The antioxidant activity of 4‐hydroxycoumarin derivatives and some sulfured analogs

Abstract

In this work, the relationship between the structure and the radical scavenging activity of seven hydroxycoumarins and their sulfured analogs was investigated for the first time by density functional theory calculation in the gas phase, benzene, and water. Our investigation includes hydrogen atom transfer, single-electron transfer-proton transfer, and sequential proton loss electron transfer mechanisms. The results revealed that the bond dissociation enthalpy values of sulfured coumarins were lower than those of hydroxylated analogs. The obtained results were in a good agreement with the experimental results. The hydrogen atom transfer mechanism is dominant in both benzene and vacuum. The sequential proton loss electron transfer mechanism represents the most thermodynamically preferred reaction pathway in water. However, single-electron transfer-proton transfer mechanism is not the most preferred one in all media. Finally, this work contributes to the understanding of the pharmacological activity of the compounds studied.

Antioxidant activity of 3-substituted-4-hydoxycoumarin derivatives

“…Natural and synthetic coumarins, notably 4-hydroxycoumarin derivatives could serve as sources of antioxidants and do scavenging activity 18,25,26 .…”

Antiradical and Antioxidant Activity of Compounds Containing 1,3-Dicarbonyl Moiety: An Overview

“…Unsubstituted 4-hydroxycoumarin 66 (Figure 10) has moderate antiradical activity in the DPPH test (EC 50 = 3.8 mM) [183][184][185]. Unsubstituted coumarin also effectively scavenges HO • .…”

“…If there is an electron-donating group (EDG) in the benzene ring at the metaor paraposition (compound 75, R 1 = orthoor para-EDG), the antiradical activity increases [183,184]. The results of the ORAC test show that a para-methyl group (compound 75, R 1 = para-CH 3 , ORAC = 6.5) or a meta-hydroxy group (compound 75, R 1 = meta-OH, ORAC = 4.9) containing 3-phenyl-4-hydroxycoumarins have a higher antioxidant activity than the unsubstituted 4-hydroxycoumarin (66, ORAC = 4.2).…”

Recent Developments in the Synthesis of β-Diketones

“…Similarly, some other antioxidant compounds possessing an enolic moiety can be considered analogs of 1,3-diketones, although they are properly β-ketoesters. Thus, apart from the archetypal ascorbic acid 15 [22,23], compounds such as dihydropyran-2,4-diones 16 [24], 4-hydroxycoumarins 17 [25], pulvinic acids 18 [26,27], and their natural analog norbadione A 19 [28] or Meldrum's acids 20 have been assessed for their antioxidant capability [29,30], as shown in Scheme 3. Aside from the antioxidative activity, some other pharmacological activities have been reported for β-diketones or their enolic counterparts.…”