A natural approach to breast cancer treatment: investigation of chemical features of aerial parts of endemic Onosma sintenisii Hausskn. ex Bornm and its antioxidant properties, in vitro cytotoxic and apoptosis induction on MCF-7 cells.

Onosma sintenisii Hausskn. ex Bornm. (O. sintenisii) belongs to the Boraginaceae family and it is an endemic species from Irano-turanian phytogeographical region (central and eastern Anatolia) that distributes in steppe areas. This study aimed to investigate the chemical composition, antioxidant, in vitro cytotoxic and apoptosis induction of methanol extract of aerial parts of O. sintenisii. As a result of GC/MS analysis, 14 components were identified, and the major compounds of the extracts are retronecine (13.94%), α.-D-Glucopyranosiduronic acid (10.86%), melaniline (7.5%) and 1,2-Butanediol (4.02%), respectively. Antioxidant properties of O. sintenisii were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP) and superoxide radical scavenging activity methods. While the DPPH free radical scavenging activity results of O. sintenisii extract varied between 62.49% and 32.27%, reducing power activity and superoxide radical scavenging activity were found to be low. The result of the MTT assay revealed strong anticancer activity of O. sintenisii extract. The most significant cytotoxic effect was noted at a concentration of 1000 µg/mL after 48 hours. These findings together with flow cytometry analysis suggest that apoptosis can be the main mechanism underlying cell death after O. sintenisii extract treatment.