Effect of pollution on the chemical content and secondary metabolites of Zygophyllum coccineum and Tamarix nilotica

Abstract

Objectives This study investigated the uptake and translocation pattern of trace metals from two medicinal plant species namely: Zygophyllum coccineum and Tamarix nilotica from two contaminated sites and a noncontaminated (NC) site. The effects of heavy metals on the amino acids and secondary metabolites of the tested plant species were assessed. Materials and methods Medicinal plant samples and soil samples were collected from three different sites: two contaminated and one NC site. The concentration levels (mg/kg) of the selected trace metals (Al, B, Cr, Cu, Fe, Mn, Mo, Pb, V, and Zn) were estimated in the tested plant species and associated soil. Results Heavy metal contents in the investigated plant species reflected the metal concentration in the soil samples. The highest content of the determined heavy metals were detected in both tested plants from contaminated sites in comparison with those from the NC site. The concentrations of free amino acids in T. nilotica and Z. coccineum plants from the contaminated sites were higher compared with those in plants from the NC site. Moreover, the concentration of free amino acids in plants from the wastewater-contaminated sites was higher compared with that in plants from the Suez industrial emission site. The content of secondary metabolites (tannins, saponins, and alkaloids) was decreased in plants from polluted sites compared with those from the NC site. The concentration of tannins ranged from 0.07 to 0.33 g, saponins from 9.99 to 8.22%, and alkaloids from 7.95 to 1.00%. Moreover, the maximum tannins and alkaloid content was detected in Z. coccineum from the noncontaminated site. Conclusion The plants collected from the investigated sites pose a serious danger. However, a periodical assessment of plants used for traditional medicine should be encouraged as this will assist in ensuring their quality and safety in herbal use, especially for people living in urban areas where the level of pollution may be very high.