Investigation of novel radical scavenging mechanisms in the alkaline environment: Green, sustainable and environmentally friendly antioxidative agent(s)

Abstract

Pharmaceutical and industrial utilization of synthetic chemicals has an immerse impact on the environment. In that sense, novel chemicals with potential for industrial application should be investigated for their behaviour in reactions with hydroxyl radical, simulating AOPs (Advanced Oxidation Processes). AOPs are known for being highly effective in wastewater management and natural water remediation. In this paper, exhaustive research on the radical scavenging activity of a newly synthesized coumarin derivative (4HCBH), as a representative of the series of coumarin-benzohydrazides with high antioxidative potential was conducted. This study took into consideration the pH value range significant for practically all living organisms (pH = 7.0-8.5). According to the experimentally obtained results, the 4HCBH showed an increase in radical scavenging activity, following the slight increase in pH values, which suggested that the formation of anionic form of 4HCBH is responsible for its antiradical activity. Further investigations led to the postulation of a novel mechanistic approach called Sequential Proton Loss Electron Transfer - Radical-Radical Coupling (SPLET-RRC), in which, by a series of steps, a new, stable compound was formed. Furthermore, it was demonstrated that the product generated through SPLET-RRC showed lower toxicity than the parent molecule.

Keywords: Advanced oxidation processes; Alkaline environment; Coumarin; Electron paramagnetic resonance; Hydroxyl radical.