Condensed tannins in extracts from European medicinal plants and herbal products

• Condensed tannins were analysed in medicinal plant and herbal product extracts.
• Most extracts had procyanidins, but one had highly galloylated tannins.
• A-type linkages were only found in procyanidins.
• Tannins in pine buds, walnut leaves, heather flowers and great water dock roots.
• Determination of thiolysis response factors for different tannin types.

Medicinal plant materials are not usually analysed for condensed tannins (CT). Thirty commercially available European medicinal plants and herbal products were screened for CT and fourteen CT samples were analysed in detail. This is also the first comprehensive CT analysis of pine buds, walnut leaves, heather flowers and great water dock roots. Acetone/water extracts contained between 3.2 and 25.9 g CT/100 g of extract, had CT with mean degrees of polymerisation of 2.9 to 13.3, procyanidin/prodelphinidin ratios of 1.6/98.4 to 100/0 and cis/trans flavan-3-ol ratios of 17.7/82.3 to 97.3/2.7. The majority of samples contained procyanidins, four contained A-type linkages (blackthorn flowers, heather flowers, bilberry leaves and cowberry leaves) and one sample also had galloylated procyanidins (great water dock roots).

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