Free, esterified, and insoluble-bound phenolic acids in white and red Korean ginsengs ( Panax ginseng C.A. Meyer)

Abstract

Phenolic acids of dried white and red ginsengs were extracted and fractionated into free, esterified, and insoluble-bound forms. The contents of individual phenolic acids in different forms were quantified by gas–liquid chromatography. Identification of all phenolic acids was confirmed by gas chromatography–mass spectrometry and comparison of gas chromatographic retention times. Twelve different phenolic acids as free, esterified, and insoluble-bound forms were identified in Korean ginsengs. Total phenolic acids in white and red ginsengs were 27.2 and 26.8 mg/100 g, respectively. Seven free phenolic acids were identified and their total contents in white and red ginsengs were 4.70 and 4.14 mg/100 g, respectively. trans-Ferulic acid was the predominant free phenolic acid, representing 47.9 and 57.7% of total free phenolic acids in white and red ginsengs, respectively. Esterified phenolic acids represented 71.9 and 77.1% of total phenolic acids in white and red ginsengs, respectively. The most predominant esterified phenolic acids were cis-ferulic acid and trans-ferulic acid. Total insoluble-bound phenolic acid contents in white and red ginsengs were 2.93 and 1.99 mg/100 g, respectively. Ferulic acid ( cis and trans isomers) was also the major insoluble-bound phenolic acids. This paper represents the first report of systematic identification and quantification of phenolic acids in different forms in white and red Korean ginsengs.