In vitro antioxidant and cytotoxic effects of three endemic plants from Turkey based on their phenolic profile

This study aimed to determine in vitro antioxidant and cytotoxic activities of acetone and water extracts obtained from Helicrysum noeanum, Onosma bozakmanii, and Sideritis amasiaca. We tested their total phenol and flavonoid content and analyzed their 14 phenolic compounds using HPLC method. Cinnamic acid, gallic acid, protocatechuic acid and quercetin were phenolics found in all extracts. Acetone extract of S. amasiaca was the experiment containing the most phenolic compounds by containing 11 of them. While the highest total phenol content belonged to water extract of S. amasiaca (189.37 mu g gallic acid equivalent/mg extract), water extract of O. bozakmanii had maximum total flavonoid rate (13.16 mu g quercetin equivalent/mg extract). Acetone and water extracts of S. amasiaca showed higher DPPH scavenging (IC50: 43.40 and 18.71 mg/L, respectively) and metal chelating (IC50: 62.26 and 61.32 mg/L, respectively) activities compared to other plants. When viability rates of human cervical cancer cells (HeLa) treated with the extracts were investigated, the experiment with the highest cytotoxic effect was acetone extract of S. amasiaca (IC50: 45.10 mg/L). Overall, our data showed that H. noeanum, O. bozakmanii and especially S. amasiaca are important natural antioxidant sources. They can be used in pharmacology thanks to their essential phytochemicals.