ABSTRACT
Medicinal plants are well known for their therapeutic and beneficial properties and represent a considerable part of traditional medicines. Plant-based medicines which are being used worldwide are rich sources of potent and useful drug components. A wide range of secondary metabolites/bioactive compounds isolated from medicinal plants have been identified in folk medicines that can be used to treat various chronic as well as infectious diseases. In recent years, the demand for herbal medicines and use of medicinal plants in human health have been increased that acquire more attention to investigate heavy metals (HMs) or other types of contamination in medicinal plants. Therefore, it is essential to assure quality of plant-based medicines prior to their use for prevention of hazardous health risks. Medicinal plants on exposure of different HMs showed changes in synthesis and accumulation of secondary metabolites. It has been reported that higher levels of HMs can suppress or stimulate production of bioactive compounds in different medicinal plants. Contamination of HMs induces oxidative stress and thus affects the production of bioactive compounds/secondary metabolites in medicinal plants. Further in-depth research is needed to clarify the detailed mechanism by which HMs induce differential responses in medicinal plants.
