polyphenolic

Polyphenolic refers to compounds that contain multiple phenol structural units. The term covers a broad class of polyphenols, including flavonoids (such as quercetin and kaempferol), phenolic acids (like caffeic and chlorogenic acids), stilbenes (notably resveratrol), lignans, and tannins. These compounds share several hydroxyl groups on aromatic rings and occur widely in plants, where they contribute to color, flavor, astringency, and defense against ultraviolet radiation and herbivores. They are typically derived from the plant phenylpropanoid pathway, beginning with phenylalanine and leading to a diverse array of structures.

In plants, polyphenolics perform roles in growth and defense, including protection from pathogens, signaling, and adaptation to environmental stresses. In humans, these compounds are studied for antioxidant properties and potential health benefits, such as cardiovascular protection and anti-inflammatory effects. However, clinical evidence is variable, and bioavailability differs substantially among compounds; many polyphenols are poorly absorbed and are extensively metabolized by gut microbiota, with biological activity often arising from metabolites rather than the parent molecules.

Applications of polyphenolics include their use as natural antioxidants and colorants in foods, as well as subjects of nutraceutical and pharmaceutical research. Analytical methods commonly assess total polyphenol content using the Folin-Ciocalteu assay and profile individual compounds with chromatographic techniques such as LC-MS, with results frequently expressed as gallic acid equivalents or as specific compound concentrations. Stability of polyphenols can be affected by light, heat, and oxidation, and some forms can complex with metals or proteins, influencing their functionality.