Absorption, metabolism and biological activities of chlorogenic acids and related compounds

Abstract

Chlorogenic acids are polyphenolic compounds that occur ubiquitously in foods of plant origin. They are quinic acid esters of hydroxycinnamic acid.Recently, naturally occurring plant phenolics have attracted considerable attention in relation to their physiological potential. Depending upon the conditions, phenolic compounds can be either beneficial or detrimental to biological processes. We comprehensively summarized chlorogenic acids and related compounds in absorption, metabolism and biological activity. Chlorogenic, caffeic and quinic acids are well absorbed in humans and rats. Metabolic transformations of chlorogenic acids in the human system may be crucial for their biological effect. The antioxidant activities of chlorogenic acids are preserved by inhibiting the formation of reactive oxygen species or by scavenging them. As a result, chlorogenic acidsmay play beneficial role in the prevention of certain oxidative diseases. The observed pharmacological activities of medicinal plants relate to the chlorogenic acidsconstituents of them. Despite the abundance of biological data demonstrating the antioxidant activities of chlorogenic acids, it remains controversial whether these compounds are potent antioxidants or pro-oxidants. Chlorogenic and caffeic acids switch from anti- to pro-oxidant activity, depending on their concentration, on the presence of free transition metal ions, or on their redox status.