3,4-dihydroxybenzoic acid is a phenolic acid found naturally in fruits, vegetables, nuts, tea, brown rice, and some Chinese herbs. It appears as a white to brown crystalline powder that changes color when exposed to air. 3,4-dihydroxybenzoic acid breaks down in boiling water, releasing carbon dioxide as well, and its aqueous solution turns green when encountered with ferric chloride and red when encountered with sodium bicarbonate. 3,4-dihydroxybenzoic acid is mainly used as pharmaceutical raw materials and widely used in the medical field, often used to prepare anti-cancer, antibacterial, anti-hyperglycemia, expectorant, antivenom and other drugs.
As 3,4-dihydroxybenzoic acid is the precursor of synthesis of complex molecules such as anthocyanins, it is possible to obtain 3,4-dihydroxybenzoic acid, as a component with a variety of pharmacological activities, by ingesting appropriate amounts of food containing anthocyanins. It can play anti – inflammatory, anti – bacterial, anti – oxidation, anti – hyperglycemia, nerve protection and other functions.