Determination of quality parameters in Hypericum perforatum grown in Saskatchewan
Hypericum perforatum, a medicinal plant known as Saint John’s Wort, has been used extensively for its antidepressant activity in North America over the past three years. The objective of this study was to establish the influence of plant part and time of harvest on phytomedicinal quality of Saint John’s Wort grown in Saskatoon. Varietal influence on quality was also investigated. Flowering tops, upper leaves and stems, and lower leaves and stems of two and three years old plants, variety Standard, harvested at seven different times from budding to post-blooming from June to September, 1998, were used for quality assessment. Extraction protocol for optimal recovery and an high performance liquid chromatography (HPLC) method for quantification of 7 marker compounds for Saint John’s Wort, hypericin and pseudohypericin, and 5 selected flavonoids (quercitrin, quercetin, rutin, hyperoside and biapigenin) were developed. The flowering tops followed by the upper most leaves contained the highest concentration of hypericins and flavonoids when harvested in late June, 0.35 % and 4.0%, respectively. The hypericins content declined by more than 90% between late June and end of August. The content of flavonoids showed a similar declining trend from early July onward. A correlation between date of harvest and quality, and plant part and quality was apparent. Two varieties, Anthos and Elixir™, were found superior in both plant yield and plant quality.
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