Antitumoral effect of Nitraria retusa bioactive compounds on two glioblastoma cell lines.

The objective of this research was to investigate the effects of proven antioxidant compounds identified in Nitraria retusa leaf extracts (Nr-extracts) on glioblastoma (GBM) cells. The antioxidant capacity was evaluated in nonenzymatic, enzymatic, and cellular systems. The antitumoral effect was demonstrated first by studying the inhibition of glioblastoma cell growth, then by examining the inhibition of cell adhesion to various purified extracellular matrix (ECM) proteins, and finally by assessing the ability of Nr-extracts to abolish the invasion of collagen gel by human glioblastoma cell spheroids. The methanolic extract (Nr-MeOH), through its isorhamnetin and carbohydrate derivatives, showed the highest antioxidant capacity. The cytotoxicity study of Nr-extracts, in the absence and presence of TEMODAL (TPZ), revealed that the chloroform extract (Nr-Chl), through its β-sitosterol and in combination with TEMODAL, exerted a more significant apoptotic effect on glioblastoma cells than TEMODAL alone. However, only the Nr-Chl and Nr-MeOH extracts inhibited the attachment of U87 cells to fibronectin, vitronectin, and collagen I. In addition, Nr-MeOH more significantly reduced U87 cell invasion compared with Nr-Chl extract. In conclusion, flavonols and sterols demonstrated strong antitumoral and free radical-scavenging activities, suggesting that a potentially synergistic therapeutic approach for glioma can be developed.