Hibiscus Flower and Olive Leaf Extracts Activate Apoptosis in SH-SY5Y Cells

Compounds of natural origin may constitute an interesting tool for the treatment of neuroblastoma, the most prevalent extracranial solid tumor in children. PRES is a commercially available food supplement, composed of a 13:2 (w/w) extracts mix of Olea europaea L. leaves (OE) and Hibiscus sabdariffa L. flowers (HS). Its potential towards neuroblastoma is still unexplored and was thus investigated in human neuroblastoma SH-SY5Y cells. PRES decreased the viability of cells in a concentration-dependent fashion (24 h IC50 247.2 +/- 31.8 mu g/mL). Cytotoxicity was accompanied by an increase in early and late apoptotic cells (AV-PI assay) and sub G0/G1 cells (cell cycle analysis), ROS formation, reduction in mitochondrial membrane potential, and caspases activities. The ROS scavenger N-acetyl-L-cysteine reverted the cytotoxic effects of PRES, suggesting a key role played by ROS in PRES-mediated SH-SY5Y cell death. Finally, the effects of OE and HS extracts were singularly tested and compared to those of the corresponding mixture. OE- or HS-mediated cytotoxicity was always significantly lower than that caused by PRES, suggesting a synergic effect. In conclusion, the present findings highlight the potential of PRES for the treatment of neuroblastoma and offers the basis for a further characterization of the mechanisms underlying its effects.

Automated summary

Natural compound PRES, composed of extracts from Olea europaea L. leaves and Hibiscus sabdariffa L. flowers, showed potential in decreasing viability of neuroblastoma cells through ROS-mediated apoptosis. The mixture exhibited a synergistic effect compared to individual extracts of Olea europaea L. leaves and Hibiscus sabdariffa L. flowers.