Hellenbrand Nils, Lechtenberg Matthias, Petereit Frank, Sendker Jandirk, Hensel Andreas
University of Münster, Institute of Pharmaceutical Biology and Phytochemistry, Münster, Germany.
Planta Med. 2015 Aug;81(12-13):1175-81. doi: 10.1055/s-0035-1545916. Epub 2015 Apr 23.
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 37 mg/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 50 mg/g) and a time-dependent decrease during the growing season to about 16 mg/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.
原花青素（缩合单宁）是以黄烷-3-醇为单体结构单元的一类低聚和聚合多酚。尽管原花青素具有很高的影响力，但这些多酚大多通过比色法或通过色谱法测定作为裂解产物的黄烷-3-醇或作为先导化合物的低分子低聚物来进行定量。对于贯叶连翘的圣约翰草，开发了一种从丙酮-水提取物中通过在Sephadex®LH20上进行色谱分离并结合在二醇固定相上进行制备型高效液相色谱来制备分离低聚和聚合原花青素的方法，得到了聚合度从3到10的原花青素参考簇。这些簇的同一性和纯度通过高效液相色谱（RP18和二醇相）和质谱得到了验证。为了鉴定和定量圣约翰草中的原花青素簇，开发了一种采用荧光检测的、经国际协调会议Q2（分析方法验证国际协调指南）验证的高效液相色谱方法，该方法使用植物材料的丙酮-水提取物，并通过固相萃取进行纯化以去除萘骈二蒽酮。该方法能够对聚合度从2到10的原花青素簇进行定量。对来自不同来源的九批圣约翰草的分析表明，原花青素含量在8至37mg/g范围内具有高度变异性。在所有研究的批次中，三聚体簇DP3是主要的原花青素（约40%），其次是DP4（约15%）和DP5（约12%）。对贯叶连翘新鲜植株季节性生长过程中原花青素分布的监测表明，幼嫩植株中的原花青素含量最高（约50mg/g），并且在生长季节中随时间下降至约16mg/g。原花青素含量最高的部位是幼叶和花，而果实不含原花青素；茎和草的较老部分原花青素含量较低。从这些数据可以得出结论，原花青素在生殖器官中作为植物防御系统的一部分发挥作用。
