Isolation and Quantification of Oligomeric and Polymeric Procyanidins in the Aerial Parts of St John' Wort (Hypericum perforatum)

Hellenbrand N., Lechtenberg M., Petereit F., Sendker J., Hensel A.

Forschungsartikel (Zeitschrift)

Zusammenfassung

Proanthocyanidins (condensed tannins) constitute a class of oligomeric and polymeric polyphenols with flavan-3-ols as monomeric building blocks. Despite the high impact of proanthocyanidins, these polyphenols are mostly quantified by colorimetric methods or by chromatographic determination of the flavan-3-ols as cleavage products or low molecular oligomers as lead compounds. For St. John's wort (Hyperici herba) from Hypericum perforatum, a protocol for preparative isolation of oligomeric and polymeric proanthocyanidins from an acetone-water extract by chromatography on Sephadex®LH20 in combination with preparative high-performance liquid chromatography on the diol stationary phase was developed, yielding procyanidin reference clusters with a defined degree of polymerization from 3 to 10. Identity and purity of these clusters was proven by high-performance liquid chromatography (RP18 and diol phase) and mass spectrometry. For identification and quantification of proanthocyanidin clusters from St. John's wort, an ICH-Q2 (International harmonized guideline for analytical validation) validated high-performance liquid chromatography method with fluorimetric detection was developed using an acetone-water extract of the herbal material, purified by solid-phase extraction for the removal of naphthodianthrones. The method enabled the quantification of procyanidin clusters with a degree of polymerization from 2 to 10. Analysis of nine batches of Hyperici herba from different sources indicated a high variability of proanthocyanidin content in the range from 8 to 37mg/g. In all of the batches investigated, the trimer cluster DP3 was the dominant proanthocyanidin (about 40%), followed by DP 4 (about 15%) and DP5 (about 12%). Monitoring of procyanidin distribution during seasonal growth of fresh plants of H. perforatum indicated the highest proanthocyanidin content in young plants (about 50mg/g) and a time-dependent decrease during the growing season to about 16mg/g. The highest proanthocyanidin content was found in young leaves and flowers, while the fruits were proanthocyanidin-free; older parts of the stem and the herb had a lower proanthocyanidin content. From these data, it can be concluded that proanthocyanidins serve as part of the plant defense system in the reproductive organs.

Details zur Publikation

Herausgeber*innen:
Seiten: 7
Veröffentlichungsjahr: 2015
Verlag: Georg Thieme Verlag
Sprache, in der die Publikation verfasst ist: Englisch
Link zum Volltext: http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84939568801&origin=inward