Elemental Analysis of Five Medicinal Plants Species Growing in North Ossetia Using Neutron Activation Analysis

Abstract

One important category of traditional remedies is medicinal plants, which are widely consumed by the population and often subjected to contamination. For the first time, the elemental composition of five wild medicinal plants traditionally consumed in the Republic North Ossetia—brook-mint (Mentha longifolia), oregano (Origanum vulgare), St. John’s wort (Hypеricum perforаtum), thyme (Thymus daghestanicus), and fireweed (Chamaenerion angustifolium)—and corresponding soil samples was determined. This investigation aimed to assess the degree of toxic element accumulation in plants and the possible toxic effect of the analyzed plants on human health. The analysis encompassed the quantification of 36 major and minor elements in soil samples, alongside the detection of 23 elements in plant samples using instrumental neutron activation analysis. According to contamination and enrichment factors, which were calculated in order to assess the level of soil pollution, elements such as As, Sb, Zn, and U in soil may originate from both geogenic and anthropogenic sources. In all plant samples, the most abundant major elements were K and Ca and their content ranged from 9870 to 49,500 mg·kg−1 and 5400 to 20,000 mg·kg−1, respectively, while among the microelements, Fe (54–2080 mg·kg−1) and Mn (27.8–190 mg·kg−1) can be highlighted as the most abundant. The transfer factor was calculated to estimate metal uptake from soil in plants. The highest values of the transfer factor were obtained for Mo, K, Ca, and Zn. The daily intake of metals and the health risk index were calculated to assess the safety of the collected plants. The health risk index was below the threshold for all plants suggesting a probable non-carcinogenic effect. Principal component analysis and linear discriminant analysis were used as classification techniques. The principal component analysis allowed us to define the main groups of elements and associate them with their sources of origin, while discriminant analysis enabled us to discriminate plant samples by species.