Comparative analysis of polar and non-polar extracts of Turkish sea buckthorn fruits and their cytotoxic effects on cancer cell lines

Hippophae rhamnoides L., commonly known as sea buckthorn, is a deciduous shrub of the Elaeagnaceae family widely distributed in Europe and Asia. It has gained increasing attention recently due to its nutritional properties and health benefits as food. Berries are a rich source of biologically active constituents, including flavonoids, phenolic acids, carotenoids, tocopherols, phytosterols, vitamins, and unsaturated fatty acids. These compounds have demonstrated a wide range of pharmacological effects. This study evaluated the effects of Turkish sea buckthorn fruit extracts of different polarities on breast (MCF-7) and colorectal (HT-29) cancer cells compared with non-tumorigenic MCF-10 A and FHC cells. According to our results, the ethanolic extract showed stronger cytotoxicity toward cancer cells, with IC50 values of 0.13 and 0.10 µg/mL in MCF-7 cells and 0.18 and 0.076 µg/mL in HT-29 cells after 24 and 72 h, respectively, while showing higher IC50 values in non-tumorigenic counterparts. The highest selectivity index was observed for the ethanolic extract in breast cells after 24 h (SI = 11.35). In addition, the extracts increased ROS production up to approximately 2-fold in cancer cells and induced apoptotic cell death, with marked increases in early and late apoptotic populations, particularly in MCF-7 and HT-29 cells. HPLC analysis was conducted to identify phytochemical constituents potentially associated with anticancer activity, because the polar extracts show enhanced selectivity. Considering the results, among the identified phenolic acids and flavonoid compounds, rutin was detected as the predominant constituent (3.3517 ± 0.0317 mg/g), while quercetin, protocatechuic acid, and quercetin-3-O-glucoside were also identified in the polar extract.