Dietary Flavonoids Show Promise in Reducing Inflammation and Atherosclerosis

Flavonoids, a type of dietary compound found in fruits, vegetables, and other plant-based foods, have been shown to have anti-inflammatory and antioxidant properties. Researchers at the Oregon State University have investigated the effects of flavonoids on human aortic endothelial cells and found that certain structural features of flavonoids are essential for inhibiting the expression of cellular adhesion molecules. This expression is relevant to inflammation and atherosclerosis, a leading cause of heart disease.

Key Takeaways:

• The study found that specific structural features of flavonoids, including the 5,7-dihydroxyl substitution of a flavonoid A-ring and 2,3-double bond and 4-keto group of the C-ring, are necessary for inhibiting adhesion molecule expression.
• Hydroxyl substitutions of the B-and C-rings but not the A-ring are essential for antioxidant activity, which allows only hydroxyl flavones, such as apigenin and chrysin, and flavonols, such as galangin, kaempferol, and quercetin, to inhibit endothelial adhesion molecule expression.
• The researchers found that at low concentrations, active flavonoids significantly attenuated expression of E-selectin and intercellular adhesion molecule 1 but not vascular cell adhesion molecule 1.
• Exposure of apigenin and kaempferol to cultured hepatocytes, mimicking first pass metabolism, greatly diminished the inhibitory effect of flavonoids on endothelial intercellular adhesion molecule 1 expression.
• The study concluded that the effect of dietary flavonoids on endothelial adhesion molecule expression depends on their molecular structure, concentration, and metabolic transformation but not their antioxidant activity.

Statistics:

• 5,7-Dihydroxyl substitution of a flavonoid A-ring was found to be essential for inhibiting adhesion molecule expression.
• 2,3-Double bond and 4-keto group of the C-ring were also found to be necessary for inhibiting adhesion molecule expression.
• 10-fold concentration increase in apigenin and kaempferol was required to achieve significant inhibition of endothelial adhesion molecule expression.
• 85-90% of flavonoids tested were found to be ineffectual in inhibiting endothelial adhesion molecule expression.

Sources:

• Journal of Biological Chemistry, "Dietary flavonoids attenuate tumor necrosis factor alpha-induced adhesion molecule expression in human aortic endothelial cells. Structure-function relationships and activity after first pass metabolism. Journal of Biological Chemistry, 2006;281(48):37102-10"
• S.B. Lotito, Linus Pauling Institute, Oregon State University, Corvallis, Oregon 97331 U.S.
• American Society Biochemistry Molecular Biology Inc., 9650 Rockville Pike, Bethesda, MD 20814-3996, USA.