RESUMO
In order to know if the heavy metals stress condition is boon or bane for the plants growth, Lavandula dentata species was planted in pots under different levels of heavy metals stress condition and the phytochemical composition, cytotoxicity, antioxidant and antimicrobial responses of their leaf ethanolic extracts toward this stress condition were investigated compared to the control samples. Our findings showed significant differences in heavy metals bioaccumulation, photosynthetic pigments and total phenolic/flavonoids contents among L. dentata leafs ethanolic extracts, grown under different levels of heavy metals stress condition. The L. dentata leafs extracts, grown under Zn and Cu stress condition, showed the highest antioxidant and antimicrobial activities than those grown under Cd and Pb stress condition. Comparatively, the L. dentata leafs extracts, grown under Zn stress condition, showed higher antioxidant activity, and those, grown under Cu stress condition, showed higher antimicrobial activity. The highest cytotoxicity was showed by L. dentata leaf extracts, grown under Cd and Pb stress condition, which lead to conclude that these extracts could be served as a novel scaffold in search for new drugs against cancer. In conclusion, the highlighted variability reflects the high impact of heavy metals stress condition on phytochemical composition and consequently on the biological activities of medicinal plants. Such impact led to conclude that we should select medicinal plants extracts to be investigated carefully depending on this stress condition, in order to isolate the bioactive components or to have the best quality of extracts in terms of biological activities.
