Modulation of Human Neutrophils’ Oxidative Burst by Hydroxylated 2-Styrylchromones: The Relevance of the Catechol Group ^†

Abstract

2-Styrylchromones (2-SC) are a group of oxygen-containing heterocyclic compounds, which are characterized by the attachment of a styryl group to the C-2 position of their chromone core. Over the years, several biological activities have been attributed to 2-SC, such as antioxidant, anti-inflammatory, antimicrobial, antiviral, and antitumor activities [1,2]. Nonetheless, there are no reports in the literature about the effect of 2-SC on human neutrophils’ oxidative burst. Therefore, the present study aims to evaluate the modulation of human neutrophils’ oxidative burst by a panel of hydroxylated 2-SC, previously obtained by chemical synthesis, and to analyze the structure–activity relationship [3]. For that purpose, freshly isolated neutrophils from human blood were stimulated with phorbol-12-myristate-13-acetate, and a chemiluminescence method was applied to evaluate the oxidative burst, using luminol as a probe [4]. Considering the OH substituents present on the B-ring of 2-SC, the tested compounds can be divided into the following three groups: group 1, with a catechol group (C-3′ and C-4′); group 2, with an OH at C-4′; group 3, without any substitution on the B-ring. The 2-SC from group 1 were the most active, with IC₅₀ values in the order of 1 µM. In conclusion, the catechol B-ring appears to play an important role in the modulation of human neutrophils’ oxidative burst by 2-SC.