Citrus Fruits May Prevent Skin Cancer

SEOUL, Korea— Tangeretin, a polymethoxylated flavonone present in citrus fruits, may have a potent chemopreventive effect in skin cancer, according to new research out of KonKuk University (J Agric Food Chem. 2011 Jan 12;59(1):222-8). Researchers examined the effects of tangeretin on UVB-induced cyclooxygenase-2 (COX-2) expression in JB6 P+ mouse skin epidermal cells. Tangeretin suppressed UVB-induced COX-2 expression and transactivation of nuclear factor-κB and activator protein-1 in JB6 P+ cells. Moreover, tangeretin blocked UVB-induced phosphorylation of Akt and mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated protein kinase, c-Jun N-terminal kinase, and p38, and attenuated the phosphorylation of MAPK kinases 1/2, 3/6 and 4. Tangeretin also limited the endogenous generation of reactive oxygen species (ROS), thereby protecting the cells against oxidative stress. However, tangeretin did not scavenge the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and influence the nicotinamide adenine dinucleotide phosphate oxidase activity. Researchers said these results suggest the anti-inflammatory effects of tangeretin stem from its modulation of cell signaling and suppression of intracellular ROS generation.