Poutaraud A, Di Gregorio F, Tin V C, Girardin P
National Institute of Agronomic Research, Colmar, France.
Planta Med. 2001 Apr;67(3):254-9. doi: 10.1055/s-2001-12003.
St. John's Wort is a medicinal plant increasingly used for its antidepressive activity. Hypericins are considered as one of the compounds contributing to the activity of the extract. These naphthodianthrones exist in various forms in Hyperici herba. Protopseudohypericin and protohypericin (protopigments) are converted into pseudohypericin and hypericin (pigments) under the action of light. The aim of this work is to study the influence of light on the phototransformation of protopigments into pigments. Two experiments were carried out. The studies were performed on one hand, on plant material in order to know the proportion of these substances in various plant parts and the possibility of transforming the protopigments into pigments under the action of sunlight; on the other hand, in the extract to determine the optimal wavelength allowing this transformation. Three parts of the fresh plant (buds, flowers, leaves) were treated with sunlight on three levels of exposure. Liquid extracts were exposed to various types of light with wavelengths ranging between 480 and 660 nm by means of diodes. The flowering tops of St. John's Wort contain a share of approximately 30% hypericins in the form of protopseudohypericin and protohypericin: buds (48%), flowers (30%), leaves (17%). After an exposure of fresh buds to sunlight for 16 hours the share of protopigments was then 32%. In the extract, the transformation of the protopigments is total and requires less energy than in the plant material. The optimal wavelength for the transformation of the protopigments in the extract is around 515 nm (green), close to the optimum absorption level of protopigments.
圣约翰草是一种因其抗抑郁活性而越来越多地被使用的药用植物。金丝桃素被认为是有助于提取物活性的化合物之一。这些萘并二蒽酮以多种形式存在于贯叶连翘中。原伪金丝桃素和原金丝桃素（原色素）在光的作用下会转化为伪金丝桃素和金丝桃素（色素）。这项工作的目的是研究光对原色素向色素光转化的影响。进行了两个实验。一方面，对植物材料进行研究，以了解这些物质在不同植物部位的比例以及在阳光作用下将原色素转化为色素的可能性；另一方面，在提取物中确定允许这种转化的最佳波长。将新鲜植物的三个部分（芽、花、叶）在三个光照水平下用阳光处理。通过二极管将液体提取物暴露于波长在480至660纳米之间的各种类型的光下。圣约翰草的花顶部含有约30%的以原伪金丝桃素和原金丝桃素形式存在的金丝桃素：芽（48%）、花（30%）、叶（17%）。将新鲜芽暴露于阳光下16小时后，原色素的比例为32%。在提取物中，原色素的转化是完全的，并且比在植物材料中需要的能量更少。提取物中原色素转化的最佳波长约为515纳米（绿色），接近原色素的最佳吸收水平。
