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Chalcones as Scavengers of HOCl and Inhibitors of Oxidative Burst: Structure-Activity Relationship Studies

Author(s):

Thaise Martins, Vera L.M. Silva, Artur M.S. Silva, José L.F.C. Lima, Eduarda Fernandes* and Daniela Ribeiro*   Pages 1 - 9 ( 9 )

Abstract:


Aims: Evaluate the ability of chalcones to scavenge hypochlorous acid (HOCl) and modulate oxidative burst.

Background: The chemistry of chalcones has long been a matter of interest to the scientific community due to the phenolic groups often present and to the various replaceable hydrogens that allow the formation of a broad number of derivatives. Due to this chemical diversity, several biological activities have been attributed to chalcones, namely anti-diabetic, anti-inflammatory and antioxidant.

Objectives: Evaluate the ability of a panel of 34 structurally related chalcones to scavenge HOCl and/or suppress its produc-tion through the inhibition of human neutrophils’ oxidative burst, followed by the establishment of the respective structure-activity relationships.

Methods: The ability of chalcones to scavenge HOCl was evaluated by fluorimetric detection of the inhibition of dihydro-rhodamine 123 oxidation. The ability of chalcones to inhibit neutrophils’ oxidative burst was evaluated by chemiluminomet-ric detection of the inhibition of luminol oxidation.

Results: It was observed that the ability to scavenge HOCl depends on the position and number of hydroxy groups on both aromatic rings. Chalcone 5b was the most active with an IC50 value of 1.0 ± 0.1 μM. The ability to inhibit neutrophils’ oxi-dative burst depends on the presence of a 2’-hydroxy group on A-ring and on other substituents groups, e.g. methoxy, hy-droxy, nitro and/or chlorine atom(s) at C-2, C-3 and/or C-4 on B-ring, as in chalcones 2d, 2f, 2j, 2i, 4b, 2n and 1d, which were the most actives with IC50 values ranging from 0.61 ± 0.02 μM to 1.7 ± 0.2 μM.

Conclusion: The studied chalcones showed high activity at a low micromolar range, indicating their potential as antioxidant agents and to be used as a molecular structural scaffold for the design of new anti-inflammatory compounds.

Keywords:

Chalcones, hypochlorous acid, scavenging activity, reactive species, human neutrophils, antioxidant activity

Affiliation:

LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Porto, LAQV, REQUIMTE, Department of Chemistry, University of Aveiro, Aveiro, LAQV, REQUIMTE, Department of Chemistry, University of Aveiro, Aveiro, LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Porto, LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Porto, LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Porto



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