Reactivity of Indole Derivatives Towards Oxygenated Radicals

Abstract

The reactivity of a series of indole derivatives was assessed in the following systems: (i) oxidation of the indole derivatives induced by the thermolysis of 2,2'-azobis-(2-amidinopropane) (ABAP); (ii) oxidation of cumene induced by the thermolysis of 2,2'-azobis-(2-methyl propionitrile) (AIBN); (iii) lysozyme inactivation induced by the thermolysis of ABAP and (iv) brain homogenate autoxidation. In systems (ii) to (iv), addition of the indole derivatives decreases the rate of the process. The data obtained indicate that common factors (i.e., oxidation potential and presence of N-H bonds) control the reactivity of the indole derivatives in the four systems considered. However, in the brain homogenate autoxidation, hydrophobicity is an additional factor that affects the efficiency of antioxidants, as illustrated by Q1/2 values (the concentration of additive required to decrease the autoxidation rate to one half that observed in the absence of additive) of 0.1 mM and much greater than 8 mM for 3-methylindole and tryptophan, respectively.

2,3-Diaryl-substituted indole based COX-2 inhibitors as leads for imaging tracer development

“…The last nding was in harsh contrast to the literature, and we suspected false positive results since the uorescence-based COX-assay is inuenced by antioxidants as noted by the manufacturer. Particularly, the indole heterocycle is a wellcharacterized antioxidant pharmacophore 49,50 and it had to be considered that possibly antioxidative properties of 3a-3m interfered with the assay and caused these deviations. This hypothesis was supported by our rst ndings in parallel in vitro experiments that indole 3g was able to inhibit not only the formation of PGE 2 but also the formation of 8-iso-PGF 2a generated via non-enzymatic oxidation aer the exposure of endothelial cells in both monolayer and organo-type aortic ring models to ionizing radiation.…”

Radical Reactions in Cavitands Unveil the Effects of Affinity on Dynamic Supramolecular Systems

“…The auto-oxidation of cumene, for example, is reported under an air or oxygen atmosphere at high temperature (>80 °C). Milder conditions can be effective using radical initiators such as AIBN ((2,2′azobis(2-methylpropionitrile)) 30 and with specific catalysts as N-hydroxy compounds 31−33 or metal complexes. 34 Oxygen abstracts hydrogen from an alkyl aromatic compound, giving a carbon-centered radical that, under an aerobic atmosphere, is quenched at diffusion-controlled rates to form a peroxyl radical.…”

“…The auto-oxidation of cumene, for example, is reported under an air or oxygen atmosphere at high temperature (>80 °C). Milder conditions can be effective using radical initiators such as AIBN ((2,2′-azobis­(2-methyl­propionitrile)) and with specific catalysts as N -hydroxy compounds − or metal complexes…”

Development of Antioxidant COX-2 Inhibitors as Radioprotective Agents for Radiation Therapy—A Hypothesis-Driven Review

“…Noteworthy, the most prominent indole compound due to its biological, antioxidant, and radioprotective activity is probably melatonin, which scavenges • OH, ROO • , ONOO − and protects against LDL oxidation [ 150 , 193 , 194 , 195 ]. The antioxidant capacity of indole-based compounds has extensively been investigated in structure activity relationship studies for melatonin and its derivatives [ 150 , 196 , 197 , 198 ] as well as other indole based compounds [ 144 , 150 , 194 , 199 , 200 , 201 , 202 ] in the past.…”