Natural Bioactive Compounds: Alternative Approach to the Treatment of Glioblastoma Multiforme

Table 1

Natural compounds and their mechanism of action in GBM and other cancer cells.

Natural compounds	Target mechanisms
Isoflavones; (biochanin A, genistein, etc.)	Inhibits MMPs and thus invasion & metastasis.; Inhibits tyrosine kinase mediated downstream signaling.
Resveratrol	Induces apoptosis by activating caspase-3.; Modulates cell cycle at specific points.
Epigallocatechin A (EGCG)	Binds to GRP78 (prosurvival component of ER stress response system) and inactivates its antiapoptotic function. Inhibits P-gp expression thus reversing drug resistance in cancer cells.
Retinoids	Reduces levels of inflammatory factors making cancer cells sensitive to radiotherapy. Increases sensitivity to specific therapies such as interferon- therapy by inhibiting telomerase activity.
Cannabis	Induces apoptosis by sustained accumulation of ceramide that also upregulates the ERK activity.; Causes ER stress and inhibition of pAkt/mTOR leading to autophagy-mediated cell death.
Neurostatin	Inhibits cell cycle progression (suppresses cyclins and CDKs and promotes inhibitors such as p21 & p27).; Impairs promitogenic pathways of MAPK and PI3K by blocking EGFR signaling.
Bipolaris setariae fungi	Disrupts the potassium ion homeostasis causing mitochondrial dysfunction and ER stress. Impairs cell cycle progression.