phenylethanoid

Phenylethanoid is a term used in natural products chemistry to describe compounds built on a phenethyl (phenylethyl) moiety bearing multiple hydroxyl groups. The term is most often applied to phenylethanoid glycosides (PhEGs), in which the hydroxyphenethyl core is linked to a sugar moiety and frequently esterified with hydroxycinnamic acids such as caffeic or p-coumaric acid. This combination yields a characteristic phenylethanoid scaffold.

Common members and structure: The best-known phenylethanoid glycosides include verbascoside (acteoside) and echinacoside. These molecules typically feature a hydroxyphenethyl alcohol linked by a glycosidic bond to glucose, with additional esterification by caffeic acid or related hydroxycinnamic acids. Isoverbascoside is a structural isomer in the same family.

Distribution and biosynthesis: Phenylethanoids are widely distributed in the plant kingdom, especially among medicinal herbs. They are produced via the phenylpropanoid pathway, assembling hydroxycinnamic acids with hydroxyphenethyl units and attaching sugars to form glycosides.

Biological activity and uses: Phenylethanoid glycosides exhibit antioxidant, anti-inflammatory, antimicrobial, and neuroprotective activities in various studies. They are of interest for potential health benefits and are used as chemotaxonomic markers in plant quality control. Clinical evidence remains limited and effects vary by compound and source.

Analytical considerations: Identification and quantification typically rely on high-performance liquid chromatography (HPLC) with mass spectrometry (MS) and NMR spectroscopy. Verbascoside and echinacoside are frequently used as reference standards in plant extracts.