Elemental composition of medicinal plant drugs sold over-the-counter in Sao Paulo city, Brazil

Abstract

Medicinal plants have been used to treat diseases for thousands of years. In Brazil, the use of medicinal plants is very popular due to the assumption that herbs which are of natural origin are safe and without side effects and they are sold over-the-counter. Medicines derived from medicinal plants are, in general, cheaper than those from synthetic products and used for selfmedication. Consequently, it becomes important to ensure the quality of the plant material and detect presence of contaminants. Trace elements present in these plants can also constitute part of active constituents. In this study neutron activation analysis (NAA) was applied to evaluate the element composition of drugs from the plants (Ginseng, Ginkgo biloba, Centella asiatica, Mulberry and Aloe vera) from different origins. Samples bought in natural product drugstores and pharmacies in capsule or tablet forms were ground to a homogeneous powder. Aliquots of these samples were irradiated along with synthetic element standards in the IEA- R1 nuclear research reactor. Short and long irradiations were carried out for determination of As, Br, Ca, Co, Cr, Cs, Fe, K, Mn, Na, Rb, Sc, Se, Zn and lanthanides. The induced gamma activities were measured using an detector coupled to a gamma ray spectrometer and the element concentrations were calculated by the comparative method. Comparisons made between the results indicated difference in their element contents depending on the origin of the sample, as well as, the age of the leaves. Correlations between the effect of the medicinal plants and their element content were found for Ca, K and Zn. Toxic elements such as Hg, Cd, Cu, Sb were not detected. Arsenic was detected in some samples but at very low concentrations at the ng/g levels. Biological certified reference materials were also analyzed for quality control of the analytical results.