Forms of Silicon in Medicinal Plants

The contents of three forms of silicon (organic, soluble mineral, and polymeric) were determined in leaves of 21 medicinal plants. At a total content of silicon of 0.74 to 3.59%, the organic, soluble mineral, and polymeric forms accounted for 0.51–1.91%, 0.05–0.51%, and 0.1–1.21%, respectively. An analysis of silicon in the condensed polyphenol fraction was performed for the first time revealing the presence of a covalently bound form in amounts of 0.1 to 0.2% of the total silicon content in the leaves. These results are of interest for food or medical applications of the plants studied.