HPIA interacts with radical intermediates formed in solution following irradiation by 60Co γ-rays. As a result, reactive radical intermediates do not cause any damage on chosen substrates like thymine or calf thymus DNA when irradiated in presence of HPIA. The study showed that reactive intermediates not only react with HPIA but that the kinetics of their reaction is definitely faster than their interaction either with thymine or with DNA. Had this not been the case, much more damage would have been observed on chosen substrates following irradiation with 60Co γ-rays, in the presence of HPIA than actually observed in experiments, particularly those that were performed in a relatively high dose. Experiments reveal radiation induced-damage caused to thymine in presence of HPIA was ~ 136 to ~ 132times that caused in its absence under different conditions indicating the radio-protection properties of HPIA. In case of calf thymus DNA, damage in presence of HPIA was much lower than in its absence. A fluorometric microplate assay for depletion of ROS by detecting the oxidation of 2′,7′-dichlorofluorescin-diacetate (DCF-DA) into the highly fluorescent compound 2′,7′ dichlorofluorescein (DCF) indicated HPIA brought about a considerable check on ROS-mediated damage to cells by scavenging them right away. ConclusionThe study indicates HPIA may be an antioxidant supplement during radiotherapy.

Highlights

Radiotherapy is commonly employed as part of a management of a wide variety of malignancies
Reactive radical intermediates do not cause any damage on chosen substrates like thymine or calf thymus DNA when irradiated in presence of HPIA
The study showed that reactive intermediates react with HPIA but that the kinetics of their reaction is definitely faster than their interaction either with thymine or with DNA

Summary

Introduction

Radiotherapy is commonly employed as part of a management of a wide variety of malignancies. Either alone or in combination with other modalities chemotherapy and/or surgery is used. It is reported almost half of all cancer patients receive radiotherapy as part of their treatment [1]. The mechanism by which damage to normal tissues is prevented is called radio-protection and the compounds involved are known as radio-protectors [4]. These are administered either prior to or shortly after radiation exposure to alter response of normal tissues towards radiation and is considered an essential component of radiotherapy [5]

Methods

Results

Conclusion