Margaret A Maher

Antioxidant effects of phyto-and synthetic-estrogens on cupric ion-induced oxidation of human low-density lipoproteins in vitro

Oxidation of low-density lipoproteins (LDL) promotes the formation of atherosclerotic plaques. Estrogenic compounds (EC) from foods and other natural products, and synthetic estrogenic compounds (SECs) may prevent heart disease by inhibiting LDL oxidation. In the present study, we tested the antioxidant capacities of two phytoestrogens, daidzein (DAI) and genistein (GEN), and four SECs, (+)- and (-)-Z-bisdehydrodoisynolic acid (ZBDDA), and (+)- and (-)-hydroxy-allenoic acid (HAA), on isolated human LDL subjected to oxidation by cupric sulfate. The effects of these estrogenic compounds on the kinetics of conjugated diene formation in LDL undergoing oxidation were evaluated with a lag-time assay with continuous monitoring of absorbance at 234 nm. Lag-time data revealed that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA had similarly stronger antioxidant activities than either GEN or DAI. We also found that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA strongly inhibited the formation of Cu+-induced thiobarbituric acid reactive substances (TBARS) in LDL, and that GEN and DAI were less effective for inhibiting LDL lipid peroxidation. Finally, electrophoretic evaluation suggested that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA protected the apolipoprotein B-100 of LDL against oxidation better than did GEN or DAI. In summary, the four SECs, (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA, were more potent antioxidants than the phytoestrogens, DAI and GEN.

Cardiovascular Effects of Consumption of Black Versus English Walnuts

English walnuts have been shown to decrease cardiovascular disease risk; however, black walnuts do not appear to have not been studied for their cardioprotective effects. The purpose of this study was to determine the effects of English versus black walnut consumption on blood lipids, body weight, fatty-acid composition of red blood cell (RBC) membranes, and endothelial function. Consumption of 30 g of English walnuts per day for 30 days, by 36 human participants, improved blood lipids; the effects of black walnuts were dependent on the participants sex. Addition of either nut to the diet did not result in weight gain. The fatty-acid composition of RBC membranes was favorably affected by walnut consumption. RBC polyunsaturated fatty acids increased after consumption of either type of nut; however, eicosapentaenoic acid increased significantly more after English walnut consumption. Endothelial function of 6 unmedicated humans with hypercholesterolemia was maintained after consumption of English walnuts with a meal high in high saturated fats; however, consumption of black walnuts with the same meal did not maintain endothelial function. Overall, these results support the recommendation that consumption of 1 oz of English walnuts per day may decrease cardiovascular risk, but more research on black walnut consumption is necessary before an appropriate recommendation can be made.