Effects of plant-derived polyphenols on TNF-alpha and nitric oxide production induced by advanced glycation endproducts.
Advanced glycation endproducts (AGEs) accumulate on protein deposits including the beta-amyloid plaques in Alzheimer's disease. AGEs interact with the "receptor for advanced glycation endproducts", and transmit their signals using intracellular reactive oxygen species as second messengers. Ultimately, AGEs induce the expression of a variety of pro-inflammatory markers including the tumor necrosis factor (TNF-alpha) and inducible nitric oxide (NO) synthase. Antioxidants that act intracellularly, including polyphenols, have been shown to scavenge these "signaling" reactive oxygen species, and thus perform in an anti-inflammatory capacity. This study tested the pure compounds apigenin and diosmetin as well as extracts from silymarin, uva ursi (bearberry) and green olive leaf for their ability to attenuate AGE-induced NO and TNF-alpha production. All five tested samples inhibited BSA-AGE-induced NO production in a dose-dependent manner. Apigenin and diosmetin were most potent, and exhibited EC(50) values approximately 10 microM. In contrast, TNF-alpha expression was only reduced by apigenin, diosmetin and silymarin; not by the bearberry and green olive leaf extracts. In addition, the silymarin and bearberry extracts caused significant cell death at concentrations >or=10 microg/mL and >or=50 microg/mL, respectively. In conclusion, we suggest that plant-derived polyphenols might offer therapeutic opportunities to delay the progression of AGE-mediated and receptor for advanced glycation endproducts-mediated neuro-inflammatory diseases including Alzheimer's disease.
Chandler
Dave
D
Western Australian Biomedical Research Institute, Curtin University of Technology, Perth, Australia.
Woldu
Ameha
A
Rahmadi
Anton
A
Shanmugam
Kirubakaran
K
Steiner
Nicole
N
Wright
Elise
E
Benavente-García
Obdulio
O
Schulz
Oliver
O
Castillo
Julián
J
Münch
Gerald
G
D000544:Alzheimer Disease / Q000517:prevention & control; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D047310:Apigenin / Q000494:pharmacology / Q000633:toxicity; D029792:Arctostaphylos / Q000737:chemistry; D002460:Cell Line; D003072:Cognition Disorders / Q000517:prevention & control; D005419:Flavonoids / Q000494:pharmacology* / Q000633:toxicity; D017127:Glycation End Products, Advanced / Q000378:metabolism / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D051379:Mice; D017628:Microglia / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D031658:Olea / Q000737:chemistry; D009994:Osmolar Concentration; D010636:Phenols / Q000494:pharmacology* / Q000633:toxicity; D010936:Plant Extracts / Q000494:pharmacology* / Q000633:toxicity; D018515:Plant Leaves / Q000737:chemistry; D059808:Polyphenols; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D012838:Silymarin / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D000975:Antioxidants; D005419:Flavonoids; D017127:Glycation End Products, Advanced; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D012838:Silymarin; D014409:Tumor Necrosis Factor-alpha; C081628:advanced glycation end products-bovine serum albumin; D012710:Serum Albumin, Bovine; D009569:Nitric Oxide; D047310:Apigenin; C039602:diosmetin