Evaluation of Phytochemical Constituents, Antioxidant Potential, and Toxicological Profile of Selected Medicinal Plants from Romania’s Spontaneous Flora

The aim of this study was to analyze the composition and dual beneficial and toxic effects of Achillea millefolium L., Mentha longifolia L., and Thymus serpyllum L. extracts. The phenolic profile, total phenolic content (TPC), antioxidant activity, and drosopterin eye content (DEC) were determined by modern methods. The viability and developmental time of D. melanogaster were assessed by a diet-dependent viability test. The results show that the phenolic profile varied depending on the extract type and plant species. The TPC ranged between 5.32 and 29.32 mg GAE/g dry weight. All the plant extracts exert antioxidant effect in the applied in vitro tests. In the case of D. melanogaster fed with a normal diet supplement with different concentrations of the plant A. millefolium L. extract, a biphasic effect was observed. A more complex effect was recorded for the M. longifolia L. and T. serpyllum L. extracts. On a high-sugar diet, all the extracts were toxic. All the plant extracts in tested concentrations influenced the DEC, suggesting an impact on gene expression. This study contributes to the expanding knowledge about the beneficial and toxic effects of local medicinal plants, suggesting the need for future studies to elucidate the appropriate use of natural products in therapy.