Toxic Element Profiles in Selected Medicinal Plants Growing on Serpentines in Bulgaria

Abstract

Populations of medicinal plants growing on serpentines and their respective soils were analyzed for Fe, Ni, Mn, Cr, Co, Cd, Cu, Zn, and Pb using inductively coupled plasma atomic emission spectrometry. Aqua regia extraction and 0.43 M acetic acid extraction were used for the quantification of pseudototal and bioavailable fractions, respectively, of elements in soil and nitric acid digestion for determination of total element content in plants. Screening was performed to (1) document levels of toxic metals in herbs extensively used in preparation of products and standardized extracts, (2) compare accumulation abilities of ferns and seed plants, and (3) estimate correlations between metal content in plants and their soils. The toxic element content of plants varied from site to site on a large scale. The concentrations of Fe and Ni were elevated while those of Cu, Zn, and Pb were close to average values usually found in plants. The highest concentrations for almost all elements were measured in both Teucrium species. Specific differences in metal accumulation between ferns and seed plants were not recorded. The investigated species are not hyperaccumulators but can accumulate toxic elements, in some cases exceeding permissible levels proposed by the World Health Organization and European Pharmacopoeia. The harvesting of medicinal plants from serpentines could be hazardous to humans.

Metals Content in Herbal Supplements

“…The content of Pb in this herbal samples was determined in the supplier G with median concentrations of 0.29 mg kg −1 of Brazilian origin, and those from supplier C, 0.55 mg kg −1 of Chinese origin been both considered save for consumption according with the limit established by WHO [38] of 10 and 5.0 mg kg -1 established by the European Pharmacopeia, respectively [38]. These data are also corroborating by Pavlova and Karadjova [45]. Ilex paraguariensis samples presented Cd values of 0.03 mg kg −1 while C. quadrangularis presented concentration of 0.02 mg kg −1 by the suppliers E and D, respectively.…”

Influence of Moderate Cd and Pb Soil Pollution on Seed Development, Photosynthetic Performance and Foliar Accumulation in the Medicinal Plant Hypericum perforatum

“…Before the beginning of the experiment, all the materials used (Petri dishes, filter papers, pipette tips, tweezers and deionized water) were UV sterilized for one hour to avoid the growth of pathogens (e.g., fungi and bacteria) inside the Petri dishes. The selected Cd and Pb exposure concentrations were within the range of concentrations detected in the exchangeable fraction and hence potentially phytoavailable [30] in geochemically altered (ultramafic serpentine) soils [24].…”

“…Several studies investigated the accumulation of toxic heavy metals in H. perforatum [21][22][23][24][25][26] and some recommended caution for its harvesting on polluted soils [27] since this plant seems to show good features as a Cd accumulator [28]. Conversely, studies on the toxicity of heavy metals on their seed development are lacking, and information on their effects on the physiology of adult plants is largely unexplored [21].…”

Cadmium-induced oxidative damage and antioxidant defense mechanisms in Glycine max L.

“…The SOD activity was determined spectrophotometrically as the ability to inhibit the photoreduction of nitroblue tetrazolium by 50% [1] . The specific activity of SOD was expressed as unit/mg protein.…”

“…Heavy metals are toxic even at low concentrations; also, they are not biodegradable, and have the tendency to accumulate in the living organisms [1] . In spite of this, the exposure to heavy metals continues and is increasing in some areas due to anthropogenic activities [2] .…”