Water extractable forms of nitrogen, phosphorus and iron in fruits and seeds of medicinal plants.

Water extractable nitrate nitrogen, phosphate phosphorus and iron(II) in relation to the total amount of these essential elements were analyzed in fruits and seeds of medicinal plants. Water extraction was chosen to simulate in the analytical procedure the way plant samples are prepared and used by people. The total amounts of nitrogen, phosphorus and phosphate phosphorus were determined in the range of concentration of mg/g of dry plant weight, however, the total and extractable iron and nitrate nitrogen in mg/kg of dry weight. The nitrate nitrogen appeared to be crucial factor in the differentiation of plant samples and its level is characterized by very wide range of concentrations, from 10.15 mg/kg to 1377.03 mg/kg of dry plant weight; however, it didn't exceed the Acceptable Daily Intake (ADI). Statistically significant correlation between N and P, N and Fe, P-PO4 and P, P-PO4 and N was found, probably caused by their co-participation in metabolism of medicinal plant's fruits. Thanks to results of PCA, the fruits of medicinal plants can be differentiated by the concentration of nitrogen and phosphorus and their water extractable fractions. PCA grouped analyzed samples into three clusters with similar concentration of elements, which depended on the plant species, and in some cases also on the place of cultivation in distant regions of the country.