Quantitative analysis of polymeric proanthocyanidins in birch leaves with normal‐phase HPLC

The proanthocyanidin composition and content in the leaves of nine birch species ( Betula albosinensis , B . ermanii , B . maximowicziana , B . nana , B . papyrifera , B . pendula , B . platyphylla , B . pubescens , and B . pubescens ssp. czerepanovii ) were studied with different methods including colorimetric assay, HPLC coupled with PAD or ESI/MS and NMR. Total proanthocyanidin content was determined using the acid butanol assay. A normal phase‐HPLC method was applied for the analysis of polymeric proanthocyanidins. The content of polymeric proanthocyanidins was estimated from a late eluting peak in the chromatogram. With this HPLC method, quantitative analysis of polymeric proanthocyanidins could be performed directly from leaf extracts: no additional purification or preparation steps were required. It was shown that birch leaves contained mainly polymeric proanthocyanidins with a degree of polymerisation greater than 10. Total proanthocyanidin content (expressed as dry weight) was found to vary from 44 mg/g ( B . papyrifera ) to 145 mg/g ( B . nana ), and polymeric proanthocyanidin content from 39 mg/g ( B . pendula ) to 119 mg/g ( B . nana ). Copyright © 2006 John Wiley & Sons, Ltd.