Free and chemically bonded phenolic acids in barks of Viburnum opulus L. and Sambucus nigra L

Liquid column chromatography, planar chromatography (TLC) on modified and unmodified silica layers, reversed-phase high-pressure liquid chromatography (HPLC), as well as ESI-TOF MS and 1H-NMR have been used for separation, purification and identification of phenolic acids in the barks of Sambucus nigra and Viburnum opulus (Caprifoliaceae). By the use of these procedures three cinnamic acid derivatives: caffeic acid, p-coumaric, and ferulic acid, four benzoic acid derivatives: gallic acid, protocatechuic acid, syringic acid, 3,4,5-trimethoxybenzoic acid, two phenylacetic acid derivatives: 3,4-dihydroxyphenylacetic acid, homogentisic acid, and two depsides: chlorogenic acid and ellagic acid were detected and identified in the bark of Viburnum opulus. Caffeic acid, p-coumaric acid, ferulic acid, gallic acid, syringic acid, 3,4,5-trimethoxybenzoic acid and chlorogenic acid were also detected and identified in the bark of Sambucus nigra. Except for chlorogenic acid, this is the first time these phenolic acids have been isolated, detected, and identified in the bark of V. opulus and S. nigra.