Chlorogenic acid: A comprehensive review of the dietary sources, processing effects, bioavailability, beneficial properties, mechanisms of action, and future directions

Phenolic acids have recently gained substantial attention due to their various practical, biological and pharmacological effects. Chlorogenic Acid (CGA, 3-CQA) is a most abundant isomer among caffeoylquinic acid isomers (3-, 4-, and 5-CQA), that currently known as 5-CQA as per guidelines of IUPAC. It is one of the most available acids among phenolic acid compounds which can be naturally found in green coffee extracts and tea. CGA is an important and biologically active dietary polyphenol, playing several important and therapeutic roles such as antioxidant activity, antibacterial, hepatoprotective, cardioprotective, anti-inflammatory, antipyretic, neuroprotective, anti-obesity, antiviral, anti-microbial, anti-hypertension, free radicals scavenger and a central nervous system (CNS) stimulator. In addition, it has been found that CGA could modulate lipid metabolism and glucose in both genetically and healthy metabolic related disorders. It is speculated that CGA can perform crucial roles in lipid and glucose metabolism regulation and thus help to treat many disorders such as hepatic steatosis, cardiovascular disease, diabetes, and obesity as well. Furthermore, this phenolic acid (CGA) causes hepatoprotective effects by protecting animals from chemical or lipopolysaccharide-induced injuries. The hypocholesterolemic influence of CGA can result from the altered metabolism of nutrients, including amino acids, glucose and fatty acids (FA). The purpose of this review was to broaden the scope of knowledge of researchers to conduct more studies on this subject to both unveil and optimize its biological and pharmacological effects. As a result, CGA may be practically used as a natural safeguard food additive to replace the synthetic antibiotics and thereby reduce the medicinal cost.

In this study, the antibacterial activity and mechanism of action of chlorogenic acid against bacteria were assessed. The data from minimum inhibitory concentration (MIC) values showed that chlorogenic acid effectively inhibited the growth of all tested bacterial pathogens, and the MIC values were ranging from 20 to 80 μg/mL. An investigation into action mode of chlorogenic acid against the pathogen indicated that chlorogenic acid significantly increased the outer and plasma membrane permeability, resulting in the loss of the barrier function, even inducing slight leakage of nucleotide. The leakage of cytoplasmic contents was also observed by electron micrographs. These results supported our hypothesis that chlorogenic acid bound to the outer membrane, disrupted the membrane, exhausted the intracellular potential, and released cytoplasm macromolecules, which led to cell death.