Bhavnani BR, et al. - In an effort to further understand the role of oxidized low-density lipoprotein (LDL) in the etiology of atherosclerosis, researchers investigated the ability of 10 estrogen components of the drug, conjugated equine estrogen (CEE), trans-resveratrol (t-resveratrol) and quercetin (red wine components), trolox (vitamin E analog), and probucol (a serum cholesterol-lowering drug) to delay or prevent the oxidation of plasma LDL isolated from untreated postmenopausal women. They also assessed the effect of long-term (> 1 year) estrogen replacement therapy and hormone replacement therapy on LDL oxidation by ex vivo methods. Various estrogens and other antioxidants differentially inhibited the oxidation of LDL isolated from postmenopausal women. The most potent was the unique ring B unsaturated estrogen components of CEE, and the least potent were t-resveratrol and the red wine component. Long-term CEE or CEE + medroxyprogesterone acetate administration protects the LDL against oxidation to the same extent in postmenopausal women. Data thereby supported that some of the cardioprotective benefits offered by CEE therapy and perhaps red wine may be due to LDL protection against oxidative modifications conferred by their components.