Dracocephalum palmatum Stephan extract induces apoptosis in human prostate cancer cells via the caspase-8-mediated extrinsic pathway

Dracocephalum palmatum Stephan is a medicinal plant traditionally used by nomadic people in Eastern Russia; however, research on this plant is currently limited. Recently, although studies have been conducted on the constituents of this plant and their antioxidant effects, data on its various pharmacological activities are still lacking. Thus, this study examined the anticancer potential of the dried leaves of D. palmatum S. (DpL) using human prostate cancer PC-3 cells. The antioxidant potential of DpL was evaluated by estimating the total flavonoid and total phenolic content (TFC and TPC, respectively). Additionally, we investigated the effects of the DpL ethyl acetate fraction (DpLE) on cell proliferation, intracellular reactive oxygen species (ROS) generation, apoptosis, and cell cycle arrest in this cell line. The expression levels of superoxide dismutase (SOD)-1, SOD-2, B-cell lymphoma 2 (Bcl-2) and Bcl-2 associated X (Bax) ratio, phospho-protein kinase B (p-AKT), cleaved caspase-8, poly adenosine diphosphate (ADP) ribose polymerase (PARP), and cleaved-PARP were evaluated by western blotting. The results indicated that DpLE causes apoptosis and exerts intracellular ROS-independent anticancer effects on prostate cancer cells, associated with increased SOD-2, cleaved caspase-8, and cleaved-PARP expression and inhibited p-AKT signaling. Thus, DpLE may be a potential resource for the development of promising chemotherapeutic agents for prostate cancer.

Keywords: Apoptosis; Caspase-8; Dracocephalum palmatum Stephan; Prostate cancer.