Lignan found in bark of some magnolia species.
Magnolol (MAG) — a bioactive biphenolic compound from Magnolia officinalis
derived from the bark (roots and branches) of Magnolia species such as M. officinalis, M. obovata, and M. grandiflora
The two main bioactive compounds isolated from these plants are MAG (5,5ʹ-diallyl-2,2ʹ-dihydroxybiphenyl) and Honokiol (3,5ʹ-diallyl-4,2ʹ-dihydroxybiphenyl) (Fig. 1) which are phenolic regioisomers.
In the bark extracts of Magnolia plants, the composition of MAG ranges from 1 to 10%, while Honokiol comprises 1 to 5%
major pathways and molecular targets involved in magnolol’s anticancer actions:
-Apoptosis: ↑ Bax, ↓ Bcl-2, ↑ cytochrome c, ↑ caspase-9, ↑ caspase-3
-Arrests cell cycle at G0/G1 or G2/M phase:↓ Cyclin D1, CDK4, CDK6, Cyclin B1, CDK1
-Inhibits NF-κB activation: ↓ IκBα, COX-2, TNF-α
-Inhibits PI3K, Akt, and mTOR phosphorylation
-Suppresses angiogenesis: ↓ Bcl-XL, Mcl-1, VEGF, cyclin D1
-Inhibits β-catenin nuclear translocation
-increase ROS production in tumor cells → triggers mitochondrial apoptosis
-Magnolol activates Nrf2 in normal cells → upregulates HO-1, NQO1: Protects normal tissue from oxidative stress during chemotherapy or inflammation.