As a building block of lignocelluloses, such as pectin and lignin, ferulic acid is ubiquitous in the plant kingdom.
In food
Ferulic acid is found in a number of vegetable sources, and occurs in particularly high concentrations in popcorn and bamboo shoots. It is a major metabolite of chlorogenic acids in humans along with caffeic and isoferulic acid, and is absorbed in the small intestine, whereas other metabolites such as dihydroferulic acid, feruloylglycine and dihydroferulic acid sulfate are produced from chlorogenic acid in the large intestine by the action of gut flora. In cereals, ferulic acid is localized in the bran – the hard outer layer of grain. In wheat, phenolic compounds are mainly found in the form of insoluble bound ferulic acid and may be relevant to resistance to wheat fungal diseases. The highest known concentration of ferulic acid glucoside has been found in flaxseed. It is also found in barley grain. Asterideudicot plants can also produce ferulic acid. The tea brewed from the leaves of yacón, a plant traditionally grown in the northern and central Andes, contains quantities of ferulic acid. In legumes, the white bean variety navy bean is the richest source of ferulic acid among the common bean varieties. It is also found in horse grams. Although there are many sources of ferulic acid in nature, its bioavailability depends on the form in which it is present: free ferulic acid has limited solubility in water, and hence poor bioavailability. In wheat grain, ferulic acid is found bound to cell wall polysaccharides, allowing it to be released and absorbed in the small intestine.
Ferulic acid has been identified in Chinese medicine herbs such as Angelica sinensis, Cimicifuga heracleifolia and Ligusticum chuangxiong. It is also found in the tea brewed from the European centaury, a plant used as a medical herb in many parts of Europe.
Ferulic acid is biosynthesized in plants from caffeic acid by the action of the enzyme caffeate O-methyltransferase. Ferulic acid, together with dihydroferulic acid, is a component of lignocellulose, serving to crosslink the lignin and polysaccharides, thereby conferring rigidity to the cell walls. It is an intermediate in the synthesis of monolignols, i.e., the monomers of lignin, and is also used for the synthesis of lignans.
Biodegradation
Ferulic acid is converted by certain strains of yeast, notably strains used in brewing of wheat beers, such as Saccharomyces delbrueckii, to 4-vinyl guaiacol which gives beers such as Weissbier and Wit their distinctive "clove" flavour. Saccharomyces cerevisiae and Pseudomonas fluorescens are also able to convert trans-ferulic acid into 2-methoxy-4-vinylphenol. In P. fluorescens, a ferulic acid decarboxylase has been isolated.
Ecology
Ferulic acid is one of the compounds that initiate the vir region of Agrobacterium tumefaciens, inducing it to infect plant cells.
Extraction
It can be extracted from wheat bran and maize bran using concentrated alkali.
