quinate

Quinate is the conjugate base form of quinic acid, a polyhydroxylated cyclohexane carboxylic acid. In chemistry, quinate salts and esters are common derivatives of quinic acid, which is found in various plant tissues. Quinate itself occurs in nature mainly as part of larger phenolic compounds rather than as a free metabolite.

Natural occurrence and sources include chlorogenic acids, which are esters of caffeic acid and quinic acid. Chlorogenic acids are widespread in coffee, many fruits, and ornamental plants. Upon hydrolysis or enzymatic breakdown, chlorogenic acids can yield quinic acid, contributing to the pool of quinic derivatives in plant metabolism. Quinate-containing compounds can influence flavor, aroma, and antioxidant properties in foods and beverages.

Biological and biochemical context: quinic acid and its salts participate in plant secondary metabolism and in the broader shikimate pathway, which leads to the biosynthesis of essential aromatic compounds such as phenylpropanoids and amino acids in plants and some microorganisms. In microbial systems, quinate can be metabolized by specialized pathways involving quinate dehydrogenase or related enzymes, providing intermediates that feed into central aromatic metabolism. The exact roles of free quinic acid and quinate derivatives vary among species and tissues, but they are generally regarded as components of plant phenolic metabolism rather than primary nutrients.

Chemistry and nomenclature: quinate refers to the deprotonated form of quinic acid and to esters and salts derived from it. It is characterized by multiple hydroxyl groups and a carboxylate functionality, making it highly polar and reactive with various enzymes and hydrolytic processes.