Evaluation of cytotoxic and antioxidant potential of Dittrichia viscosa (L.) Greuter used in traditional medicine

Abstract Ethnopharmacological relevance Dittrichia viscosa (L.) Greuter (“Sari ot, Yapiskan andiz otu” in Turkish) is a medicinal plant that has been traditionally used in the Mediterranean area. This plant is used by the local population for the treatment of cancer. Investigation of their biological activities is therefore very important to be supported by scientific basis for traditional use. Aims of the study In this study, it is aimed to assess the phytochemical composition, in vitro antioxidant, cytotoxic, and antiproliferative activities of the aqueous and ethanolic extracts obtained from the aerial parts (stems, leaves, flowers) of D. viscosa, collected from two sites in Turkey (Istanbul and Marmaris) against breast and prostate tumor cell lines. Materials and methods Validated methods were used to evaluate the in vitro antioxidant capacity (DPPH, ABTS, CUPRAC), cytotoxicity (Cell Viability Assay), antiproliferative (Apoptosis assay), and phytochemical compositions. The nepetin (N), 3-O-methylquercetin (Q), and hispidulin (H) in the extracts of D. viscosa were quantified by HPLC and LC-HRMS. Furthermore, in order to control the standards of benefiting from the plant in a healthy way, the contents of some heavy metals were also assessed by ICP-OES in the plant and soil samples as well as the species soil's physical and chemical characteristics. Results We have found that heavy metal accumulation in the soil does not exceed the allowable limit value except for the nickel. The results showed that ethanol extraction is an efficient strategy to get NQH molecules with a higher content compared with other extraction techniques. However, using the same extraction method revealed that the amount of NQH molecules in the samples of two different regions were variable. The results suggested that all extracts had a high amount of total phenolic content (12.354–22.184μg GAE/mg) and total flavonoid content (4.442-17.263μg QE/g). In the antioxidant assay according to the DPPH method, the aqueous ethanol extracts (IC50; 21.00 μg/mL) showed stronger antioxidant activity than BHT. A significant reduction in cell viability was particularly observed in MDA-MB-231 cells, which were sensitive to ethanolic extracts in Istanbul (12-22%) and in Marmaris (14-15%), while PC3 cell lines were also more sensitive to extracts of the aqueous in Istanbul (16%) and the decoction in Marmaris (12%) after 72 h. Especially, it was observed that Marmaris and Istanbul samples induced the toxicity against PC3 cells. Conclusion The study supports the medicinal use of D. viscosa as a potential anti-cancer against breast and prostate cancer cells in vitro and underlines the immense therapeutic potential of the plant.