Investigation on chemical composition and bioactivity potential of endemic centaurea goeksunense aytaç & H. Duman.

The genus Centaurea L. (Asteraceae) is represented by 158 species in the flora of Turkey, 94 of which are endemic. Centaurea species are used traditionally as appetiser, emmenegog, wound healing etc. Phytochemical investigations on Centaurea species are generally revealed of isolation of sesquiterpene lactones, flavonoids and lignan glucosides. In this study, hexane, chloroform, methanol and buthanol extracts, prepared from overground parts of South Anatolian endemic Centaurea goeksunense Aytaç & H. Duman and chemical compounds were determined by chromatographic methodes such as HPLC (high pressure liquid chromatography) and TLC (thin layer chromatography). In addition, antimicrobial, cytotoxic, antioxidant and antiinflammatory activities of extracts were investigated with different assays. As a result; luteoline (flavone) from chloroform, methanol and buthanol extracts; chlorogenic acid (phenolic acid) from methanol extract and apigenin (flavone) and β-sitosterol 3-O-D-glucoside (phytosterol glucoside) from buthanol extract were obtained. The most effective cytotoxic activity was determined against PC-3 (prostate cancer) cells by MTT assay. Hexane and chloroform extracts were showed highest cytotoxicity on PC-3 cells with IC50 values of 7,052 and 8,861 µg/ml, respectively. Methanol extract did not exhibited any cytotoxic effect on tested cell lines. In the study, maximum tested dose was preferred as 50 µg/ml. The results were evaluated with regard to potential pharmaceutical uses. To determine antioxidant activities of extracts, their total phenolic and flavonoid components, DCFH and OH.- radical scavenging activities and total antioxidant capacities were detected. The highest total phenolic compunds were established in methanol, chloroform and hexane extracts, respectively. The highest flavonoid compounds were detected in chloroform, hexane, methanol extracts, respectively. In all concentrations, methanol extract showed highest radical scavenging capacity due to the OH.- radical scavenging activity assay. As to DCFH assay, chloroform, methanol and hexane extracts, respectively had radical scavenging activity (IC50:1,434; 1,242 ve 5,97 µg/ml, respectively). In all concentrations, methanol extract had the highest antioxidant capacity, then chloroform and hexane extracts in TEAC assay. Most effective doses of all extracts were 1 mg/ml. Antiinflammatory activities were examined by iNOS and NF-ƘB inhibition assays. Altough there is no cytotoxic effect on cell lines (IC50:>50 µg/ml), significant iNOS activitiy inhibition of hexane extract were determined (IC50:4.886 µg/ml). iNOS inhibition IC50 of chloroform extract was 11,33 µg/ml. On the HeLa cell line, has stable NF-kB gene reporter system, hexane extract was the highest activity on NF-ƘB inhibition, then chloroform extract. Moreover all extracts were studied for antimicrobial activities and any of the extracts showed no activity. This is the first study on chemical compounds and biological activities of C. goeksunense Aytaç & H. Duman.