Determination of antioxidant capacity and cytotoxic effects of astragalus davisii (Erek geveni) and astragalus gymnalopecias (Müküs geveni) plant extracts on cancer cell lines

Astragalus is one of the largest genera of flowering plants in the Fabaceae (Legume) family, with medicinal effects and usage dating back more than 2000 years. In the literature, antioxidant, anticancer, antidiabetic, antiviral, immunomodulatory, cardioprotective, hepatoprotective properties of various species of the Astragalus genus have been reported. Astragalus davisii (Erek geveni) and Astragalus gymnalopecias (Müküs geveni) are endemic species distributed in Van Province, and no study investigating the potential therapeutic effects of these species has been found in Van Province. In this study, it was aimed to determine the antioxidant potentials of hydromethanolic extracts obtained from various organs (root, leaf, flower) of A. davisii and A. gymnalopecias species and to elucidate the cytotoxic effects of these extracts on cancer cell lines. To determine the antioxidant activities of A. davisii and A. gymnalopecias plant extracts, two radical scavenging assays (DPPH and ABTS), determination of total phenolic and total flavonoid contents and metal chelating activity assays were applied. In addition, the potential cytotoxic effects of the extracts were evaluated on MCF-7 (breast cancer cell) and HT-29 (colon cancer cell) cells and for this purpose XTT experiments were performed. When the DPPH and ABTS+ radical scavenging activities of the extracts were considered, a concentration-dependent increase was observed. In addition, the lowest IC50 value was found in A. gymnalopecias leaf (5.58±0.22) for DPPH and in A. davisii leaf (5.54±1.06 mg/ml) for ABTS+. The highest total phenolic content was observed in A. davisii flower extract (217.97±2.82 μg gallic acid equivalent/mg extract). The highest total flavonoid content was found in the flower extract of A. davisii (1303.47±20.13 μg quercetin equivalent/mg extract). Considering the metal chelating activity, the lowest IC50 value was determined in the flower of A. gymnalopaecias (2.80±1.39 mg/ml). In the investigation of cytotoxic activities on MCF-7 and HT-29, hydromethanol flower extracts of A. davisii and A. gymnalopecias were used. It was found that the cytotoxic effect of the plant extracts on MCF-7 cells increased depending on the applied dose and incubation time and reduced the viability of cancer cells. The lowest IC50 value was seen in A. davisii (6.49 ± 0.53 mg/ml) with 72 h incubation time and maximum concentration (12.5 mg/ml) and A. davisii was found to have the highest cytotoxic effect. The cytotoxic effect of the extracts on HT-29 cells was found to be highest at 24 h application time and in A. davisii (IC50, 3.93±0.51 mg/ml). According to the data obtained in this study, it was concluded that A. davisii and A. gymnalopecias extracts at the studied concentrations showed high antioxidant and cytotoxic activity and have the potential to contribute to complementary therapy. iv Keywords: Antioxidant, Astragalus davisii, Astragalus gymnalopecias, Cytotoxicity, Total flavone, Total phenol.