Mineral content of some famous medicinal plants grown in darab region, Southern Iran

High concentrations of nutrients in medicinal plants may be harmful to humans and animals. Therefore, the aim of this study was to determine the concentration of some macro-nutrients (calcium, sodium, phosphorus and potassium) and micro-nutrients (iron, manganese, copper, and zinc) in five famous native medicinal plants grown in the rangelands of the Darab region, southern Iran. The concentrations of micro-nutrients, calcium and magnesium, were obtained by atomic absorption spectrometry, sodium and potassium by flame photometer, and the concentration of phosphorus by spectrophotometer in the extract obtained from the dry combustion method and dissolved in 2 N HCl. The results showed that the variation range in the concentration of measured elements was wide. The studied medicinal plants contained significant amounts of calcium (0.325-1.925%), phosphorus (0.096-0.266%), and potassium (0.188-4.312%). The highest concentrations of iron (517.45 mg kg-1 DM) and copper (11.8 mg kg-1 dry weight) were observed in Maryam nokhodi (Tecurium persicum). The greatest concentrations of zinc (22.5 mg kg-1 DM) and manganese (200.75 mg kg-1 DM) were observed in Shekar shapha (Otostegia persica) and Konar (Ziziphus spina-christi) plants, respectively. The content of micronutrients in the studied medicinal plants (except copper) was higher than the standard limit reported by the World Health Organization (WHO) for edible plants. Finally, in the case of excessive and continuous consumption of these medicinal plants, harmful side effects are not far from expectation. The amount and time interval of the studied medicinal plant consumption must be done according to the opinion of medicinal plant experts.