St. John’s wort has been used for centuries in traditional medicine of many cultures, and nowadays it is well-known as a clinically important antidepressant drug. Considering the rising market demand for Hyperici herba, quality control of crude drug is of paramount importance. In this paper we performed HPLC-DAD chemical profiling of St. John’s wort tea samples obtained at local markets, pharmacies and health food stores in the Balkan Peninsula countries, Austria and Turkey. Furthermore, water alcoholic extracts of the collected samples were evaluated in terms of their antioxidant potential, as well as the ability to inhibit biologically important enzymes such as acetylcholinesterase, monoamine oxidases A and B (MAO-A and MAO-B), α-amylase and α-glucosidase. Significant variability within the samples in the quantities of hypericin, hyperforin, rutin, quercetin, gallic, chlorogenic, caffeic and p-hydroxybenzoic acid was noticed. Chemotaxonomic modelling enabled the identification of three clusters of samples based on the quantities of rutin, hypericin and hyperforin. Generally, the extracts exhibited a significant potential to inhibit MAO-A (median IC50 = 10.01 μg/mL) and α-glucosidase (median IC50 = 12.40 μg/mL). The results of antioxidant potential evaluation suggest strong neutralization of hydroxyl and nitroso radicals, but moderate inhibition of lipid peroxidation process. Overall, the conducted study emphasizes the possibility of St. John’s wort teas quality control, taking into account unavoidable variability of chemical profile as well. The stated is of great importance when grinding degree of herbal material excludes taxonomic identification of biological origin as an option within quality control.

中文翻译：

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圣约翰草凉茶 - 质量控制的生物学潜力和化学计量学方法

几个世纪以来，圣约翰草已在许多文化的传统医学中使用，如今它作为临床上重要的抗抑郁药而广为人知。考虑到金丝桃的市场需求不断增长，生药的质量控制至关重要。在本文中，我们对从巴尔干半岛国家、奥地利和土耳其的当地市场、药店和保健食品商店获得的圣约翰草茶样品进行了 HPLC-DAD 化学分析。此外，还评估了收集样品的水醇提取物的抗氧化潜力，以及抑制生物重要酶的能力，如乙酰胆碱酯酶、单胺氧化酶 A 和 B（MAO-A 和 MAO-B）、α-淀粉酶和α-葡萄糖苷酶。样品中金丝桃素、金丝桃素、金丝桃素、注意到芦丁、槲皮素、没食子酸、绿原、咖啡酸和对羟基苯甲酸。化学分类学建模能够根据芦丁、金丝桃素和金丝桃素的数量识别三组样品。通常，提取物表现出抑制 MAO-A（中值 IC50 = 10.01 μg/mL）和 α-葡萄糖苷酶（中值 IC50 = 12.40 μg/mL）的显着潜力。抗氧化潜力评估结果表明对羟基和亚硝基自由基有强中和作用，但对脂质过氧化过程有中等抑制作用。总体而言，所进行的研究强调了圣约翰草茶质量控制的可能性，同时还考虑了不可避免的化学特征变化。